brundz

my speedometer says i'm doing 80 when i'm doing about 60 and it says 60 when i'm at about 40...my friend had a mustang a couple years ago that did the same thing...so i'm guessing its a common problem. anybody know how to fix it?

89Ford

do you have gears installed

mattdel

you need to have a custom built speedo gear calibrated for your tire size and rear end ratio. 20 mph off is alot, i'm runnin 16's instead of stock 15's and i'm off by 5

brundz

not to my knowledge of gears installed. and the tires are pretty much the same hieght as stock ones. i went from 28's to 33's on my jeep and it only made the speedometer off by 10. it also read's higher when you go to a smaller tire and lower when you go to a bigger tire. i could see it 20 off wiht like those 13 inch dayton wire wheels that ghetto people use...but that aint my style

mattdel

probably a good chance that the teeth in your speedo gear are worn to the point that it actually spins faster... something to check.

brundz

ooo yea wow u just reminded me. he pulled his speedo gear to see what was goin on and it was torn to crap...thanks haha