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

3.73 Gears from 4th to 3rd?

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Old Nov 30, 2009 | 01:36 AM
  #1  
Borkhart's Avatar
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From: Cambridge IL.
Car: Black '89 IROC-Z
Engine: 5.7 350 TPI
3.73 Gears from 4th to 3rd?

I have a 1989 iroc-z and not to sure what gear ratio is in it stock i always find conflicting numbers. but anyway my buddy has a Ws6 trans am 2002 and is going to give me his 3.73 gears while he goes for some 4.56 and i was wondering if they would just fit right in or if i'd have to but anything..
Any info would be great and save me some money .
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Old Nov 30, 2009 | 06:59 AM
  #2  
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: 3.73 Gears from 4th to 3rd?

Originally Posted by Borkhart
I have a 1989 iroc-z and not to sure what gear ratio is in it stock i always find conflicting numbers. but anyway my buddy has a Ws6 trans am 2002 and is going to give me his 3.73 gears while he goes for some 4.56 and i was wondering if they would just fit right in or if i'd have to but anything.
Welcome to TGO. If the 89 rear is a 10-bolt, the gears will fit. If the 89 has 26-spline axles, which is probably does, you'll need to purchase a set of 28-spline. The following link will provide more FAQ will provide info that may be useful:

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

JamesC
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Old Nov 30, 2009 | 08:06 AM
  #3  
big gear head's Avatar
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Re: 3.73 Gears from 4th to 3rd?

You don't have to change the axles if you are just changing gears.

If your car has a 10 bolt and it has a 3 series differential then the 3.73 gears will fit. You will have to set the pinion depth, bearing preload and backlash. If your car has a 2 series differetnial then you will have to change that to a 3 series.
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Old Nov 30, 2009 | 08:18 AM
  #4  
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: 3.73 Gears from 4th to 3rd?

Originally Posted by big gear head
You don't have to change the axles if you are just changing gears.
My bad. I'm used to recommending a limited slip swap as well.

JamesC
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