super slow 5.0

I have a 1990 GT stock gears stock gauges problem is at low speeds the mph gauge bounces all over the place then past 30mph it goes anywhere from 10 to 15mph off.. What is the problem if ?? If I were to put the gauge cluster out of a parts car should that fix the problem??

white93pony

the bouncing is common ive never had one that diddent it being 10-15 mph off tells me it has gears in it and someone diddent change the trans gear

90lxstang

Mine only bounces above 60, which is in reality 50 because the speedo is 10 off. I just watch the tach since the only reason I get that fast is for cruising, doesn't bother me enough to fix it

Grundy

mines off by about that much as well, with stock gears. 95km/h is actualy 115km/h on mine....yes im canadien

white93pony

mines kinda the opposite mine bounces worse below 30-35 and smooths out above but never stops im guessing you prolly have 3.73 gears and if you have a 5 speed you should be at about 55 at 2000 if you want to correct your gauge get a 21 tooth speedo gear and it should fix you mph

super slow 5.0

I dont think it has gears its a auto and according to the little badge on the rearend it has 273's I know they normally bounce but it dont stop