changing the Diff gearing
Thread Starter
Racer
Joined: Feb 2004
Posts: 348
Likes: 6
From: Las vegas Nevada
changing the Diff gearing
I'm considering replacing the standard (2.42) gearing in my Coupe to 3.79's. What do I expect to gain from this change in performance and fuel mileage and is it worth it?
Melting Slicks
Joined: Nov 2002
Posts: 2,884
Likes: 261
From: Jamison Pa
St. Jude Donor '11-'25
???
I put 4:10's in my car (from 3:42's) and my gas mileage didn't chage too much (about 1mpg loss).
Bob K.
Melting Slicks
Joined: May 2005
Posts: 3,461
Likes: 161
From: Las Vegas Nevada
St. Jude Donor '08
Melting Slicks
Joined: Mar 2005
Posts: 2,364
Likes: 1
From: Rugby North Dakota
Couple things - the standard gearing is 2.73, not 2.42; and you would be installing 3.73's, not 3.79's
Also, just so you know, you don't just swap the gears w/in the pumpkin/carrier like you did in old cars - instead, you swap out your stock carrier for a carrier w/ the gears that you want -
Also, if you are going to do it, save yourself some $$$ and install a Torque Converter at the same time - gears and T/C will compliment each other and the labor is the exact same to swap them - therefore, while you are working in that area, do BOTH.
IMHO, 3.73's w/ a SS3200 or SS3600 stall are the PERFECT combination!
Also, just so you know, you don't just swap the gears w/in the pumpkin/carrier like you did in old cars - instead, you swap out your stock carrier for a carrier w/ the gears that you want -
Also, if you are going to do it, save yourself some $$$ and install a Torque Converter at the same time - gears and T/C will compliment each other and the labor is the exact same to swap them - therefore, while you are working in that area, do BOTH.
IMHO, 3.73's w/ a SS3200 or SS3600 stall are the PERFECT combination!
Melting Slicks
Joined: May 2005
Posts: 3,461
Likes: 161
From: Las Vegas Nevada
St. Jude Donor '08
Couple things - the standard gearing is 2.73, not 2.42; and you would be installing 3.73's, not 3.79's
Also, just so you know, you don't just swap the gears w/in the pumpkin/carrier like you did in old cars - instead, you swap out your stock carrier for a carrier w/ the gears that you want -
Also, if you are going to do it, save yourself some $$$ and install a Torque Converter at the same time - gears and T/C will compliment each other and the labor is the exact same to swap them - therefore, while you are working in that area, do BOTH.
IMHO, 3.73's w/ a SS3200 or SS3600 stall are the PERFECT combination!
Also, just so you know, you don't just swap the gears w/in the pumpkin/carrier like you did in old cars - instead, you swap out your stock carrier for a carrier w/ the gears that you want -
Also, if you are going to do it, save yourself some $$$ and install a Torque Converter at the same time - gears and T/C will compliment each other and the labor is the exact same to swap them - therefore, while you are working in that area, do BOTH.
IMHO, 3.73's w/ a SS3200 or SS3600 stall are the PERFECT combination!
Clayton from Las Vegas
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Racer
Joined: Jul 2005
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Go with the 3:90's!!!
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
I imagine the 3.90's are a little bit more controllable, especially with launching.
Of course - if one is willing to mod the rear suspension, and put on proper tires when at the track... I can believe a skilled driver can control the 4.10's as well.
Melting Slicks
Joined: May 2005
Posts: 3,461
Likes: 161
From: Las Vegas Nevada
St. Jude Donor '08
Race Director
Joined: Nov 2001
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St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12
Race Director
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St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12
Burning Brakes
Joined: Mar 2000
Posts: 962
Likes: 6
From: Jackson MI
I went with 3:73 that has 432 rwhp and I found it to be a great compromise between power and the ability to keep rpms low at cruise in sixth gear. A;most stock quite at cruise and screaming loud at ful pedal and high rpm.
Melting Slicks
Joined: Mar 2005
Posts: 2,364
Likes: 1
From: Rugby North Dakota