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Transmission Ratios 

GM Transmission Ratios 
Borg-Warner T-5 (GM Applications) 2.95 1.94 1.34 1.00 0.63
Borg-Warner T-5 (GM Close Ratio) 2.75 1.94 1.34 1.00 0.74
Borg-Warner T-10 2nd Design 2.64 1.61 1.23 1.00 n/a
Borg-Warner T-10 2nd Design 2.88 1.74 1.33 1.00 n/a
Borg-Warner T-10 2nd Design 3.44 2.28 1.46 1.00 n/a
GM Muncie (M-21, M-22) 2.20 1.64 1.28 1.00 n/a
GM Muncie (M-20) 2.52 1.88 1.46 1.00 n/a
GM Powerglide 1.76 1.00 n/a n/a n/a
GM Turbo Hydra-Matic 350 2.52 1.52 1.00 n/a n/a
GM Turbo Hydra-Matic 400 2.48 1.48 1.00 n/a n/a
GM Turbo Hydra-Matic 200-R4 2.74 1.57 1.00 0.67 n/a
GM Turbo Hydra-Matic 700-R4 3.06 1.62 1.00 0.70 n/a

Final Drive ratios
Using the 200
1st -> 10.22
2nd -> 5.85
3rd -> 3.73
4th -> 2.49
Using the 700
1st -> 11.41
2nd -> 6.82
3rd -> 3.73
4th -> 2.68
Using the 350
1st -> 8.61
2nd -> 5.19
3rd -> 3.42
Using the 400
1st -> 8.48
2nd -> 5.06
3rd -> 3.42

Final drive ratios for TH200R4 and TH700-4R with 3.73:1 gearing.
Final drive ratios for TH350 and TH400 with 3.42:1 gearing.

TH200R4 rebuild info

These are modifications that I do to the TH200R4 when I Rebuild them. As I have stated before, I am NOT Art Carr or Mike Kurtz or Level 10 or ?.. Just a hobbyist who likes to do things himself whenever possible. Some people may disagree, some may not, but it is what has worked for me(so far). Some modifications are for VERY hard shifts and are not necessary for a mild rebuild(items are noted). Any other things that I have missed or people do different, I would like to know. I’m always open for new ways, idea’s and methods. One thing I must mention is that you need a shop manual and/or someone who is VERY familiar with these transmissions. For example, there are a lot of torrington bearings that MUST be installed a certain way (some not the way you would think the are to be installed) and clearances that MUST be set correctly or it will break (trust me I know...).

Disassembly. Pretty straightforward for disassembly. One thing to note is the input drum teeth to direct clutch drum notches. Mark both drums as to their mating for reassembly (can be seen after dropping the pan). Remove everything from bottom of trans (filter, valvebody, wiring/TCC solenoid,governor/cover,1-2 accumulator housing/backing plate, separator plate, 3-4 accumulator and check balls). Remove front pump bolts. Although there is a special puller for removing the pump, I use a brass drift/hammer(lightly) on the exposed portion of the rear pump body. Same with removing the center support(exposed outer area of the support). For the low/reverse clutch housing, I use a piece of #6 solid copper wire bent in a "L" shape inserted between the output shaft and the housing. Turn wire to get it under the housing and pull it out(kinda crude but works for me....). As you disassemble the main drive pieces, assemble them back together(I use the converter, on the floor, hub up ,install pump and the rest of the main drive in the order that it came out of the case). Clean/inspect everything thoroughly one section at a time. Carb cleaner works great for removing all the clutch dust in the drums/housings and valves. Average about 6 large cans. Foamy Brite works good on the case/valvebody for removing grime and clutch dust(although if possible take the case to a machine shop and have it hot-tanked. Assemble with new clutches/bearings(if needed) and re-assemble outside case.

Inspection -Most of the problem spots are: 4th clutch is usually burned or hot spots on the steels/backing plate. Direct clutch and Forward clutch have same problem. Pump converter bushing worn/galled. Rear pump body grooved from pump rotor(requires replacement of pump assembly) Stator support splines chewed up/worn. Broken 1-2 accumulator spring. Sometimes 2nd gear band burned/pitted(from broken 1-2 accumulator spring).
Rebuild kits/Shift kits This section I am biased on what to use. I use Art Carr’s Super rebuild kit and Mike Kurtz/Art Carr shift kits. Although some people like the B&M shift kit, I personally don’t like using the spacers for the accumulators. I would rather use a stiffer spring, but all three work well. Some of the modifications are from a Trans-go kit(front pump seal drain hole) but I have never installed one of these kits. A friend gave me the instructions from this kit and this is the only modification I use from them.

Re-assembly -Start with the front pump modifications. Once finished, you can install the pump upside-down in the case and torque the bolts for the two pump halves. This will line the pump halves up(and will eliminate the requirement for a special tool). Front pump -A few modifications in this area. First drill the front seal area drain hole(angled passage viewed from the front of the pump with the seal removed)to a ¼". Drill the intersecting passage and mating passage in rear pump half to 5/16". This will help front seal drainback to the pan and will keep from blowing the front seal out. Re-assemble pump slide and pressure relief with stock springs. If on a budget re-use stock 7 vane pump(here comes the flaming responses...) although I use 10 vane pumps. They are not too expensive(around 55.00. I get them from a transmission warehouse). Main item here is the pump vane rings. Stock ones are cast and if the haven’t failed consider yourself fortunate. Install hardened steel pump vane rings. Remove stock stator support from rear pump body and install new hardened spline stator support. Replace existing pressure regulator valve/spring in rear pump body with new design valve/spring. I use Art Carr’s valve although Mike Kutrz’s is the same.

