New Gears and WORSE MPG

[Waterman]

I have a 02 7.3 and recently changed the 3.73 gears to 4.88. The truck has a 8" lift and 37" tires. There's a 4" MBRP exhaust and air raid intake and throttle body spacer. Before the gear change I was getting about 11 MPG and now I'm at 8.5 MPG. Any idea's on what the problem is since I was told it would help my MPG's.

[7.3PwrHse]

Originally Posted by Waterman

I have a 02 7.3 and recently changed the 3.73 gears to 4.88. The truck has a 8" lift and 37" tires. There's a 4" MBRP exhaust and air raid intake and throttle body spacer. Before the gear change I was getting about 11 MPG and now I'm at 8.5 MPG. Any idea's on what the problem is since I was told it would help my MPG's.

Whoever told you going to a 4.88 would improve mileage lied. Most times you go to a lower gearing, its going to hurt mileage.

Sent from my Milestone X2

[linehaul]

4.88 for rockcrawlin, 37" tire 4.10 is all i would go. motor must be screamin at highway speeds

[Waterman]

My goal was to bring the truck as close to stock performance as I could while keeping the 37's and then build up power from there. What should they have told me to go to for that goal.

[theplumbingmedic]

oh how cruel hope that wasn`t a friend with that info for ya

[Waterman]

It's what the shop reccomended that did the job. Another shop told me that I should go with 4.56's but I trusted the first shop since they had a great reputation for building rigs.

[gomer pyle]

Is that hand calculated? I prob would have done 4.10 unless you tow

[Waterman]

I'm not sure what you mean by hand calculated. As far as towing, I don't do a ton of towing but I do pull trailers on occasion.

[JSchuricht]

37" tires with 4.30 gears would be about the same as stock tires with 3.73 gears. 4.88 is insane unless your towing really heavy or always off the pavement.

[Waterman]

Thanks for that one JSchuricht. I'll look into getting those changed out for that.