Speedo over reading!
 

Hey is anyone running a det gearbox with the s12 speedo drive had any problems with over reading? Mine is 10mph out at 30 and gets further out the faster you, dont know if its to do with the gearing in the box or the mech itsself?

ive never done it, so this could be wrong but...

on the tailshaft that runs through the back of the box to the spline that the prop slides onto, theres a small worm gear circlipped on. These can be changed, to suit the wire drive, or 'leccy pickups for the speed sensors, and I think to can swap between all the setups from s12 mk2 box thru s13 thru to s14, but does mean pulling the box apart to swap.

Thanks, might be worth a look at if I pull the motor out again, might try another speedo cable and drive and see of it changes anything. If not I will stick some markers onto the clocks to mark the correct speeds .

Not sure they are all interchangable as some of the speedo drives are longer than others. I think my box is the same as an SR (S14) box though, I couldn't find one to fit, even got Nissan pick up ones etc and nothing fitted.

I just remember speed limit speeds in certain gears are at certain rpm's, had both the rally cars like that for years now.