Alright, so my speedometer is registering the wrong speed and after replacing the cable, i think its that im not using the right gear in the speedometer. Whats the equation you need to use to find out which one I need to use. Im running a 352FE with cruiseomatic and 3.75 gear ratio and 14" wheels. Any help would be great as I would rather replace my speedometer gear than buy a whole new speedometer.
check out this website, this should get you going in the right direction: http://www.tciauto.com/components/speedometer_gears.htm also, changing your speedometer will make no difference, as all US speedometers are calibrated at 1000 rpms of the speedo cable will read 60 MPH
You won't be able to change the speedo drive gear because it is machined onto the shaft, even on your cruise-o-matic, I believe. It definitely is on the c4 and c6. So you'll have to settle for changing the driven gear but luckily it's easy.
quicky tech example: Drive over a measured mile, see how far the odometer moves, such as 1.15 miles. Calculate how far off the thing is now: 1.15 -1.00 = .15, or 15% Find out how many teeth are on the driven gear now: say, it's 18 figure out if you need to add or remove teeth: Adding teeth slows down the speedo, which you want to do in this case 15% times 18 = 2.7 more teeth needed so try to find a 21 tooth, or maybe a 20 tooth.
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