Are GTA's 9-bolt? I know they come stock with 3.27 gears but can't get a clear answer if they are 9 or 10....I heard that only GTA's are 9 bolt and that is kinda rare. I can't check my car since I am away. Also, if they are 9 bolt, does anyone know a good place to buy 4.11 gears for them?? Everything is for 10 or 12...

 

3:27 gear ratio is for a 9-bolt. You are SOL finding 4:11 ratio for that rear. Just run what you have or spend $2500+ for a 12- bolt.

 

I'm pretty new to rearend stuff. I'm more into stuff involved with engines so sorry if it seems like i don't know what i'm really talking about. Is there any kind of gear out there for a 9 bolt higher than 3.27? I may be doing some more upgrades to my engine and I want to make sure power is getting to the wheels. Will a 3.27 support a supercharger?

 

You mean a lower ratio, a 3:45 is lower and 2:77 is higher then the 3:27. The only ratio that may be avaible for the 9-bolt is a 3:73 which will be the lowest ratio out there.

 

A search is a good thing on this site. The info here may help:

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

JamesC

 

they do make a 4.10 for a 9-bolt, but it is very hard to come by. The 3.70 is available from a few sources.
Gear ratio has nothing to do with supporting "X" power. The steeper(numerically lower) of a gear you can truly "pull" the faster you'll be.

 

Its actually a 3.70

 

only in top speed

 

Not necessarily. For really torquey motors with little top end power, steep gears are better. for example... it would run out of gear too quickly if you had a stock 350 that topped out at 4200 rpm and you put something like a 4.10 gear behind it, and you'd spend more time between gears than actually accelerating the car (with a manual trans)

If he has a relatively stock TPI engine in the GTA, then he'd be best off with something like a 3.45 or 3.70 gear, not a 4.10.. thats way too much gear for a TPI motor.

 

If his car is actually a 91 GTA like his info says, then it's a ten bolt, not a nine bolt. The last year for the nine bolts in any of the f-bodies, including GTA's was 1989. The rearend in my 89 RS is out of a 91 GTA 5.7 auto car, and it's a pbr disc brake, 3.23 ratio, posi ten bolt. I also pulled the gears and posi carrier from another 91 5.7 auto GTA in a local junkyard, and it was also a disc brake, 3.23 ten bolt rear. If you find a 91 GTA with a 5 speed, it's usually a 3.42 ten bolt.

 

all right i think i just realized where i or someone else got confussed.around here steeper gears usally means higher numbers i.e stump pulling gears 4:56
plus your talking about 1/4 mile times. in any 60 foot 4:10 will kill 3:42 on same car,but will run out of gear at the end that's why they say set up third gen to hold 3rd gear at line