View Full Version : Choosing a transmission

11-18-10, 08:53 AM
I am wondering which transmission is a better fit. I am putting a 350 Oldsmobile motor into my car and I need to decide which is the best transmission to put in. The th350 or the 700r4 or if I can get my hands on one the th400. Thanks everyone for your input.

11-18-10, 09:05 AM
I'd get a 700.

11-18-10, 09:37 AM
I found this one but would it work even though its been hooked up to a v6.? So the 700r4 would bolt up to the Oldsmobile block with no problem? Also is there a way I can find out what tranny I have now I think someone on here said it was a 200r4

11-18-10, 02:27 PM
All '86 RWD Cadillacs have the THM200-4R transmission.

The TH700R4 is a 4 speed overdrive transmission with a lock up-converter, just like your current transmission. The problem with the 700, is that it uses the Chevrolet bolt pattern and would require an adapter to be mounted to an Oldsmobile engine.

The TH400 is a 3 speed transmission that does not have overdrive or a lock up torque converter. The 400 used the Universal (BOP) bolt pattern and can bolted to an Oldsmobile engine with out an adapter.

I would also recommend using the TH700 because of it's durability and fuel saving overdrive feature (the lockup converter may or may not work after the swap). The only difference between a V6 and a V8 TH700 is the bell housing (the 3.1 liter 6 has a smaller pattern that the V8's and larger V6 engines). The gearing between the two is the same and they are identical inside and out.

11-18-10, 09:30 PM
OK excellent so I will go.with the 700r4 is it hard to find the adapter to fit it on the Oldsmobile block. Ill check eBay tomorrow and what not

11-18-10, 10:42 PM
Jegs should have one.

11-24-10, 04:38 PM
So You suggest putting the 700r4 in. Would it be the same if I had my 200 4 r rebuilt? I have been having good luck finding 700r4 s for under 500 with low millage so they say. Or is the 700r4 just an over all stronger tranny. I have heard so many good things about the 700

11-24-10, 06:09 PM
The 200 won't be strong enough to last and doesn't have the gearing available to bring out the performance of the 350.

11-24-10, 06:47 PM
Right on thanks

11-25-10, 07:05 AM
The 200 can be built up as strong as you need. I'm not a big fan of trans adapters but I would (and have) use one if I had a free trans laying around. If you are going to spend money on a used or rebuilt trans, I don't think it would be much more money to have a properly rebuilt 200. 4 gears are always better than 3, and both 4 speed automatics have a lower first gear to get you moving and the nice overdrive for effortless cruising.

When you use an adapter you should put a spacer (washers) between the torque converter and flex plate. If not the torque converter won't be fully seated in the trans pump. I'm sure people have used the adapter without spacing the torque converter with no problems but I wouldn't risk it. There are lots of trans rebuild shops offering high performance 200-r4's for reasonable prices.

12-05-10, 08:57 PM
Thanks for the info. Are there any other hints or suggestions when I put the 700 IN?

12-07-10, 08:25 AM
Adapters are easy find...


A 700 is not near as reliable as a 350 or 400, but OD and the short first gear are great additions. And the 700 can be built easily to fix all the problems. My 94 Fleetwood has a stone stock 4L60E, the electronic 700, with 250k miles on it, and the pan only has been off to get the filter changed.

Yoke might be a minor installation issue, but not too bad if you had to. Look them up.

Would be worth a call to Shane @ CPT Transmissions, he is an 4L60E/700 expert. http://cpt4l60-e.com/testimonials.html

12-07-10, 01:51 PM
Thanks. I completely forgot about the yoke. Would I be able to use my old one or am I going to have to find one that fits into the 700?

12-07-10, 02:19 PM
Yoke is same on 350/700 and 200/200-4R


12-08-10, 11:57 AM
Is it possible to use the same torque converter as well? I doubt that I can but I am not sure or should I try to find one the TC arleady with it.

12-22-10, 06:20 PM
I found a 700R4 from a 1990 GMC I was wondering how do I find out if its a lock up or not? Also can I use the same one from my current tranny? If not what am I looking at for installing another lock up converter? I herd I can get them from jegs. Thanks

12-22-10, 07:12 PM
I believe all 700's came with a lockup converter... I might be wrong on that.

But it doesn't really matter anyway. If you're disconnecting the computer to install the engine, you will lose the command circuit for the lockup solenoid. Without the lockup converter you will only see a fuel mileage decrease by about 1-2MPG over average; something that will never be noticed after an engine swap.

So use the torque converter from the 700 and disconnect the TCC solenoid, if equipped.

12-22-10, 07:23 PM
Ok so I dont need to do anything computer wise or electronic wise when I put the new tranny in.

I have been reading this site and it looks like they say it can be done.
One guy says to bring it to a tranny place and have the four connectors changed into one and hook it to the brake pedal so it un locks it.

12-22-10, 09:49 PM
I wouldn't worry about it. If it has a lockup converter, then the converter just wont lockup, so the converter will function the in the same manner as a non-lockup torque converter.

12-23-10, 08:08 AM
So you're comfortable going with the adapter plate? I guess it's not rocket science and they have been used successfully for years. Keep us posted.

12-23-10, 09:24 AM
I read on one of the websites that I can just get a switch that turns it on and off. But in the mean time I'm just gunna throw it in. Thanks man and thanks for the center cap.

12-23-10, 02:28 PM
You're welcome...

12-26-10, 07:53 PM
I picked up the 700R4, but now im on the hunt for a tail housing that will mount right up to the support arm. Sometime this week im going to pull the pan and check to see if there is any fuzz in the pan and change the filter.

01-06-11, 09:03 AM
So I found a tail housing and it came in yesterday but I have not been able to see if it works. An issue was run by me because the 700 I bought was a 4 wheel drive one and I am not sure that the output shaft is long enough. I will put the tail housing on and check it out. If its not is it possible to just get a longer yoke instead of replacing the entire output shaft? Thanks

01-08-11, 01:44 PM
No ideas if the 4 wheel drive tranny will work?

01-08-11, 01:55 PM
Not without full dissassembly.

01-09-11, 07:34 PM
Well she doesnt fit I tried it today. The only issue is that its about an inch and a half short from the output shaft from the tranny. So if I could get my hands on a longer slip yoke I would be ok, or im going to have to rebuild it with a new output shaft. But I am going to call the tranny place where I had my trucks rebuilt and see how much it will cost me to have them do it.

PS I broke the bolt off when I was removing the drive shaft in the housing piece that the u bolot bolts to. So it looks like I will be doing some drilling and taping. It happened when I was removing the old tail housing from the tranny as well.