speedo setting
 

Can someone with an acurate speedometer take a look at thier speedo when the car is not moving. On 80's 911's the first mark on the speedo I believe is 10. This is represented by a "|" The first number is 20 then "|" then 30 and so forth. When the car is sitting still should the needle be sitting on the first "|" or 5 degrees below it. On both my cars it is sitting on the first "|". I do not believe this is correct. For this reason both cars read fast. At least I think they do. Any help would be appreciated. By the way if your odometer breaks it is fixable! Its a little plastic gear inside the can. Not much fun to replace but it can be done.

do your tires have the stock rolling diameter? good for bs ing your way out of tickets!! most other speedometers i have start at 2-5 mph. to calibrate ,try to hold a steady 60 for 10 miles on the interstate or borrow a gps.

Ed -

An easy way to test your speedo's accuracy is to grab a stopwatch and locate a stretch of highway with milemarkers posted. Travel at a constant speed, and time how long it takes to complete one mile.

60/X * 60 = mph

(X = # of seconds)

Those mile markers are very accurate, and my speedo tested perfect from 45mph to 80mph using this method. That's as slow and as fast that I could drive at a constant speed on the highway one day.

This is also helpful to do if you change your rear tire/wheel diameter from stock.

If your speedo is off, you can adjust it in two ways. The needle can be twisted on its' shaft so it will rest at a higher or lower position thus changing it's reading throughout the entire range. My 160mph speedo rests a needle's width below that first mark you mentioned.

Or you can adjust the Trimpot. You'll need to drill a hole in the speedo's case to access the trimpot easier. In the photo below, I have the needle pointing to the trimpot.

If you've fixed your odometer yourself, I'd really like to know where you located the replacement gear ???

-Rob

i use a piece of waxed linen to install a stripped 1/10 gear. loose on the shaft, but the teeth where still good. i have never had to get parts. they strip from pushing the odometer reset while moving.

I did an adjustment on the pot.. and posted a pic of where to drill the hole..............Ron

http://forums.pelicanparts.com/porsche-911-technical-forum/83337-86-carrera-speedometer-calibration.html?highlight=speedo

Just ran across this post in the archives. I have a similar problem with the gears breaking for the odometer. The problem is the teeth broke off, the remaining teeth are very brittle. Has anybody located a source for these?

try Palo Alto Speedo or Hollywood Speedo. They are the only ones in the country that would even talk to me. I had to pay 35 for the gear but hey it was better than 150