Best affordable manual transmission for just shy of 407 ft lbs torque?
 

I've got an 84 corvette with the motor out of it right now. Im in the process of rebuilding it as i go since its more of a sunday driver than anything. Ive had the engine ran at an engine dyno and it put out around 329 hp and 407 ft lbs. Anyways. Im aware that a tremec or ZF are good options but id like something that is more on budget. Used would be acceptable. Any suggestions? Thanks!

Get yourself a used ZF. The trans will handle (with ease) your engine out put and you will have a damn near bulletproof tranny. I'm not sure what you mean by "on a budget"...?? You might find something "cheaper" but it will most likely fail and need replacing. That blows any budget.

This is a Corvette; there are no suck things as "high quality, fool proof transmissions for cheap."

Hah! Well said. I'll look into the ZFs. Thanks

Bill is pretty much right. Common "strong" options are the ZF6, T56 or TR6060, or a Tremec 3650 (?).

A "cheap" option would be a T5...and that could last behind 400 ft-lbs if you're careful.....but it probably wouldn't. And T5's are that cheap or available anymore, I've noticed.

Other options that I've thought about are the NV3500 (out of a late '90's Silverado 1500).

There are foreign options which you could adapt, like a Supra transmission...but he gear ratios (5th/OD specifically) wouldn't be right.

You could try to find a late '90's, early '00's T45 from a Mustang, then use a Chev/T56 bellhousing. That might be the best/cheapest option.


EDIT: I went looking on our local classifieds and found THIS for $150. I think it may actually be a T45.

Also found this T56 for a pretty reasonable price.

There are options...few are great....none are cheap.


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In life, I have found that if it is cheap, it is wanting. Good stuff isn't cheap because it can't and doesn't have to be. Cheap stuff isn't good because it can't be

What's wrong with the current trans? I'd be more concerned with the Dana 36.

The wide ratio (2.88 first gear) is a limiting factor, but the only way you'll ever put that much torque through the trans would be with ~3600 lbs on the rear axle (407 * 2.88 * 3.07) while at the torque peak at WOT in first gear. So if car can't maintain a sustained wheelstand or won't be used for tractor pulling, I don't see any reason for concern.

A new close ratio gear set might be a relatively cheap option to increase torque capacity if really needed. I've never heard of anybody re-gearing the 4 speed part of a 4+3, but I assume it is possible.

Might be able to get away with just a new input shaft, cluster gear and 3rd gear. Looks like first and second gear have the same number of teeth for all gear sets.

http://www.thegearbox.org/SuperT10.html

Do you want or need an overdrive tranny? there must be a zillion Muncie and Borg Warner 4 speeds still out there; trick is to find one with the mounting points on the tail shaft housing to hook the C beam up to

I decided on a 5 speed t56. You can find them used from 800-1000 out of c5s in good condition. Just gotta figure out how to mount them now and what kind if bellhousing + c-beam and such i'll need.

No such thing. You either got a T45 out of a Mustang (which is a 5 speed version of a T56) or you got what you said; a T56 out of a C5 which is a 6 speed and will not have a usable trail shaft housing or shifter for a C4.

Sorry i meant 6 speed. Mustve hit 5 when writing it. Anyhow it will be a t56.

The t56 for a C5 uses a torque tube and is mounted in the rear of the car. Not going to work in a C4.

Copy that....but then there is this:

Sorry about my naivity.. will a ZF 6 speed work then? They are rather pricey but it sounds like its going to be one of my only choices for anything near 500 ft lbs.

I listed a bunch of viable options for you above.

Check out post #4.

But yes, I ZF6 will bolt right in, and can take ridiculous amounts of abuse.

If you'll pardon me asking. It will bolt right into my stock Automatic location so long as i have the cbeam and bell housing for it right? What year bellhousing do i need? Also is the ZF6 the one with the very hard to find dual mass flywheels or synchros or whatever that the later c4 manual owners run into when trying to rebuild them? Just wanna make sure im making the best descision here.

The ZF is probably a bit easier to swap in. I put '95 Z28 T56 into my car and i am well pleased with it. There is a lot of fabrication to put a
t56 in a C4 since the factory never did it. The ZF was a factory option so i imagine it to be some hole cutting and installing mostly factory parts. This is in no way minimizing the work involved in a ZF swap. Good luck on whichever path you take.

75 on chevy V8 Monza's and Third generation (or starting with 4th generation ?) F cars used a three link rear suspension and the tail shaft housing has substantial mounting points; not a direct swap, but (I assume, lol) fabricating an adapter plate would be easier for a C beam mount; also 1984 (first year C4) used a four (not 4 +3) speed. Also, anything not C4 specific will require some sort of an adapter for the C beam to mount to.

No C4 got a 4 speed. The '84s were 4+3s too. The adapter bracket is a pretty simple piece. The price was low enough i bought mine, but one can be fabricated with a saw and a welding machine pretty easily.