Transmission Case- (not necessary for mild rebuild) The objective of most shift kits is to limit the travel of the accumulators either by stiffer springs or spacers(plus a few valvebody mods and pump operating pressures). In my personal cars, I eliminate the accumulators completely so that all the oil is directed to the clutches. Tap the passage that feeds the 3-4 accumulator with ¼-20 tap. Install a ¼-20x1/2" allen screw with red loctite in the passage to block it off. Perform the same modification to the 1-2 accumulator housing. The only accumulator left in the oil circuits is the 3rd accumulator which is needed to "push off" the 2nd gear band. Trans-go kit installs a .030" washer under the 3rd accumulator spring, but I have found no difference with or without it... I also change (if it’s not a Grand National trans) the servo cover, servo piston and 3rd accumulator to a Grand National servo setup. The piston is larger than other pistons and allows for more fluid area to apply the band for 2nd.(haven’t done one in a Monte Carlo yet. It may have the large cover/piston/accumulator already). All the other transmissions did not have these pieces. I also step up one size in the servo apply pin. These pins are identified by the number of rings on the pin tip that fits in the band. Trans-go kit installs a washer between the 3rd accumulator and the apply pin. I would rather use the next size apply pin. Be warned though, I have burned up the 2nd gear band because there was not enough clearance between the band and the direct drum. It’s best to assemble the servo with the original apply pin. If the 1-2 shift is not "hard" enough for your taste, then you can change the pin in the car(although a cat converter makes it fun.....)
Valve Body -Install the springs supplied with the shift kit your using. Most shim/change the line bias valve spring so that it stays closed from exhaust. Some kits change the Throttle valve spring to a stiffer spring. Some kits remove the throttle valve modulator downshift spring. Some kits change the 2-3 valve shift spring. What-ever kit you use, install what the require. The separator plate mods are usually the same. Most drill the "RND4D3" orifice, 2nd oil feed(next to 1-2 shift valve check ball) and "RND4" orifice to 1/8" (shown in the factory or ASTG manual).  Mike Kurtz also drills the 3rd clutch(direct) orifice and the throttle valve orifice to 1/8" also(which is what I use). Which ever kit you use, go with their instructions.
Main drive/assembly in case -Now for the fun part. Although the special "J" tools make it easier, this method has worked for me. After new rear bushing/seals are installed, it’s time to install the main drive assembly. I use a new driveshaft yoke installed in the rear of the transmission. Install the rear output shaft into the case and into the yoke. Set the depth of the yoke in the rear of the trans so that the rear internal gear(on the output shaft)teeth are centered with the parking pawl. Tie off the yoke ends with a piece of bailing wire to the outside of the trans to secure it in place(I know...crude method but it works for me...) This will hold the output shaft/rear internal gear in the correct place for re-assembly of the lo/reverse clutch, rear carrier, clutch housing, input drum, front carrier, front internal gear and rear selective thrust washer and snap ring.

Lo/reverse clutch- Original setup uses 6 clutches and 7 steels with 1 wave plate. New setup uses same amount. I install a new wave plate from GM (see part number listing). Also install a copper thrust washer on the back of the input drum(original is plastic except for GN’s).Also if not already provided, install new roller thrust bearing in rear carrier roller clutch(see parts listing). Some rear carriers have a plastic thrust washer instead of a bearing- Get a bearing if you can- more durable. Assemble main drive to snap ring on output shaft. Remove yoke setup once snap ring is installed and check rear unit endplay. Set up dial indicator(I use an old brake drum and set the tail shaft in the center to allow the output shaft to hang freely) with clamp and set to "0". Pick up transmission and set down on output shaft. Read dial indicator(should be .004-.025". I try to set it at .006-.012"). If not within this clearance (usually is with original washer) then rear selective washer must be changed to bring clearance within tolerance.

Forward clutch- This clutch is not too much of a problem spot although the housing/splined shaft is in higher horsepower applications. I have broken the shaft right out of the housing and broken the splines off the end of the shaft. When this happens you have NOTHING(forward or reverse). Last year I was talking to Mike Kurtz at the GS nationals. He was TIG welding the splines to the shaft but still suffered failures. He was experimenting with heat treating the spline/shaft. I don’t know if he had success or not with it. For higher horsepower applications I install a new housing from GM and have not had a problem(so far....). Original setup uses 4 clutches, 3 steels, with 1 wave plate and 1 backing plate. New setup also uses same amount. I install a new backing plate from GM(backing plate is usually burned or hot spotted). See part number listing.

Direct clutch- This clutch is usually burned and is a problem spot. Original setup uses 6 clutches and 6 steels with 1 backing plate. New setup was 7 clutches (now has gone to 8) 7 steels (also gone to 8 using Art Carr’s super rebuild kit) and 1 backing plate. I install a new backing plate from GM(backing plate is usually burned or hot spotted). See part number listing. I also modify the retainer/spring assembly. Original retainer uses 16 springs for piston return. I remove 6 springs from the retainer so that the piston does not have to overcome so much spring pressure to apply. Setup retainer springs so that there are 3 springs (starting with the center of the three over the check ball in the piston) 2 removed, 2 installed, 1 removed, 3 installed 2 removed, 2 installed and 1 removed. I install a new backing plate from GM (backing plate is usually burned or hot spotted). See part number listing. Assemble forward clutch into direct clutch, lining teeth from input drum into direct clutch drum (indicator mark from disassembly). Install center support and bolt in place. Stand trans on end of output shaft. Install dial indicator on spline tip of forward clutch shaft and "0".

Check front unit endplay - by pulling up on forward clutch shaft and read dial indicator ( I use a small pair of vise grips on the spline end to pull it up. They don’t need to be SUPER tight (spline damage) just enough to pick it up) (BTW, I recommend that you wrap the shaft with something to save the splines but won't slip- Tom). Front unit endplay should be .022-.051" (I set at .026-.030"). If not within specifications, (this is the fun part...) you have to tear the main drive all the way down to the output shaft and change the front selective washer. Start with the original one and work from there. If you are a picky as I am you will do this 4-5 times to get the clearance you want (also helps to have all 15 front selective washers...).

Fourth clutch- This is also where Art Carr has improved over stock. Install new shorter piston(supplied in rebuild kit). Install spring retainer and snap ring(I use one large screwdriver to push the spring retainer down and work the snap ring in the snap ring groove working in a circle). Original setup uses 2 clutches and 3 steels with 1 backing plate. I install a new backing plate from GM (backing plate is usually burned or hot spotted). See part number listing.

Overrun clutch- Nothing special here. Original setup uses 2 clutches 2 steels 1 backing plate. New setup uses same amount. I install a new backing plate from GM (backing plate is usually burned or hot spotted). See part number listing. If a firmer torque converter clutch lock-up is desired, remove the check ball in the end of the input shaft. This allows the lock-up clutch to apply faster due to no restriction for exhaust of the oil (If you notice the check ball has a small hole the allows oil to pass by the check ball at a certain rate). Another warning, some converters have weak springs in the lock-up clutch and can break (although I have not had this problem, just passing it on...) from the fast apply of the clutch. Install pump without o-ring and gasket to check the overdrive unit endplay.(last one... finally....Are we having fun yet???). Stand up trans on end and set dial indicator to read tip of input shaft. Pull up (3 lbs of force...) till you "feel the snap ring on the end of the input shaft hit the bottom of the overrun carrier(I usually see about .024-.028") then "0 dial indicator. Pull up harder(20 Lbs...) and read clearance. Should be .004-.027" clearance(I set to .006-.012"). If not within specifications.. guess what...another selective washer to change. You have to tear down the maindrive all the way down to the rear output shaft...(Just kidding...).  Just pull the pump and change the overdrive washer on the back of the stator support. I use petrolatum jelly to retain the washer to the back of the stator support to bring clearance within specifications. This clearance is VERY important!!! If set too loose the overrun carrier will thrust back into the overdrive internal gear and hammer the thrust bearing until it fails (Trust will). Try the 3 lbs force/20 lbs force a couple of times till you get a feel for the snap ring hitting the overrun carrier and the overrun clearance. Bolt the front pump in with o-ring and gasket installed and new bolt washers and your done!!! (whew...) at least with the main drive....

