THM200/THM200C 3spd Tech

[MADMIKE]

The transmission in my '87 Cutlass was 'rebuilt' prior to my purchase. It is not the original unit(trans VIN#2619 Car VIN#4319). The problem I currently have is the transmission upshifts too early for the final drive ratio causing the engine to ping.

Under light acceleration the transmission will upshift to 3rd by 30MPH, It does not feel erratic, or incorrect except it is too soon for the given final drive. With 2.14:1 rear gears it bogs and causes engine knock. TCC has been disconnected in testing to verify the lockup converter is not sticking or jamming. The 307 Intake has been thoroughly cleaned of carbon build up in the passages and a new Delco EGR valve installed.

Powertrain is a 307 Oldsmobile with a 'KBB' code TH200C, and a rear end ratio of 2.14:1. TV adjustment and line pressure checked out. But it is hard to locate any definite information on the different governor springs or weights used in the TH200. Or any codes for the TH200.

Does anyone know if the TH200 governor is the same part as the TH2004R governor? Any GM techs with access to a parts book?

Applicable RPO codes on decklid;

LV2- Oldsmobile 5.0L V8 (307)
MV9- AT 3spd THM200 lockup
G72- 2.14 Ring and Pinion gear

Driving around in 2nd is not bad and usually does not require upshifting til speeds reach ~40MPH. It would be nice to regain full automatic control.
I think also this may help during smog testing as the car does bog/knock when it upshifts to 3rd at less than 25MPH on the rollers.



FWIW 30MPH with 2:14 is about 850rpm. 55MPH is 1500rpm. 90MPH is a mere 2500rpm
TIA

[Jake's Performance]

It's a different governor than the 200-4R.

I can probably help you out by modifying a governor.

[MADMIKE]

As of late I haven't driven the car much. Took it out for a few spins, mostly at night, and the transmission seems to be shifting normally. Although I had the car parked in my driveway at an incline and initially did not want to go into any gear. Fluid level is correct. Possible internal leak at the valvebody and case?

Plan on pulling the pan valve body and governor. Anything I should look for in particular to the TH200/TH200C?
According do some parts books I've found there are two governors for the TH200/TH200C, although nothing specific as to why there are. No specs on weights/springs.

It's a different governor than the 200-4R.

D'oH! I know the Turbo guys have issues of chucking the governor springs on the 4R.

Wasn't there a company that was modifying Th200 as a feather-weight replacement to the TH350, this was probably back in ~'00.

[slowcamaro]

Wasn't there a company that was modifying Th200 as a feather-weight replacement to the TH350, this was probably back in ~'00.

I believe once upon a time dana @ pro-built offered to put together a performance rebuild(for the 200c) kit for me. I'm not sure of the cost/pro's and con's of going this route though.

[MonzaRacer]

As for a th200,250,200c/250c I have yet to se a benfit of any of those trans.
Most of the mods made them th350 inside or nearly as heavy.
Why everyone wants to build a lightweight trans then beat on it is beyond me.
Some said 200r4 was weak but it was simply the cushy tuning GM gave them, well and they never had a performance backing till the GNs. Then they got "fixed" Art Carr pioneered development of tougher parts for those.
If you have a need for a 3 speed just build a decent th350/th350c and use good performance parts.
I have seen 350s take 1000+ hp and live built right, oh and the performance diff over a "built" th200/th250 was less than 10 hp on chassis dyno.

[MADMIKE]

I believe once upon a time dana @ pro-built offered to put together a performance rebuild(for the 200c) kit for me.

Thanks. I'll look them up. I just recall a website that had bits and pieces for improving the longevity of the 200.

I have yet to se a benfit of any of those trans

It's in the car. It's behind ~140HP of RAW 307 Oldsmobile fury. That and did TH350s have a proper combination of drive/driven speedo gears for a 2.14:1 FD? Without an added reducer/multiplier adapter? I prefer the TV cable adjustment that the TH200 series allows verses the vac modulator. Can get hot/tedious trying to tune the modulator that's under the car and next to the exhaust.

It's not going to be behind a warmed over 455. Just need the trans to work correctly.

[slowcamaro]

Thanks. I'll look them up. I just recall a website that had bits and pieces for improving the longevity of the 200.

I was inquiring about a rebuild for a th350 long ago, when Dana suggested the possibility of just upgrading the 200c.

Perhaps a call or email will get you some input as they are more geared towards well...it obvious.

http://www.700r4l60e.com/

[Jake's Performance]

Dana is a good guy to deal with and I'm sure can help you out.

I can also provide tech advice and parts for any of the GM automatics as I have done on this post already. I'm a forum sponsor as well...

[Jake's Performance]

As for a th200,250,200c/250c I have yet to se a benfit of any of those trans.
Most of the mods made them th350 inside or nearly as heavy.
Why everyone wants to build a lightweight trans then beat on it is beyond me.
Some said 200r4 was weak but it was simply the cushy tuning GM gave them, well and they never had a performance backing till the GNs. Then they got "fixed" Art Carr pioneered development of tougher parts for those.
If you have a need for a 3 speed just build a decent th350/th350c and use good performance parts.
I have seen 350s take 1000+ hp and live built right, oh and the performance diff over a "built" th200/th250 was less than 10 hp on chassis dyno.

A TH200 and a TH250 are two completely different transmissions.

The amount of power consumed by a transmission will differ mostly dependent on the "rate of acceleration". A slow accelerating dyno will not show the differences.

There is a reason I do 200 3 speeds for the Stock Eliminator guys occasionally.