Speedometer accuracy after clutch rebuild

[MStier]

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?

[pampadori]

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

[Cairo94507]

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

[MStier]

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.