Assemble valvebody and related parts(check balls installed per instructions (use petrolatum to hold in place), modified separator plate, accumulator housing, governor and cover, and wiring. Another trick is to JB weld the edges of the filter where the metal is crimped to the plastic. On hard acceleration, the oil goes to the back of the pan and the pump will suck air from the leaks at the front of the crimp on the filter. Also trash the little orange filter ring on the filter tube and use 2 o-rings. This offers a better seal around the filter tube to the pump inlet. That’s It... Hopefully the rebuild box will be empty except for a few Teflon accumulator rings. When you open the rebuild box and look at all those rubber parts/seals and think "What the hell am I doing?" It’s no too bad just TAKE YOUR TIME and READ the shop manual before and while your doing the rebuild. These transmissions are NOT for the novice!! If you have any questions or something is not clear you can E-mail me at

Tools Required- Press, Dial indicator with clamp and 8" adjustment rod, Drive shaft yoke, Snap ring pliers, Brass drift Hammer (Ford wrench...) Screwdrivers, 10mm socket, 13mm socket, Torque wrench (3/8" preferred), Feeler gauges(I use a .008 gauge for a lip seal tool but lip seal tool is preferred) ,#27 Torx bit(stator support change), Misc. Sockets (seal drivers.. That ¾" drive set has to be used for something...) Drill (3/8 variable speed) ,and drill bits, Bushing drivers.

Andy just e-mailed me, and let me know that some of the part numbers have changed, He's going to e-mail the new numbers to me and I will post them... Meanwhile, your friendly (unfriendly?) GM dealer should be able to cross reference them. 

Parts List Rebuild kit ,(Art Carr or Mike Kurtz) Shift kit, (Art Carr or Mike Kurtz) Pressure regulator valve, (Art Carr or Mike Kurtz) Transmission drain plug(now’s the time to install it) Hardened stator support (Art Carr or Mike Kurtz), 10 vane pump(optional) (Art Carr or Mike Kurtz) Hardened pump rings (TransGo ,Art Carr or Mike Kurtz) 2nd gear band (kevlar preferred, Art Carr or Mike Kurtz) if not use GM #8634919 Bearing(sun gear to internal gear), GM #8628962(if required) Bearing(Thrust Rear carrier to lo/reverse roller clutch) GM #8648389 (if plastic washer installed) Plate(lo/reverse clutch waved) GM #8633371 Washer(input drum to housing copper) GM #8626372 Bearing(front carrier to sun gear) GM #8633875(if required) Bearing(internal gear to carrier) GM #8628202(if required). Plate(forward clutch backing(6.31mm)) GM #8628088 Plate(forward clutch waved) GM #8628085 Plate(Direct clutch backing(4.50mm)) GM #8632570 Bearing(overdrive carrier to internal gear) GM #8634035 (if required) Bearing(overdrive carrier to sun gear thrust) GM #8634035 (if required) Plate(overrun clutch backing) GM #8634864 Plate(4th clutch backing) GM #8634866 Screen(pump solenoid) GM #8627509

Thanks to Art Carr, Mike Kurtz, Level 10, and TransGo for the painstaking research to cure the TH 200 R4's problems, and  parting with their latest high tech fixes! Many tranny guys don't want to tell you anything unless you hand them a pile of cash...

Making the 200-4R "bullet-proof" 

Updated by George Dumpit (4/97)

The TH700R4 is a stronger tranny, a disadvantage is slightly higher ratios for all gears (except 3rd of course) I say "disadvantage" for those of us who want to get a little more gas mileage out of it. For full race, the 700R4 is an easy choice. Aftermarket 700r4's can be found for around $1550.

The TH350's and TH400's are good trannys as well but the SS's love 4th gear. For more good info on building up the TH200-4R's, talk to a GN owner...

TH200-4R build-up parts list:

Proven neck snapping shifts good to roughly 450HP. (estimated)

A higher stall converter along with a nice strong limited-slip rear is also recommended. Good u-joints are a must. Traction bars are a plus. :)

GM Throttle Valve (TV) Cable Adjustment 

GM has a number of automatic transmissions that, instead of having a vacuum modulator to sense engine load, use a Throttle Valve Cable, attached to the throttle linkage. When the throttle is depressed, the cable is "pulled" progressively with throttle position. In addition to providing forced downshifts (kickdown), and progressively later (higher speed) upshifts at higher throttle settings, the throttle valve also adjusts main line pressure in the transmission. Operating a transmission with the TV cable out of adjustment, can, not only produce early, or late upshifts, but incorrect line pressure, as well. What this means, in simple terms, is that TV pressure that is too low, will produce main line pressure that is also too low, and will eventually "burn" the transmission clutches.

Before a transmission is test driven (after installation) a preliminary adjustment must be made, and then "fine tuned" during the test drive. Adjust the cable so that it will be pulled all the way, when the throttle is simultaneously opened all of the way (with the engine turned off, of course). Make sure that the cable returns (with no binding) when the throttle is released. This preliminary adjustment will frequently be too "high", and the throttle pressure will have to be reduced, to attain proper shift points. I prefer to start with an adjustment that is "too high", and then work down, rather than "too low" and work up.

How to adjust your Throttle Cable

To raise throttle pressure (raise shift points, and makes "kickdown" more responsive) move the cable housing towards the firewall (away from the throttle linkage), as you simultaneously depress the 'D' shaped button on the cable housing. Move the cable housing adjustment a small amount at a time (one "click"); a small adjustment can often make a world of difference. Naturally, to lower the pressure (lower shift points, and make "kickdown" less sensitive) move the cable housing towards the throttle linkage.

200-4R vs. 700-R4 

From: Jim Dobravec ( For those who are still debating between the 200-R4 and 700-R4.... there is an article in the March 1995 Hot Rod issue where they do a  tranny comparo between the two. They basically asked the "experts" at Art  Carr and TCI about the two trannys. Some of the highlights were: - 200-4R comes with a universal bolt pattern bellhousing (fits Chev Buick    Olds Pontiac engines) - 700-R4 is a Chev only pattern. - 200-4R offers full-throttle upshift into overdrive, while only the 91    and later Corvette 700-R4s offer this feature. - a few years ago GM ghanged the 700-R4 designation to 4L60 same tranny    except 4L60-E is computer controlled.  - Most tranny companies agree that the early 700-R4s had some durability    problems and must be highly modified to make good performance    engines.(didn't say what the mods are) - the early 82-84 700-R4 units had a smaller 27-slpine input shaft and    should be avoided. - the 85-87 700-R4s can be upgraded but both companies recommended    starting with an 88-93 700-R4  - as for the 200-4R, the best are the ones used in the turbo Buick    T-Types and Grand Nationals, but any of the 86-88 gearboxes are good cores. - Art Carr claims both are equally durable and both can handle up to 600    lbs-ft of torque and around 700hp (not stock I'm sure!!) - Art Carr has been adapting the 200-4R for use in automatic equipped    Mustangs. (sounds like putting chevy engines into a Ford again :) ) Bottom Line: - both TCI and Art Carr also agree that HOW you use the tranny is a big    factor in selecting the correct performance automatic. If blasting 9's    on the dragsrip is your plan of attack a performance built Turbo 400 or    powerglide is the best choice. Both the 200-4R and the 700-R4 will live    on the dragstrip behind some pretty powerful engines. However keep in    mind the quicker the car runs the more abuse the tranny has to endure,    which in turn will reduce its life expectancy. --- From: J Gray (         I know this subject has already been discussed, but as I was digging though my old HOT ROD magazines and I found this interesting article "THE GREAT DEBATE (700-R4 vs. 200-R4) Which is the Better Overdrive?                         "HOT ROD MARCH 1995"         Here are a few highlights that I copyed straight for the article. All 200-R4s offer full-throttle upshifts into overdrive while only the '91 and later Corvette 700-R4s offer this feature.           The early '82-'84 700-R4s units had a smaller, 27-spline input shaft and should be avoided.  The '85-'87 700-R4s can be upgraded, but most companies recommend starting with an '88-'93 700-R4.  These transmissions offer a number of advantages that enhance durability.  The best 200-R4s are between '86-88.         While the 700-R4 offers the deepest first-grear ratio, this does not necessarily make it the best choice.  Note that the 700-R4's first-to-second-gear drop is far greater than the 200-R4's.  This will hurt acceleration.                      1st         2nd          3rd        4th 200-R4              2.74         1.57         1.00       .67 700-R4              3.06         1.62         1.00       .70         "The key is that the 200-R4 is as durable as the 700-R4"

