Calculating rear end gearing
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Pro
Joined: Mar 2002
Posts: 527
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From: Colchester VT
Calculating rear end gearing
Could some one tell me how to figure out if I have a 2.73 or 3.15 rear end in my 98 A4. Bought car used and doesn't have the usual sticker with options in the glove box. Thanks guys. :seeya
Team Owner
Joined: Apr 2001
Posts: 54,204
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From: S.W. Ohio. . . . . . NRA Life Member
Re: Calculating rear end gearing (98silverC5)
you can get under th car and look for a tag on the carrier; it would state the ratio on the tag.
Or you can drive the car at a constant 75mph with the automatic transmission in third gear and divide the rpm by 1000.
2.73 = 2730 rpm
3.15 = 3150rpm
[Modified by Mike Mercury, 11:21 PM 7/21/2002]
Or you can drive the car at a constant 75mph with the automatic transmission in third gear and divide the rpm by 1000.
2.73 = 2730 rpm
3.15 = 3150rpm
[Modified by Mike Mercury, 11:21 PM 7/21/2002]
Burning Brakes
Joined: Jun 2002
Posts: 1,202
Likes: 0
From: Clarksburg MD
Re: Calculating rear end gearing (Mike Mercury)
you can get under th car and look for a tag on the carrier; it would state the ratio on the tag.
Or you can drive the car at a constant 75mph with the automatic transmission in third gear and divide the rpm by 1000.
2.73 = 2730 rpm
3.15 = 3150rpm
[Modified by Mike Mercury, 11:21 PM 7/21/2002]
Or you can drive the car at a constant 75mph with the automatic transmission in third gear and divide the rpm by 1000.
2.73 = 2730 rpm
3.15 = 3150rpm
[Modified by Mike Mercury, 11:21 PM 7/21/2002]
Is it 75 mph or 70mph. For some reason I thought it was 70..
:confused:
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Joined: Oct 2001
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From: Southern Maryland Maryland
Re: Calculating rear end gearing (98silverC5)
Food for thought on what gears to choose.
Here is my take on gears. If you plan on running the stock sized tire I would go with the following:
4.10:1 -> stock motor to H & C upgrade up to 450rwhp
3.90:1 -> stock motor to H & C upgrade up to 450rwhp with slightly larger tire or tall slick H & C nitrous combo
3.73:1 -> stock motor with H & C or stroker and nitrous with stock size tire
3.42:1 -> stock motor with H & C or stroker and nitrous with slightly smaller tire
Let me know what ya think.
Phillip :boxing
[Modified by Phil97SVT, 5:43 PM 7/24/2002]
Here is my take on gears. If you plan on running the stock sized tire I would go with the following:
4.10:1 -> stock motor to H & C upgrade up to 450rwhp
3.90:1 -> stock motor to H & C upgrade up to 450rwhp with slightly larger tire or tall slick H & C nitrous combo
3.73:1 -> stock motor with H & C or stroker and nitrous with stock size tire
3.42:1 -> stock motor with H & C or stroker and nitrous with slightly smaller tire
Let me know what ya think.
Phillip :boxing
[Modified by Phil97SVT, 5:43 PM 7/24/2002]