200r4 mod info

grumpyvette

Administrator
Staff member
I found this posted else ware but figured some guys here could use the info also

When you upgrade to a 200R4 OD transmission to get the benefits of the 0.67 overdrive, it is rare that the automatic shifting sequence occurs at the proper speed. Most likely you have lower rear end gears and a cam so you want the shifts to occur at a higher RPM but the donor tranny is likely set up for a grocery getter and results in 1-2, 2-3 shifts way too slow for your setup. Thus you are stuck with manual shifting which is fun but there are times you want to set it in drive and run it automatically.

A lot of people suggest changing the shift points by adjusting the throttle cable. DON'T DO THAT! That cable needs to be set properly and left alone. It is the governor that sets the shift timing and you have to modify it.

We did ours on our '59 El Camino running a 307 w/ corvette cam & 283 PowerPack heads. We put 3.54 gears in the rear so our auto shifts were occurring @ ~1000rpm lugging the engine badly.

We bought a couple spare governors from PATC Automotive who specializes in 200R4 trannys.

http://www.transmissioncenter.net/200-4r.htm

I am giving them a plug because their authentic GM parts governors are less than $10! We bought two to play with.

It is a hassle to do this modification because you need to take the pan off to get at the governor. There are YouTube videos on doing that step so look it up if you don't know where the governor is. It is an easy swap. Here is a good video

http://video.search.yahoo.com/video/pla ... 11a6g44gh&

http://video.search.yahoo.com/video/pla ... 11a6g44gh&

http://video.search.yahoo.com/video/pla ... 11a6g44gh&

Photo 1 shows the modified governor on the left and the stock one on the right. We took a huge amount of weight off the modified one (power hacksaw and files) but we took the design from a picture of a governor from a Grand National Buick. Plus we still have two more to play with if we screwed this one up. We cut half the skirt off the small weight and ground the top of the large one even with the top of the small one, about 1/8".
200r41.jpg

Photo 2 shows an end view of the small weight. These things come apart very easily knocking out the pin at the base of the weights. Watch where the two ball bearings go! When putting them back together, 'glue' the bearings in their holes w/ Vaseline.
200r42.jpg

Photo 3 shows a couple more modifications we made. First we took out the spring in the big weight leaving the spring in the small one. We took our cue on this again from the Grand National Buick version. Second, we brazed a short nail in the spring hole in the small weight. Word is that that spring has a tendency to hop out on hard shifts so this is a common hi performance mod.

200r43.jpg

Photo 4 shows another view of the nail.
200r44.jpg

There are other sites on the web showing how to calibrate the speedometer by changing our the big plastic barrel gear on the shaft of the govern with the speedo gear that is removed by taking off the speedo cable at the back of the tranny. Do that while you are doing this. I think PATC sells the cheapest gears too. They have a ratio calculator on their site so if you know your tire diameter and rear end ratio, you get the perfect speedo ratio.

Oh, we ended with perfect shift points for the street; ~2000rpm @ 1-2 and 3000rpm @ 2-3. We havent tried it yet but I assume at WOT the shiftw will rise accordingly to higher in the power band.
 
http://www.cpttransmission.com/overdriveability.htm

viewtopic.php?f=57&t=176&p=210#p210

http://www.jegs.com/InstallationInstruc ... -35265.pdf

http://www.transmissioncenter.net/2004RTIP.htm

http://www.ckperformance.com/resources/ ... RNORS.html

http://www.jakesperformance.com/200-4R_ ... _Tech.html

http://www.442.com/oldsfaq/oft200.htm

http://www.tciauto.com/tc/200-4r-700-r4 ... g-kit.html

http://www.youtube.com/watch?v=G0OmQrtkp5k;



The REAL Art Carr
Technical Information


T.V. Cable Adjustment

WARNING: PERMANENT DAMAGE WILL OCCUR IF THE T.V. CABLE IS NOT ADJUSTED OR HOOKED UP.

THE DAMAGE WILL OCCUR WITHIN A FEW FEET OF DRIVING THE VEHICLE!


The TV cable on the 700R4 and 200-4R transmissions controls line pressure, shift points, shift feel, part throttle downshifts, and detent (full throttle) downshifts. So if the TV cable is not adjusted properly, it can cause numerous transmission problems.

