Speedometer Problems

[muddphish]

I have a 94 S-10, 2.2, 5-speed, the speedometer is off 5 miles per hour at 35, then 10 at 45 etc...

[GSsg98]

Originally Posted by muddphish

I have a 94 S-10, 2.2, 5-speed, the speedometer is off 5 miles per hour at 35, then 10 at 45 etc...

I own a 93 / 4.3L / Manual 5-sp....and mine does the same.
I bought it a couple of years ago and just delt w/ it, but would like to fix it too. My S-10 had the rear end (differential) replaced just before I bought it (from 3.08 to 3.42 ratio).

Somebody out there correct me if I'm wrong, but I think we need to put a Scan Tool on our PCM's to read the right Gear Ratio.

[NoSpudsInIdaho]

So what size tires are you running on? And what size is on your door sticker? Running different sized tires from stock will throw your speedo off by a percentage. What you're describing is about 12%, or about the difference from 195's to 215's. Changing the ratio in the differential will throw it off too.

Years ago, when I bought my first S10, I put bigger tires on it for off-roading and put my speedo off nearly 20%. At that time, someone made a converter that went inside your dash between the speedo and the cable. It would gear up or down (I went down for larger tires) by a set percentage to bring you're speedo within 1 or 2%. Maybe someone out there knows where to get one of these things?