jdm767

I currently have an '03 Z06 with a new engine which we think is producing about 490hp (haven't dynoed it yet, but it's a 383 stroker with 220 heads and 1 7/8 ARP headers, and has a compression ratio of 11.5:1)

Anyway, the rear end is stock and I'm being advised to rebuild it to a 410. I know that it would be great coming out of the corners, but how will it do going down the straights? Will I end up in 5th (where I'd normally be in 4th) and just "lugging" along?

I'm not super serious, so I'm not changing the rear end out for each different track (seriously - I know guys who do!). However, I would like to take advantage of the best that has been built.

What are your thoughts?

Thank you in advance!

Jeff

froggy47

brkntrxn

Leave it with the stock ratios. With that much power, you are more than fine. The vast majority of us that race still have stock ratio rear ends.

froggy47

Even with the stock ratio there are upgrades to several parts in the diff, you probably already knew that.

Last C5

+1 for stock ratios.

Jeredk21

I am running 4.10 gears but only have 360 hp to rear so it works well with the long non z06 tranny. If I did it again I would do 3.90 gears.

jdm767

Thanks guys, I appreciate hearing about your experience and thoughts on the matter!

Jeff

370camaro95

Here's a couple videos at the same track, in two different corvettes.

The first car is a 99 frc, h/c/i stock trans and rear end, on r compounds

The second car is a 02 z06, h/c/i, stock z06 trans, 3.90 rear gear.

The yellow car is definitely faster, I just wish I didn't have a cracked rotor, which caused a really soft pedal after the initial brake pedal application, when the track dried up and i started pushing it. I think the gear made it a lot of fun too. I bought the car on this forum with the rear diff already installed, and all 3 previous owners tracked it. I hope to get into time trials next year, to hopefully see how it does competitively.

VGLNTE1

I have a 4.10 gear with 500rwhp and an MN6 trans. Sometimes I love it, sometimes I don't. I see a 3.73 probably being perfect. The 3.42 was just to little for me. Tracks like road America love the 4.10. I can still do 175mph in 5th gear. The small tracks is where you shift yourself to death.

brkntrxn

You bring up a good point that needs to be stressed to the OP. Talk to people that run tracks that you will run most often and ask them. There may be areas at tracks where having the longer rear gear helps or hurts.

jdm767

All good points, and appreciated.

I think for the time being I should stick with the stock and see how I run next year. If I need the a different rear end to be competitive, then I'll change it out.

Since I am an "enthusiast" and not an all out racer, compromise is probably in order.

I'm going to go out for a spirited drive right now!

Thanks again!
Jeff

Z06Tracker

I would not change it until you really understand your driving style on the tracks you run. I changed from the M12 to the MN6, and I was faster with the M12. While one may be better than the other in "theory" or for someone else, it may not be better for you.

jdm767

Once again, thanks to all for sharing their experiences!

I have decided to run with the current rear end for next season. Then, if it is clear that there is an advantage to changing the rear end, I will.

Soooooo.... any thoughts on an MGW shifter?

jstout

Put money in your brakes. That will lower lap times faster than any other modification you could do. Jerry

drivinhard

The 2.66 M6 box with the 1.78 2nd gear and 3.42 is a pretty good all around box. 4th is good for 150, the 2-4 spread is fairly decent. If you have enough motor to pull more than 150 on most tracks, then the .74 5th gear isn't going to be bothered too bad. Going to a lower rear gear makes 2nd gear low speed corner exits unusable, so you become a 3-5 box, using 5th more, with a tall OD, which isn't ideal.

The 2.29 boxes with a 3.90 is probably the best "all around" combo that you can show up anywhere and not feel like it's really ever out of place.

drivinhard

Here's a very useful tool for calculating what you need, based on your specific track mph range, tire height, rpm range, etc

http://www.grimmjeeper.com/gears.html

jdm767

Thank you very much!