700R4 Overhaul Tips 


The 700r4 (or 4L60 as it is now called) is a fully automatic 4-speed transmission with a lock-up torque converter. It was first introduced in 1982, and came mainly in the General Motors pick-up truck line. Later, the transmission started showing up in almost all of the rear-wheel drive automobiles in the Chevrolet and GMC line, until 1993 when it was discontinued (The 4L60E and the 4L80E replaced the 4L60). During the 11 years of production, there have been a multitude of changes; Some worked . . . and some didn't, but overall, the transmission has become a reliable gearbox after overhaul, as long as the proper "updates" have been made, and a little care is taken.

In the early days of the 4L60 transmission (back when they called it the 700r4), there were LOTS of week points. The technicians hated them. The backyard mechanics hated them. People were putting TH350's and 400's in place of the 700r4. It seemed that every one that was overhauled, came right back....blown up.(Not every one, but it sure seemed that way!) Actually, the TH350 was that way when it first came out; The HEI ignition system (GM electronic ignition) was that way too; people were putting Powerglides in the place of the "unreliable 350's"; They took out the HEI, and put "point-style ignition" in it's place; And lots of backyard mechanics have been known to disable the self-adjusters on drum brakes, claiming that they , too, are unreliable. Well, now, as with all the other examples, we have learned what works....and what doesn't, and are able to build a 700r4 that is reliable.

Overhaul Tips

I have been overhauling 700's for about 10 years now, and during that time I have learned alot. (Why do I always have to learn the hard way?) I now overhaul, on the average, about two a week (that's average; some weeks more and some weeks less.) I picked up some "tricks" along the way, and have found this unit to be both, a reliable and a desireable transmission after a few modifications. As with all the other late-model generation of transmissions, this trans must be clean and care must be taken during inspection and assembly. Follow torque specifications closely.

There are basically 3 major versions of the 700r4. From '82 until '84 there was a small-input-shaft unit with the same spline as the 200c transmission. It took an RPM part# C-21 (gas) or C-37 (diesel) torque converter*. Make sure not to use the later torque converter. It will install just fine, but the vehicle will not move when you are finished! From '85 to '87 there was a large input shaft version, which has the same spline as a 350 trans. It takes an RPM part # C-40 (gas) and a C-39 (diesel) torque converter*. The early torque converter ('82-'84) will not install, so there is no danger of using the early torque converter on the large shaft. From '87 1/2 up, the large shaft is still used, but GM incorporated an auxilary valve body to cushion engagement into drive.

There are some interchange problems that arise. There have been many changes to the 700r4 trans since it's first production. Obviously, input shafts (and the drums that connect to them) are different. Reverse input drums come in three different varietys ('82-early '87, which has a square oil orifice, and a steel piston, '87-'92, which has a smaller round oil orifice, and an aluminum piston, and '93, which has an aluminum piston and a larger square orifice (similar to the early drum). Pump stator supports, and their respective pump halves have changed through the years. There are, as you may have guessed, small shaft, large shaft, and '87 1/2 up auxilary valve body versions. There is an early ('82 to '84) sprag assembly that has gold thrust washers, and uses the plastic washer between it and the front planet; And the later version of the sprag assembly, that has silver thrust washers and Does not use the plastic washer between it and the front planet....put a washer there and you will eliminate all thrust end-clearance, and the unit will fry (I told you, I have to learn everything the hard way....Oh well, at least this way, I never forget this detail!). Always replace the valve body separater plate with the same code stamped on the plate. Watch the checkball location. Different years take different locations. Prior to '87 1/2, there are (5) 1/4" check balls in the case and (3) 1/4" check balls in the valve body. Later years take (4) and in rare cases (5) in the case and (2) in the valve body and (1) in the auxilary valve body.

During overhaul, I grind two flat spots on the Pressure regulater valve (GM has an updated valve which essentially does the same thing), and I replace the TV Boost valve with GM part #8634940. Replace the check ball capsule (GM# 8634400)in the case (the one that extends into the servo area). I remove it by threading a 3/8 coarse long bolt into the capsule, and "slide hammering" it out. Install using an old PR valve, and align the holes in the capsule with the opening in the servo area. I also remove the check ball that is in the capsule at the rear of the case (the one that feeds the low/reverse piston) on later units that have the ball (the early units don't have the ball). I drill four holes in the separater plate; 3/4 release hole to .078", 2nd band apply to .110", 2/3 apply to .110" and T.V. balance hole to .055". Also, make sure that the gaskets do not cover the hole in separater plate.(see photo). I install GM part # (8642970) lock-up valve on the early transmissions that don't have computer controlled lockup circuits, shortening the spring by one coil with a set of side cutters for the gas rigs, and installing the valve with the spring unaltered for the diesels. I put washers between the TV plunger and the TV valve spring to effectively make the spring longer (one washer for the gas rigs and two washers for the diesels). Put new iron vane rings (RPM #54222A) in the pump assembly (the early ones were prone to breakage). Loctite the pump seal with red #271 Loctite. Check to make sure that the rear ringgear is the updated GM version that comes as standard equipment on (I think) '85 and newer (it will have 3 lines stamped in the side of the park teeth). If not, replace with GM part # 8667055. Replace the early accumulator pistons (again I'm only guessing) '85 and older, with later pistons with rubber rings rather than teflon. On '87 and later models, I discard the 3/4 release springs and drill the 3/4 release hole in the separater plate (see photo). I install solid type teflon rings on the input shaft with a special tool (RPM # J29569). Set up the end clearance (.005-.036); The #70 selective washer seems to work 80% of the time. On the 6 cylinder versions (S10 and camaro) I replace the 3/4 apply "fingers" in the aluminum drum with the V8 version, which is lower, allowing one more clutch and steel than the original. In addition, on the 6 cylinders, I remove the aluminum plate and top overrun steel plate from the forward clutch line-up and replace with a V8 version apply pressure plate, allowing one more forward clutch and steel plate. On the same application, I replace the reverse input piston with a V8 version, which is shorter, and will accept one more clutch and steel. On the later ('87 1/2 up) reverse input drum pistons (the later drum comes with an aluminum piston.), I reduce the size of the bleed-off orifice in the piston by installing Fitzall part#77761C cup plug. On the earlier ('82-'84) 700's, I also replace the 1-2 shift valve spring with one that is a little stiffer (the gil-younger shift kit has the right spring); the early versions shifted into 2nd gear way too early. 90% of the time I replace the governor gear; they are always worn out. This transmission is equipped with a lockup torque converter; Make sure that it is working correctly on the test drive; If not, fix it.....don't ignore it, unless you like working on the same transmission, over, and over, and over and........... Check the sungear shell, carefully, for cracks around the splined area; They break occasionally. (If it seems that I am jumping around alot, I'm sorry, I am doing this all from memory as I go.)

