ok so i have an 85 IROC Z28, 305 TPI (soon to be mild 350), 700r4 with a shift kit, it originaly had a 2.73 disc brake posi 10 bolt.... well that grenaded one night while launching it....

NOW i put in what im told was a 3.23 10 bolt, disc brake posi, NOPE i looked at it closer last night and its DEF not a 10 bolt, i even glanced at my sport coupes for refernce

i also noticed the car seems a lil more slugish off the line with this rear

is a 9 bolt better then a 10 bolt? whats better gear ratio for a street cruiser/ocasional track car? would 3.73 be better or 2.73 over 3.23?

what is a 9 bolt exactly iv never heard of that before.....

 

https://www.thirdgen.org/forums/faq-...now-about.html

10-bolt info:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

thanks alot

 

ok so i have a 3.27 not wat i was told


OK so about gear ratios, like i said i had a 2.73 from the factory, with my 3.27 it seems a bit more slugish off the line, or is that just me? would a 3.73 be any better? or stay factory with a 2.73? is there that much of a difference?

 

If your 1985, TPI IROC had the factory rear end, it was a 3.42 not a 2.73.