The TV cable is connected to and operates the throttle lever, and bracket assembly mounted on the valve body. The function of the throttle lever and bracket assembly I to transfer the movements of the throttle plate in the carburetor to the TV plunger in the valve body. This causes TV pressure and line pressure to increase according to throttle opening and also controls modulated and detent downshifts. The proper adjustment of the TV cable is based on the TV plunger being fully depressed with the engine at wide-open throttle (see figure 9). When the TV cable is properly adjusted the movement of the TV plunger in the valve body is calibrated to the movement of the fuel delivery system. This means the transmission will always have the correct oil pressure and shift feel regardless of engine torque. Simply put, due to this calibration, engine torque and transmission line pressure/shift feel will always be in balance.

If a change is made, such as a different carburetor installed, the change in geometry could disrupt this balance and proper adjustment may never be achieved.

Many people try to defeat the self-adjusting TV cable and tailor shift points of shift feel. However, remember that on the 700R4 and 2004R Transmission the TV cable controls both shift feel (clutch apply pressure) and shift points, you therefore cannot alter one without altering the other.

Let's discuss briefly what happens when someone tailors the TV cable:

Shortening the Cable : If you shorten the cable (move it towards the adjuster tab), this raises both one pressure and shift point. However, when the drive performs a full throttle downshift the TV cable will readjust to its approximate normal position.

Lengthening the Cable : If you lengthen the valve, this lowers both line pressure and shift points. Under this condition, the TV cable will not readjust during a full throttle downshift. What you have effectively done is allowed the engine torque to be ahead of transmission line pressure and shift points. Operating the vehicle under this condition will cause premature clutch wear and transmission malfunction.

DIAGNOSIS

A TV cable that is sticky; misadjusted, broken or incorrect for the vehicle can cause various transmission malfunctions. A sticky or binding TV cable can result in delayed or full throttle upshifts (figure 9). At other times, the TV cable may stick or bind only when the engine off. To check for this problem, run the engine at idle with the transmission selector in neutral and the parking brake set. Pull the end of the TV cable located on the throttle linkage, through its full range of travel, then release it. It should return to rest against the cable terminal (figure 10), it may be caused by one or more of the following conditions:

1. A sharply bent or damaged TV cable hosing. To correct this problem, try rerouting the cable. If this doesn't cure the problem, replace the cable.

2. A burr or sharp end on the TV link. This condition would cause the link to drag in the TV cable housing. You can correct this situation by filing the end smooth but Do Not shorten the link.

3. Misalignment of the throttle lever and bracket assembly on the valve body. Correct the alignment and torque the bolts to the proper specifications as noted in your service manual.

4. A bent TV link. Straighten or replace the link as required.

5. A binding or damaged throttle lever and bracket assembly. Straighten or replace the assembly as required.

6. An unhooked or damaged throttle lever spring. Reconnect the spring if it is unhooked. If it is damaged, replace the throttle lever and bracket assembly.

7. An incorrectly adjusted TV cable. (A) If the cable is adjusted too long, one of the following conditions may result: (1) early shifts, slipping, and/or no detent downshifts; (2) low line pressure. (B) If the cable is adjusted shore, or not hooked up at all, line pressure and shift points will rise and full throttle operation may not be possible.


ADJUSTMENTS


Before adjusting the TV cable, check the following:
1. Transmission oil level. Correct if necessary.
2. Proper engine operation. This can cause problems similar to a malfunctioning transmission.
3. Dragging brakes. This can cause detract from vehicle performance and cause transmission malfunction.
4. Check the TV cable to insure that it is the right part for the vehicle. If you do not hear at least one "click" from the TV cable during the adjustment procedure, it may be the wrong part.
5. Check the cable to insure that it is properly connected at the transmission. "Clicks" will still be heard during adjustment.Adjustment procedure (self-adjusting cable)1. Stop the engine.

Adjustment procedure (self-adjusting cable)

1. Stop the engine.
2. Depress the adjusting tab and move the slider back through the fitting away from the carburetor until it stops.
3. Release the adjustment tab.
4. Move the throttle linkage to rest against the full throttle stop, then release it .
5. Check the cable to insure that it is not sticking or binding.
6. Road test the vehicle.
7. If the problem still exists, refer to the cable diagnosis section.

tec2001.jpg


TV CABLE BRACKET FABRICATION

This section is only for those that do not have a previous TV cable setup, or for those who's TV cable will not fit into the specifications in the previous pages.

