dbs1

I am just curious on those with an M6 that have gone from 3.42 gears to 3.73's what gains you've seen in the qtr mile and what mpg losses on the street?

I have an 02 ss that may not see any of the 1/4 mile but does see the road course several times a year and I am curious how much gains in acceleration you see vs gas consumption. About 415 rwhp.

I've got some oem 3.73's sitting here. I would rather run 3.90's in the puny 10 bolt, but don't want the whine that seems to accompany them, and 4.10's are more then I want for my application. Info from those that have done it or know someone who has? Thx!

skanknova

iTrader: (3)

the driveability difference between a 3.73 and a 4.10 is not much, I broke my 4.10s and went with 3.73's and was my biggest regret with the entire project, just go with 4.10s

gofastwclass

iTrader: (2)

I have a 3.70 in my car and the difference was very small in acceleration and fuel mileage. The main thing I noticed is I can now use 6th on the highway without feeling like I'm going to bog the car. 2000 RPM = ~73 MPH in 6th in my 02 WS6 on stock height tires.

Whatever the decision, you will need access to a tune program to fix your speedo.

Hope this helps.

dbs1

Thx for the replies! NO 4.10's! The road course track I race on would require me to go to 5th and then downshift within a very short time to make the corner.

After calculating it out, the 3.90's would need me to rev to 6500+ to get where I need to be mph, where the 3.73's get me there at closer to 6200 rpm. My shift light is set at 6000, but fuel cutoff is set at 6700, though the engine begins to lay over around 6600 and I'm sure It's much harder on the valve springs.

With the possibility of a small 50 shot of nitrous I think the 3.73's make more since for the street and track. With a few more tweaks and a little fine tuning (already have edit) I think we'll be at 425 rwhp, and a little weight reduction with that 50 shot should have us at the no roll bar limit of 11.5 (if I want to use my left over slicks and blow up the puny 10 bolt). I have the 3.73 gears so I think I'll throw them in before I spend 3 grand on an aftermarket rear end and see if the calculator is right.

Thanks again!

ToxicWS6

there was a noticable gain when i went from 3.42s in my 10bolt to 3.70s in my 9inch, not a crazy gain but could feel the diff, makes me wanna know what 4.10s are like lol

therobman

iTrader: (39)

<3 my 4.10's, i had 3.73's go 4.10s

ToxicWS6

ya i was thinking about it, i wanna get a few other things done first but been thinking about it, if i do it, u recommand (being a 9inch) just buying all new 3rd member with 4.10s or buyin just the gears?

Arctic2002ss

I did that change. It bogs down a lot less when launching. I don't drag race much but would say it knocked 3/10ths, maybe even 4/10ths off my 1/4 mile time. I was topping out 4th at 140mph and now it's 130mph. At Texas World Speedway road coarse I have to go to 5th now on the big straight. On the highway, it may actually get better mileage.

ToxicWS6

ahh, might do it when i up grade tires, right now launchin isnt bad but think tires are half my reason lol, and i do 95% city/60mph and under so highway stuff im not to worried about

2002 T/A

I had 3:90s in for less than 100km, went to 3:73 and very happy for my driving style, I found the shifts too tight!

jim ravencraft

Hi,
use the wallace racing calculator and get a ball park figure. 1/4 mile is .2
from 3.23 to 3.73 gear change. I would use a gear that keeps you in the power
band for your engine. Road racing requires lower gears depending on the track. Stay in the power/torque curve/rpm range for your build.
HAVE A BLESSED DAY........JIM

96lt4c4

iTrader: (5)

Hated 4.10, liked the 3.90 but was to noisy, now I have 3.70 and like this ratio as well. If I ever setup another center section I may buid a 3.90.

ToxicWS6

so u think i would be shooting threw gears way to quick with 4.10s? i like my 3.70s but i like them cause it made me feel like i had more power, maybe i just need to get my cam and stuff done and see lol

redtail2426

iTrader: (10)

if you have less than 500rwhp then go 4:10's.If you have over 500rwhp then go 3.90 or 3:70.This suggestion works good for stock weight cars.If your car is under 3100 then go 3:70 or 3:90 even with less then 500rwhp.Also factor in your rear tire height

therobman

iTrader: (39)

^ eaxctly a n/a ls1 should have 4.10's full boltons with h/c/i and 4.10's is a nasty combo. once you start to get over 500 the shifts will come too fast but you could always up the tire height

trans665

this should be a sticky

VincesSS

iTrader: (1)

3.43 to 3.73 netted me about .15 faster 1/4 with a nearly identical 60'.

jb7241986

iTrader: (4)

I have 3.73s.....love them i dont track my car or itd be 410

2002 T/A

"^ eaxctly a n/a ls1 should have 4.10's full boltons with h/c/i and 4.10's is a nasty combo. once you start to get over 500 the shifts will come too fast but you could always up the tire height"

Not to sound rude but why not use the stock tire height and gear the car to your usage? Or are you saying that you can always tweek it with the tire height? There is always a compromise and IMHO once you go 4:10 or numerically higher with an M6 it now becomes a close ratio M5? I am not arguing with the 4:10 + guys who could blow my doors off, I am just saying the the application is more purpose built at that point! Les>>>

dbs1

Well I made the switch form the 3.42's to the 3.73s with my 02 M6 and it is an improvement for sure. I would say that if it was a track only car and not being used so much on the street the 3.90's would be my choice (or if they were not so noisy), but with the amount of street/trip driving the 3.73's give it more grunt.

I would like to measure how much better it works on the long course of the group I road race with, but will be moved to Texas by then. Darn.