I'm having a hard time finding a rearend for my IROC. I have disc brakes on the BW 2.77. I came acr5oss a 4.10 rearend but was wondering if that is too much gear for my car. I'm pulling 13.3s on the 2.77 and I can more than max out my 145 mph speedo. (ABove 135mph it sucks the rearview off the post with the T-Tops out). So can anyone provide me with guidance on the 4.10s, what you think the 1/4 mile improvement might be, or should I hold out for something like 3.42s????

 

I'd say 4.10's are too much, especially for a street car.

If it's mainly track, I'd say 3.73's

If it's track/street/daily driven, I'd say 3.42's.

 

Just noticed the TPI in the sig as well.

Yes 4.10's are too much for TPI. I wasn't even willing to go with 3.73's on TPI, although I also drive my car every day.

 

I got 3.42 in my 90 Iroc, and I can manage 1.8x 60's on street tires. So, I'm cool with them, don;t see any need for 3.73's, such a marginal improvement.

 

I think 4.10 is fine... lots of 3rdGens came with 3.73s, and 4.10 is only 1 tooth different on the pinion gear.

 

how the hell is it possible to pull 13's with 2.77s and tpi?????

 

13s on TPI/w 2.77 Well for one it helps that the motor has been bored and stroked to 383 ci. Also I have heads and a cam.

 

I think the 3.42s or a 3.45 would be ideal. It is mostly a street race/track car. I put down 4 competitors last night. S-10, Ranger 4.0, Nissan Sentra SE-R, and a 68 Chevelle.

 

what kinda suspension mods are ya runnin?

 

for RPM, you'll be turning around 2900 at 70mph. To me, that's too much. Your mileage may vary, no pun intended.

Ovrclck is right; taller gears (lower numerically) would make more of the power with the long runner tpi intake.

Thusly, I think you should mini-ram it.

 

I have 3.73s with no overdrive and I tach 3100 @ 70 mph and 2700 @ 55...I could never imagine 4.10s

 

You must have some tall tires.

 

255/50/15s....Not tall....Just a TH-350, and what I GUESS are 3.73s...Not 100% sure

 

they ain't 3.73s.

on a car w/ 26" tires, you'll get roughly gear ratio * 1000 = rpm @ 70. So 3.73 should be about 3730 rpm at 70mph.

 

Well I figured it was either gear or the tranny was the reason my speedo was off..It says Im doing 73 when Im goin 55...Just figured it was gears

 

I'm not running any suspension mods, it's all stock.