Hey some of you know that I recently broke my 8". Now I'm working on switching to a 9", but I need to get some opinions on gear ratios... It has a 408 stroker making close to 500 lbs of torque. I have a t5 with a .68 OD. Any suggestions?

 

I like the 3.50:1 in mine with a T5 but I ain't making close to 500hp!

 

I would use a gear calculator to determine what ratio you need. Find the rpm where your cam starts it powerband, mine was about 2200 rpm.Then determine what speed you want to be traveling (this was my cruising speed of 60 or 65 can't remember now) and ended up purchasing 3.70's. I havn't had the car on the road yet so I can't tell you exactly. I thought about going with 3.89 but many rear end guys said that the ratio made much more noise than that of the 3.70. Something to do with the number of teeth on the pinion gear was less. I don't know if this help but good luck. I have a roller efi302 putting out what should be close to 370 horsepower and a T5.

 

how long will the t5 last with that much torque????

Assuming you will replace it with another 5 speed when you blow that one to bits, I'd look at 3.5 or 3.7.

it comes down to revs...try this link because it has the t5 ratios http://www.corral.net/tech/gearcalc.html

you can work out how quickly you will run out of 1st gear of the line right thru to cruising revs and even a theoretical top speed!

 

3.7 or more with that final. It will do great in 5th at 75-80 but will be slugish around 50-55. I like a 3.5 with a .82 final. Thats me though.

 

4:10......That's what I have with an AOD...

 

do you know what your od ratio is LCC
Superdavids is 0.68 which is a hell dropoff IMO.
I'd wanna know the 1,2,3 ratios as well before I went as high as 4.1

5th at 70mph roughly
3.5 2200rpm
3.7 2300rpm
4.1 2600rpm

 

Mine are:
1st = 2.40
2nd = 1.47
3rd = 1
4th = .667

 

so that gives you about a 2.73 final drive...Nice for cruising
Does it feel like you are through 1st and 2nd too quick?
I dont think my engine revs high enough to take advantage of 4.1...I went from 3.0 to 3.5 and pretty happy with that for most situations but without the o/d it does run a bit high in the rev range at 70-75 cruising speed.

if I had someone elses check book my ultimate would be to fit a 5 speed but somehow retain the original 4 spd shifter with the reverse lockout... a stealth o/d if you will. I will be dreaming for a while!

 

I've run this trans with 4:11 for so long that I wouldn't want it any other way. I love the way it goes through the gears and then when I get onto the highway I flip a switch and baam, It shifts into overdrive...