Another Speedometer Problem
 

The speedometer in my 87 911 was staying at zero until the car got to about 30 mph, at which point it would spring to life and work properly. The odometer would continue to turn over, even when the speed was not registering.

I did a search on the forum and found this:

Since this TSB described my exact problem, I'd thought that I had found the solution. I replaced the sender and spring with the part numbers listed, but I still have the same problem. If anything is different, I might say that now I have to be going a little faster to bring the needle to life.

Is there something else I should be looking at, or is the solution "Send it to North Hollywood Speedometer"?

I'm going with North Hollywood.
If you do it send accurate tire circumference information and they'll calibrate your speedometer so you'll have also have one of the few Porsches in the country with an accurate speedometer.

A longer test ride reveals that the speedometer now has no real relationship with actual speed. Previously, it was accurate above 30 mph. Now, it always reads between 20 and 40, regardless of how fast I'm going. As a bonus, the needle now bounces around a lot.

It appears that I have wasted $75 and a few hours work. I will be reinstalling the original sender and sending out the speedometer unless someone suggests otherwise.

Oh, and tires are original size.

voltage regulator or bad ground maybe? or even running alternate wires for testing purposes from the sender.

keep us posted

Hi,

I have a long shot for you, My tach won't register after the car has been sitting in the hot sun, then all of a sudden it shoots up to where it should be and works fine. When I talked with Hollywood about another gauge problem, I also asked about the tach. They said that sometimes the plastic gauge lens can touch the needle and cause issues. maybe this is happening to your speedo.

Rutager

The car is garaged, so it's not the hot sun. Grounds have recently been cleaned.