hi guys, l've got a 1990 IROC Z with a 305 TPI(150 shot nitrous) , l got a question about installing a 3.73 gear. l'm not positive about the gear, but l know for a fact that l've got the numerically lowest rear end that came in the IROCs l wanna say 2.56 l think? someone correct me if lm wrong, also, what do you guys think about a 3.73 goin in? lm not worried about fuel efficiency but approximately how much do you think it would take off the 1/4 lm not sure what my car runs yet, ld venture to guess low 13's with the 150 nitrous, but does anyone know if lm gonna have any traction problems with a 3.73? can anyone reccomend a good brand or place to buy it off of? any anyone give me any specifics of what to look for?
thanks a lot guys l appreciate it!

 

have one built with richmond gears,or get an after mnarket ford 9" unit (converted to fit GM),limited slip w/ LCA relocatioin brackets and all the other tricks will keep the rear planted....check out the suspension/brake section for more on this.

if you have 2.52:1 now,you will love 3.73:1 gears, I know because I'm stuck with 2.77s right now until I get my 3.73s built.

you may need to tune your engine,maybee new cam ect. to get the full effect,my car came stock with 3.73s so it runs like sh t with 2.77s
try these guys : SW racing 18005233353 they didn't have any thing when I called,but they claimed they're getting 9" GM units in soon.

 

I went from 3.23 posi to 3.73 gears I think the 3.73 are easer to race and drive with. It seems like you can give it power smother so it plants better and goes.

 

thanks for the responses guys, the question l've got now is in the JEGS mag l found a ring and pinion set for the 7.5" 10 bolt and it says right underneath it 77-up all GM models except monza vega and starfire, then under that it says 82-up camaro z28 firebird and trans am, is this what lm looking for? and also l would be using the 3.08 and numerically lower carrier correct?

thanks again guys

 

Jegs should be able to tell you what you need.
I dont know about the carrier and stuff "Dady built mine" but I did not like my 373's for a street car.
They will rip A** if you can hook up but they are agressive you might want to try 343's instead if its a street car.

 

If you've got a 90 305 TPI automatic, you've got a 2.73 2-series gear right now. I highly suggest heading over to www.slponline.com and getting their take-off Torsen posi, and a set of 3-series 3.42 or 3.73 gears. You'll also need the speedo gears for your trans so your speedometer is correct.


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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.23 @ 107.62 MPH
Southern California
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