Stage7

I'm planning on switching diffs on my C6 Z51 (402 stroker w/7.2 rev limiter). Right now I'm running 3.90s and I'm planning to put a diff w/stock 3.42s back in.
Is it the right move?

Interestingly enough, my car felt faster from a roll with the 3.42s, but of course gets off of the line much better w/the 3.90s.

I ran the North Course @ Pocono with the 3.90s and overall it felt good, although after the fact, I wondered if I would have shifted less with the 3.42s and been able to run smoother/faster.

I'm too new at the this to really know the answer, and I'd like some input from the seasoned veterans.

Thanks in advance.

AU N EGL

for any road racing ( DEs) a 3.42 would be a better choice. ( a 3.73 is an option too )

Wolf Dog

I agree with Tom. I have 3:90's on my modified 02 Z and I'm shifting way too much, run out of rev's when others are motoring by. Going into 5th on short straights just to keep off the rev limiter. Wish I hadn't done it. Was actually the first mod I made but now that the car is putting out 435hp and 400lbs at the rear wheels I don't need the lower gears

xsiveone

Although, IIRC, David Farmer was using 4.10's in his C5 WCGT car. I wonder why because I haven't seen anyone else using rear end gears like that for road courses.

AU N EGL

WCGTs must use 4.10s or 3.90s with the GM motorsports trans ( close ratio) according to the rules.

John Shiels

do you shift at the road courses at 7200? What will you run Thursday 3.90? What gears were you in at the North course in various turns or top out at straights?

Stage7

7200??? LOL... try 4500-5000rpm!! I was focusing on being smooth and consistent with my lines while keeping my momentum. I didn't use 1/4 of what my car had in it because I don't have the skill yet (plus I'm running stock RF tires, and brakes).

I'll be running the 3.42s on Thur. I'm having Cartek switch out the rear tomorrow.

Looks like my harness will be just about late. I hope my hardbar gets here tomorrow. It has to, for all of this to work out like I'm hoping.

John Shiels

If your not hammering it and just getting your feet wet I wouldn't worry or rush to swap the rear if you can't get it done in time. Hope to see ya Thursday.

Stage7

On the North course:

1) I short shifted on the main straight and feathered 100mph through the apex and as I followed the blocks to the wall, I eased to 120mph plus- All in 4th gear.

2) Braked at the end of the main straight to 110-115mph took the quick turn to the infield. Braked again athe end of the quick turn. If I downshifted to 3rd, the car would jump (have to try the heel/toe thing).

3) Sometimes I stayed in 4th gear through that first turn after turning into the infield. It was the smoothest way for me, and if I kept my speed up, with the 3.90 gear I would hit ~100mph in the short shute staying in 4th gear. Otherwise I would downshift to 3rd AFTER (if someone was behind me)the turn and hit 4th (would get over 100mph then) before braking and downshifting again.

4) The rest of the infield, I stayed in 3rd gear, although I did a few laps in 4th all through the infield until the end, just to experiment and try to use as little brake as possible.

I'm already scheduled to go to Cartek so unless there is a setback, should be good to go w/the 3.42s.

I think I like those gears better all around anyway.

I look fwd to meeting you on Thur.

xsiveone

Thanks. I didn't know that.

Wicked Weasel

with my power I found that 4.10s were way too much for the track. I would assume that 3.90s would be the same.

at first I thought the 4.10s would be ok, but as I got faster I realized I started to shift way too much.

I dropped down to 3.73s and think these are the best gear for my setup. I make a lot less shifts now and my car is happy about that.