Just picked up my 2011 JKU Sport from 4WheelParts where it got new 4:88 gears front and rear. I went with G2 gears because of their warranty. I also got the 3 year/36 month warranty on the install. I had to drive it 100 miles home and was assured it would be ok. They said they took care of the initial breaking in on the rack. Not sure how that is done. So far everything is good except for my speedo being off by 5 mph at 70. I did the reset on my Bullydog tuner so I'm baffled. Any ideas and suggestions.

 

You used mfg spec instead of actually measuring?

Just keep adjusting until it matches the gps.

 

Not sure how that particular tuner works, but did you just set tire size to 35"? They will not actually measure that height when on the Jeep.

 

No, I actually measured them. I believe they measured 33.8 inches under load on the Jeep. It was spot on when I installed the tuner a week ago. All I have done is adjusted the gear ratio to 4:88. I will have to adjust it a little at a time until it is accurate.

 

That is strange.

 

Use the speed from a GPS to dial-in the tire size in the tuner until the speed reported from the GPS matches the speedometer.

 

there are different reading between Odometer and GPS i thought GPS reading is less than odometer

 

that tire size is 34.4
I'm within 1mph with mine

 

Ur GPS gives ur speed? Mine don't.....