Rear end ratio?
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
Rear end ratio?
Wife's '95 turns 1900 to 2000 rpm at 60mph. Has auto trans. What's the rear end ratio on her car? Thanks
Last edited by old motorhead; Jan 12, 2006 at 12:33 AM. Reason: correction
Race Director
Joined: Aug 2003
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From: San Jose Pat Tillman - American Hero
There's a forum member named Nathan Plemmons (also his screen name). Send him a Private Message (or maybe he'll chime in here). He has an Excel spreadsheet that will calculate that stuff for you.
On a automatic '95, you've got two options, though - 2.45 or 3.07 (for the G92 performance axle option).
On a automatic '95, you've got two options, though - 2.45 or 3.07 (for the G92 performance axle option).
Racer
Joined: Nov 2005
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From: Commerce GA
Originally Posted by ckd
According to an online calc I found it says you have 2.54s but it could be wrong.
Team Owner
Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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You have either 2.59 or 3.07 if its stock, the previous post wasnt exactly correct.
You can look in your RPO codes to determine what came with the car, look for any codes starting with the letter G and post them here. GM1, G44, G92, etc. are things youre looking for.
My car has 3.07s and runs 70mph at 2000rpm in OD. To me it sounds like someone has done something to your rear, but the tach isnt exact.
You can look in your RPO codes to determine what came with the car, look for any codes starting with the letter G and post them here. GM1, G44, G92, etc. are things youre looking for.
My car has 3.07s and runs 70mph at 2000rpm in OD. To me it sounds like someone has done something to your rear, but the tach isnt exact.
Burning Brakes
Joined: Nov 2004
Posts: 1,107
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From: RI
raise the rear up, put the car in neutral and make a small mark on one of the tires and on the driveshaft. Watch how many rotations the driveshaft does for 1 full rotation of the wheel.
Or you could just reference with your RPO codes but who knows if someone before you had changed the gearing.
Or you could just reference with your RPO codes but who knows if someone before you had changed the gearing.
Racer
Joined: Sep 2005
Posts: 484
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From: Germany
Excel spreadsheet
Hi,
I have an Excel spreadsheet, too.
Text is german, but I think it's helpfull ... Excel spreadsheet
I have an Excel spreadsheet, too.
Text is german, but I think it's helpfull ... Excel spreadsheet
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The original ratio is stamped on the rear. But the easiest way is to look at the RPO or do the tire spin method described above.
Drifting
Joined: Sep 2005
Posts: 1,867
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From: Pasadena Maryland
I got this from the web site below.
http://www.nightrider.com/biketech/c...mulas_page.htm
Formulas for MPH RPM gears & tires
mph = (rpm x tire diameter) / (gear ratio x 336)
rpm = (mph x gear ratio x 336) / tire daimeter
gear ratio = (rpm x tire diameter) / (mph x 336)
tire diameter = (mph x gear ratio x 336) / rpm
http://www.nightrider.com/biketech/c...mulas_page.htm
Formulas for MPH RPM gears & tires
mph = (rpm x tire diameter) / (gear ratio x 336)
rpm = (mph x gear ratio x 336) / tire daimeter
gear ratio = (rpm x tire diameter) / (mph x 336)
tire diameter = (mph x gear ratio x 336) / rpm
Burning Brakes
Joined: Nov 2003
Posts: 914
Likes: 1
From: Redding Ca
I have the 2.59 ratio and my car tachs at 1600-1700 at 65 to 70. So my guess is yours is 3.07. Be sure to jack up both rear wheels to do the wheel rotation method or your posi will make for a bad day. 
This is really pretty simple. For a 3.07 you should get almost exactly 3 driveline rotations for one wheel rotation. If the driveline mark comes around about a 1/3 to 1/4 turn less than 3 full revolutions, you probably gave the 2.59. 
This is really pretty simple. For a 3.07 you should get almost exactly 3 driveline rotations for one wheel rotation. If the driveline mark comes around about a 1/3 to 1/4 turn less than 3 full revolutions, you probably gave the 2.59.
Le Mans Master
Joined: May 2005
Posts: 5,214
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From: Queensland, AUSTRALIA
1900-2000rpm at 60mph isnt a stock ratio, id say thats around 3.31-3.33 or 3.45:1. 3.07 should see 1,800 at 60 mph as previously stated, and 2.59 will see around 1,550-1,600 at 60mph. Im led to believe 3.54 will be about 2,200 at 60mph.
Safety Car
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From: VA
