Rear End Question
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Senior Member
Joined: Apr 2003
Posts: 102
Likes: 0
From: Schertz, TX
Rear End Question
Hello Everyone!
I'm new to the site but so far I have really enjoyed it. I know this has been asked before, but here we go again. My 03 Crew has the underpowered 4.6 motor and the 3.55 limited slip rear end. I installed a Pro Comp spindle lift and an add a leaf in the rear for a 3" overall lift. Then I added BF Goodrich A/T tires that are 285/75/16. The truck came with 255/70/16, and as you can imagine the gas mileage has gone from 17mpg to 13mpg and what little power it had before is now non existant. I'm going to change the rear end ratio but I can't decide if I should go with 3.73 or 4.10. Someone in an earlier post said not to only jump in .25 increments, that it would be bettter to go in .50 increments. Does anyone have a similar setup like mine with 4.10 gears. If so what is the gas mileage on the highway with running at a higher rpm? Any help would be greatly appreciated.
Craig
I'm new to the site but so far I have really enjoyed it. I know this has been asked before, but here we go again. My 03 Crew has the underpowered 4.6 motor and the 3.55 limited slip rear end. I installed a Pro Comp spindle lift and an add a leaf in the rear for a 3" overall lift. Then I added BF Goodrich A/T tires that are 285/75/16. The truck came with 255/70/16, and as you can imagine the gas mileage has gone from 17mpg to 13mpg and what little power it had before is now non existant. I'm going to change the rear end ratio but I can't decide if I should go with 3.73 or 4.10. Someone in an earlier post said not to only jump in .25 increments, that it would be bettter to go in .50 increments. Does anyone have a similar setup like mine with 4.10 gears. If so what is the gas mileage on the highway with running at a higher rpm? Any help would be greatly appreciated.
Craig
Junior Member
Joined: Apr 2003
Posts: 3
Likes: 0
From: Huntsville, AL
Because of the larger size of your tires your truck runs more miles with the same rpm. If you didn't adjust your speedometer you have of course a worse gas milage because your speedometer counts less miles than you are really driving. The right ratio for the axle would be 3.88 (as it is between the two tire sizes) so the 3.73 comes next to this and your gas milage will get better, too. And your speedometer will show only less than 4% lower speed than you are really going.
Mike
Mike