HELP PS - SPEEDO 40% HIGH

Hi, peeps. Running a GTI Engineering (2L) 1985 cabbie, 5sp box. My rev counter reads correctly, but my speedo always reads 40% high. Presume I have the wrong speedo for the engine…what have I got, what should I have? Car goes like stink, when I'm up to 100 (legally) the speedo says 140. No, it ain't. Any ideas?? yzzidog@ymail.com

You can buy little gearboxes for the speedo cable,  but they tend to be rather pricy.
Also look into different speedo gears for the gearbox

have the clocks been fiddled with, i.e. is there a while dial kit on them or something? if so strip them and reset the speedo needle. when the speedo is removed there is a little alignment mark it should point at when the needle is lifted over the stop:
4130 Products - Step-By-Step

but before you do that remove the speedo cable from your gearbox and check the gear colour, then get underneath and look at the gearbox code. the colour of the gear is matched to the final drive that is fitted:
020 GEAR RATIOS