indy300

Guys, my C5's differential is leaking. I was thinking that if the diff has to be pulled to fix the leak, why not toss in a bette gear... I have a MN6 and would like quicker acceleration for normal driving and plan to take the car to a HDPE every now and then. What gear ratio do you recommend and why? I was leaning towards 3.90 for a good compromise for normal driving/HDPE.

Lets hear it.. Thanks.

RAFTRACER

make sure your leak is not just from the vent on the rear differential after your Putnam episode. GM has updated rear axle seals for the past year or so. 3.42 is pretty good roadcourse gear , especially for Putnam.

MrEracer

If you like extra shifts between turns you can go to a lower rear gear on DE tracks. I like the MN6 trans with a 3.42 rear gear for my road racer C5 as the best gearing for most tracks. If you are more into autocross a lower rear gear may better suited... This is my opinion, yours may differ.
Shirl Dickey

Roadrace65

My 3.90s/MN6 are Great for AutoX and a ball on the street....but...I ran out of RPM on the front and back straight during a High Speed event at Rockingham and had to shift to 5th.......

AU N EGL

M6 and 3.42 are the choice of most.

I drove a M12 with 4.10s on VIR and I ran out of gear in 5th. Way too much shifting in the slower parts, and limited top end.


On a side note, I am still scratching my head about the WC vetts with the GM Motorsports( close ratio) trans, 4.10s and the 7300 now 7100 rev limiter. Would not they get better power or lauch with something other?? Forget the rules for moment.

Stock trans and stock diff, or Motorsports trans and 3.90s or 4.10s
reagarding gear alone, not to take into account the stonger GM motorsports parts

Wicked Weasel

I just took out my 4.10s because they were too much gear for track use. Granted they were fun on the street and at the strip, but on road courses I was shifting all over the place.

I changed over to 3.73s and love them as an all around gear.

Wolf Dog

I have 3:90's in my '02 Z, 425HP/420lbs at rear wheels and its too much for the track. As just about everyone mentioned, too much shifting. You would think that would not be the case. I run out of rpm too quickly. IMHO, I would stick with the stock 3:42's if thats what you have, perhaps 3:73's.

MrEracer

Quote from Au N Egl:
"On a side note, I am still scratching my head about the WC vetts with the GM Motorsports( close ratio) trans, 4.10s and the 7300 now 7100 rev limiter. Would not they get better power or lauch with something other?? Forget the rules for moment. "

The only thing I can figure is they may be running a 28" or taller tire...
Shirl Dickey

RAFTRACER

I don't think their tires are anywhere near 28", but I do know the first gear in that motorsports gearbox is 2.20:1 . Anything less than a 3.73 and their itty-bitty carbon clutches would not be happy , or they would have to leave at such a high-rpm from the standing start that the rear tires would just go up in smoke. 5th gear is useable in that box and if you think about using 2nd-5th the gear spacing is closer than 1st-4th. tighter gear spacing on course and a "launch gear".

AU N EGL

The Corvette and Viper rear tires are Toyo 18x335/30s

Lou mentioned that on the Long Sebring and Long Beach GP straights that he was maxed out at 7400 rpms in 5th gear w 4.10s at 160 mph. Now they reduced the revs to 7100

I like the strenght of the motor sports gear box, but not the gearing.

indy300

Thanks for everyone's input. Is a 3.73 too much for occasional track use?