erratic speedo

[tjb]

I have the standard Ultima speedo in my Sports. It has an intermittent problem where the speedo goes completely haywire. e.g I'm actually doing 60 and the speedo is readaing 140, then 180, then 200+, then 0 !!!

This seems to occur most when it is hot, and last Sunday PM leaving Le Mans the speedo was all over the place for most of the 3 hour run to our overnight stop.

Any ideas what might be causing this?

Thanks,

Tony

[shithotfast]

I had this.... It was a bad earth/connection on mine. One of the ultima loom wires from the sender is braided (on my car anyway) I earthed the brading to the gbox, and on the dash at the other end. The other cause could be that the sender is either too close or too far from the rotating plate which is on the drive shaft. (assuming you are not using the 911 gbox sender, but the "add on" sender. The gap should be about an 8th of an inch in old money!

[B1 ECC]

I agree with Paul, I run a stack system but had erratic readings because the sensor wasn't close enough to the pickups (i.e. driveshaft bolts)

[BogBeast]

I had the same problem with my sports.

Ran a completely separate shielded cable. from RS iirc

[gtr-gaz]

I have this problem, although only intermitant.

I checked all the connections, they seem ok?

Gary