Question about a Jeep Transmission

Ok, I'll admit right off the bat that I don't own a Jeep. But I am building a Frankenstein Bronco II and I need a compact but yet strong transmission that uses a hydraulic clutch to make my life easier. I like this trans because of the low first gear (I really want a granny gear) and it's compact size which would be excellent for my compact Bronco.

Here's the catch, my innocent little Bronco II is going to be running a 347 Stroker that's going to be putting out about 450-475ft.lbs.

So I guess my main question is just how strong is this transmission? I'm going to be using this truck for off-road and on road use so it will take a beating because I'm that kind of driver.

I'd like to run a small transmission but if it's going to blow up I'll be going for a ZF from an F-250.

Thanks

Ben

DamageInc4x4NY said:

--- I am building a Frankenstein Bronco II and I need a compact but yet strong transmission that uses a hydraulic clutch to make my life easier. ---
Here's the catch, my innocent little Bronco II is going to be running a 347 Stroker that's going to be putting out about 450-475ft.lbs.
So I guess my main question is just how strong is this transmission? ---
Thanks

Ben

Click to expand...

You didn't say which trans you were interested in.
I don't think any late model (post 1980?) Jeep trans will realistically deal with the torque you're engine puts out.
Also, it would appear you're talking about a Ford engine--so not many people here will have a lot of experience adapting our choices to your engine.
Some of us have shoe-horned the 200lb NV4500 trans into our XJs, intending to deal with the torque of a V8 (normally Chevy); the NV4500 is rated to around 450 lbs ft torque, granny low, and a good OD. Don't know if any adapters exist to bolt it to a Ford engine.
Over on Pirate4x4, there's a thread discussing the "short comings" of the NV4500, and possible alternatives. You might look here http://www.pirate4x4.com/forum/showthread.php?t=869339

I think your torque numbers are wildly optimistic. Even considering the 380 lb/ ft you're likely to get, I still can't recommend any manual that came behind a 4.0 from the factory.

Long ago I had a '78 F-150 with a four speed. I can't remember whether it was a Warner or what, but it was a rock crusher, and it had a very low first gear, low enough that it was routine to do second gear starts even with the 6-300 engine. It might be worth a bit more research, even though it wasn't a hydraulic clutch. I don't see any reason why it couldn't have been set up with a different actuator.

Crap I knew I forgot something...lol I was looking at the NV3550, I know someone with one in a Ranger with a mild 302.

As for my torque numbers I will be making in the mid 400s I'm fairly confident about that. Not at the wheel mind you, at the crank. Most 347s make 400hp ish with ease if you build it right and they're torque monsters so 450ish ft.lbs is pretty easy to imagine.

Ben

The zf trannys are bullet proof.

They put em in bimmers...