Calibrating Speedo
Posted: Mon Apr 19, 2010 11:06 pm
I found a great website to help sort out you speedo if your changing clocks, engins or wheelsize.
The speedo drive in the gearbox consists of two parts ,a worm and a cog and by changing them you can change the ratio output to the speedo. On this page if you input your wheelsize, final drive and speedo tpm you can then try different ratios to get the closest match between speed and speedo reading.Ideally this could be done when the engine is out but I managed to do mine on an A+ box in the car although it did have a flip front. My speedo has gone from 15% to 2% accuritcy.
http://www.guess-works.com/Gearbox/Technical/ratio.htm
The speedo drive in the gearbox consists of two parts ,a worm and a cog and by changing them you can change the ratio output to the speedo. On this page if you input your wheelsize, final drive and speedo tpm you can then try different ratios to get the closest match between speed and speedo reading.Ideally this could be done when the engine is out but I managed to do mine on an A+ box in the car although it did have a flip front. My speedo has gone from 15% to 2% accuritcy.
http://www.guess-works.com/Gearbox/Technical/ratio.htm