Diff Ratio
Thread Starter
Racer
Joined: Apr 2008
Posts: 452
Likes: 8
From: Washington DC
Diff Ratio
I have a '98 manual. Trying to find the actual ratio. I don't have a glovebox (track car) and the tag on the diff doesn't show the ratio. Any other way to know for sure? Although most manuals are 3:42s I believe some came with the 3:15 as well. So unless you have some concrete info on this, please don't suggest that it is 3:42 by default.
Pro
Joined: Feb 2009
Posts: 651
Likes: 33
From: North Port Florida
I have a '98 manual. Trying to find the actual ratio. I don't have a glovebox (track car) and the tag on the diff doesn't show the ratio. Any other way to know for sure? Although most manuals are 3:42s I believe some came with the 3:15 as well. So unless you have some concrete info on this, please don't suggest that it is 3:42 by default.
Safety Car
Joined: Sep 2008
Posts: 4,753
Likes: 167
From: Youngsville North Carolina
Thread Starter
Racer
Joined: Apr 2008
Posts: 452
Likes: 8
From: Washington DC
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Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
If its non standard its in your RPO Codes in the glove box:
G90 Axle, Rear, 3.15 Ratio
G92 Axle, Rear, Performance Ratio
GU2 Axle, Rear, 2.73 Ratio
GU6 Axle, Rear, 3.42 Ratio
G90 Axle, Rear, 3.15 Ratio
G92 Axle, Rear, Performance Ratio
GU2 Axle, Rear, 2.73 Ratio
GU6 Axle, Rear, 3.42 Ratio
Team Owner
Joined: Jul 2006
Posts: 22,141
Likes: 4,156
From: Kannapolis NC
Actually in a 98 it was under the left rear compartment cover. The OP says he doesn't have a glove box, so I'm assuming he doesn't have a compartment cover either.
All manual cars came with a 3:42. The number of revolutions on the tire when jacked up won't change because of tire size, the mark will be the same place on the hub for any size wheel.
All manual cars came with a 3:42. The number of revolutions on the tire when jacked up won't change because of tire size, the mark will be the same place on the hub for any size wheel.
Former Vendor
Joined: Oct 2006
Posts: 278
Likes: 17
From: Auburn/Dacula/Lawrenceville Georgia
There is no such thing as a manually equipped C5 with a 3.15 gear unless it was installed by a previous owner or a mistake happened in production.
Safety Car
Joined: Dec 2010
Posts: 3,938
Likes: 498
From: Fords, NJ
If you jack up the rear end and use jackstands for safety, please,put the car in neutral and rotate the rear wheels one complete revolution while having someone else observe the driveshaft, noting how many times it goes around. This will give you the rearend ratio. Good luck, remember, JACKSTANDS!!!!!
Thread Starter
Racer
Joined: Apr 2008
Posts: 452
Likes: 8
From: Washington DC
Actually in a 98 it was under the left rear compartment cover. The OP says he doesn't have a glove box, so I'm assuming he doesn't have a compartment cover either.
All manual cars came with a 3:42. The number of revolutions on the tire when jacked up won't change because of tire size, the mark will be the same place on the hub for any size wheel.
All manual cars came with a 3:42. The number of revolutions on the tire when jacked up won't change because of tire size, the mark will be the same place on the hub for any size wheel.
Thread Starter
Racer
Joined: Apr 2008
Posts: 452
Likes: 8
From: Washington DC
Actually in a 98 it was under the left rear compartment cover. The OP says he doesn't have a glove box, so I'm assuming he doesn't have a compartment cover either.
All manual cars came with a 3:42. The number of revolutions on the tire when jacked up won't change because of tire size, the mark will be the same place on the hub for any size wheel.
All manual cars came with a 3:42. The number of revolutions on the tire when jacked up won't change because of tire size, the mark will be the same place on the hub for any size wheel.