Proper installation and adjustment of the TV cable is the most important aspect of a transmission. Don't think of it as "just a kick-down cable" - on the nonvacuum-modulated Th700R4 and Th2004R the TV cable controls line pressure, shift points, shift feel, part-throttle downshifts, and detent downshifts! As the accelerator pedal is depressed and the throttle opens, the TV linkage relays the motion to the valve body's throttle plunger. In stock installations, the geometric relationship between the TV cable and carb throttle shaft bellcrank produces the required TV cable extension (pull) for the transmission to function properly under different degrees of throttle opening. Failure to preserve the correct geometric relationship in custom installations will inevitably lead to early transmission failure.

1. Measure your TV cable to establish its particular mounting dimension as follows: First retract the slider by depressing the lock tab, then pull the cable housing until the flats on the slider are flush with the end of the adjuster housing. (To illustrate components in this photo the slider is shown extended, and the lock tab is not fully inserted through the bracket face.)

2. Then, with the slider retracted, fully extend the cable by pulling the cable end fitting out until it stops. Holding the end fitting out, measure the dimension from the face on the adjuster housing that registers with the mounting bracket to the center of the cable and connector.

3. Add 1/16 inch (.19) to the measurement obtained in step 2 - this is the perpendicular measurement from the rear face of the TV cable mounting bracket to the wide-open-throttle position of the TV cable connector pin on the throttle bellcrank.

4. To ensure that the TV mechanism moves in correct proportion to the throttle opening, the TV cable bellcrank must be perpendicular (90 degrees) to the TV cable when the throttle is about a quarter open. The cable connector pin's mounting location must be established on the throttle bellcrank at a radius of 1.094 to 1,125 inches (also see step 3). If there is no suitable existing hole in the bellcrank, drill a new hole or fabricate a suitable attachment, as required, to properly locate the connector pin.

5. The proper location of the TV cable mounting bracket is determined by the angular and radial position of the TV cable connector pin on the throttle bellcrank. Make sure that other cables and rods will not interfere with the TV cable. Mount the TV cable adjuster housing so that the lock tab is readily accessible.

6. Fabricate the bracket using .090- to .125-inch sheet metal to these housing cutout dimensions. If thicker stock is used, a chamfer is required on two sides of the cable mounting cutout to allow the lock tabs to expand properly. The adjuster requires approximately 18 pounds pull to ratchet out, so make the bracket as rigid as possible.
tec2002.jpg
 
I just tried this modification on the governor in my 86 Olds 442. Previous owner had swapped in a Turbo 350 so I hunted down a 2004r, came out of a station wagon. Had my local tranny guy rebuild it. But it shifted way too quickly. Now it shifts just like I wanted. Thanks for these tips.
 
I found this posted else ware but figured some guys here could use the info also

When you upgrade to a 200R4 OD transmission to get the benefits of the 0.67 overdrive, it is rare that the automatic shifting sequence occurs at the proper speed. Most likely you have lower rear end gears and a cam so you want the shifts to occur at a higher RPM but the donor tranny is likely set up for a grocery getter and results in 1-2, 2-3 shifts way too slow for your setup. Thus you are stuck with manual shifting which is fun but there are times you want to set it in drive and run it automatically.

A lot of people suggest changing the shift points by adjusting the throttle cable. DON'T DO THAT! That cable needs to be set properly and left alone. It is the governor that sets the shift timing and you have to modify it.

We did ours on our '59 El Camino running a 307 w/ corvette cam & 283 PowerPack heads. We put 3.54 gears in the rear so our auto shifts were occurring @ ~1000rpm lugging the engine badly.

We bought a couple spare governors from PATC Automotive who specializes in 200R4 trannys.

http://www.transmissioncenter.net/200-4r.htm

I am giving them a plug because their authentic GM parts governors are less than $10! We bought two to play with.

