The Oldsmobile Connection

[nwmaximus]

Overdrive Transmissions- :confused:
TH-200-4R versus TH-700-R4 - Which one should I use behind an Olds
Most people believe that the TH-700-R4 is better tranny than the TH-200-4R. Both can handle 600 lbs-ft of torque and around 700 hp." TH-200-4R's have either a BOP bell housing or a universal bell housing (BOP & Chevy). This makes it a direct bolt in for your Olds.
The TH-200-4R is the same length as a TH-350 and uses the same drive shaft, but has the mount for the cross member in the same location as a TH-400. As for the TH-700-4R, it only has a Chevy bell housing so an adapter plate will have to be used. It is also longer than a 400 by 2".
TH-200-4R versus TH-700-R4 Gear Ratios
One important thing to look at while choosing an overdrive for your Olds is the gear ratios they have. The TH-700-R4 has a huge jump from 1st gear to 2nd gear, which will hurt acceleration. The car will really launch in 1st gear but puke when it hits 2nd. As for the TH-200-4R, the gear jumps are more evenly spaced out, and it has a better overdrive ratio.
You want to make sure you have enough gear in the rear end to keep the engine RPM's a little higher than your stall speed.You might want to change the gear detent plate so that your shifter will have a position for all four gears.
The 200-4R is a good transmission but is very tempirmental and you may need patience to get it to work correctly. And I hear it can self-destruct in a matter of miles if the throttle cable is too far out of adjustment. If the throttle cable is adjusted right and the trans isn't abused, it will last a long time.
Since your car is probably already geared for optimum mileage with a 3-speed transmission you may not gain much with the 200-4R.If you installed a rearend with a lower ratio in conjunction with a 200-4R you could improve acceleration without compromising mileage.
The swap is fundamentally a "bolt-in".It can be performed for less than $500. A TH-200-4R will bolt up just fine, because it's the same bolt pattern and length as a TH-350 or TH-200 or TH-250. See chart above. Thankfully, older Olds' have the frame drilled for just about any tranny imagineable. It DOES however use a TH-350 driveshaft yoke. Doing the reverse, swapping a TH-350 in place of a TH-200-4R is a direct swap.
Cores to Use-
According to Mike, the most important thing in rebuilding a TH-200-4R is the core you use. 1986 and 1987 Turbo Regal transmission are the best cores to use while the 1985 and under Turbo Regal's, Monte SS's and 442/Hurst's are the next best. The reason the 1986 and 1987 TR transmissions are better cores is that they have a larger reverse boost valve, special governor, and a larger 2-3 intermediate servo. The 1985 and under Turbo Regal's, Monte SS's and 442's transmissions are very similiar, and use the same valve bodies (which is important), and they can be upgraded to 1986 and 1987 Turbo Regal types with parts from GM. To determine what type of core you have or need, you have to look at the code. This code can be found on the passenger side of the transmission near the driveshaft and is attached with one rivet. Sometimes these tags were installed backwards at the factory, so it is possible that the code is facing the wrong way. The tag is a small piece of aluminum that will be either natural and yellow or natural and blue, and will have the 2 or 3 letter code on it along with the serial number stamped on it. The serial number will also include the 2 or 3 letter code mentioned above. This code is EXTREMELY important! Most people do not know that there is a difference between these transmissions.
never had any success with any other valve bodies than the ones marked with asteriks above. Although the casting numbers are the same, I am pretty sure that the bore sizes of the valves within the valve body are different. This makes a big difference in the shift quality of the transmission. Gotchas-
The biggest problems you will run into with the TH-200-4R is the rear crossmember mount, the driveshaft, and the throttle cable. The TH-200-4R crossmember mount is the same location as a TH-400.
The transmission is exactly the same length as a TH-350, and it is one inch shorter than a TH-400. If a TH-200 is shorter than a TH-200-4R then you'll need a longer driveshaft. The throttle cable on a 2004R must be located perfectly for the transmission to survive, and an adapter will probably be neccesary to mount the throttle cable. A TH-350 kickdown cable can be used in place of the TH-200-4R cable if it makes adaptation any easier, and there are universal throttle cable mount kits availible.
The torque converter lockup can be controlled with a toggle switch. The gear shifting is done completely by the valvebody in 88 and older(I think) transmissions. Another problem you could run into is the final drive ratio. If the rearend ratio is something like 2.8 or 2.5, the TH-200-4R will give you too high a final drive ratio. For instance, a 2.75 rear end ratio and a .67 overdrive in the TH-200-4R will give you a final drive ratio of 1.8425.
You can either hook up a simple toggle switch (I'd get fancy using a momentary pushutton to energize a relay and light an LED and tie the brake lights into the system to de-energize the relay and unlock the TCC when you use the brake), or Summit sells a kit to lock up the converter in non-computerized cars.
As it is, the benefit would be gas mileage and reduced engine wear from lower RPM's. If you swapped the rear gears out for something steeper, you could gain a bit of performance while still using the overdrive to still keep your RPM's at or below where they were with your 3-speed (in 4th gear).
Parts, Upgrades to Use-
Governor:
