American Muscle Challenge!!!

[Big Dave]

Good! It is a stick.

A T56 will not be an easy swap but it has a 0.5:1 sixth gear and you should be purring down the road 1500 RPM @60 MPH. That will help a lot.

Fourth is straight through and you should still get good quarter times. Few cars get beyond fourth in the quarter.

[Widetracker]

I'll actually be following this thread for selfish reasons. I have a 1969 Firebird convertible that I'm trying to maximize economy. Very little assistance or tolerance for mpg talk in a lot of the forums. I just found the site today linking over from a CRX forum and plan to do a lot more exploring. Hope to share what I've learned studying this subject over the last six years or so. Good luck with the Stang and thanks for the welcome guys!

[roflwaffle]

Originally Posted by Big Dave

A T56 will not be an easy swap but it has a 0.5:1 sixth gear and you should be purring down the road 1500 RPM @60 MPH. That will help a lot.

It doesn't seem to be too bad, but it is pricey, so swapping/flipping fifth on a T5 would probably be cheaper but way more labor intensive.

Edit- A 3.08 rear end swap seems to be the easiest and most economical, but that'll hurt acceleration, so a taller fifth in a T5 seems to be the cheapest and best for performance provided the owner is handy and there's enough room in the case for the taller OD gear.

[Widetracker]

Actually Cobras came with a t-56 so it might not be a bad swap. Six gears is like having your cake and eating it too- super low gears with a deep overdrive.

[sonicsqwirl]

what exactly is a T56?

[Big Dave]

A T-56 is a six speed made by Tremec. It is used on a lot of high performance cars. Essentially, it is a close-ratio four speed with two overdrives on it. Fourth is straight-through. Fifth is 0.72:1 IIRC, and sixth is 0.5:1. It does exactly what you are looking for - gives you great quarter-mile performance AND low-revving economy gearing.

Corvettes do not use the T-56 but they have been in Camaros, Firebirds, GTOs, and Mustangs for years. They will probably be availalbe on the Pontiac G8. You can get rebuilt or remanufactured T-56s if cost is a big item.

With OEM-sized rubber you can expect 1200-1500 RPM @ 60 MPH depending on your axle gearing.

I was always under the impression that a T-5 is a throwaway and any work you put in it will cost more than it is worth.

The other workable alternatives are:

Regear the car to 3.08 or 2.73.
Install a Gear Vendor or US Gear overdrive

If I had a pony car I loved I'd be thinking T-56. I even briefly thought about one for my diesel but it is not heavily enough built to take the sustained loading a diesel can put on it.

[Big Dave]

My bad!

Correction to previous post.
The overdrives for a regular T-56 are 0.8 and 0.62.
The overdrives for the "Chevy/Viper" T-56 are 0.72 and 0.5.

Maybe I need to think about a "Viper" T-56. I have been thinking about a US Gear or Gear Vendor overdrive for my diesel but if it can live with 650 ft-lb, that's more than my diesel makes. A USG or GV goes about $3500 installed.

[Widetracker]

Actually the Vette uses it too in addition to the new GTO. Small variations between all the applications though. Check www.sixspeedinc.com. They have a great reputation on LS1tech.com. My 99 TA uses the T-56 and is big factor in its performance in mileage, acceleration and ridiculous top speed.

Should run you about 1500 without a core I believe. Not sure what else is involved for the late model Mustangs, but like I said the Cobra ran it so it should be a bolt in with the right parts. Check the Ford boards out to see.

[sonicsqwirl]

i have a low profile grill insert installed on the stanger-banger... got it done this weekend... drove to work successfully and it stayed attached (which is amazing... FULL OPEN grill... nothing to attach to, had to be creative)

[Big Dave]

DD Performance offers T-56 kits esecially for Mustangs.

I wonder if one of their T-56 (650 ft-lb) will work with my diesel?