It is a hassle to do this modification because you need to take the pan off to get at the governor. There are YouTube videos on doing that step so look it up if you don't know where the governor is. It is an easy swap. Here is a good video

http://video.search.yahoo.com/video/pla ... 11a6g44gh&

http://video.search.yahoo.com/video/pla ... 11a6g44gh&

http://video.search.yahoo.com/video/pla ... 11a6g44gh&

Photo 1 shows the modified governor on the left and the stock one on the right. We took a huge amount of weight off the modified one (power hacksaw and files) but we took the design from a picture of a governor from a Grand National Buick. Plus we still have two more to play with if we screwed this one up. We cut half the skirt off the small weight and ground the top of the large one even with the top of the small one, about 1/8".
200r41.jpg

Photo 2 shows an end view of the small weight. These things come apart very easily knocking out the pin at the base of the weights. Watch where the two ball bearings go! When putting them back together, 'glue' the bearings in their holes w/ Vaseline.
200r42.jpg

Photo 3 shows a couple more modifications we made. First we took out the spring in the big weight leaving the spring in the small one. We took our cue on this again from the Grand National Buick version. Second, we brazed a short nail in the spring hole in the small weight. Word is that that spring has a tendency to hop out on hard shifts so this is a common hi performance mod.

200r43.jpg

Photo 4 shows another view of the nail.
200r44.jpg

There are other sites on the web showing how to calibrate the speedometer by changing our the big plastic barrel gear on the shaft of the govern with the speedo gear that is removed by taking off the speedo cable at the back of the tranny. Do that while you are doing this. I think PATC sells the cheapest gears too. They have a ratio calculator on their site so if you know your tire diameter and rear end ratio, you get the perfect speedo ratio.

Oh, we ended with perfect shift points for the street; ~2000rpm @ 1-2 and 3000rpm @ 2-3. We havent tried it yet but I assume at WOT the shiftw will rise accordingly to higher in the power band.
Hey Rick, thats the same pictures somebody posted when you said yours was shifting too early, I still, as I said before think I can do those mods to the governor for you easy with a small angle grinder and a file. The mod for the spring is easy drill a hole for the peg and weld it in.
 
Too many other things to do first, but when I do get ready to modify the governor, I
will let you know if I can't grind it myself. I already have the post to keep the spring
from jumping out.
 
I'D REMIND YOU THAT INSTALLING A TRANS FLUID COOLER ,WOULD BE A BIG potential IMPROVEMENT TO DURABILITY
now you of course have lots of options for that t-bucket , one Id consider almost mandatory

http://www.summitracing.com/parts/prm-13318
prm-13318.jpg

Twisted_Metal" said:
This is my first draft of a write-up of the process to convert a TH350 3-speed auto LATE 2nd gen Camaro to a 2004R 4-speed Overdrive tranny.

Parts you need: (Listed by the supplier I used.)

2004R 4-speed OD tranny (Purchased locally in a recently rebuilt condition...$520)
Flexplate (Stock is fine. Mine was bent and needed to be replaced.)
Shiftworks:
Shifter cable (The stock one should work but mine needed replacing.)
Shifter conversion kit ($80)

Shiftworks Camaro Shifter Conversion

The detent in the shifter is quite a bit different.
detents.jpg


BowTie Overdrives:
Lock-up Converter ($175)
Lock-up Wiring Kit ($70)
TV Cable & conversion kit ($110)
Speedo Gears ($60, I needed both gears.)
Crossmember (The 75-81 crossmember is different from the 70-74 style. $175)
Torque Converter cover ($20)
Dipstick (Universal $30)
Gasket & Filter
All new hardware for everything ($30)

Ebay:
B&M Super Cooler tranny cooler ($40)

Total parts cost= Approx. $1365

The Tranny preparation....

Clean out pan.
Install new speedo gears.
Install new lock-up wiring. (Good instructions with kit.)
Replace Throttle Valve return spring with one from TV cable kit. (Again... good instructions.)
Replace filter.
Install lightly greased gasket.
Install Shiftworks conversion shift arm on tranny.
Place the shifter cable bracket on the pan & torque pan bolts to case @ 9ft/lbs.

The tranny is ready for installation!
biggrin.gif


Shifter Preparation:

Remove shifter from car.
Install Shiftworks kit following the instructions.
Reinstall shifter. (Then cuss about the lousy label they use to redo the gear indicator lettering on the plate. It is invisible at night!)

Design new shifter indicator part and hand letter new letters with white paint ofn the back side of the plexiglass I used.
Reinstall all shifter components.

The newly converted shifter will still work quite well on the TH350 so this can be done ahead of the tranny install.

