posi rear

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Jul 18, 2005 | 09:07 PM

TheBandit

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Joined: Jul 2005

Posts: 589

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From: Sayreville, NJ

Car: 72 Fbird. Want another 3rd gen :(

Engine: Poncho 350

Transmission: Turbo 350

posi rear

If i were to install a posi rear in an '86 trans am.. automatic 305.. what gear ratios should be used?

Last edited by TheBandit; Jul 18, 2005 at 09:09 PM.

Jul 18, 2005 | 09:27 PM

ShiftyCapone

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iTrader: (7)

Joined: Feb 2001

Posts: 13,753

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From: Cincinnati, OH

Car: '90 RS

Engine: 377 LSX

Transmission: Magnum T56

Re: posi rear

Quote:

Originally posted by TheBandit
If i were to install a posi rear in an '86 trans am.. automatic 305.. what gear ratios should be used?

You will want to determine how you want your car to perform before you select a gear size. Are you concerned with fuel mileage or just perforamce? Take some time to use the search function to research gear swaps. You will uncover hundreds of threas ready for you to read them.

TGO welcomes you

Jul 19, 2005 | 11:42 AM

TKOPerformance

Supreme Member

Joined: Dec 2003

Posts: 2,391

Likes: 1

From: Newark, DE

Car: '86 Camaro, '02 WRX, '87 K5, '67

Engine: 350 TPI, 2.0turbo, 383 in the works, 289-4BBL, 232, A-head 4-cylinder

Transmission: T56, 5-speed, 700R4, C4, T176, semi-auto 2-speed

Axle/Gears: 3.73, 3.90, 4.88, 3.55, 3.54, 7.00

It's hard to go wrong with a 3.73. 4.11 is a bit of overkill, and anything shorter won't give you the same seat of the pants feel. If you are concerned about milage then maybe cut it back to a 3.42. You've got overdrive though, so the difference in RPM isn't going to be that great on the highway.

Jul 19, 2005 | 11:55 AM

stroked1990RS

Member

Joined: May 2005

Posts: 126

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From: west warwick , Rhode Island

Car: 1988 formula 350

Engine: 350

Transmission: 700r4

Axle/Gears: 373

yeah 373 is a nice gear .

Jul 21, 2005 | 05:52 AM

Pro Built Automatics

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Joined: Jul 1999

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From: Calimesa, California, U.S.

I carry both, give me a call at 909 446 8959.

Jul 25, 2005 | 09:43 AM

mdricken

Senior Member

Joined: Mar 2003

Posts: 523

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From: Marion, Iowa

Car: 92 Camaro

Engine: ZZ4 Crate Engine w/Hot Cam

Transmission: Rebuilt 700R4 with Transgo and MW 3

Axle/Gears: 3.73 Eaton Posi

My gas mileage was unchanged when I went from a 3.23 to 3.73 on my 350 crate. I say go with the 3.73s you'll be much happier, ESPECIALLY if you get a higher stall converter some day.