New Member, Need Held With An Incorrect Speedometer

[cadman77]

Hello,

I am new to the forum. Just bought a 95 Mustang GT, automatic w/ overdrive. I knew the speedometer needed repaired when I bought it. Thought it would be simple. So far I have had the gauge cluster repaired and replaced both speed sensors in the transmission. The speedometer is still reading too fast and the odometer is counting to quickly. The speedometer seems to be more incorrect the faster you go. At around 25 mph real speed, the gauge reads 35-40. I was thinking maybe someone before me changed the gears in the rear axle? Not sure how to check that. I am out of ideas now. Does anyone have any suggestions? Thanks in advance!!

 

[Gearbanger 101]

Lift the rear of the vehicle, place it in neutral and rotate the back wheels while counting the driveshaft rotations (ex 3 1/2 turns, 3 3/4 turns, etc). Let us know what you come back with for a number and we'll go from there.

 

[cadman77]

Hello. First, thanks for the fast reply. I counted slightly more than 4 turns of the drive shaft.

 

[Gearbanger 101]

Hello. First, thanks for the fast reply. I counted slightly more than 4 turns of the drive shaft.

Sounds like you've got 4.10 gears in there. Assuming your'e running the stock tire height, the calculations work out to a need for a 6-tooth (black) speedometer drive gear and a 19-tooth (tan) speedometer driven gear.

The good new....the gears are cheap can be had for about $35. And the driven gear is a snap to swap.

Mustang 6 Tooth Speedometer Drive Gear for T5 (79-98)

Mustang 19 Tooth Speedometer Gear & Clip Kit (83-95) Auto Transmission

The bad news....changing the speedometer drive gear is a fairly involved process and will require the transmission to be removed and disassembled. My guess is that the previous owner either didn't care for speedometer accuracy or found out later on that this step was required and simply didn't want to go through the trouble and decided he could live with the speedometer being out.

The question now is......can you?