Speedometer reading wrong???

[daman]

My '95 GT 3100 is reading high(55 on the gauge is 50mph),would this
be a speed senser problem,new one would fix it????

[3100]

what size are the front tires?

also the speedometer on most GM vehicles are of the air-core design. This is a moving needle operated by a magnetic coil. Since there is no direct mechanical connection, there is some variation in accuracy that cannot be eliminated.

here are some variations at different speeds

20mph variation 4
45mph variation 3
65mph variation 2

according to GM specs any air-core speedometer which reads within these limits should not be returned for service.

[daman]

Stock low pro tire can't remember the size off hand,but 5mph is allot i think for a variation.

[3100]

yes it is too much it should be between 1 and 2 mph according to specs. As you can see you can't do much with it but to replace complete ipc. Or get yourself one of those scan gauges that reads fuel economy codes etc. there you can adjust mph that will be 100% correct since it will get signals straight from VSS.

[daman]

so changing out the VSS wouldn't help your saying??

[xeroinfinity]

5 mph is way off for a stock tire, it can probly be adjusted a little with the proper scan tool. That tool can also verify the VSS is working within tolerance.