What rear ratio

[PolarBear]

I am planning on rebuilding my other 10 bolt for the 73 soon. I have a Torsen T2R to put in it and 30 spline axles, should be bullet proof for the most part with what I plan on doing with it.

Currently the car has 3.42 in it but with an LSx based engine compared to the BBC I don't think that will be enough gear. I don't want to go too crazy high though.
I have to figure out what ratio to put in it. I am guessing either 3.73 or 3.9 gears. The car will have the LS1 T56, and a 26" tall tire, I think 274/40-17 right now, but I will be going to an 18 when I get the Fikse wheels and I am not sure what height tire I will run eventually, but it should probably be something close to what I had on the Solstice (245/45-18) when I put 18's on the Camaro. I think the 3.42 wont be enough with an LSx and a T56 with a .5 (right?) 6th gear

Opinions/Experiences welcome

[WildBillyT]

3.90

[PolarBear]

Originally Posted by WildBillyT

3.90

Reasoning? If you have any. I am not sure how to pick

[WildBillyT]

With my 28" rear tires I am doing 1500 at 60 with 4.11's. I think that's perfect for the highway. With 26" tires you'd get the same performance with 3.90s.

[PolarBear]

Hmm, I was going to go with Yukon since my 3.42 is nice and quiet but they dont have a 3.90, so I have to pick someone else or go with 4.11.

I used one of the gear calculators. With a 27" tire and the .5 6th gear the 4.11 would be ~1682 at 65mph... that is a lot lower than what I thought it was going to be. Maybe I should just go with that

[Featherburner]

Everybody runs 4.11, I say you should go with 5.57 gears. You don't want to be like everyone else, do you?
Here's a quick link.
http://www.summitracing.com/parts/rmg-6901751/overview/

[PolarBear]

Yukon only goes to a 5.38 for an 8.5" GM

[WildBillyT]

Originally Posted by PolarBear

Hmm, I was going to go with Yukon since my 3.42 is nice and quiet but they dont have a 3.90, so I have to pick someone else or go with 4.11.

I used one of the gear calculators. With a 27" tire and the .5 6th gear the 4.11 would be ~1682 at 65mph... that is a lot lower than what I thought it was going to be. Maybe I should just go with that

Yup. Go 4.11 then. Any lower numerically and I don't think you'd use 6th that often.

[LTb1ow]

4.11s, its a 6 speed, dont be a lame

[WildBillyT]

Or go 2.73 for the lulz

[BonzoHansen]

4.11

[The_Bishop]

Time for a D-60 and 5.13's. Be different!

4.10's should work fine. Might make traction in 1st interesting, though.

[PolarBear]

Originally Posted by The_Bishop

Time for a D-60 and 5.13's. Be different!

4.10's should work fine. Might make traction in 1st interesting, though.

lol

I am not really going to be drag racing and if I do it will be on street tires most likely.

[PolarBear]

OK with the ~26.68" tire over the 25.7" the 4.11 will act more like a 3.96:1 according to the calculator over at Wallace Racing

[PolarBear]

Looks like 275/40-18 is a size with a lot of offerings from tire manufacturers

[stealth355tpi]

275/40/17 tire 4.10 gear, I'm doing 70 at 2000rpm in 6th

[NHRABill]

If you like the drag strip I would do the math and see how far I can get from each gear. (1st gear to rear gear to tire height to desired power band shifting RPM) and so on so you know where you will be on a 1/4 mile track or 1/8th mile. I hate shifting too quick and screwing 60' time or 1/8 mile cause I ran out of gear. Its reason I have 3.90 in my Vette with a 28" tire running a th400.

I am sure someone out there thought it through already.

[PolarBear]

I'm not a drag racer, so I don't think I need to go to that extreme.

Thanks though