Speedo/odo read high

[timc]

Just bought a 1986 930 with approx 33,600 miles. Driving home, I noticed the speedo appeared to read a little high approx .05%, and after investigating, the odometer adds .5 miles for every 2 miles traveled . The tires are stock, frt 205/55/16, and the rears are 245/45/16, Yoko AVS ES100's.

[Rot 911]

The 911 speedos are notorious for being up to 10% optomistic. However, the odometer is usually right on the money.

[Porsche virgin]

Welcome to the board. Do a search (in the upper right) on this topic. There is plenty of info.

You'll find that this is a common problem among 911s. My speedo is very optimistic as well.

[timc]

I'll do additional checking tonight on the odometer.

[pmillikin]

Coincidently I just spoke with N Hollywood speedometer about a repair this AM. They said the "older" Porsche speedos (mine is an 86) are typically set from the factory 5-8% high.

[timc]

Would this 5% to 8% high on the speedo affect the odometer also?

[pmillikin]

I didn't discuss it with NHS, so I don't know for certain.
The signal comes from the tranny. Conversion of the signal to speed and distance comes from the common signal but I'm not sure if the two are directly related.

[joetiii]

Is North Hollywood the company that will exchange the speedo gear on older cars?

I have 69 that originally came w/ a sportomatic and reads 12% high w/ the 911 tranny. I need to change it out this winter when I have it in the shopp all apart.

[450knotOffice]

All I can add is...you are on the road to discovery of air-cooled 911 ownership. This is just one of those well known situations that we have all eventually discovered, one by one.

[WPOZZZ]

I sent in my speedo for recalibration and repair of the odometer gear to Palo Alto Speedo. My car is a RoW and guess what, the odo read 1.6 miles for every 1 true mile. I wonder why? lol Speedo and odo was recalibrated and now it reads 1 mile for every 1 mile travelled. I guess when the car was federalized, the faceplate on the speedo was changed and that's it.