Alright, I finally got my vibration issues fixed. Bad pinion bearing. But, I noticed today after picking up the car, that it felt like I was going slower than the speedometer showed and people were going by me. I borrowed a GPS and checked at different speeds. It was pretty close 10-35mph, but started getting off around 40. The faster I went, the more it was off, but generally around 5mph off. The speedometer is 5 mph faster than I am actually going.

So, is there something they may have done while replacing the rear end? I heard there are 3 sensors that measure speed and distance? Does this mean that I am racking up more miles than actual?

If I take it in, can they calibrate the speedo there or do they have to send the gauge unit back to FORD?

 

I've read some other threads and forums that apparently quite a few people are experiencing the same thing with the speedo being off and increasing with highway speeds?

 

Nobody else has any experiences with incorrect speedos?

 

I would say your best bet is to take it into Ford..

 

I talked to the local Ford dealers, two of them. They both said that this is a pretty normal occurance for Mustangs and Fords in general, and unless it is off by more than 10%, they can't do anything. And at that they can't calibrate it on the fly, it would have to be replaced or something. I'm noticing that for every 5 miles my odometer reads, the GPS only registers 4.5 miles. That will add up over time.

 

Its possible that they replaced your gears with a different ratio and didn't recalibrate it.

 

Maybe the GPS is off? I don't know, just a thought...

 

Maybe he should try the GPS in different vehicles to see if they are also off by the same amount, or if the GPS matches.

 

I have tried it with two different GPS's, both mine and my dad's, both showing the same results. I asked about the gears and recalibrating, and the advisor stated that the tech. checked that. I guess I'll have to follow-up with my Ford Customer Serv. rep I have been dealing with concerning my case with the vibration and mention this and see what they have to say. If the car is talleying more miles than it is driven, that would make a case for something to be done.

 

here is what to do
go on a highway that has mile markers, when u come up to a mile marker at 60mph for example, reset the trip and see how many miles your car registers after 5 miles. Do at least 5 miles and you will def know if it is off.
say for instance u drive from mile marker 100 to 105 and your trip says 7.5 miles then you know it needs calibration
good luck