Rear end gears?

[Grandprixpaul]

I have a 1987 grand prix with a 350-sbc-366hp, and a 350 turbo trans with shift kit heavy duty built for street- strip 2000 stall converter , what will be the best all around posi gears for rear end , I keep hearing 373 , but want to hear from somepeople about it before I start looking for it , and how do I know if I find a unit for sale that it is a 373 is it stamped? Thanks paul

 

[cuttybuddyluva]

3.73 (SS's) would be great for a cutty same ones i put in my cutty and i have a 305 bored .30 and it gets up. You have bigger ones like 4.10 (Chevelles) and 4.26 for (Drag) and smaller ones like 3.26 (Camaro) but just stay away from anything lower cause the SUCK! . everyone told me to renforce my rear.....Heavy duty springs, new shocks etc....and match your unit i think its a 7.5 10 bolt but you need a posi so try finding camaro or monte carlo with a posi unit and swap guts. Use new bearings!

 

[G-Body_Vet]

I have a 1987 grand prix with a 350-sbc-366hp, and a 350 turbo trans with shift kit heavy duty built for street- strip 2000 stall converter , what will be the best all around posi gears for rear end , I keep hearing 373 , but want to hear from somepeople about it before I start looking for it , and how do I know if I find a unit for sale that it is a 373 is it stamped? Thanks paul

That all depends on your goals and what you're trying to build. Is this a street car, track car, do you give a $hit about gas mileage, or are you trying to strike a good overall balance?

Running a 3.73 with a 3 speed trans will turn your car into a buzzbomb at highway speeds.....like 3200 rpms at 65mph with a 26" tire, not fun at all. Personally i wouldn't use a 3.42 or 3.73 without an OD trans in a car that I do much commuting with, especially since we're getting our *ss handed to us with gas prices again.

Here's the trans ratios http://www.montecarloss.com/SSThunder/drivetrain.html
Here's an rpm calculator http://www.csgnetwork.com/multirpmcalc.html

I'd suggest playing around with the numbers to make a decision on what rpm range you intend to use the car and pick what's suitable.

To figure out what gear ring and pinion theres two ways to do it. One way is counting the teeth on the ring and divide it by the number of teeth on the pinion. The easy way is to look for the numbers stamped on the ring. For instance if you see the numbers 12/41 on the ring it's a 3.42. 41/12= 3.42 get it? 41 is the number of teeth on the ring, 12 is the number on the pinion. A 3.73 would be 11/41, 3.08 would be 13/40, etc.

I've been contemplating a rear end change for awhile and I've been looking for the most cost efficient route without sacrificing reliability & performance.

 

[dogsht]

Gbodyvet ditto

 

[Veltboy618]

everyone told me to renforce my rear.....

How do you reinforce your rear end?

 

[3XBrownCutty]

Reinforce by using a girdle cover
http://www.justdifferentials.com/index.php?main_page=product_info&cPath=28_69_184&products_id=178

I have a set of 7.5" 3:23's for sale if your interested.

 

[Grandprixpaul]

Thanks for the info guys , I am looking for a 8.5 posi just wasn't sure what gearing I would want, would like to take to strip little street race got to keep these ricers in check, but decently not a daily driver thanks guys

 

[Veltboy618]

Reinforce by using a girdle cover
http://www.justdifferentials.com/index.php?main_page=product_info&cPath=28_69_184&products_id=178

I have a set of 7.5" 3:23's for sale if your interested.

How do those help reinforce the rear end ?

 

[pontiacgp]

the bolts support the bearing caps...the way the gears are cut the crown is forced outwards putting pressure on the caps

 

[-83MONTESS-]

With that much power I would reccomend anything from 3.08s to 3.73s. To the guy who said anything lower than 3.42s suck a 305 has no torque to begin with so yea there gonna be sluggish but put power behind it and you dont have to rely on your gears to get you going . I know a guy with a 69 442 (455 BBO) with a 12 bolt runnin 3.08s and he runs a 12.9 in the 1/4. Thats why I love the saying " Horsepower sells engines, torque wins races!"