Speedo Error - 87 Carrera Coupe

[Kurt S]

I checked my car's speedo against my hand held GPS today and confirmed what I suspected - the speedo is off. 35mph on the gauge = 33 on the GPS and 70 on the speedo is 64 on the GPS. The car has 15" Fuchs with the correct size tires and the speedo sending unit on the gearbox was replaced several years ago.

Is this common to have an innacurate speedometer? Solutions? I'd hate to make a coversion chart to tape next to the speedo.

Kurt

[Mrdi]

Yup,
My 88 is 15% fast with the 16" Fuchs. That means my oil and valves are changed and adjusted 15% sooner.
You could put taller tires on the rear, but you'll be a little slower at the lower RPM's.
Grinder Know?

[Jorgeman]

Kurt--my '66 read 5 mph fast and Porsche brought it forward to my '86 which is also about 5 mph fast. It's supposed to make your significant other's eyes bulge just a wee bit earlier than normal and make YOU feel better when "the man" quotes a speed a little lower than you expected!

George 86T

[Eric Coffey]

Hey Kurt,

I think the `ol `87 deserves a 7" & 8" x 16" Fuchs upgrade! Seriously, if it bothers you enough to have it fixed, you can send your speedo out to be recalibrated by places like N. Hollywood Speedometer (818.761.5136), or Palo Alto Speedometer (650.323.0243).

-Eric