Well that's all there is to it. I may have left something out, but I will update if I think of something else. Let me know if you have a "trick" that is not listed here. I will have the pictures up as soon as I take them (Now what the heck did I do with my Poloroid?)

* There are other part #'s, as well, but these are the most common

TH700R4 conversion tips 

Installing a 700 in a "non-700" application, is not too difficult, and is even easier if the vehicle is GM made and happens to already have an automatic transmission. It is impossible for me to include every detail that you may need to know for your intended project, but the following details apply to most installations. I have installed 700's in many different types of vehicles, ranging from a '34 Ford Coupe, '40 Ford pickup, numerous 50's Chevy pickups, and my own '57 Studebaker 2dr wagon, to late model Camaros, GM two, and four-wheel drives, and plenty of other applications, and have used these following suggestions, repeatedly, to produce what I think is a "sanitary" installation. Keep in mind, as you perform a conversion of any type, what your overall goals are. I am reminded of a story about a person that wanted to improve his Jeep truck (he loved to fourwheel), by installing a V8 in place of the original 6 cylinder engine. Nearing completion of the conversion, he noticed that the front driveshaft would not easily fit in it's original location; It was interfering with the engine oil pan, so he left the front drive line out, and can no-longer go fourwheeling! Some improvement!!

Generally, what I want, in any type of conversion, is to IMPROVE the vehicle. I also happen to have great respect for the engineers that originally designed the vehicle. For the most part, they did a great job designing the vehicle, making the vehicle safe, reliable, and delivering satisfactory performance, for most normal applications, and it would seem to me, to be arrogant, on my part, to think that I can, so easily, improve on what a team of engineers, and plenty of research and development funds were able to do.

With this in mind, do your conversion meticulously;

One question that I am frequently asked: How long is the 700?, and did they make one that would fit a Buick, Pontiac, Olds (B.P.O.), Cadillac?
The 700 is approximately the same length as a "medium shaft" 350 (6" long tail housing), which came as standard equipment in many GM trucks in the '70's, which is about 3" longer than the common "short shaft" 350 that came in many GM Cars, and trucks, and the output shaft on the 700 is the same spline as the 350, as well as the 200 transmission, and the yokes are interchangeable, making for an easy installation in most GM vehicles. The 700 is only available in the Chevrolet version, and I do not recommend the "adapter plate" that converts the chevy to the B.P.O. bolt pattern.

Wiring the TCC(Torque Converter Clutch) controls

There are two main controls governing TCC application. First, there are hydraulic controls, that control lock-up timing, and application, and Second, there are electrical devices that control, and override the hydraulic controls.
The electrical controls include, a lock-up solenoid, pressure switches, low-vacuum switch, and a brake-cancel switch.
The following is my recommendations for wiring the lockup circuit in an earlier conversion.

I recommend running an accessory hot wire (hot only when the key is on), through a normally open brake cancel switch. This switch will allow current flow, only when it is depressed; The brake pedal depresses the switch, normally, and releases the switch when the brake is applied. This switch works exactly opposite the brake light switch, whereas the brake light switch allows current, only when the brake pedal is depressed, the cancel switch interrupts current when the brake pedal is depressed, thereby unlocking the torque converter clutch in a panic stop.
From the brake cancel switch, power is routed through the low-vacuum switch (GM part#14014519 interrupting power when the vacuum is low, such as heavy throttle), and connected to the transmission. Inside the transmission, I normally route power through a 4/3 switch (GM part# 8642346 normally closed), and then to the solenoid. I use an internally grounded solenoid (GM part#8654123), so there is no need to run a separate ground circuit. There are other ways to accomplish the same thing, but I feel this is the easiest way to do it RIGHT!!

Torque Converter Clutch Schematic 


Here's how I interpret the circuit:

TCC Disable switch HOW-2
Locate the the switch near the top of the brake pedal arm. It should have a pink/black wire and a purple wire connected to the switch. Follow the Purple wire and select a good place to splice a (12v) switch into it. When this switch is in the "off" condition the TCC will not engange at all.

TCC Engaged light HOW-2
Connect a (12v) light between pin "F" on your ALDL connector and the purple wire running from the Brake pedal switch.

TCC Forced Engage switch HOW-2
This one is easy, connect a switch between pins "A" and "F" on your ALDL conector. 

If you would like all three options wired then you can do the following:
First you need to find the correct switch.
You want a LIGHTED DPDT switch with a center "off" position rated at 12v 3a These are tough to find!
The one I used was an automotive type switch that came with a small mounting bezel.

  1. Cut the purple wire from the brake switch and connect the switch end of the purple wire (B) to terminal #3
  2. Connect the other end of the purple wire (A) to terminal #1 and place a jumper wire from terminal #1 to terminal #5
  3. Connect a wire from terminal #4 to pin "F" on the ALDL connector
  4. Connect a wire from terminal #6 to pin "A" on the ALDL connector
  5. My switch lamp was connected to terminal #3 and terminal #4. If you use an LED #3 is positive, #4 is neg.

       In Operation when the switch is "Up" TCC engagement is normal.
      When the switch is in the center "OFF" position the TCC is DISENGAGED
      When the switch is "Down" the TCC is FORCED ENGAGED

          The light comes on whenever TCC is engaged, forced or not.

Planetary Gearsets

Planetary gearsets have been in use since the earliest automatic transmissions. Planetary gearsets are made up of three components, constantly in mesh; A sungear, A planetary carrier and planets, and a ring-gear. When one gear is held stationary, and another gear is rotated, the third is driven at either a reduction , or an increase in speed, or a rotation in the opposite direction. Today's automatic transmissions are actually using "compound planetary gearsets" because they are basically two planetary sets that have common parts. Typical 3 speed transmissions, use two ringgears, two planetary carriers, and a common sungear (all one piece, but long enough to mesh with both planetary carriers.) By changing which gears are rotated, and which gears are "held", we get two different gear reductions (1st gear, and 2nd gear) a reverse, "gear" and a 1:1 ratio (third gear). Devices, known as clutches, and bands, and one-way clutches (sprags or roller clutches) are what does the "holding". One-way clutches, hold in only one direction, and freewheel in the other, like the freewheel on ratchet wrench. These sprags allow the planetary gear to be held under acceleration, but to freewheel under deceleration.