Camaro Preparation:

Install Tranny cooler. (Follow kit instructions anf use zip ties or create your own mounting configuration.)

Disconnect downshift cable from carb and remove carburetor from intake.
Install the TV cable conversion hardware.
Reinstall Carb.
(The TH350 downshift cable will need to be disconnected from the carb to allow the new hardware to fit.
You can still drive your TH350 but you will need to downshift manually.)

Wire the car's portion of the lock-up harness.
(I added a lighted switch so I could see when the lock-up feature engages.)

The car is ready!
biggrin.gif


Installation:

I got lazy here and paid AAMCO to watch them perform the actual tranny swap.

Disconnect battery ground and remove distributor cap so it doesn't get cracked while you jack around on the engine and tranny.

After getting car high enough on tall jack stands or a hoist...
Drain pan, remove torque converter cover, and dipstick tube, disconnect driveshaft, cooling lines, detent cable, backdrive linkage, modulator vacuum line and speedo cable.
Support tranny with a jack.
Remove crossmember bolts.
Remove tranny to engine block bolts and TC to Flexplate bolts.
Remove crossmember.
Lower tranny.


Put fluid in new lock-up torque converter.
Mount TC to tranny. (MAKE SURE it is fully seated in the pump tangs.)
Raise tranny in place and align with pins on block.
Install crossmember and bolt the tranny to the block and crossmember.
Install dipstick/fill tube.
Connect speedo cable.
Connect shifter cable. (Some adjustment to Shiftworks bracket was required.)
Connect cooling lines. (Some bending is required. The fittings are the same between the two trannys.)
Reconnect driveshaft and backdrive linkage.
Plug in the lock-up wiring.
Connect TV cable to carb and tranny.
Cap the open vacuum connection at intake.
Fill tranny with fluid.
Reconnect battery and install distributor cap.

Lower car and enjoy Overdrive!

Problems encountered:

Shiftworks .... Poor design on shift indicator labeling. (built my own as a solution.)
Tranny mounted bracket needed to be modified to get better geometry on the shifter arm.

BowtieOverdrives... Crossmember interference with stock exhaust flange at the inlet to the catalytic converter.
Cat was removed for the install but Y pipe needed to be shortened for clearance. An aftermarket cat was then welded into the exhaust system after the tranny install was completed.


http://www.tciauto.com/tc/trans-dim

http://www.superchevy.com/how-to/46140-chevrolet-transmission-swap-guide/

http://www.superchevy.com/how-to/60978-transmission-swapping-tech/

http://www.rowand.net/Shop/Tech/AutomaticOverdriveTransmissionSwap.htm
2000r4.png

auto_trans_id.jpg


if your cars got an automatic transmission and a higher stall speed converter its a damn good idea to install an auxiliary trans fluid cooler with an electric fan,
OK FIRST LOOK UP THE TRANSMISSIONS FLUID CAPACITY
HERES A LINK


http://fluidcapacity.com/
http://www.cartechbooks.com/techtips/autotransfluid

keep in mind most performance cars with an auto transmission and a higher rpm stall converter, will need an auxiliary trans fluid cooler, Id strongly suggest you find one with an electric fan and 1/2" or AN#8 line size as you'll want to allow a minimum of 2 gallons a minute trans fluid flow rate

its CRITICAL to keep the trans fluid clean and ideally changed about every 70K miles and use of a auxiliary cooler that keeps the fluid temp under about 170F is going to extend service life a good deal longer
Ive helped do at least 7 of these big block engine swaps now for other people and obviously results vary with the components being used but most of the swaps required a trans cooler and Ive installed 2 now in the rear tire carrier area, 200f -230f temps on trans fluid are very common on stock transmissions, with stock original engines when your beating the hell out of the trans racing, but 190f-210f on the street while cruising is more common using the stock radiator trans cooler in the lower radiator trans fluid cooler.
I had a larger than original capacity aluminum aftermarket radiator most of the time , in my corvette even with the current 383 sbc, and if I ran a 180f T-stat both the coolant and trans fluid tended to run about 190f UNTIL I swapped to a 3200 stall converter , where the temps jumped noticeably by about 20f higher, if I pushed the car ,but those temps dropped rapidly if I was just cruising in O.D. but I felt I needed a better system, to cool the trans fluid, adding the additional rear mount aux cooler drops temps to 150f-160f with the fan on and about 170f=180f with it off even if Im pushing the car so I wired a switch to the fan, and a sensor that turns the fan on at 175F

