What Rear gear with 6l80e??

[STV-R33D]

I'm looking at replacing my rusty and crusty 10 bolt in my 1971 Firebird with a MOSER 12 bolt but I'm not sure what gears to go with? I did a LS swap with a LS2/6l80e from a 2011 Caprice PPV cop car. My tranny has a fixed yoke so how do I fix that issue?

I have no plans to race the car but don't much care about mileage either. It's a six speed trans so it should get decent mileage no matter what. I have Speartech's shifter so I'll be able to use the manual shift.

I'm thinking 3.73's?? Any suggestions??? THANKS!

[dhutton]

Drive Shaft Shop can build you a drive shaft to work with that fixed yoke.

Can't help you with the rear end ratio. I think wheel and resulting tire diameter will play a role in the selection.

Don

[STV-R33D]

I'll be running a set of Year One 17" Rally II's with BFG 275's Also have a stage 2 Ride Tech 4-Link if it makes a difference? Thanks!

[1989GTA]

"I think wheel and resulting tire diameter will play a role in the selection."

Exactly. For my car which is primarily a street car I have a tire diameter of 26". I chose a 3.23 rear axle gear to go with my 6L80 transmission. First gear in those things is like 4.05:1.

[astroracer]

3.73's will work great! I did this in my '02 CETA and it really woke the car up off the line. The OD ratio is the same as a 4L60.

[BonzoHansen]

That's a lot of first gear. I suspect something closer to 3.23 would be better.


1 2 3 4 5 6 R
4.027 2.364 1.532 1.152 0.852 0.667 3.064

[hifi875]

a very high numeric gear ratio will result in a unusable 1st gear under hard accelleration.

[STV-R33D]

I placed my order today and decided to go with 3.73's There's another $3K stuck into this project! I have a Pontiac G8 GXP with the same trans and even in sport shift mode it won't let you keep it in 1st, it always shifts to 2nd on its own.