Let's use a typical 3 speed automatic transmission(A TH400, TH350, etc.) to illustrate what happens as the trans goes through the gears. First, as the transmission is shifted into drive, the forward clutch engages, and the low one-way clutch holds; You have 1st gear. To shift into second gear, the front, or intermediate band is applied; the forward clutch is still engaged (to move forward), and the one-way clutch freewheels, giving you second gear. When shifting to third gear, the direct clutch engages and the band is released, the forward clutch is engaged, and the one-way clutch is still freewheeling, giving us third gear. For reverse, the forward clutch is disengaged, but the direct clutch is engaged and the reverse band is applied. These clutches and bands are used to "hold" the different components of the compound planetary gearset, allowing different combinations of gears.

Controlling Shift Quality

In automatic transmissions, the Governor, Shift Valves, and Vacuum Modulator, work in unison to select the proper gear. In light throttle conditions, very little hydraulic pressure is needed to apply the bands and clutches. As load increases, higher hydraulic pressure is needed to apply the bands and clutches to change gears.

Automatic transmissions monitor engine load with a TV valve or modulator to get information for shift timing. The valve body uses this information to adjust the hydraulic pressure, to compensate for varying engine loads. The pressure regulator valve has a spring "pushing" on one end of the valve, and hydraulic pressure "pushing" on the other end of the valve. When the hydraulic pressure is high enough to overcome the spring pressure, the valve moves, and bleeds off the excess pressure.

The Throttle Pressure Valve, or modulator, helps the pressure regulator valve, by varying fluid pressure depending on engine load. This pressure coming from the modulator, is directed to the pressure regulator valve, and helps the spring "push" on the valve. This makes the spring seem stiffer, hydraulic pressure must be higher, to overcome the increased pressure, caused by both the spring and the throttle pressure helping the spring, before the valve can bleed off the excess pressure.

In this way, hydraulic pressure increases with engine load. By the way, this hydraulic pressure is commonly referred to as "Main Line Pressure", and it varies, from transmission to transmission, but tends to be around 50 or 60 PSI at an idle, in neutral, and may go as high as 250 PSI under certain highload conditions. This accounts for some of the shift-quality-improving characteristics of a modern automatic transmission.

There are other ways, commonly used in conjunction with main line pressure "altering", to improve shift quality. One way, is to provide a restriction, in line, to "slow down" the application of the friction components. The fluid must pass through a small hole,or orifice, before applying the friction component, similar to "pinching" a garden hose, to slow water flow, thereby filling a bucket with water more slowly.

To further cushion the shift, engineers often incorporate Accumulators. An accumulator can be, as simple as a piston with a spring on one side. When a shift is commanded, hydraulic pressure is routed through an orifice and into a chamber, acting on one side of the piston (the side of the piston, opposite the spring). This hydraulic pressure "pushes" on the piston, compressing the spring (on the other side of the piston), and "absorbing" some of the hydraulic pressure that is also acting on the friction component needed to create the desired gear change. This acts to "slow" down the application of the friction component, and smooth the application, and make the gear change less harsh.

Torque Converter Clutch Application 

The clutch in a lockup torque converter is quite a bit different from any "typical" clutch seen in other applications. It is made up of a spring steel, with clutch lining on the outer diameter of one face, that mates with a corresponding "flat spot" on the inside of the torque converter housing. The torque converter housing is directly bolted to the engine flexplate (some people call it the flywheel), so it is obvious that the converter housing turns at exactly engine speed. The spring steel clutch is splined to input shaft (it is actually splined to the turbine, which is then splined to the input shaft), so it is also obvious that the clutch turns at exactly turbine, or transmission input shaft speed.

Fluid enters the torque converter through the input shaft, where it is "dumped" in behind the spring steel clutch, inbetween the clutch, and the converter cover, creating a highpressure area behind the clutch, forcing the clutch to spring away from the converter cover, and keeping the converter "unlocked". Fluid then enters the rest of the converter, leaking past the "gap" between the clutch, and the cover and does its normal job within the "pump", "turbine", and "stator", before exiting through the hub, and on to the cooler passage.

When conditions are right for a "lockup" to occur, fluid is reversed, by the lockup valve; Fluid enters the converter through the hub area, does it's job within the "pump", "turbine", and "stator", and creates a high pressure area on the opposite side of the clutch, forcing the clutch against the converter cover. The clutch material "grabs" the converter cover; The clutch, which is splined to the input shaft, becomes "one" with the converter cover, allowing no slippage between the two; ....or lockup.

Setting Up a Differential Ring & Pinion 


Setting up a differential is probably one of the most under-rated jobs that a mechanic can tackle. I have seen many mechanics "slap new bearings in" or "throw a new gear-set in" a rearend, and then take it to our shop to let one of our technicians "set it up" so it won't make noise. "Setting up" a rearend, involves so much more than merely replacing parts, and installing them without any regard to the tolerances that the "parts" must be held to. Proper setup requires patience, cleanliness, and attention to detail.

Some Terms Relating to Differentials

Ring & Pinion gears

The driveshaft is connected to and drives the pinion gear, which in-turn drives the ring gear at a reduced rate and at a 90 degree angle from the driveshaft. The ring gear is basically connected to the wheels.


This is the term used to describe the "clearance" between the ring & pinion gears and is usually measured in thousandths-of-an-inch by a dial indicator. Example .008-.012"

Drive / Coast

The drive side of the ring gear is the side of the tooth that is contacted when the vehicle is accelerating / The coast side is the side of the tooth on the ring gear that is contacted when the vehicle is decelerating (during engine-braking).


This refers to the tooth contact area of the gearset; In other words, Where the Ring gear and the Pinion gear "Rub" together.


The Pinion bearings and Carrier bearings run a little tight, similar to the way a wheel bearing should be "loaded". The tapered bearings are adjusted to eliminate any play and then they are set a little tighter, making them a little "hard to turn". This is measured by checking the torque required to turn the bearings with a dial torque wrench. Example 15 to 25 in.lbs.

Pinion Depth

This is set with "pinion shims" and controls how the pinion contacts the ring gear in relation to the axle center.

Crush Sleeve

A piece of "pipe" that is used to hold the pinion bearings apart and offer some resistance for the pinion nut. The pinion nut must be tightened down, crushing the crush sleeve, until proper pinion preload adjustment is achieved.