http://www.summitracing.com/parts/der-16759

http://static.summitracing.com/global/i ... -16759.pdf
garage25.jpg

cooler+diagram.jpg

faq098.jpg


internal cross sectional area of the fluid transfer lines matters, anything less than 1/2" or AN#8 can be restrictive to flow
Sizing-FittingThreadx.gif


fluidcapk.png

fitsp1.png

fitsp2.png

trn_dim_small.jpg
 
Last edited:
Did you mean to post a link to a Dual Circuit Cooler. I'm not having any trouble
with radiator coolant temperature measured at the input to the radiator.

I'm going to use a passive cooler, if that don't work then I will add it to my air
compressor cooling and buy a cooler and fan similar to your link above. It takes
45 minutes to reach 200° F, so it don't seem to be a big problem. I would go
over kill if I had the wiring room for more devices. I've yet to wire the AQ-1,
which should add another 16 wires to an already crowded space under the
seat. I'm going to need another 8 terminal block, but where?
 
yeah I posted a dual cooler simply because having both the trans fluid and engine oil running through it may stabilize both and allow both fluids to reach operational temps a bit faster.
now If you have read through a previous thread, posted on the site, you might remember I started out with a dual fluid cooler, installed on my corvette, and converted to a larger single fan cooled trans fluid cooler , and just use the large oil pan and large oil filter to cool engine oil along with the factory installed oil cooler above the oil filter, simply because Id found that engine oil temps rarely if ever needed cooling with my large baffled oil pan, but the trans fluid temps DID benefit from the additional cooling, and yes theres zero doubt my 3400 plus lb corvette with a 3000 rpm stall converter generates more trans heat than your t-bucket

https://www.monstertransmission.com...Complete-Rebuild-Kit_p_5059.html#.XlKgHmhKi9I

https://www.oregonperformancetransm...MIo5qR04To5wIVgYbACh08fAqOEAQYBiABEgJrKvD_BwE

http://garage.grumpysperformance.com/index.php?threads/200r4-mod-info.7116/#post-51649





http://garage.grumpysperformance.com/index.php?threads/cooling-off-that-c4-corvette.3954/

http://garage.grumpysperformance.co...sion-and-oil-cooler-increases-durability.176/

http://garage.grumpysperformance.co...ans-cooler-on-a-c4-corvette.10514/#post-44498

https://haynes.com/en-us/general-mo...MIo5qR04To5wIVgYbACh08fAqOEAQYByABEgI5rPD_BwE

https://www.hemmings.com/blog/article/gm-th200-4r-transmission-conversions/

HEMMINGS MUSCLE MACHINES
GM TH200-4R Transmission Conversions
By Jim O'Clair from the January 2006 issue of Hemmings Muscle Machines

SHARE


GM TH200-4R has an economy 0.067:1 fourth gear

With gasoline prices reaching all-time highs, some of you may have considered converting your two-speed Powerglide or even your Turbo Hydra-Matic 350 or 400 to a more miserly overdrive transmission. Many enthusiasts recommend installing a TH700R-4, however another alternative for an overdrive on the cheap is the TH200-4R. Because the TH200-4R uses less engine horsepower to operate than any of the two- or three-speed transmissions, not only will you save some money on fuel, but this transmission will allow your engine to operate at a lower rpm, saving you wear and tear on the engine as well. Converting to an overdrive transmission also allows you to add taller rear differential gears without sacrificing fuel mileage.

These transmissions, when properly adjusted and maintained, can be as reliable a unit as any other GM automatic. TH200-4Rs are also readily available from your local pick-a-part because they were used in many different GM body styles, from A and G-Bodies right up to full-size cars. That means when you do find one, most of them can be pretty inexpensive as well.

The TH200-4R was used in all GM nameplates, including Cadillac. Production of this transmission began in 1981 and they were used continually up into the early 1990s. The TH200-4R is an adaptation of the TH200 with the addition of an overdrive drum that adds an overdrive gear.

