I have a 78 Cutlass with the 260 and 2.21 rear as a daily driver.

The TH200 is giving me the typical problems at 115,000 miles. I was told by a local transmission shop that installing a TH350 will slow this car down and I should rather rebuild the TH200.

Since I don't stomp on this car and it is a daily driver, is rebuilding the TH200 a viable option (quoted $800)?

Is it really true installing the TH350 will make the car slower and require more work, such modifying the throttle cable?

Could I change the rear gears and install a newer, non electronic overdrive transmission as another option?

Thanks

 

I've heard the TH350 is heavier and takes more power to turn so possibly slowing it down some. Not sure on the modifications. The 200R4 would be a good option to install but you might have some modifications again. 1st and 2nd gear would be lower. Changing he rear gear would help with whatever trans you go with.

 

Thanks 455 man, that does make sense, yet in my 78 olds manuals, the TH350 came in different configurations. For example the 78 Starfire with the Buick V6 used the TH350; albeit it used a 2.41 ratio. I figured if the V6 can use the TH350 why not the Olds V8? The Chevy 305 used a TH350 and that was different than the TH350 in the Starfire.

This is my daily driver, not something I am going to do holeshots or take it to the drag strip. It might be cheaper to rebuild the TH200 than go with a TH350 and then have to up the gears to 2:41. I figure if this transmission lasted 35 years with 115,000 miles, having it rebuilt should last a least another 10 years or more.

 

So you're considering geting a new rear and a new transmission as a way of saving the cost of a transmission rebuild?

I'd have to see the math.

Why not just get a TH200 from a junkyard?
It's only a '78 Cutlass with a 260.

- Eric

 

I agree MDchanic. I was just outlining my options. I am leaning toward a rebuild of my existing transmission. The other option as you suggested getting one from a junkyard would be riskier since these TH200 were known to have issues.

 

If you are going to consider a change in the rear gear I'd do a bigger jump than that. Even a 2.73 gear would still be high geared depending on tire size. This link can help you figure your RPM's
http://www.ringpinion.com/Calculators/Calc_RPM.aspx
I'm thinking the TH200 has a lock up converter too so this will lower RPMs a little.

 

The th200 is a light duty transmission for modestly powered cars, I had three cars equipped with one, a '79 Olds 88 diesel, a '79 V6 Buick Century wagon and a '78 Olds Regency with a 455 installed. I used the wagon and diesel Olds for towing, with a transmission cooler installed.
The first two had no transmission issues, the Regency held up while I owned it, but gave up when the guy I sold it to gave it too much right foot, no surprise there!.

I agree with Eric (as I often do, he knows what he is talking about), a properly built and sensibly driven 200 should be good for another 115k miles.

Roger.

 

Simplest and probably cheapest way is to rebuild what you have.

If fuel economy is one of your goals, I'd stick with the 2.21 axle and find a 200C version for ease, light weight and simplicity. The C is for the lockup clutch in the torque converter. The TH200C's date from 1981, the first year of GM lockup transmissions, and came in many GM cars. The lockup feature can be easily controlled by a simple switch, or other available more complicated methods.

Depending on driving conditions and speed, converter slippage becomes a factor in engine RPM and heating of the automatic transmission fluid. With the ratio's in the low 2's, lower vehicle speeds and/or climbing or accelerating, engine speed can be 10 or more percent faster than it would be with a locking torque converter.

If you want to mix performance with economy, the 2004R has an OD ratio of .67:1. An Axle ratio of 3.30 with the 2004R will give you the same overall final drive ratio as the 2.21 and a 200C. All 2004R's have the lockup feature.

 

Thanks everyone for the input. I will look to rebuild my transmission in the Spring. I am in the Boston Mass area and will be looking for a decent shop in the area which knows how to rebuild it and make any minor improvements. Right now it is slow shifting when accelerating when cold (30 degrees F) and of course slow engaging when shifting into D or R.

 

So you got 115,000 miles out of a 2004R...rebuild that sucker and put it back, Jack!

 

Thanks again for the input. Here is the update:

I got the transmission rebuilt and here is what they replaced:

Forward Drum (original was cracked)
1-2 band
updated sprag
sun shell with washer
front pump bushing
case bushing

and they installed the TransGo shift kit:

http://transgoonline.com/products.ph...dcountview=Yes

I just got the car about an hour ago and so far I am impressed. The car has much more pick up. The transmission was in pretty bad shape; however back in 1996 the previous owner supposedly had it rebuilt and the torque converter replaced. But I can't believe they did anything based on the parts they replaced in the recent rebuild. My shop did use the converter.

 

I like it when folks come back and update their threads on their progress. thanks.

I think you made a good choice rebuilding your current trans.

 

Good choice.