Extra Tools Needed For Proper Differential Overhaul

Differential Overhaul

Before removing the differential carrier from the housing, a pattern must be taken if the original gearset is to be used over again, to determine how the gearset contact has been running. This is accomplished by painting a number of teeth on the ringgear (both the drive and the coast side) with a nondrying paint compound such as Persian blue or regular artist's paint in a tube (that's what I use). Then have a friend "load" the carrier by prying between the differential carrier and the rearend housing, making the pinion yoke hard to turn. Then turn the pinion yoke with a ratchet slowly and evenly, first in one direction and then the other, through the painted area of the ringgear. This will show you where the gear teeth are touching each other. The gearset will "wear" a pattern that may or may not be serviceable. A desirable pattern will be at the same height (or distance from the Toe) on both the drive and the coast side, and slightly closer to the Toe than the Heal side (see photo). If the gearset shows a pattern tending towards the "desirable pattern", the gearset may be reinstalled, but the original pattern must be adhered to; minor changes may be made to pinion depth and/or backlash to enhance the pattern, but only as long as the final pattern has plenty of contact surface. If the gears are determined to reusable, check backlash with a dial indicator and note the reading. Consult the manual for your application and compare with recommended specifications.

Mark the position of the differential bearing caps with a center punch or letter stamp set to insure proper location and orientation during reassembly. Remove the differential carrier from the housing (it may be a tight fit due to carrier bearing preload). Note the position of any shims and their location. Remove the pinion nut (a 1/2" impact wrench is real handy for this, although I have heard of people making a tool to hold the pinion yoke, but keep in mind that the pinion nut will install with roughly 200 or 250 ft. lbs. of torque), and tap the pinion out of the housing (protect the threads on the pinion; they can be easily ruined). Remove the pinion bearing races from the rear-end housing. Remove the carrier bearings from the differential carrier and the pinion bearings from the pinion gear.

Inspect the rear-end housing closely in the area where the pinion bearing races are pressed in and where the differential bearing races are "clamped in" by the bearing caps. Are there any signs of the races spinning or fitting loose? How about on the bearing caps? Check the differential carrier and the pinion gear for signs of loose fitting bearings or spinning bearings. If the rear-end housing does not check out, a replacement should be found or the housing may be repaired by a reputable shop such as Lincoln Welding in Sacramento. If the carrier of the pinion gear are found to be damaged, a replacement should be found.

Install the bearing races into housing with any applicable pinion shim/s, but make sure that there are no burrs in the housing that might hold the bearing races up off of the bottom of the machined bore (sometimes burrs are made when removing the old races). Install the bearings onto the differential carrier, and again, check for burrs on the carrier that might keep the bearing from being driven all the way on. If the ringgear was removed, check for burrs on both mating surfaces where the ringgear contacts the differential carrier (I always run a flat wetstone over both surfaces to remove any burrs) and reinstall the ringgear. Torque the ringgear bolts to specification (you need a manual here; try the library, or e-mail me and I will try to find out the specifications for your particular application.), and while your at it put some Loctite 271(RED) or 242(BLUE) on the bolts just to make sure. Install the pinion bearing on the pinion gear and don't forget any applicable pinion shim/s.

Install the pinion gear temporarily with the old crush sleeve (tap on the side of the crush sleeve while it is on the pinion gear to make it "longer" or "uncrushed"). Put some motor oil or gear oil on the bearings. Install the outer pinion bearing and the pinion yoke (don't install the new pinion seal at this time). Put some motor oil on the pinion nut and tighten down until a preload of the proper specification is achieved (I stay on the loose side of the specifications. i.e. 15-25 inch pound spec. , I use 15). Install the differential carrier (it should also be preloaded to specification, so it will have to be tapped in), and torque the bearing caps to specifications.

Check the backlash and adjust to specification if necessary. Remember how you pattern checked the gears when you first started? Well, now you get to do it again. If your pattern comes out "desirable", you're almost done. If not, consult the picture for what changes to make to your setup; Make those changes and reinstall and pattern check, and consult the picture for what changes to make to your setup; Make those changes and reinstall and pattern check, and consult the picture for what changes to make . . . . well you get the idea. You have to have patience. Keep at it until you are satisfied; This is the place where most people fall short of proper setup, and blame the gear noise on a "noisy set of gears". If the pattern looks good, than there wont be any excessive noise. Note that all gears make an acceptable amount of noise; Rearends, Transmissions and Engines all make noise; It is up to the rubber engine, transmission, spring, and body mounts to insulate those noises from the passengers . . . so don't overlook these items when chasing excessive noises.

After you are satisfied with the pattern, disassemble the rearend and install a new crush sleeve, and reassemble (don't forget the new pinion seal). Reinstall the old pinion nut with motor oil and tighten until all play is eliminated in the pinion gear (but not preloaded yet). Remove the pinion nut and clean threads on pinion gear and new pinion nut with carburetor cleaner, and install nut with Loctite 271(red) or 242(blue) and tighten down until proper pinion preload is obtained. Install the differential carrier, and torque the differential bearing caps (it wouldn't hurt to install Loctite on the cap bolts). Pattern check one last time (hopefully), to make sure that you reinstalled everything properly, check backlash one last time; If within specification, your done with the setup.

Install the axles, tap the rear cover surface flat (if yours has one). Now, if your cover is a heavy duty one with stiffening ribs, reinstall with a gasket painted with "brush-on" Aviation Permatex and snug cover bolts moderately. Otherwise, if your cover is flimsy (or worse . . . a cheap chrome one), install with no gasket and use Permatex Ultra-Black. If you insist on using regular silicone glue with a gasket (Lord knows why), install bath-tubs, or caulking around household windows, and let somebody else work on your car!


Transmission- The TH400 and 4L80E are the most durable, followed by the TH350, TH700R4 and TH200-4R. With a primarily street car with 500 hp or less (including any nitrous use) I recommend the 700 R4 with overdrive and using a lockup converter. A TH200-4R can also be used but I would say it's safety limit is roughly 425hp with a good rebuild as described below. Art Carr says that a high tech rebuilt 200-4R can take 625 hp. This will give you a comfortable RPM on the highway with plenty of gear for a standing start. A TH350 can also be used up to 450 hp, but no overdrive. A TH350c is a TH350 which is actually a little stronger and has a lockup converter for gas mileage on the highway. The main advantage is that the TH350 is lighter in both recriprocating mass and overall weight and consequently will give you a little quicker time in the drags. Many of the NHRA Stock Eliminator drivers use a TH350 over the TH400 when they can. The TH400 is virtually unbreakable but weighs right up there with a ton of bricks. For heavy cars, lots of power, and nitrous use this is the way to go. The TH400's spinoff, the 4LE80-E (WAY heavier that a TH 400- 250+ lbs with converter) is overdriven and has a lockup converter, and is strong as hell but is costly and must have a computer to run it. A TH400 can be converted to "switch pitch" which is a torque converter that has two different stall speeds depending on the position of the switch. Very streetable, but max stall speed available for a switch pitch converter is about 3200 rpm's in high stall mode. If you need more, get used to a lot of slippage as your only choice is an inefficient 10 inch or smaller converter on the street. The parts for this cost about $150 plus converter and are available through Darryl Young. The parts needed are the torque converter, the front pump, and the input shaft.

