speedo setting

[Ed Russell]

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.

[tryan]

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.

[1980SC]

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

[tryan]

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.

[RoninLB]

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

'86 Carrera Speedometer Calibration??

[frogers911]

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?

[Ed Russell]

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