The TH200-4R can be identified by its odd-shaped 16-bolt pan, which roughly resembles the state of Nevada (check your maps), and the transmission pan bolts have 13mm heads. The TH200-4R was used in GM rear-wheel-drive cars equipped with the 231 Buick, 301 Pontiac, the Oldsmobile 307, as well as the 350 gas and 350 diesel engines from 1981-’90. Many Chevrolet 267 and 305 engines also used the TH200-4R with a multi-fit bellhousing. You can look for one in any of these vehicles with those engine sizes:

1981-’88 Buick LeSabre and Electra RWD
1981 Century
1981-’87 Regal
1981-’90 Cadillac Fleetwood, Deville and Brougham
1982-’90 Chevrolet Impala and Caprice
1981-’88 Chevelle, Monte Carlo, Malibu and El Camino
1984-’87 GMC Caballero
1982-’90 Olds Delta 88, 98 and Custom Cruiser
1983-’88 Olds Cutlass 4-4-2 and Supreme
1983-’89 Pontiac Bonneville, Parisienne and Safari Wagon
1981 Pontiac Firebird with 301
1984-’87 Pontiac Grand Prix

The transmission identification is on a plate on the right side of the case towards the tailshaft. This ID tag is usually held on by one rivet. The plate will have a two- or three-letter transmission code in large letters, and then a 13- or 14-digit identification number along the bottom:

1st digit: month of production (A through M, skipping the letter “I”)
2nd-3rd: production day of the month
4th: shift transmission was produced (1st-3rd shift)
5th: assembly plant (T: Three Rivers, MI; J: Windsor, Canada; W: Warren, MI)
6th-7th: decade and year
8th-9th: or 8th-10th: transmission ID code
10th-13th: or 11th-14th: transmission serial number

The TH200-4R, like the TH350, uses a 27-spline input shaft. It is also similar in length to the TH350 and the TH200, making it a natural for conversions where an overdrive transmission is desired. The TH200-4R is also similar in length to the Powerglide as well, which makes it a natural for converting from a two-speed to a four-speed automatic. Overall dimensions for the TH200-4R will be added to our online database, located in the parts locator section of our website: www.hemmings.com/parts-locator.

Shift ratios for this transmission: 1st 2.74:1; 2nd 1.57:1; 3rd 1.00:1; 4th 0.67:1.

As a rule of thumb, the taller the rear-end gearing you have in the car, the more gas savings you will realize. Generally, installing a TH200-4R in a passenger car with a gear ratio of 2.73:1 or less will not give you much in the way of fuel economy. This is because when the 0.067:1 overdrive gear is applied to the 2.73:1 differential ratio, this will reduce your final drive ratio to 1.82:1. Final drive numbers that low can actually work out to be worse for your gas mileage than sticking with your stock transmission. So rear-end gearing is something you should check into before considering this conversion.

The most desirable TH200-4R for speed enthusiasts are the units manufactured for Buick Grand National, Olds 4-4-2 and Chevy Monte Carlo SS in 1986-’87. These units used a special valve body. They also had a larger reverse boost valve and 2nd to 3rd intermediate servo and a specially designed governor assembly. Buick units are identified by the BQ or BRF transmission codes. Monte Carlos used the CZF code. The Hurst Olds/4-4-2 units had a KZF or an OZ code. Many aftermarket suppliers offer an upgraded replacement valve body to retrofit into all TH200-4R transmissions. It duplicates the design used in these G-body transmission codes. The governor on a standard TH200-4R is designed to shift at about 3,000 rpm leading to a quick upshift through all four gears using a minimum amount of power. The specially designed governors used in the aforementioned performance transmissions are designed to shift at over 4,500 rpm making more efficient use of your engine’s power band. Performance governors with this higher shift rating and the larger boost valves are available from the performance transmission parts suppliers as well.

When purchasing any used transmissions, we always recommend that you go through the transmission thoroughly before installation. Check the condition of the steel and friction clutches and the passages in the valve body carefully. You should always change the fluid, fluid filter and oil pan gasket, and you might want to consider installing a shift kit while you have it apart. It is much easier to do it now while it is on the kitchen table instead of later while you’re on your back on the cold ground.

This transmission is a great candidate for swapping into cars with a TH350 or a Powerglide, because the overall length and the bellhousing bolt pattern of the TH200-4R are the same, and your original driveshaft does not have to be shortened. Moving the crossmember will be necessary though, because the TH200-4R crossmember is mounted on the extreme end of the tailshaft. Using an aftermarket crossmember in vehicles where the crossmember must be moved back makes this relocation much easier. It will save you the trouble of re-drilling mounting holes and shortening the crossmember in some cases.

