What kinda gears would be best for my 1991 RS 5speed. Its a 305 TBI...and what kinda of diffrence will they make?

 

I'm in the process of swapping out a Z28 rear that I've had rebuilt with 3.73 Gears.I originally had a 3.08 single-legged drum brake rear in my 92 RS,5 Speed car.Z28 rear that I got came with 3.23 but I figured if I was going to the trouble of going through all of it, Id go a little deeper than the lowest factory available 3.42.Most people I know with TBI 305 or TBI 350 motors are currently running 3.42 or 3.73. As a matter of personal preference, I'd say if you're more concerned with stoplight-to-stoplight acceleration, go with the 3.73, otherwise the 3.42 is a good compromise.Both will get you out of the hole a lot quicker than the 3.08 or 2.73 you have now.
-Rich-

 

3.23 = decent accel, best mileage
3.42 = better accel, less mileage
3.73 = best accel, decent mileage

I wouldnt recommend 3.73's on a stock motor, since it will be winding up all the time.

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1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."
"Ponies can run, but birds can fly..."

 

Winding up??

 

Winding up = Too many rpms for an engine that chokes at 4500rpm.

3.73 gears should only be used on an engine with around a 6000rpm redline in my opinion.

 

Why would you have to rev it past 4500 with 3.73 gears? Just shift at 4500(or where ever) like normal. Sure the engine will wind up faster, but you don't have to wind it up any tighter just because you have deep gears.


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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro

 

If you shift lower, you will start the next gear at lower rpm, which could be below your power band. On the other hand, if you have to shift gears at 5000+ rpm, a stock 305tbi has little power there too, which is why I would not get 3.73 gears on a stock 305 like I originally said.

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1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."
"Ponies can run, but birds can fly..."

 

Why shift above/below the powerband with a gear change to 3.73's? Shift at the SAME rpm as before the gear change. Don't shift lower or higher than before. I agree with not shifting too early(ending up on the lower end of the powerband) and not shifting too late(past the powerband), but what does that have to do with the gear ratio?

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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro

 

since it is a 5-speed i think it comes with 3.23s. since it is a 5-speed, i would DEFINITLEY go with 3.73s, becaue you can actually keep it in high gear. like, with my 700R4, i cant really go much past 3.42s without having problems going into 4th gear.

but with 3.73s you want to try to get the rest of teh engine/tranny into the same ballpark of performance. like, you wont get the best benefits of then geras unless you have a better cam and maybe a torque converter. if you cant keep the 305 in its powerband, you will wats eyour money on 3.73s. if not, go with 3.42s.

going from 3.23s (if thats what you have) will make a small difference going to 3.42s, and alittle more difference going to 3.73s. if you are like me and have 2.73s, either will be a kick in the pants! i cant wait till i get mine in.

-Brian

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1991 Camaro RS - ultra blue metallic, t-tops
GMPP 350 HO crate engine - 454 TBI, MSD ignition, SLP exhaust, everything is new
700R4 - 2,400 stall converter, vette servo, shift kit
z28boy.cz28.com
Central New York F-Body Association
z28boy@twcny.rr.com AIM - "Z28 Boy"
1998 Pontiac Grand Prix GT - 2 door, black

[This message has been edited by Z28 Boy (edited October 04, 2001).]

 

My 305 5-speed came with 3.08 Gears.

 

I also have a 1988 IROCZ 305 TBI auto....what kinda gears should i get for this.?