my speedometer was fine until i got new axles with new gears and then my speedometer was off by 15mph...its got a 4 in lift with 35s so i know its gonna be alittle off from the lift and tires but i dont think its suppost to be that much off..how do i fix it..do i just go to a shop and ask them????or is it just the speedomter sensor goin bad???

 

When you put larger tires on a vehicle, it throws off the overall effective gear ratio. The truck is calibrated for 3.73's and 30" tires, for example, and you put 35's on it, it would be just like putting a 2.50 gear in the rear axle and not telling the speedo whats going on. I dont know what type of truck you have, but look into an aftermarket programmer with a speedo correction feature, or superlift makes the truspeed calibrator.

 

ok you could go to a calibration place and figure out your actual speed off of your own speedometer.....its usually like 45 bucks.....

 

agreed. . anytime you change tire size or gears your speedometer is going to change . . take it to a speedometer calabration place . . it's simple to do if ya got the right stuff . .if it's your 81 chevy then has a little plastic gear in the back of t-case and they jsut swap it out for a different tooth gear but you have to have the parts and know which way to step up on that gear . . . anyhow yeah just take it to a place and have it calibrated

 

yeah its a 81 scottsdale and i had 35's before and once i put 4.10 gears in..it jump like crazy!!..i thought you could have an autoshop calibrate it..casue thats what i was planning on doin but he told me he could fix it which was odd..but thanx for yall advice