The governor in a TH-200-4R determines the WOT shift points while the location of the TV cable determines the shift points at anything under WOT. The tranny's marked with an asterisk (*) above have special governors that will shift anywhere between 4800-5000 rpms at WOT, depending upon their car model application. Stock governors on non-performance based cars shift at 3000 rpm at WOT. This is important because with the 3000 rpm type governor, the transmission will shift from 1-2-3-4 very rapidly which makes for poor acceleration at mild or light throttle.
Upgrades:-
TH-200-4R's. These include a 10 vane pump, heat treated stator, pressure regulator valve, and a shift kit.
Pump:-
To replace the stock 7 vane pump, a 10 vane pump with heat treated vanes and steel rings is used. This reduces irradic pressure readings with the addition of the extra vanes while the very brittle cast iron ring is replaced with a steel ring. (This brittle cast iron ring is a common weak point in the TH-200-4R.)
Heat Treated Stator:
If you look at the stator in a stock TH-200-4R, you will probably observe extreme wear marks on the splines. Art Carr claims that a worn stator will cause premature failure on the thrust bearing in the engine. Therefore, most aftermarket companies sell a heat treated version to replace the worn stock one. This has to be pressed into the pump, and costs around $70.
Pressure Regulator Valve:
To increase the line pressure and also reduce pressure fluctuations, the stock pressure regulator valve can be replaced with a 'performance' one. This costs around $20 and is available from Art Carr and Mike Kurtz @ PMAC. My trans kept starting off in 2nd gear as well as not shifting at WOT from 1-2. I spoke with a tech at Level Trans and he told me to replace the high pressure regulator valve and spring with stock items. I used a valve and spring from my 1986 Monte SS core and this completely solved the problems.
Shift Kits:
There are a couple of kits available on the market, but the one most of the guys on the TR list recommend is the one from Mike Kurtz. His kit is a modified Trans GO kit that works very well. I have installed it on my transmission and am very happy with it. B&M also makes a kit that works well, but a few guys have had trouble with them. As for the Trans GO kit, they strongly recommend you avoid this kit due to a missing parts, etc. One of the newer Trans Go kits has you drill the valve body itself which is bad news since you can never go back to where you started. Keep in mind that a new TR valve body from GM costs over $500 with a $250 core charge.
Overdrive Activation:
The overdrive in a 200-4R is activated by the valve body in the trans if it is an 1988 or older. The torque converter lockup is activated by computer. You could either ignore it and suffer in gas mileage or activate the lockup via a switched 12 volt source. There is also a kit availible that will lockup the converter automatically using some type of pressure sensor in the valvebody. If the car was originally availible with the overdrive then the means for automatic lockup by the car's computer may already be there. Ignoring the lockup may cause exessive heat buildup due to the torque converter slippage, and lead to premature transmission failure.
Results-
My TH-200-4R resides in my 403 powered 1979 Cutlass. The car is equipped with 245 60 rear tires with an overall 25.75" diameter. I just installed 4.10's in the 8.5" 10 bolt and the engine tachs 2350 rpms at 70 mph in 4th gear! With 28x9 slicks, the car crosses the traps in the quarter at 5000 rpm in 3rd gear (high 13's at 97 mph).
TH-700-R4 Swap
There are a couple of things to keep in mind when searching for an overdrive tranny, whether it be an automatic or a standard. To mention a few, one would be gear ratios while another would be practicallity. Also, The early TH-700-R4 had a different spline count than the current ones, and suffered in quality.
As for the gear ratios, if you ever plan on racing the car (¼ mile or whatever), be leery of the TH-700-R4. Although 1st gear is extremely low, 2nd gear is much higher, which really hurts acceleration. The car will really launch in 1st gear but when it hits 2nd it will puke. As for the gear ratios for the 6 speed, I cannot quote the exact numbers, but I do know that some of the gears are very close to one another, and therefore you can skip gears with no problems.
As for praticallity, an adapter plate will have to be used for the TH-700-R4. TH-700-R4's have Chevy bolt patterns so it will have to be converted to a BOP. Hot Rod did an article on a 4L80E build up, and since it is behind a 3.8 Buick V-6, it will work behind an Olds (maybe they ran an adapter plate as mentioned before). The only problem with this is that the transmission requires a computer, which is a little more than most people want to tackle, especially in older cars. Aftermarket kits are available to take care of this.The TH-4L80E is essentially a TH-400 with overdrive.
I think my 700R4 is pre-1987. I didn't know better (at the time) to request post-87. I did request that all updates be installed (my trans builder said he did install the updates along with a shift kit).
The swap required:
700R4 Transmission (of course).
Plug for TH350 vacuum line.
New kick-down (correct name?) cable.
New rubber trans mount.
New oil-filler tube (old one may be used with some patient bending).
Mechanical speedometer cable connection adapter (later 700R4's came with electric speedometer interface).
Speedometer gears (both shaft and cable).
Change electric connector (provides +12V for torque converter lockup solenoid). Old one was 2-pin, new one is 4-pin.
New flex plate. Only because old flex plate had cracks where it bolts to crank shaft. Look for these and replace if found. May cause torque converter to wobble and leak oil shortly after install, due to excessive oil seal wear.
Relocate cross member about 1" (from original position) towards rear.

