Afraid of getting a too technical answer for my question, I'll try here. I already posted this same question on "Gears & Axles" with no success at all.
I'm on the built of an AWD V8 chassis for a project. I'm using a 4L60/65 with T-case removed from a 2003 Silvarado SS.
On the rear we got a 3.15 gear.
What ratio should I use in the front? Same as rear?
Afraid of getting a too technical answer for my question, I'll try here. I already posted this same question on "Gears & Axles" with no success at all.
I'm on the built of an AWD V8 chassis for a project. I'm using a 4L60/65 with T-case removed from a 2003 Silvarado SS.
On the rear we got a 3.15 gear.
What ratio should I use in the front? Same as rear?
Are you using the exact same tire and wheel combination front and rear? If you are you need to keep the axle ratios VERY close. If you are not, you need to figure/measure things like revs per mile of the diferent tire/wheel combinations.
As I recall, the Silverado SS T-case is a New Venture 149 which has a viscous coupling and a 38% front/ 62% rear nominal torque split so it won't act like a "solid" transfer case with minor variation in front/rear wheel speed. You still want to match front and rear gears with tire revs/mile as closely as possible. What are your available choices for front gears?
If you had 3.08 fronts and 3.15 rears you might run 245/45-17 fronts and 275/40-17 rears wihich would get you within 1% of same revs/mile. That should work.
Jon
__________________ "Being able to "think outside the box" presupposes you were able to think in it." --Bob Lutz "You can't rape Mother Nature."--Tom Ankeny "Doin' what they say can't be done."--Bo Darville "Who gives a cluck?"--Stroker Ace
I have a friend that bought an old 70's chevy 4x4 for a few hundred bucks. We locked the hubs in the snow on a day of fun on the trails and holy crap... It was fishtailing EVERYWHERE!!! Turns out, it came with 3.73s, but someone had swapped out an entire exle with 3.08's in the rear. When we had it in 4wd the back was spinning a whole lot faster, lol. Good thing we never found any pavement!
Thanks guys! I really appreciate all the wisdom shared.
And sorry for the not high tech question, but it seems it is high tech for the "Gears & Axles", and of corse for me.
My question was based on the T-case torque change it does, so I thought maybe the gears were different due to that.
Tires I am using on this thing are: 285/35/19 and 235/40/18 ('06 Vette wheels, not Z06)
__________________ TYHPOON Z06 turbo,pt76gts,inovative progate,turbosmartII,AFR 225 heads 8019 springs, z06 cam, 4l80e,WRE 365 FI short block, doing the nickle, dime stuff. that cost thousands of $$$.
click here for pics http://www.turbols6.com/gallery/view...HOON-LSX-TURBO
2002 SILVERADO Z71 4X4( stock except dual pipes)
have to have something to drive!
http://www.syty.net/ Almost all the high powered sytys even with the the 4.3 are running 4l80e trans, after destroying thier 4l60. when you have excellent traction and a lot of power, it tends to find the weak link, which seems to be the transmission.
__________________ TYHPOON Z06 turbo,pt76gts,inovative progate,turbosmartII,AFR 225 heads 8019 springs, z06 cam, 4l80e,WRE 365 FI short block, doing the nickle, dime stuff. that cost thousands of $$$.
click here for pics http://www.turbols6.com/gallery/view...HOON-LSX-TURBO
2002 SILVERADO Z71 4X4( stock except dual pipes)
have to have something to drive!
Thanks guys! I really appreciate all the wisdom shared.
And sorry for the not high tech question, but it seems it is high tech for the "Gears & Axles", and of corse for me.
My question was based on the T-case torque change it does, so I thought maybe the gears were different due to that.
Tires I am using on this thing are: 285/35/19 and 235/40/18 ('06 Vette wheels, not Z06)
That's a lot of difference in tire diameter and revs/mile. 5.7%
You are not doing nice things to the viscous transfer case with that big of a spread in tire size. I would not recommend that combinatiion.
Good luck.
Jon
__________________ "Being able to "think outside the box" presupposes you were able to think in it." --Bob Lutz "You can't rape Mother Nature."--Tom Ankeny "Doin' what they say can't be done."--Bo Darville "Who gives a cluck?"--Stroker Ace
http://www.syty.net/ Almost all the high powered sytys even with the the 4.3 are running 4l80e trans, after destroying thier 4l60. when you have excellent traction and a lot of power, it tends to find the weak link, which seems to be the transmission.
Oh! I got you. Compared to the 4L80 and adding turbos. You were right years ago. Thanks.
When I destroy the 4L60, i might upgrade to 6L**. I like 6 gears.
Last edited by LSfan70s; 08-22-2009 at 12:51 AM..
Reason: add info
That's a lot of difference in tire diameter and revs/mile. 5.7%
You are not doing nice things to the viscous transfer case with that big of a spread in tire size. I would not recommend that combinatiion.
Good luck.
Jon
Jon, so if I want to stick with the 2 different diameters, I will need to calculate how much more the font wheels will spin and get a higher gear in the front right?
That means if the difference is 5.7% and I already got a 3.15 gear in the rear I will need 3.329 in the front for almost 0% difference. Right? Smaller wheels spin more right?
By the way, this experiment is making AWD a not AWD car. So I'm starting the chassis from scratch. And I would like to use a GM front differential.
Jon, so if I want to stick with the 2 different diameters, I will need to calculate how much more the font wheels will spin and get a higher gear in the front right?
That means if the difference is 5.7% and I already got a 3.15 gear in the rear I will need 3.329 in the front for almost 0% difference. Right? Smaller wheels spin more right?
By the way, this experiment is making AWD a not AWD car. So I'm starting the chassis from scratch. And I would like to use a GM front differential.
Smaller wheels do spin more. In order to spin the wheels faster at the same engine RPM, you need a lower numerical gear, not higher.
AWD experiment. 
I can get this done with different gears in secs 
lol
TYHPOON Z06 turbo,pt76gts,inovative progate,turbosmartII,AFR 225 heads 8019 springs, z06 cam, 4l80e,WRE 365 FI short block, doing the nickle, dime stuff. that cost thousands of $$$. 
