Karnage214

Any help would be appreciated. I'm having a lot of trouble trying to find a transmission for what i want. I really want an OD transmission that has a full manual valve body. Im in the process of building a ~500HP engine and adding 200-300 shot of nitrous to it. Is it possible to build up a 700R4 (what i currently have) to be able to handle this, or possibly a 2004R. Or maybe even swap to a built T-56? I'd rather have a 4 speed automatic though, what are my options for this?

Karnage214

TTT - are my only options pretty much getting a built TH350 or TH400?

Johnny Blaze

iTrader: (15)

Plenty of shops can build a Th700R4 to your specs.

Give 'em a call.

SaintedCorrupt

another option is to get yourself that external overdrive from Gear Vendor's and bolt that baby up to the back of a TH350 or TH400. those overdrives are supposed to be able to handle 1200 hp or something rediculous like that.

Karnage214

Only thing with those though, those are quite costly. Would love to have that on a TH350, but dont have that much extra cash just to be spending to have an OD transmission. When monday rolls around, im gonna see if any shops can build my 700R4 to handle it; hopefully i'll have some luck.

TKOPerformance

I would say stay away from a 700R4 with that kind of power. Let's be frank, you're talking about 700-800hp. Can it be done? Probably, but what you'll have is a breakage prone part that will need to be rebuild fairly often due to the compromises that must be made in order to get it to live behind that kind of power.

A T56 with G-Force gears will fill the bill.

If you want to go 4-speed auto think 4L80E.

Karnage214

How hard is it to bolt a 4L80E up to a late third gen?

TKOPerformance

It will bolt right up to the motor. Just make sure to use the right flexplate (1-piece or 2-piece RMS design, whichever motor you have).

You will need a different crossmember I believe, probably one designed for a TH400 will work, but I'm not 100% sure. You will definately need a crossmember that mounts the torque arm on the crossmember, as the 4L80E has no provision for the TA, since it was never used in F-bodies.

You will also need a trans controller, because the 4L80E is computer controlled. These are available from TCI and others. Essentially they are a stand alone computer from a Diesel that has been reprogrammed for use in a car. Some systems even allow you to tailor the shift points, line pressure, and shift firmness with a laptop. Pretty slick.

You'll need a shorter driveshaft.

You can probably get the stock auto shifter to work, or you can just use an aftermarket shifter, you would probably want a ratchet shifter anyway.

Karnage214

Also possible to just get the 4l80e with a full manual valve body right? And that wouldnt need any electronic hook ups would it?

Yeah, i was already planning on getting some type of ratchet shifter.