Average cost with converter- all performance rebuilt-if you pay to have it done
You can do a LOT better if you do the work yourself.

TH400 - $450 + $200 for 11 in. converter-add $150 for the switch pitch conversion

TH350 - $550 + $200 for 11 in. converter ($250 for 12 in.lockup)

TH700R4 and TH200-4R - $1100 + $150-350 for 12 inch lockup converter, $550 for 9 in. lockup converter

4LE80-E - $2500 (with computer preprogrammed, wiring harness) (what Art Carr sell's 'em for) + $250-550 for a custom converter.

(with this tranny either the GM diesel controller or the Motec engine control computer is needed, plus whatever deal you can find pricewise on the tranny in the junkyard. These trannys don't need any high tech rebuild like all the other automatics to be run with 4-600 hp without exploding). More than this, a good rebuild would be highly recommended...

Newsflash! I just got off the phone with Mr. Gasket and they told me that the ACCEL (aka) Hurst transmission controller has been discontinued. I was planning to do this swap myself with the Hurst controller, but it is no more... I don't know who has chips for the GM diesel controller, but I'll find out and let you know, or if any of you know please e-mail me.

(a non performance rebuilt price varies widely based on core charge and the fact that most tranny shops start tacking on lots of bills when they hear the word overdrive.)

Rebuilding transmissions- better to have a large amount of quality tools- a dial indicator, feeler gauges, a pump puller (this you can make) an inch-pounds torque wrench, and an infinite amount of patience. But it can be done at home. I recommend that you acquire a good transmission manual (the ATSG is a good one). There are good books on rebuilding that go beyond the factory manual available for the TH400 and TH350 that go deeper in depth in explaning how the rebuild is done. Also, these books detail some hopups for harder, faster shifts and increased reliability. Art Carr, TCI, Level 10, and B&M are good sources for hopup parts. Usually,a local tranny shop is usually willing to help you find parts, such as a pump assembly or shims, saving much time and money over the factory. Try to go when thay aren't busy, and be patient! Another good gamble is to purchase complete trannys straight out of the core pile at your friendly local junkyard. You can get lucky and end up with the parts you need for as little as $20-30. 

Strength improvements- On the TH 400, the intermediate sprag is the weak link in the transmission, failing at about 500! hp. The sprag is about $50-60 and usually requires an early (64-70) drum.  I have only seen those fail when a 4000+ rpm converter and a trans brake is used with slicks. On the TH700R4 and TH200-4R, the stock pump vanes are brittle and easily break under load. A pump kit is available that upgrades the vanes to better material and should include a new pump slide spring and if your stock pump is only a 7 vane unit, you should upgrade to a 10 vane unit. This helps the tranny live by providing a steadier flow of fluid under pressure. Furthermore, on the TH200-4R, the stock converter spline support is too soft and will eventually fail, even in a stock application. Art Carr has a rebuild kit for the TH200-4R that increases the clutch pack count and should be considered  mandatory in a performance application. Art also sells the converter spline support that is made of tougher heat treated steel that will not wear like the stock one. In the TH350, the main weak point is the intermediate sprag race, which often bites the big one even in a stock tranny, especially one that is manually shifted often. 

Converting an old Chevy to overdrive- Not as hard as you might think. TH200-4R's are about the same length as a TH350, so with a TH400 crossmember and a little relocation they fit like a glove. Use the original TH350 or TH400 driveshaft with a TH350 yoke, you may need a special u-joint with smaller cups that is made by Lakewood for rear axle swaps. The TH200-4R mount is farther towards the rear of the car than a TH400. If you have a TH350 or the old Super Turbine 300 2-speed that you want to dump, most older Chevys had a TH400 option at one time where you can get the crossmember from and you will be on your way (Camaros/Firebirds). Or, on the 67-72 A bodies the stock frame is drilled in different places so just slide the crossmember back and drill new holes . The driveshaft may be a little short, check before driving (1/2 inch difference or less). With the TH700R4's, it's a little more complicated. The driveshaft will be too long in any case, and needs to be shortened. The trans mount is closer to the front of the car than a TH400 and the crossmember will have to be moved forward and possibly the mounting pad on the crossmember cut off and rewelded to mount facing forward rather than the back (as is the case with 67-9 Firebirds with the TH400 option.) Also, since every TH700R4 The TH350 and TH400 use a vacuum modulator for part throttle shift timing and quality regulation, where the TH 200- 4R and TH700R4 use a TV cable. This cable is very critical- if it is not adjusted right or you don't use one at all, the trans will last about 30 miles before it blows up. TCI sells a bracket and cable which works well, but is pricey. A stock cable can be adapted, but the correct angle and pull distance must be maintained or the tranny will fail. When shopping in the junkyard for a core, remember that newer is better in case of the overdrive trannies. With TH200-4R's the years to look for are 86-89, and with TH700R4's the years are 88-91. Also, the horsepower rating that the tranny was originally built for matters- the higher the HP rating, the better the tranny. For a indicator dial that shows OD, order a 85-88 Monte Carlo SS indicator- It will fit most Chevy consoles with a little trimming.

Transmission Length
Case to ext. housing  Overall length  Bellhousing to mount 
Powerglide (short tail)  15 ¼  24 ¼  19 ½ 
Powerglide (long tail)  15 ¼  27 ½  20 ½ 
THM 200, 200C (the 3 speed)  27 5/8  27 5/8  20 1/8 
THM 250  21 5/8  27 5/8  20 3/8 
THM 350, 350C  (short tail)  21 5/8  27 5/8  20 3/8 
THM 350, 350C  (long tail)  21 5/8  30 5/8  20 3/8 
THM 400 (short tail)  24 3/8  28 ¼  26 ¾ 
THM 400 (long tail)  24 3/8  34  28 
200R4  27 ¾  27 ¾  26 7/8 
700R4, 4L60, 4L60E  23 3/8  30 ¾  22 3/8 
4L80-E  ? 31.5 30.38

TH200-4R notes of interest

The rubber mount bolts are M10x1.5 · speedo cable interchanges with TH350, but some factory applications have a 1 ft. longer extension cable· cable shifter bracket is GM 10026014 · convertor bolts are M10x1.5 x 15mm · use the TH700R4 filter (with the pickup on the bottom of the filter) and two O-rings on the neck of the filter as the filter is prone to drawing air on a hard launch. The filter is a tight fit, you have to snug the bolts in the pan to get it to fit correctly. This problem only seems to be apparent on higher HP cars. Mike Kurtz recommends using O2 sensor safe rtv, and running a bead around the crimp of the filter as this crimp sometimes leaks where the metal crimps around the plastic... Mike also recommends running the tranny 1 pint over full.. not enough to foam, but enough to keep the filter submerged. Mike said the danger of the TH700R4 filter is if the clearance between the opening and the pan bottom is too small... IE: the ridges are smaller on some brands of filters... then the trans self destructs due to total loss of fluid pressure. And the filter plugs up faster as sediment doesn’t sit on the bottom of the pan and now gets sucked into the filter..

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