TheSamba.com :: View topic - re-calibrating speedo?

Mon Apr 09, 2007 2:53 pm

been told it's not possible to calibrate a speedo, but surely someone in here would know a way. i have aftermarket wheels and tires, and my speedo tends to be 10-15% too fast for the speed i'm actually going. (says i'm doing 45 or so, but i'm really doing 40-ish. this is kinda fun with someone in the passenger seat on the highway thinking my little car is actually capable of 85, but isn't helping me to not get pulled over!)

your help, as always, is appreciated!

william
vw newbie, mechanical retard

Mon Apr 09, 2007 3:04 pm

I've never seen or heard of anyone re-calibrating the speedometer. Even when refurbishing one, it is extremely important to replace the needle exactly where it was originally in order to get the speedo to correctly read, so I'm not sure how you would determine how or where to reset the needle for calibrating purposes.

I just use the "calibrate my eyes" method, i.e. figure your speedo says 70 mph, actual speed ~ 65 mph. You can figure out the calculations here.

http://www.net-comber.com/tirecalc.html

Tue Apr 10, 2007 7:44 am

Try North Hollywood Speedometer.

http://www.nhspeedometer.com/

A freind of mine had his vintage Saab speedo refurbished and recalibrated by them a few years back and was pleased with the results.

Thu Apr 12, 2007 7:27 am

VanderBus wrote: Try North Hollywood Speedometer.
Absolutely.

I had my kph speedo calibrated to read in mph by them. I had to count the revolutions of my cable including the fraction of the last revolution over a 1/100th mile distance. I sent that info with the speedo to them and it came back perfect. It wasn't inexpensive but it was high quality work that was worth it to me.

Thu Apr 12, 2007 7:39 am

i heard that if you change the tire diameter the speedo reading isnt correct anymore.

Thu Apr 12, 2007 7:58 am

That is correct. My speedo calibration was needed to account for both the kph-to-mph differences and a slightly smaller front tire diameter.