[86Delta]

a 700R4 is a Chevy only trans so you can't use it behind an olds engine, not without an adapter plate anyway.

[TheDarkShadow]

If one did decide to use a 700R4 on lets say a Cutlass originally equipped with a 200-4r, one would have to use an adapter plate as stated b4.... but would the use of this adapter plate would require crossmember modification and drive shaft shortining for it to work?

[88 Coupe]

TheDarkShadow wrote: If one did decide to use a 700R4 on lets say a Cutlass originally equipped with a 200-4r, one would have to use an adapter plate as stated b4.... but would the use of this adapter plate would require crossmember modification and drive shaft shortining for it to work? Hi DarkShadow, hello All

If one were take the trouble to do that conversion, I would hope the one in the car was FU, the replacement was in very good condition, the owner was too short on funds to do it right and needed the car yesterday.

Having said that, the adapter is about 1/8 or 5/16 thick and might need shims of equal thickness between the flexplate and converter in order to properly engage the converter in the front pump.

Bearing in mind that I think in terms of V8 torque, I would not recommend the adapter for much more than a slightly modified application.

Since both transmissions were designed for use behind early smog motors, neither ratio set is particularly good for performance use.

While most of the facts in the first post are accurate, some of it is incomplete and a lot is misleading.

If I were to believe the entire post I would have had TH200Rs in my coupes 20 years ago.

For performance applications, the best yet for GM AOD (excluding Allison) is Gearvenders Overdrive behind a TH400.

Regards, Norm

[BigBlockOlds]

You also have the 4L80E overdrive trans. Essentially an electronic overdrive
version of the TH400.

The gear vendors unit I've heard good things about also.

But with the above transmissions, you don't get as steep of a first gears or as high of a 4th gear as you do with the TH-2004R.


1st 2nd 3rd 4th

TH400 2.48 1.48 1.00 N/A

TH400 w/GV 2.48/1.93 1.48/1.15 1.00/.78

4L80E 2.43 1.49 1.00 .75

TH-2004R 2.74 1.57 1.00 .67

TH-700R4 3.06 1.62 1.00 .75

TH-700R4 3.06/2.39 1.62/1.26 1.00/.78 .75/.58

So a car with 26.1" rear tires, 3.73 gears you would have these effective gear ratios:

1st 2nd 3rd 4th

TH400 9.25 5.52 3.73 N/A

TH400 w/GV 9.25/7.2 5.52/4.28 3.73/.78

4L80E 9.06 5.55 3.73 2.79

TH-2004R 10.22 5.85 3.73 2.49

TH-700R4 11.41 6.04 3.73 2.79

TH-700R4 11.41/8.91 6.04/4.69 3.73/2.90 2.79/2.16
w/GV

With the TH-700R4 and gear vender unit you could have a set of 3.73's and all the benefits of a steep first gear for killer launches and the in 4th gear, activate the GV unit and have the equivilant to a TH400/TH350 with a 2.14 (or close to it) gear.

With a 26" tire you would only be turning 1677rpm at 60mph or 2796 at 100mph. :))))

You can also see that the TH-2004R beat all the others in the overdrive area (excluding the TH-700R4 with GV) by roughly 200-250rpm.

