OK, I have an 02 s2k and at 70 mph on the dash I am really going 77 mph using GPS as a guide. I know all about the whole using stock tires and how it can through it off but 7 MPH seems kind of high. I bought this car wrecked and I am suspicious that they may have put another rear-end in it causing the Speedo to be off. Any thoughts?

 

Well, the stock dif is 4.10 ratio, as far as I know there are no higher ratios normally installed in the S2K dif, if it was a 4.57 or something lower, you'll be off on the opposite direction.

You're under 10% off. How different are your tire heights than stock? The other less likely thing is that it used to have a non-stock diff, it's got the calibrator on it to change the reported speed but, now has the stock dif in it.

 

What wheels and tires ARE you using?

 

Stock 16in Wheels, and 225/50/16 Bridgestone Potenza S-03 Tires on the rear.

 

So you're basically driving on rubber bands?

Just kidding. Typo I'm sure.

 

Better recheck that tire size

BTW, 10% is AHM's acceptable speedo error

 

Opps sorry my bad! That would be 225/50/06

 

Drive next to another stock s2000. Compare speeds.

 

importroadster Posted on Oct 11 2006, 12:18 AM
How and where was it "wrecked" ?
Check for a (leftover) Yellow Box / Jacket underneath the dash, close to the ECU.

 

10% over is pretty close to what would be dialed in for a 4.57 gearset. I think I dialed in 11% on my yellow jacket. If the diff were replaced with a stock unit, without removing the 'correction', then this is exactly the type of speedo error that would result.