Speedometer accuracy after clutch rebuild
 

I got my car, an '88 911, back from a clutch rebuild a couple of weeks ago. While we were out with it today, we went through a couple of those radar setups that tell you your speed (yes, they told me to slow down). At both, my speedo closely matched the speed the radar told me I was going. That's strange, because before the clutch job, my speedometer always read about 4-7 MPH more than the radar installations claimed I was driving. Is it possible that the clutch job affected the speedometer accuracy?

No. Speedo reads rotational speed of bits within the transmission independent of engine/clutch speed. Tire size, yes. Clutch or flywheel changes, no.

Use the Waze app while you are driving to verify the accuracy of your speedo.

Thanks for the heads up on Waze--will do. I never use it because when I did years ago it always drained my battery faster than it recharges, but I gather later implementations are better.

That said, I've always had good agreement between the stationary radar readout units and my other vehicles' speedometers, so I do tend to trust them.