speedo error

86930 · 08-08-2003, 08:59 AM

I recently purchased an 86 930. On the trip home, I noticed the speedo didn't seem accurate. My guess would be it was reading 10 mph high at 75 mph. I timed the car using mile markers and verified that it was not accurate. Is there a way to calibrate the speedo without removing it? My concern is that it is a low mileage car (18K) and by removing it, does it create a question in the future as to the legitimacy of the mileage?

I would rather live with the inaccuracy than to be accused of odometer tampering. Thoughts?

masraum · 08-08-2003, 09:08 AM

no problem removing the speedo. They come right out. As long as you don't tamper with the odo it shouldn't be a problem.

Jadams1 · Jadams1's Garage

I have a 80 Euro SC and my speedometer is off by aproximately 8 mph, reads high. While driving to Heshey this year, Jim Garfield and I were travelling at the same speed and both our speedos read the same value, but high. Jim has a 78 SC. I checked my speedo against one of those roadside speed detectors, my other cars were dead on, my Porsche was off.

masraum · 08-08-2003, 09:09 AM

besides, if your speedo is off then so is the odo

86930 · 08-08-2003, 09:13 AM

"besides, if your speedo is off then so is the odo"

Really? That thought crossed my mind, but I wasn't sure if that would be the case. So, if my speedo is reading HIGH by 10%, would the car show 10% more miles than actual?

CHILI · CHILI's Garage

Mine seems high too. I'm wondering.....
Do all of you have 16 inch wheels on your cars? My car was converted to 16" and maybe that has something to do with it?

RoninLB · 08-08-2003, 11:10 AM

I adjusted my speedo.. the odometer isn't part of the same circuit.. at least when I adjusted mine the odo stayed the same. I posted the info. it's in the archives.........Ron

86930 · 08-08-2003, 11:17 AM

Yes, I have the 16's, but I know the car came stock with them. Unless the overall diameter of the wheel/tire combo changed, the size of the wheel would not have an impact on the speedo.

I'm beginning to wonder if Porsche makes all their speedos read high to make you feel like your going faster. ;-)

RoninLB · 08-08-2003, 11:19 AM

Quote:

Originally posted by 86930

I'm beginning to wonder if Porsche makes all their speedos read high

maybe.. is seems like it's a common occurance around here.....Ron

Adman · 08-08-2003, 11:30 AM

Quote:

Originally posted by 86930
I recently purchased an 86 930. On the trip home, I noticed the speedo didn't seem accurate. My guess would be it was reading 10 mph high at 75 mph. I timed the car using mile markers and verified that it was not accurate. Is there a way to calibrate the speedo without removing it? My concern is that it is a low mileage car (18K) and by removing it, does it create a question in the future as to the legitimacy of the mileage?

I would rather live with the inaccuracy than to be accused of odometer tampering. Thoughts?

Use the search button, upper right corner of the page and type in, "Speedometer Calibration" or any other variation. Tons of information for you. It wouldnt be as much fun as posting but just about any question you can ask can be found in the archive.

Adman · 08-08-2003, 11:36 AM

Quote:

Originally posted by masraum
besides, if your speedo is off then so is the odo

Steve... I thought that I had read in numerous places on the forum that the circuits were separate. If they are not I am getting my speedo calibrated. I know that on mechanical speedos the odometer and speedo share the error.

scedmonds · scedmonds's Garage

My '83 SC speedo runs 10% higher than actual. I've had it serviced but did not get it calibrated.

My wrench told me the odo and speedo are different systems.

Cheers!

C.