Hi guys,


Are 4.10 gears to much for an automatic? Or are 3.73 a better idea. Also how do i find out what size of rear end i have in my 1988 GTA 305TPI, is it a 10 bolt and 7.5 diamater ring gear? Thanks

 

id bet your 88 gta has a 9 bolt. but it *could* have a 10 bolt. i wouldnt stick 4.10s in a TPI auto unless you are running a miniram or LT1 intake.

 

I believe if you look at the sticker that came in the glove box or whatever, it has a bunch of 3 digit codes. Mine had GU5 which is 3.23 but I might be mistaken.

I had 3.73 gears and later switched to 4.10 and found that the mileage hurt and was not that much better bucause you have a ton of wheelspin in gear 1. Switched back to 3.73

 

I went out and looked in the glove box, i have GW6 which according to the GTA Source page is 3.27 gears, so does that answer weather i have a 9 bolt or a 10 bolt? Thanks

 

thats a 9 bolt

clench your teeth and go to www.9bolt.com for parts. they are more expensive because they have to be imported.

 

Thanks Diabolical, just one question, why didnt GM just use a 10 bolt? Thanks

 

cost. they were cheaper than the 10 bolt. mostly used in the pontiacs.

went from 3.42 to 4.10. gained .1 in the quarter. not worth it. unless your motor is designed to run 3000-6500 it will be overgeared.
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moderator @ www.fl-thirdgen.org '86 t/a, 3.27, auto, homemade CAI, hypertech AFPR, comp cams 1.52 roller tip rockers, holley prostrip annililator ignition system, shift kit,
OEM corvette 2100 rpm convertor, lakewood adjustable panhard rod and trailing arms, edelbrock 6872 headers, catco 6007 3" cat, flowmaster 17151 3" single outlet catback. 14.91 @ 90.57 177.7rwhp 356.4rwtq

[This message has been edited by mrr23 (edited July 23, 2002).]

 

thats not right. the 9 bolt cost way more than a 10 bolt. gm stopped the 9 bolt due to import costs. they used the 9 bolt because the rear end is strong as all get out, its almost on par with a ford 9 inch. they put them in the irocs and gta's as a hi performance option. and it was used in mostly chevy irocs, t/a's could come with 10 bolts, but irocs had the 9 bolt


[This message has been edited by mr diabolical (edited July 23, 2002).]