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| 200-4R Rebuild |
| Introduction |
| Here is something I wrote for rebuilding the 200R4 for your reading enjoyment...
These are modifications that I do to the 200R4 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...). |
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Disassembly and Inspection |
| Pretty straight- forward 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 bee 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). |
| Reassembly |
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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 1/4". Drill the intersecting passage and mating passage in rear pump half to 5/16". This will help front seal drain back 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 vain pump(here comes the flaming responses...) although I use 10 vain pumps. They are not too expensive(around 55.00. I get them from a transmission warehouse). Main item here is the pump vain rings. Stock ones are cast and if the haven't failed consider yourself fortunate. Install hardened steel pump vain 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 1/4-20 tap. Install a 1/4-20x1/2" allen screw with red locktite 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. I'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 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" 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. Assemble main drive to snap ring on output shaft. Remove yoke setup once snap ring is installed and check rear unit end play. Set up dial indicator(I use an old brake drum and set the tailshaft 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 end play 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). Front unit end play 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 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 end play.(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 main drive all the way down to the rear output shaft...(Just kidding...). 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 me...it 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 alehosk@crosslink.net. Tools Required Press Parts List Rebuild kit (Art Carr or Mike Kurtz) |
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