Rear gear ratio

[70PTRS]

I'm going to be running a 25.9 tire (Rival 335/30/18) and a T56 magnum with a 2.97 1st gear and .5 6th behind a 450 rwhp LS1. What's the optimum rear gear ratio for my set up?

[WSSix]

What type of driving? All around, autox, competitive autox, road coarse, etc?

[70PTRS]

What type of driving? All around, autox, competitive autox, road coarse, etc?

Mostly all around with an occasional autox and a few trips to the drag strip every year.

[Sieg]

It's a loaded question!

Here's the best tool I found to help me make the decision: http://www.tremec.com/calculadora.php

Do you already have the transmission?

[70PTRS]

It's a loaded question!

Here's the best tool I found to help me make the decision: http://www.tremec.com/calculadora.php

Do you already have the transmission?

Yes I already have the trans.

I'm thinking a 3.70 or 4.11? With a 3.70 at 1800rpms I'm cruising at around 75 in 6th;
With a 4:11 at 2000 rpms I'm cruising 75.
3:70 at 6500 in 4th gear Im going 135, 4:11 is 121 which is around what the car should trap in the 1320.

[WSSix]

I was going to suggest a 3.73 or 3.90 ratio for an all around car. I think any gear in the 3.70 to 4.10 range will work well for you honestly.

[Moose]

I have the 4.11 in mine with your exact same setup. Love them. Pulls hard out of corners on autocross. It will spin the tires at drag strip, you're going to find that right launch point.

The 3.73 are just 1 step up over stock for original 4th gen f-bodies.

One last thing. on power tour in 2014, I was getting 24-26 mpg when I kept my foot out it..

Mike

[70PTRS]

Awesome info; I think a 4:11 is what I'll be ordering. Thanks guys!

[Tony V]

Same set as yours and i went with 3.70

but put together a quick table to evaluate options

http://i280.photobucket.com/albums/kk174/e071307/Slide1_zpsbe74abc1.jpg

I can send you the excel file if you want to play around with the options....

[70PTRS]

Same set as yours and i went with 3.70

but put together a quick table to evaluate options

http://i280.photobucket.com/albums/kk174/e071307/Slide1_zpsbe74abc1.jpg

I can send you the excel file if you want to play around with the options....

I think any one of those 3 will work. I may split the difference and go with the 3:90's

Which gears are better quality and quieter, Motive or US Gear?

[WSSix]

I have US Gear 3.90s in my TA. I love them and so far they are quiet. I only have a few miles on them though. I also haven't done any events with the gears. However, it's a big difference compared to the 3.42s and I'm very happy at this point with them.

[70PTRS]

I have US Gear 3.90s in my TA. I love them and so far they are quiet. I only have a few miles on them though. I also haven't done any events with the gears. However, it's a big difference compared to the 3.42s and I'm very happy at this point with them.

That's good to know; I've been told to stay clear of the 3.90's because they are very noisy. Anyone else using 3.90's have plenty of miles on them and are happy with no noise issues?
.

[WSSix]

Really? Never heard that before. I've actually put 3.90s in a number of six speed cars and never had an issue. Maybe I got lucky. :EmoteClueless:

[Sieg]

FWIW - I'm running Motive 3:73's in a 12 bolt and they seem as quiet as the 3:31 OEM gears I replaced, but I'm running a 'quiet' gear drive and Flowmaster exhaust so quiet isn't relative to my car. :)

I've also heard numerous arguments of 3:73's being inherently noisy.

I think it really comes down to who sets the gears up for you. The guy that did mine has over 40 years experience and specialized in drag racing setups in his earlier.