POLL: What Gears for restomod project?

[Sam8950]

OK, what's you opinion on gears for my '89 hatch restomod project. Here's the basic final set up: naturally aspirated 347 stroker with proportional sizing of intake and exhaust components, and a T56 trannie. How I plan to use it: 75% driving to work (about 30 miles with about 20 of that being freeway); 20% for cross country trips; 5% for those rare trips to the strip. In 6th gear, a 3.25 rear gives 70 mph at 1700 rpm (just like the stock T5 and 2.73s) while 3.55 gears yield 70 at 1855 rpm. What's your vote? Or would you suggest another final drive configuration?

 

[BlownStangGT]

if ur doing alot of driving with it stick with 3.55s i guess...but hell..id put 3.73s in it

 

[jrichker]

The new Cobra's use 3.55's with a T56. Your HP output is likely to be in the same neighborhood, so look at what they can do. I would go with the 3.55's, as 3.73's would be too much wheelspin on those track vists without slicks or drag radials.

 

[mustangt93]

with a t56 i would go with 3.90's man, @70 im sure the rpms cant be worse than 2250. thats what im gonna do when everything is said and done with my project

 

[sleeper89]

well, given its a daily driver with minimal strip duty and lots of power..... go with the 3.55s. 3.73s with that power and street tires is too much IMHO given your intended usage.

-steve

 

[331 cobra]

4.11's

With a double overdrive T56, it will be almost like a T5 with 3.27's on the freeway.

 

[Sam8950]

Keep the comments coming! Guess I should have gone ahead and put 3.73s on the list, too; but given the intended use, the middle ground might be the best overall solution.

 

[331 cobra]

Are you going to travel cross country? If not, you will almost never use 6'th gear if you get the 3.55's.

4.11's will make 6'th useable and it will rocket out of the hole if you get sticky tires.

 

[88stangmangt]

loved my 4.10's................................

 

[Sam8950]

The new Cobra's use 3.55's with a T56. Your HP output is likely to be in the same neighborhood, so look at what they can do. I would go with the 3.55's, as 3.73's would be too much wheelspin on those track vists without slicks or drag radials.

Since you mentioned it, I checked the 04 Cobra specs and found something interesting.

The '04 Cobra T-56 ratios are

2.66, 1.78, 1.30, 1.0, 0.80, and 0.63

Some older information I had for a Tremec T-56 gave ratios of

2.9, 2.07, 1.43, 1, 0.84, and 0.57

Guess one needs to pay attention to which T-56 version they're getting.

 

[Sam8950]

Are you going to travel cross country? If not, you will almost never use 6'th gear if you get the 3.55's.

4.11's will make 6'th useable and it will rocket out of the hole if you get sticky tires.

Yes, I want to be able to take it cross country comfortably. Anyway, my daily commute now includes close to 20 miles of open (usually not too much traffiic) interstate each way. In the not to distant future, I'm facing a job relocation that will up that to about 70 miles of daily interstate driving; plus a high potential for a lot of long weekend cruises. I think I'll get good use out of 6th on a daily basis, even with the shorter gears. . . . And who really cruises at 70 anyway?

 

[Sam8950]

If any body is really interested in the numbers, the attached file contains my spreadsheet analysis of gear ratios, transmissions, and resulting speeds at RPM.

Gears_and_Speed.pdf (41.3 KB)