TH-200-4R Trans Detail

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General Information

I highly recommend checking out the Buick Grand National web site at http://ni.umd.edu/gnttype/www and visiting their technical archives. In which you'll find plenty of documentation on this tranny and plenty of recommendations and personal experiences with shift kits.

Most TH-200-4Rs use a universal bell housing design. This will fit the BOPC bolt pattern and the Chevy bolt pattern. The starter for Chevy's are on the right, while starters for Olds are on the left side.

[ Thanks to for this information. ]

Governor
The governor is mechanical, and only controls shift points.

[ Thanks to Greg Pruett for this information. ]

Tag Decode
For example, a TH-200-4R transmission tag:

___________________________________________
|   60                         G           |
|                                          |
|                                          |
|  117                    1T86OG0346       |
____________________________________________
117 = Julian date of day of year
1T86OG0346
1 = shift built 1, 2 or 3
T = Three Rivers
86 = Model year
OG = Model
0346 = Serial number
[ Thanks to Matthew Mayer for this information. ]

Torque Convertors
For pre-1989 TH-200-4Rs, the lockup torque converter is the only thing the computer has to do with the transmission. This control is only on or off.

[ Thanks to Greg Pruett for this information. ]

Buildup

BTW: The info I am passing on here is something I learned first hand. I had an 84 Olds Cutlass OG trans built for my 403 powered 79 Cutlass. I cannot begin to tell you how dissapointed I was when I first installed it. It shifted terrible and really took away from the enjoyment of hammering the car. With out a word of lie, there was times when I had the tranny pan off 5 or 6 times a night. I would drop the pan, drop the valve body, change something, reinstall everything, take it for a burn, and start all over again. It got to the point where I was just draining the fluid into a clean pan and then dumping it right back in. I spent almost two full summers working out the bugs, but it all paid off in the end. Thats why I am trying to help everybody out with these trans so they don't have the same problems as me. I really learned the hard way.

All suggestions I've heard from quite knowledgable and experienced people were to "Grand Nationalize" the TH-200-4R. Just a basic rebuild will not help the trans last too long, but with the GN components and a shift kit it will last and be able to handle lots of torque for a long time. One guy, who has succesfully built over 20 12-second or faster cars, put one in his 84 Malibu wagon with A Chevy 400. He said he bought a TH-200-4R at a junkyard for $175 and had it "Grand Nationalized" for about $200. Not a bad deal at all to step into the overdrive advantages. He chose the TH-200-4R over the TH-700-R4 because, in his experience, the TH-200-4R holds up better and can handle more torque.

A rebuilt TH-200-4R with the race hardened parts and a clean system, should more than handle anything that you could do to the 307 including nitrous. Art Carr claims that the TH-200-4R and TH-700-R4 can handle about 600 ft. lbs. of torque and 700 hp.

Core to Use
You can use a plain Caddy tranny if you want, but if you want it to perform like a built TH-350 or TH-400, you will have to upgrade it.

Parts to Use
The two most important things that will affect how it performs are the valve body and the governor. A plain valve body uses the same casting as a performance one (GN, 442 etc...) but the valves inside it have different diameters. Not just one or two valves, but a majority of them. The plain ones have a very mushy shift to them. 9 times out of 10 a shift kit will not correct this. Take a look on the Turbo Regal web page, there are pages and pages of problems that guys had with shift kits. The governor determines the WOT shift points, and the plain ones are designed to shift at 3000 RPM @ WOT. The performace ones vary from 4500 to 5200 depending on the model.

Sure, you can buy these parts are the dealer. The valve body costs around $600 and the governor costs about $60. This is why I recommend locating a performance one to begin with. Keep in mind that there are also a few other parts that you need also.

The valvebody for starters. There were a lot of differences there that stiffened up the shifts. The 442, Regal GN and Monte SS had similar high-performance valvebodys, I think buick trannies got the best. Also, the 1-2 servo apply pin is a different legnth, longer I think. The governor shifts at a different RPM too, 5000 RPM instead of the standard 3000.

Make sure the TH-200-4R has hardened stator shaft (to prevent peened splines), shift kit, and heavy duty input shaft/clutch drum. See Buick Regal GN/T-Type web page for TH-200-4R build up tips.

Line Pressure
What little I can say is according to the service manual, the line pressures are the highest in the OZ trans. The Cadillac AA has the lowest. Gearing is all identical. I am sure shift points are different, and the higher line pressures will make for firmer shifting. Also the valves in the trans are larger in the better trans.

Shift Kits

Torque Convertors
For an "OZ" torque convertor, it is a part # "8653400". This is written on the yellow tag along with the letters "CBBF".

[ Thanks to Tom Millard, Thomas Martin, Ray Costanzo for this information. ]

Buildup Examples

Low Buck Strong Shifts
After installing a B&M shift kit in my 442, I was not happy with the shifts.