On a TH200-4R, the length and adjustment of the detent cable is critical. One of the biggest complaints about the reliability of the TH200-4R can be traced back to a poorly adjusted detent cable. When installing in an earlier vehicle that used no detent, you will need the proper cable for the transmission you are installing as well as a bracket kit to connect the carburetor end to the throttle linkage. There are some really trick steel-braided aftermarket detent cables available too.

When exchanging the TH350 with the TH200-4R, the existing TH350 detent can be used, but it is best to make sure the cable length is the same as what you need for your particular engine size. The engine computer activates the torque converter lockup; however, an aftermarket universal lockup adapter can be purchased for non-computerized cars and trucks. We have seen some toggle-switch-designed lock-up creations that have been made to replace the lock-up adapter too, but we recommend the pre-packaged lockup adapter to make the exchange look a lot more professional. Some of the aftermarket lockup adapters contain a manual override setup, if you need that option for a racing application. Whatever method you choose, the lock-up should be used or the torque converter will slip too much and cause a lot of extra heat in the transmission. This will lead to early transmission failure.

GM also sells many replacement speedometer gears available to correct for inaccuracies in the speedometer, after this installation is complete. If your speedometer is reading low, you add driven-gear teeth. If your speedometer is reading too high, you subtract driven-gear teeth. Each tooth up or down will change your reading by about 5 percent. A listing of GM part numbers is also included on our www.hemmings.com/parts-locator web site in the same parts locator section where the transmission dimensions are displayed. The easiest way to calibrate how far off your speedometer is reading is to take the car to an area where you can do 60 mph and that has mile markers. Measure the amount of time it takes for you to travel mile marker to mile marker holding your speed at 60 mph as indicated on the speedometer. Your actual miles per hour will be 3,600 divided by the time taken to travel that distance:
Actual MPH = 3,600 ÷ Elapsed time in seconds to complete 1 mile

For example, a time of 65 seconds indicates a speed of 55.3 mph, an error of 4.7 mph (or 8 percent) lower than actual speed. In this particular example, you would add two teeth (10 percent) to correct this reading.

The TH200-4R can be a great transplant unit for AMC, Ford and Mopar as well. Adapters are available to mate the multi-fit bellhousing to many different makes. In fact, just about anywhere that you can transplant a TH350, you can substitute the TH200-4R.

As we mentioned in this column in the November 2005 issue, many collector cars can benefit from this conversion as well. This includes Hudson, International trucks and Studebakers, in addition to early Buick, Chrysler, Lincoln, Cadillac, Ford and Edsel engines.

If you were scouring through a salvage yard looking for a unit with a multi-fit bellhousing, it would probably be a little easier to check out the full-size Cadillacs first. Most of the used multi-fit units you are going to find these days seem to be turning up on Cadillacs, because most of the Chevrolets may have already been picked through. If you have to remove the used unit yourself, or you are calling ahead to have the unit removed, make sure to grab the detent cable, ECM lockup harness, and the 27-spline slip yoke from the driveshaft. If the transmission was already removed and the yoke is not included, Spicer makes a new replacement slip yoke that fits the TH200-4R as well as the TH350, and mates to the 1310 series driveshaft used on GM cars and trucks (Spicer part number 2-3-4911X).

Checking into finding a TH200-4R at a reasonable price, we discovered used transmission pricing for a TH200-4R with the B-O-P bellhousing runs between $350 and $450. If you happen to find a BRF code unit, they run about $800 used. (We did actually manage to find one BRF code in Florida for that price.) Rebuilt units with the B-O-P bolt pattern are available for around $1,050; however, that pricing reflects having a trade-in unit to return.

Multi-fit units with the bellhousing for Chevrolet and everything else run anywhere from $375 to $600 for a good used one. We could not locate a multi-fit CZF-coded unit used at any price. This is probably one instance where finding a decent used unit and building it up to simulate a CZF-coded transmission is your best course of action.

Opting to convert to a four-speed automatic will pay for itself in the long run. Although many are of the opinion that the TH700R-4 is the way to go, a TH200-4R uses much less engine horsepower to operate, and with proper modification can handle engines producing up to 350hp.
 
Last edited:
Back
Top