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

how to check rear end ration with out pulling the cover?

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Old Feb 14, 2009 | 08:09 PM
  #1  
my90bird's Avatar
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From: Sanford Maine
Car: 1990 firebird formula
Engine: 5.0 tpi
Transmission: t-5
how to check rear end ration with out pulling the cover?

my car has a posi and not sure what axle ratio was.how can I check it with out pulling the diff cover off?
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Old Feb 14, 2009 | 08:25 PM
  #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: how to check rear end ration with out pulling the cover?

Originally Posted by my90bird
my car has a posi and not sure what axle ratio was.how can I check it with out pulling the diff cover off?
IMO, without yanking the cover, you can't really be positive.

JamesC
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Old Feb 15, 2009 | 08:20 AM
  #3  
big gear head's Avatar
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Re: how to check rear end ration with out pulling the cover?

This is true, but you can get a rough idea of what it is by counting the drive shaft revolutions. If it has a posi and it is in good working condition then try this. Raise the rear tires off of the ground and put the transmission in neutral. Mark the rear tires in the 6:00 position. Have someone else watch one tire while you turn the other. Mark the drive shaft where you can see it. Turn the tire exactly one full revolution. Have the other person watch the other tire to be sure that it also turns exactly one revolution. If it doesn't then this will not be accurate. Count the number of times that the drive shaft turns. If it turns just over 3 times then it is a 3.08, if it turns 2 3/4 times then it is a 2.73, if it turs 3 1/4 times it is a 3.23, if it turns just short of 3 1/2 times it is a 3.42, and 3 3/4 times would be a 3.73.
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Old Feb 15, 2009 | 10:33 AM
  #4  
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From: Victoria, Tx
Car: 1992 Camaro RS Convertible
Engine: L03
Transmission: 700R4
Axle/Gears: LS1 posi/disk 3.42
Re: how to check rear end ration with out pulling the cover?

have you tried checking for the RPO code in the center console? just a thought assuming you car is completely stock, but yea pulling the cover would be the surest way to tell........

GU2 = 2.73
GU4 = 3.08
GU5 = 3.23
GU6 = 3.42
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Old Feb 20, 2009 | 09:09 PM
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Re: how to check rear end ration with out pulling the cover?

thers a code on the passenger side of the axle on the tube on the front u will have to clean it off with a wire brush or something like that a 3 digit code then you can check it with the haynes manual
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Old Feb 20, 2009 | 09:15 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: how to check rear end ration with out pulling the cover?

Originally Posted by jeffj30
thers a code on the passenger side of the axle on the tube on the front u will have to clean it off with a wire brush or something like that a 3 digit code then you can check it with the haynes manual
The codes are generally rusted beyond recognition. Like the RPO's, they only reveal what was in the car new, not what might be lurking inside the diff housing at this late date. However, here's a link that provides those codes:

http://sethirdgen.org/reardata.htm

JamesC
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Old Feb 20, 2009 | 09:18 PM
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Re: how to check rear end ration with out pulling the cover?

well i got mine off my 87 i live in snowy alberta canada
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Old Feb 20, 2009 | 09:19 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: how to check rear end ration with out pulling the cover?

Originally Posted by jeffj30
well i got mine off my 87 i live in snowy alberta canada
Lucky man.

JamesC
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Old Feb 20, 2009 | 09:27 PM
  #9  
1brd2brd3brd4's Avatar
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From: Evington,Va
Car: 93 Formula,88 T/A,01 WS6
Engine: 93 LT1,88TPI305,01 LS1
Transmission: 93 700R4,88 700R4,01 T56
Axle/Gears: 93 3:73's,88 3:42,01 3:40
Re: how to check rear end ration with out pulling the cover?

Just pull the cover,its not hard to do and it probably way over due for a gear oil change anyway......dont forget to put in limited slip aditive!
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