I originally installed the medium level firmness which included the stronger pressure regultor spring and drilled out spacer plate. The 1-2 was still hard at part throttle and soft at WOT. I then added the 1-2 accumulator spacer and line bias spring. Now it was harder at WOT, but still somewhat mushy. Also, the WOT shift point was varying between 4800 and 5500 depending on how much I was rolling before stepping on it. I decided to remove the accumulator spacer, the line bias spring, drill out the spacer plate holes slightly larger, and install the Grand National intermediate servo piston and cover. Now the 1-2 was firm but not harsh at part throttle but at WOT it would bark both rear tires hard. The WOT shift points were still varying. Finally, I pulled the pump pressure regulator spring out and re-installed the stock spring.

At this point, all B&M parts were removed from tranny. The WOT shift points are solved. It now shifts at 5000 RPM no matter what the conditions. The part throttle shifts are quick but not too firm, and the WOT shifts are strong, but not neck snapping. I am very happy with it at this point.

So the final mods were - 1) Spacer plate drilled out to 1/8" on holes (as recommended by Art Carr), and 2) Grand National Intermediate Servo Piston and Cover assembly.

[ THanks to Steve Ochs for this information. ]

Rebuilding

Tuning

Governor
Replace the governor if its only shifting at 3600 RPM. Get one for a Monte Carlo SS or 442 which will shift the highest of any 200-4R governor (5000 RPM).

Here is the scoop on 200-4R governors:
The governor in a 200-4R controls wide open throttle (WOT) shift points. The governor consists of (2) weights and (2) springs. The lighter (smaller) the weights, the higher the shift points.

All non performance trans received governors that were designed to shift at 3000 rpms WOT. Monte SS (CZF) trans shifted at 4800 rpms WOT as did the 442's. The 84-85 Turbo Regals shifted at 4800 rpms WOT, the 86's shifted at 5200 WOT, and the 87's shifted at 5000 rpms WOT. You can buy these directly from GM at about $60 garage cost.

Some common governor problems: Occasionally when the trans shifts from 3-4 at WOT, the springs in the governor like to fly out. This will cause a no-shift at WOT from any gear. The solution is to drop the pan, take out the governor and put the springs and check balls back in it. It should be noted that the 86 & 87 TR trans only have one spring (thus higher WOT shift points).

It should also be noted that the trans line pressure also influences the WOT shift points. It you use Art Carr's high pressure valve and spring, the RPM's quoted above might increase. I ran into a problem where my car would not shift at WOT. I checked the springs in the governor as mentioned above, but that wasn't the problem. I had the Monte SS governor in the trans as well as Art Carrs high pressure spring and valve. I wanted my 403 to shift at 5000, but the RPMS kept creaping pass that at WOT. I felt it eventually would shift at 6000 rpms or so, but at the expense of my 403 staying in one piece. So I put the original Monte SS valve and spring back in the trans and lowered the line pressure considerably and that solved the no shift at WOT problem. Now the car shifts a 5000 rpms very consistently.

[ Thanks to Tom Millard, Steve Ochs for this information. ]

Miscellaneous

The tail shaft housing for the TH-700-4R that will allow it to bolt to the cross member in the same place as a TH400 (with a TH400 mount) the GM# is 8673406.

Swapping

Throttle, TV Cable Brackets and Linkage
The only bracket that is different would be were the throttle cable connects as well as the TV cable. All 307 Olds powered cars with Q-jets had this bracket. I am sure you can find it at the junkyard for peanuts. Once again since the TH-200-4R originally came in cars with Rocket V-8s, you should be able to find a correct throttle cable bracket that would fit your 403. A modified TH-350 kickdown cable brakcet might do the trick too.

The linkage from the TH-375 in my Vista Cruiser works fine with the TH-2004R. The shifter cable bracket that mounts to the side of your 3-speed will need to be transfered to the 4-speed. Dunno if the bolt patterns will match but you can probably re-drill it. If not then you can get the correct bracket out of the junkyard.

The shifter detents in the VC matched up with the 2004R shift pattern, and the gear indicator worked well. The P,R,and N match up, D indicates overdrive, S indicates drive, and L indicates second. The needle just slides off the scale for low. I don't have an overdrive in my calais, but I was looking at the shifter when I had the console off and it looks like you could do the same with it. You may need to modify the detent plate with a little creative hacksaw work to allow it to shift into first.

[ Thanks to Greg Pruett for this information. ]

TCC Lockup
If you keep the lock up converter, you can wire it up yourself. It is very simple. You don't need a computer to control this transmission. Lockup control is the only tranny function handled by the computer.

