buick 350 and tranny swap

I'm gonna put a buick 350 in my CJ5 and was planning on putting a t-18 behind it, but now wondering about putting a th350 behind it instead. How many people have done this, and to what success? I know Daryl runs autos in his Jeeps, but I think he moves the motor forward. I'll be running the v8, so won't be able to move the motor forward. I'm also going spring over on 75 waggy axles front and rear, quadratrac axles, and keeping my dana 18. Was thinking about moving my rear axle back about as far as possible to stretch the wheelbase a bit (no comp cut though, just open up the rear wheel well, giving about 85-90* departure angle). So, anyway, anyone done this, and what do you think of it, how did it work, and what kind of rear driveline length you think I'll be looking at? So short it'll be horrible, or if I can get the rear axle back 3" or so, will it be okay? Post pics of it setup if you have them, too! Thanks guys.

 

A TH350 is a long transmission, you would need to extend the wheelbase to make it fit, maybe even more than the 3” you mentioned.
If a plain ole GM transmission will bolt up to a Buick, I don’t know of the bell housings will swap between them or not, you may want look at an SM465 or even an SM420. The 465 is shorter and will have better clearance for the front drive shaft but the 420 has a killer 1st gear, 7.08:1.
The problems with extending the wheelbase on one of these depends on the suspension you plan to run. If you’re planning a simple spring over on arched leaf springs then when you’re suspension compresses the axle will move up and back towards the shackle. You can install a set of TJ fender flares as they allow you to cut the tub and open up the wheel well a bit but still it won’t take much for your tire to get into the tub.

 

I have a t-18 bolted to a 225 right now. Its got a 18 already on it, would be perfect for what you are talking about. Give me a call if you want it. Or just buy the whole set-up.

 

I must have not clarified in my post originally. I have a buick 350 and I have a t-18 mated to it that I got with the motor. It works perfectly, just wanna look into getting an automatic instead. Buick made th350 autos that bolt right to the buick 350. A chev th350 will not bolt up (top of bellhousing is different). I will be running larger tires (around 36") and move the rear axle back, and relocate the rear springs more rearward on the frame as well. I will also have to cut out a decent amount more of the wheelwell opening to a) accomodate a larger tire and b) to accomodate the tire being back further on the body. I will be running waggy axles, so the tires shouldn't be getting into the inside part of the tub at all. The wheelwell cut will most likely terminate right at the rear corner of the jeep, however, instead of having that 4" or so of sheetmetal before getting to the back corners of the jeep. It will be about like the pic of this guy's jeep from the side about half way down the page in this thread http://www.pirate4x4.com/forum/showthread.php?t=777868&page=4 I plan on running either YJ leafs or wagoneer leafs. Anyway, I don't need options on granny 4-speeds, I already have one, I just was looking for more info on the automatic. It appears it will be roughly 7" or so longer drivetrain than what I have now, and I think I can move the rear axle back 4", so I'm wondering if a 3" or 3.5" shorter driveline will be horrible or not? Like what is really the length minimum?

 

Ah, thanks for the explanation, I understand now.
Interesting looking cut on the rear fender, I’ll have to keep that in mind.
I also don’t think there is a set minimum for rear drive shaft length so much as it needs to be long enough to allow the rear axle to cycle through its suspension travel without getting in a bind.
I think the spec for the average u-joint is around 15* of misalignment, and of course a CV or double cardon will double that angle before binding.

 

Pardon my ignorance but what is a BOP TH350?

 

BOP = Buick, Oldsmobile, Pontiac and Caddy too I believe.

 

There is an adaptor for the buick/pontiac v-8 engine to standard chevy th350 including the 4x4 th350wich is shorter than the 2wd th350. the adaptor closes up the gap at the top of the bellhousing to engine and place an adaptor from the th350 to your dana 18 and your in business! hope this helps you.

 

Some info on autos (this threads happens to be behind a 225 but the info is there.)
http://www.earlycj5.com/forums/showthread.php?t=66584

The 350/TH350/D18 will fit in a stock application but it will be very very tight, guessing something like a 10" driveshaft.

Stretch the front with a long fender nose (read stretch frame) allowing the engine to be pushed foward and move the rear axle 3" back, should work with the SOA, but most likely still going to be a short driveshaft with a CV joint.
Don't forget about all the problems that come with a SOA.

Could probaby stretch the frame simlar to this, since you will have to outboard the springs to fit waggy axles.

 

thanks for all the help guys. The front end stretch is always an easy way to get stuff moved forward, but I really don't like the look of the longer hood cj-5's, I like the shorty's. That is actually the reason why I didn't buy an intermediate instead. I am aware of the soa problems. I know I'll have to outboard my front springs, I know I'll have to build a trac bar, I've got flat top waggy front axle, so I'm gonna have it machined for hi-steer and get hi-steer arms for it so I don't have to run any wierd, scary steering. I was planning to run a CV rear driveshaft and rotate the rear axle pinion toward the transfer case. Just didn't want to get this all dialed in and realize a 10 or 12 or 14" driveshaft just isn't feasible...

Also, the 4x4 th350's are shorter than the 4x2's, but are you referencing that because the 4x2's have that hugely long tailpiece on the back of them, or is the body of the tranny itself longer too? I assumed the body of the tranny (ie case) was the same length, and it was the tailpiece that was long making it longer overall.

 

Think the shortest adapter you can get is the Advanced, IIRC it's about 1".
The problems:
The trans has to be pulled all the way apart to insert the output shaft.
The u-joint won't fit. Either a small "v-6" type needs to be used or I seen grinding the trans to clear the standard u-joint works too.

I had a 231/TH350/D18 in a Cj-2a, the rear driveshaft was 13"
A friend had a 350/TH350/D18 in his Cj-3a (novak adapter) and his rear driveline was 9.75". He also had 2 small electric fans because he had NO room for a engine fan, the fans kept it about 220 on a good day.
There isn't much room in the shorty for that long combo.

 

well, I have a v6 in my rig right now, so luckily I already have the small u-joint for the front drive shaft. As far as tearing the whole tranny apart to get the shaft put in, I'm considering having a guy rebuild a tranny for me, so I'll ask him if it'll cost any more if I bring him the part before he puts the tranny together for me or not.

 

I understood that the 4x4 th350 was the better aplication for the early CJ-5 because it gave you enough space and length without stretching the frame all was needed was an adaptor for the Dana 18 and the rest just fell in you still probably adjust your rear driveshaft but in the end it all worked out.

 

Run a th400 from a v-6 commando/jeepster bolt up the 350 and pull the 20 and install the 18 if you can't find one with an 18 already. You shouldn't have on problem with the rear driveshaft. I am running a bad boy jr rear shaft from these guys. http://www.arizonadrivelines.com/ it is all slip, no tube. A little pricey, but takes all the issues out of running a normal cv at a high angle. Your front drive shaft should be ok because it angles down and farther away from the tranny to hit the wider front axle.

 

I was thinking about just using a th400 that was already mated to buick 350, but the 400's are longer, and driveline length is at a premium under the cj5's. As far as 4x4 vs. 4x2 bop th350, does it really matter? It looks like the advanced adapters adapter kit comes with a new output shaft, so you would just do away with the whole 4x2 tailpiece and run the advanced adapters new output shaft out the back of the tranny, right?

 

Take a Buick 350, add a BOP adapter, slap a 4x4 th350 tranny, put the transfer case adapter on tailshaft, place on Dana 18 and presto, measure driveshaft and your'e in like flint. You can check out trans adapters or advance adapters or novack, they will have an adapter to run a 4x4 chevy th350 on a Dana 18 and possibly Dana 20