Hello,

The 700R4 in my 89 Formula 350 is pretty much toast. I am debating on having it rebuilt or swap in a T56. I am aware of the cost and work required to swap in the T56 and it will probably cost more than the auto rebuild. The car will see some street, strip, and autocross action. I'm just having a little difficulty deciding what direction I should take. What should I do? Opinions please.

Thanks,

 

The t56 should get much better gas mileage.that's what is what I want to do too but i don't have 1500 minimum to do it.

 

T56 all the way

 

I’ve always preferred the simplicity of driving an automatic. Although the manual will give it more of a sports car feel, so if you don't mind being“CONSTANTLY" busy with your hands and feet than that's the way you should go.

 

Replacing the slush box with a proper transmission was the best upgrade I ever made to my IROC, and that was only a T5. The enjoyment I get from the manual trans is orders of magnitude more than what I got with the auto.

 

Having a t-5 or even the t-56 didn't do dick for my gas milage.

If you can get a good condition t-56 with a good clutch setup then it's worth it. I ran into lot of problems when I did my swap, think I had to drop the tranny 7 or 8 times to get all the bugs worked out tell I could finally enjoy my ride. Btw your going to need to change your rear gears as well.

I never did try a upgraded torque converter, might be something worth thinking about if you decided to keep the auto and wanted a little more fun out of your ride.

 

the T56!! i did my swao for about 2000 dollars you just have to find good deals

 

RAD5 ,

Did you have a shift kit in your trans. or at least a Corvette servo. ?
Just out of curiosity what gear ratio do you have?
Stock was either 2.77 or G92 opt. 3.27 or has it been changed to something else ?

I’ve got a 3.42 ratio with Eaton posi. and a simple Corvette servo and I get nice firm shifts. Hit WOT from the line and it spins them for a second then hooks and barks the tires nice and loud from 1st to second and chirps them from 2nd to third pushing me back into the seat locking the shoulder strap.

I can be cruising in second and hit WOT and it will drop down into 1st pushing hard then shift nice and hard with a loud bark from the tires then chirp them from 2nd to 3rd no problem. This is with a 5.0. and basically a stock 700r4. Or I can just take it easy and cruse nice and still be able to"feel" and "hear" the Trans shift either up or down.

I’m not trying to say that a 700r4 is more fun to drive than a manual but if I can do that with my little 5.0 than a car with a 5.7 or larger and a built 700r4 with the proper rear gearing and posi. unit and the right stall converter is no slouch.

 

I went T5. I ended up with the same price in the T5 swap, as I would've with a rebuilt 700R4, but I wanted a manual trans as a personal preference. With the 700, I averaged 20-22 MPG. With the T5, I'm averaging 25. Part of that may have to do with the fact that I've matured a little, and the gas pedal isn't an on/off switch anymore.

 

Should be fun, if you drive like an adult a T5 can last a good long time. There are plenty of people on the board who have done it.

 

Full manual auto.... Best of all worlds

 

The car has the stock 700R4 and 9 bolt rear with 3:27 gears. I think I will probably keep the auto just to keep the car original. Monster Transmission is down here in FL, I might just take it to them. For the price of the manual swap, I nicely built auto can be had for a little less. If I find a good deal on a T56 then I might change my mind. Thanks for the input!