You just need a toggle switch on the dash that puts 12 volts to the lockup torque converter. You'll need to cut the plug that connects to the transmission off of some car in the junkyard that had a 200-4R. You turn on the lockup when you hit your desired cruise speed and turn it off when you slow down to less than 35 mph. Total cost in parts: $15.

The lockup saves you some mileage by cutting down engine RPM by a few hundered at cruise. It's supposed to be worth 1 MPG or so. It also helps the tranny run a little cooler.

For your lockup converter (which you WILL need to prevent excess heat generation), use the system used on 1986 and previous Canada TH-200-4Rs which did not have a computer. I believe it used 3rd and 4th gear switches in the tranny, brake switch, and vacuum switch. This would make it automatic instead of using a manual switch.

The lock up converters have a clutch in them that engages once the car is cruising to increase mileage and reduce heat in the transmission by eliminating torque converter slippage. The torque converter clutch works just like a manual transmission clutch when it's engaged. When it's disengaged the converter acts just like any other converter. They have an added advantage in that you can use a high-stall converter and still get decent mileage.

The lockup is activated by computer in stock applications but you swap the tranny into an older car (i.e. no computer) the lockup can still be activated. It's just a matter of applying 12 volts to the correct pins in the little electrical connector on the transmission case. There are kits availible that will lock up the converter automatically for you when the tranny is in overdrive, but you can get away with just having a toggle switch somewhere that you can turn on yourself when you want lockup. You just have to remember to turn it off when you don't need it.

Most of the time the lockup converter is the way to go. The non-lockup are more for serious drag strip cars because they're lighter. They save some weight and are less stress on the input shaft of the tranny but unless there's serious horsepower involved they're not neccesary.

Driveshaft
The 350 and 200-4R are the same length and use the same yoke, so there's not need to cut the driveshaft. All you have to do is relocated the crossmember further back. The 200-4R is very close to the legnth of a TH-350, so if you already have a TH-350 behind that 403, you probably don't need any driveshaft modification. Even if you did you should be able to find the driveshaft out of a cutlass that originally came with the 200-4R and use it. If for some reason you do have to modify your driveshaft, it shouldn't cost much more than $150.

Shifter
With any luck the factory shifter should work with a little linkage adjustment. That's all the column shifter in my Vista Cruiser needed when I swapped the TH-2004R in. You might need to modify the detent plate to get the shifter to move far enough to manually shift into low, but I didn't have to and I haven't heard of anyone needing to do that yet. My gear indicator is slightly off since there's no symbol for overdrive. "Park",. "R" and "N" work fine but it reads "D" for overdrive, "S" for drive, "L" for second gear, and it'll just slide off the scale for low gear. I would think that you'll get similar results, can't say for sure though.

Time Required For Swap
You can do it yourself if you have some basic tools,a good jack, and an extra weekend. It would be an unbolt-rebolt procedure if you can swipe all of the parts you need off of a junker.

[ Thanks to Tom Millard, Greg Pruett, Steve Ochs for this information. ]

Replacing A TH-200
The overdrive (TH-200-4R) tranny's rear mount is closer to the rear of the case than the non-overdrive (TH-200). In fact, the distance between the rear mount and the bellhousing is almost the same as the TH-400. I think the overdrive and non-overdrive TH-200s are the same overall legnth.

Specifically Into 1964-1972 A-body Cars
When I installed the TH-2004R in my '70, I had to have the driveshaft shortened about an inch. You are not supposed to have to do this, but my just fit too tight for comfort. Also, the bracket on the frame that the pivot arm fits into on the column shift had to be located out just a little, the position of the shift linkage mount on the TH-2004R is a little further inward than the TH-350. I accomplished this by installing washers between the bracket and the frame, about a quarter of an inch worth. I can not be 100% sure you will have the same problems, I think it's more or less a hit and miss type of thing.

On A body cars w/column shift, the bottom shift linkage arm going to the transmission is about 3/4 inch too short. The arm would not stay in the pivot cup. To solve this, I removed the pivot cup from the frame, bought some longer bolts and spaced it out from the frame with 2 nuts on each bolt. This effectively moved the pivot cup out far enough to catch the linkage arm end.

1) On 64-72 A bodies w/column shift, the pivot hole bracket must be relocated out 3/4, because the factory shift are is too short for the TH-200-4R's linkage location. This can be accomplished by installing 2 nuts on each bolt that holds the pivot hole bracket to the frame.

2) This should also be added to the TH-400 sections as well; Because the crossmember must be moved rearward about 3 inch, you need to install a TH-400 intermediate parking brake cable in order to retain parking brake functionality. Located the crossmember rearward created slack in the cable that cannot be adjusted out.

Your best bet would be to use a TH-400 intermediate cable. Another option would be to reposition the two cable idlers further outboard. This may take up the slack.

[ Thanks to Stephen Hoover,for this information. ]



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Submit corrections and additions to this information to The Olds FAQ Compiler.