I personally would go with a TH2004R for ease of installation, price and gear ratios. Next in line would be the TH400 with GV unit, although I don't like the overdrive ratio personally and the 400 is going to suck more power. 3rd would be the TH-700R4 with GV unit. I think that one could be really fun. :)))

Just some thoughts.

[88 Coupe]

Hi BigBlockOlds. All
Quote: You also have the 4L80E overdrive trans. Essentially an electronic overdrive version of the TH400. I didn't mention it because during the redesign, they weakened it considerably. If they had kept the strength, it would have been my first choice. Quote: But with the above transmissions, you don't get as steep of a first gears or as high of a 4th gear as you do with the TH-2004R. Thats why they are not good for performance applications. As I said above, those ratios were used in order to meet EPA regulations.
I have TH350s, a 700R4, and a 2004R, and am familiar with the real world characteristics of all of them.
My point, both above and here is: Such raw numbers can be misleading and are only a small part of the information needed to make a trans choice. Quote: So a car with 26.1" rear tires, 3.73 gears you would have these effective gear ratios: So, Would the above numbers be better or worse with 28" tires? :lol:
Regards, Norm

[BigBlockOlds]

[quote="88 Coupe"]I didn't mention it because during the redesign, they weakened it considerably. If they had kept the strength, it would have been my first choice. Quote:

Weakened it? I've seen these advertised as handling 1000hp and living behind 10 second cars. Is this not the case?
Granted, this was a rebuilt model but you would likely need to at least adjust the shift points as this was a truck only trans.

Quote: Thats why they are not good for performance applications. As I said above, those ratios were used in order to meet EPA regulations.
I have TH350s, a 700R4, and a 2004R, and am familiar with the real world characteristics of all of them.

What exactly is bad about the gear ratios? I realize the 700R4 has a huge jump from 1st gear to 2nd but the TH-2004R isn't nearly that bad and has a 1.17 drop between 1st and 2nd compared to the TH-350's 1.00. That means the 2004R is only going to drop the rpm's another 100rpm or so below what the TH350 is when using a 3.73 gear and 26" tall tires.
Or are you saying the ratio's are bad because they are steeper which generally makes the transmission weaker?

Quote: So, Would the above numbers be better or worse with 28" tires? :lol:

LOL, got a little ahead of myself on that one.
Regards, Norm

[88 Coupe]

Quote: I've seen these advertised as handling 1000hp and living behind 10 second cars. TH 400s, Right? I wonder why the Chev Pickups use allisons behind their Hi PO engines. Quote: What exactly is bad about the gear ratios? ............... Or are you saying the ratio's are bad because they are steeper which generally makes the transmission weaker? Ratios have nothing to do with the strength of the trans. A performance trans needs close ratios. If a car is under powered it needs a lower first gear to get it moving.
The overdrives were intentionally overgeared to keep wear on the reciprocating assembly down, so it would still be within emission specs at 50K miles as required by EPA regs. Killed power, but, it lowered the interior noise level.
How much cam, stall, and what carb do you think would be best to cruise at 1677 RPM and still achieve mid 12s with a 3500# cruiser.
What would happen if you geared a BBO to run through the lights at 6500 RPM in fourth gear?
Regards, Norm

[BigBlockOlds]

88 Coupe wrote: ]TH 400s, Right? I wonder why the Chev Pickups use allisons behind their Hi PO engines.

Well, the 4L80E trans is what I've seen.

Quote: Ratios have nothing to do with the strength of the trans.

I take it then that this only applys to automatics? I do know that with a manual transmission, the power rating is directly related to how steep the first gear ratio is.

When researching a manual trans for my '87 I talked with Richmond about their 5 and 6 speed transmissions that were only rated at 450ft/lbs. I was told that was for the first gear ratio of 3.06. If I went down to a 2.77 first gear the transmissons torque capacity went up to around 500ft/lbs.
Thanks.

[88 Coupe]

Quote: Well, the 4L80E trans is what I've seen. Thanks for the update, I've just learned they are being built almost as strong as the 400s for about 3X the price, plus a Chev to BOP adapter, and the price of a computer if the car has none. Quote: I take it then that this only applys to automatics? A gear is a gear. Quote: If I went down to a 2.77 first gear the transmissons torque capacity went up to around 500ft/lbs. Didn't they make the 2.77 gear stronger because it was to be used behind higher torque engines?
My above reference to a BBO, and either of the OD trans, geared to go thru the lights at 6200 in 4th was an exaggeration to help understand the concept of too low a gear for an application, and to show why I used TH400s instead.
BTW: the 3.0 first gear would work well in a land speed racing environment as traction in 1st gear is generally non existent.
Regards, Norm