Transmissions and Drivetrain Need help with your trans? Problems with your axle?

2.73 Rear to 3.73 Rear

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Old Aug 26, 2009 | 05:40 PM
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2.73 Rear to 3.73 Rear

What else do i need to upgrade on my 1990 Pontiac Firebird EFI 5.0 305, to make this work properly
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Old Aug 26, 2009 | 09:41 PM
  #2  
toomany's Avatar
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Re: 2.73 Rear to 3.73 Rear

The gear in the tansmission will need to be changed to keep the speedometer accurate.
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Old Aug 27, 2009 | 03:53 AM
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Re: 2.73 Rear to 3.73 Rear

so, would that be a ring and pinion gear like this ...

http://cgi.ebay.com/ebaymotors/GM-7-...Q5fAccessories
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Old Aug 27, 2009 | 04:03 AM
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From: plano texas
Car: 91 RS Vert, 87 SC T-Top
Engine: LO3, LG4
Transmission: 700r4's
Axle/Gears: 2.73, not sure yet
Re: 2.73 Rear to 3.73 Rear

Originally Posted by jmooreofpure
so, would that be a ring and pinion gear like this ...

http://cgi.ebay.com/ebaymotors/GM-7-...Q5fAccessories
No. Tho's are the gears in the carrier its self. I think its a small plastic gear and it goes behind the tranny I believe.
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Old Aug 27, 2009 | 04:19 AM
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Re: 2.73 Rear to 3.73 Rear

Originally Posted by Chezoom
No. Tho's are the gears in the carrier its self. I think its a small plastic gear and it goes behind the tranny I believe.
Do you have any idea what that part is called? If you are able to search for it on ebay copy and paste the link in a reply
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Old Aug 27, 2009 | 04:29 AM
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From: plano texas
Car: 91 RS Vert, 87 SC T-Top
Engine: LO3, LG4
Transmission: 700r4's
Axle/Gears: 2.73, not sure yet
Re: 2.73 Rear to 3.73 Rear

not something you get on ebay, chevy dealership

use this thread, you might have to pm the OP

https://www.thirdgen.org/forums/tran...eedometer.html
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Old Aug 27, 2009 | 07:24 AM
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Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: 2.73 Rear to 3.73 Rear

You'll need the ring and pinion, of course, and all that goes with replacing them, as well as the drive and driven gears to make the speedo read correctly. Phone these guys for what you need:

http://www.transmissioncenter.net/sp...n_______va.htm

The following FAQ may provide some info to consider:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

Last edited by JamesC; Aug 27, 2009 at 07:36 AM.
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Old Aug 27, 2009 | 02:44 PM
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Re: 2.73 Rear to 3.73 Rear

Will replacing the drive and driven gears to match the rear affect the way the car drives (or shifts)?
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Old Aug 27, 2009 | 02:50 PM
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JamesC's Avatar
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From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: 2.73 Rear to 3.73 Rear

Originally Posted by jmooreofpure
Will replacing the drive and driven gears to match the rear affect the way the car drives (or shifts)?
No.

JamesC
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Old Aug 27, 2009 | 03:25 PM
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Car: seeking '90.5-'92 'bird hardtop
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Re: 2.73 Rear to 3.73 Rear

PM me if you need any more help figuring it out.
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