Options for Rear Diff's

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Mar 22, 2006 | 02:33 PM

98C5RT

Thread Starter

Burning Brakes

Joined: Jul 2005

Posts: 998

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From: Somewhere between the Red and the Rio Republic of Texas

Options for Rear Diff's

I currently have a 3:15 ratio with an auto trans but want to bump it up some. I don't want to go to a 4:10 ratio but somewhere in between 3:42 and 4:10. I would like a ratio that will accelerate off the line but will not severely limit my top end. What are my options? What will the change do to my MPG?

Any suggestions?

Thanks!

Mar 22, 2006 | 03:18 PM

94legaleagle

Melting Slicks

Joined: Mar 2005

Posts: 2,364

Likes: 1

From: Rugby North Dakota

Two most common gears in your "asking range" are 3.73's or 3.90's -

I'm not sure what effect you will see on gas mileage, but I think from what I've read that 3.73's would give you the acceleration you want without reducing your top end too much.

3.90's are going to cut into (bring down) your top end speed more than 3.73's will.

Mar 22, 2006 | 04:03 PM

2000whitec5

Burning Brakes

Joined: Feb 2006

Posts: 917

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From: 10.54 @ 129 346 N/A A4 Record 9.78 @ 139+ on 150 shot

Quote:

Originally Posted by 98C5RT

Thanks!

if your car is a daily driver go with 3.42's and like a 2800 stall converter.. .. if you do the gears get the converter done !!! if you dont take a lot of long trips 3.73s and a 3200-3600 stall .. .. i have 3.73's and 3600 stall.. i hit 130 in "3" before i have to shift into overdrive so dont worry about top end... as for MPG .. you own a vette do you really care? .. but if you must know under normal driving i still get atleast 22 and i have other mods done.. hope it helps ..

Mar 22, 2006 | 04:14 PM

98C5RT

Thread Starter

Burning Brakes

Joined: Jul 2005

Posts: 998

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From: Somewhere between the Red and the Rio Republic of Texas

Thanks for the responses. Sounds like 3.73 setup may be my best bet. As for the MPG, in the back of mind I know it doesn't really matter but I'd rather spend the $$$ on mods rather than gas. No long trips, mostly just to and from work.

I like to think of every red light as a new starting line

Mar 22, 2006 | 04:21 PM

next victim

Instructor

Joined: Mar 2006

Posts: 109

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From: oregon

what ever you do, do not go with 3.90 those are a waste of money, a lot of people i have read and talked to that got those wruined their dif and wished they had never gotten it, those 3.90's are weak for some reason go with the 3.73 no problems there

Mar 22, 2006 | 04:41 PM

Face

Le Mans Master

Joined: Aug 2000

Posts: 5,294

Likes: 2

From: Suffolk, Long Island NY

Unless you plan on driving 160+ mph, gears will not ruin your top end. 3.73's off the best of both worlds, I'd recommend them.

Mar 22, 2006 | 05:45 PM

Mike Mercury

Team Owner

Joined: Apr 2001

Posts: 54,204

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From: S.W. Ohio. . . . . . NRA Life Member

Quote:

Originally Posted by next victim

...(3.90 )a lot of people i have read and talked to that got those wruined their dif and wished they had never gotten it, those 3.90's are weak for some reason go with the 3.73 no problems there

source or links ?

Mar 22, 2006 | 07:17 PM

tiojames

Team Owner

Joined: May 2005

Posts: 23,682

Likes: 9

From: Flagstaff Az.

gears

I went to 3:42s and 3500 yank from 3:15s. Gas milage went from 29-31 to 24-26. Thats a pretty good drop. I would not recommend going lower than 3:42s if you do a fair amount of highway driving.