overdrive trans info

What is the best automatic overdrive transmission option to put in my 82 spirit?It has the original GM 2.5 inline 4 cylinder.

Not knowing the GM 2.5 bell housing bolt pattern but if the same as a 200 r4 or is it 200 4r? but I would look into that thinking it would be the easiest if bolts are the same.

Now when checking that out also check what gear ratios are used in the rear with that trany. Because the car has a 3 speed now it may have a higher ratio to keep the RPM down on the Hi Way but bolt in an OD trany and the RPM may be too low to use OD with the 2.5 motor.
The other thing to look at is the first gear ratios in both tranys. If the OD is a little higher than the 3 sp. you may want to change the rear gear to a lower ratio and that would work better with the OD trany.

It is a lot to check but to have a car that is nice to drive over one that is good to drive is doing all the home work first.
Keep us posted
Dave ----

purple72Gremlin wrote: Probably a 700 R4. But what bellhousing pattern does it have? Older ones had the SBC pattern, but later ones have the same one as the 2.8 chevy V6.

A 700 with a 2.5L 4 cly would that be too much of an over kill?? IIRC the 700 was used with HO v8 and diesels & LT trucks and why I say that.

Dave ----

uncljohn wrote: Your 2.5L 4 cylinder engine is mated to the Chrysler 904 transmission using an adapter. I am not sure whether the torque converter is a lock up converter or not, but if it is, have a 2200  rpm stall converter built for that package and then use a 2.53 rear axle. This would give you a simulated 4 speed au tomatic and the 2200 rpm lock up would pull well from a dead stop but when in  high with the torque converter locked  up it would act as if it is geared for about  1000rpm/32 mph giving a nice cruising speed.  I have my 80 Spirit set that way but it also has 258 cu in engine. The next option would be to look into 200R automatic. The 2.5L engine has a Chevy bell  housing Bolt pattern so it would bolt up to the thing. The question would be is there a flex plate and torque converter that would work. There is a GM aftermarket parts book that I have that I think might call  those things out.   But maybe going to a GM parts location,  something that at least talks performance and asking if there is flex plate, torque converter package that would let  you bolt up a 151 c u in Pontiac 4  cylinder engine to the 200R automatic. Cause that is what that engine is and  it was in a lot of cars and was an option on the Pontiac Firebird and that would have been the 200r4 speed automatic transmission.

It should be the SBC pattern 904 (CJ guys want those) Late '82 could be AMC 2.5 which has the 2.8 60 degree V6 pattern. 200R4 (or whatever you call it) off a 229 '81ish Chevy Malibu is SBC pattern. S10s used the 60 degree 700R4.


There is no adapter on the 2.5 to 904 that I have seen.

Actually, it's the converter that is unique. The 4 and V8 take the same flexplate unless it uses a Ford style starter.