Back in Dec i blew a head gasket, my father and i got the gasket set, and changed all most all the gaskets that came in the kit. they shaved the head a lil not much. so really im just trying to figure out why its so far off. oh and by the way i have to get this fixed because i got a ticket on the highway doing 82 in a 70. i thought i was doing 70.

Drive till it says 50 mph and you'll be doing 40mph. :)

no my car is going faster then it says on my speedometer

did you get larger tires/rims?

what do rim sizes have to do with the speedometer??

mine is off by about 5 but the other way 50=45

its weird I also have stock rims and tires,but i got my car used to so no telling

I can't explain it but it does.

think of the tires and rims as gears on a 10 speed bike. diff size gear= diff speed

If your circumference of your tires is different then the circumference of the original tires your speedometer will be off because the speedometer goes by the transmission not the tires. If your tires have a larger circumference that means every time your tires go around your car is actually going farther then what your speedometer "thinks" your are. In other words you are going faster then the speedometer says you are going because you are going a farther distance then the car "thinks" you are in the same amount of time. if your circumference is smaller then its the exact opposite because you aren't going as far for every rotation of the transmission. I hope this explains it.

well i stopped by a transmission shop and they said it would cost 30 to fix, and that when i blew my head gasket that when i was replacing it that when they shaved the head that somehow something must have been messed with in the transmission and that is why it is off, i dont know much about my car yet to disagree, so im gonna pay the 30 today.

Their probably just gonna unhook your battery for 30 mins then hook it back up. :haha:

lol

I'd pay that to have it fixed as well.

The best way I have found is to take your speedo needle off and have someone pace you. When you hit the speed you want notice your rpm's. Set your cruise control at that rpm and put your needle at the speed you are going. What happens when people do the white face gauges and stuff they don't realize that the shaft that your needle is on sometimes rotates back behind zero. Does this make sense?