Question about Speedo cable

[The Shape]

My speedometer reads about 10 miles faster than I am actually going. It also seems to get more off the faster I go. (I had a friend who is a cop clock me with his radar a few times to determine this.) Anyway I have stock 225/60/R15 tires rolling on stock turbines. As far as I know I have stock gears, the car still had the air silencer when I bought it so I kinda doubt the previous owner was into mods. Just wondering if a bad speedometer cable would cause this?

 

[jrichker]

Not likely.

The speedometer cable turns the speedo head unit. One turn at the speedometer transmission pickup equals one turn at the speedo head unit unless the cable is broken. Then one turn at the transmission pickup equals no turns at the speedo head.

In order for the speedo to read fast, the cable would have to make more turns at the speedo head than it did at the speedo pickup on the transmission. That is not going to happen.

Make a trip to the speedo shop if there is one in your area. Or put the car up on jacks and turn the rear wheel one turn and count the turns of the driveshaft. Stock was either 2.73 or 3.08 depending on the year model and transmission type. If the driveshaft turns 2 3/4 turns for one turn of the wheel, you have 2.73 gears. If the driveshaft turns 3+ little more for one turn of the wheel, you have 3.08 gears. Other gears will produce similar results.

 

[The Shape]

I was kinda thinking that. I am installing an FMS driveshaft this weekend. I will count the rotations and see what I have. Maybe I have had gears all along.

 

[87gtconv]

and maybe just a speedo that is just not accurate like I do!! I just got the speedo tuned by using different sized tires!