Speedometer Error

[biblebob]

My 1972 tii registers WAY too fast, about 10 mph from a standstill and thereafter. 20 is really 10 mph, 60 is really 50 mph. Can the needle spring be reset?

[c.d.iesel]

whats yer wheel and tire size ?

whats yer rear diff ratio ?

[BakesCO]

I'm interested in replies as well. My stock 76' has 13" wheels and is accurate to about 50mph, then it jumps to about a 10 MPH + read. 80 is really 70...

Thanks

[bnam]

If the error is constant 10mph -- you can probably pull off the speedo needle and reposition it.

If the error varies then the it needs recalibration. Buy a used good one or even buy a new one avail at Walloth & Nesch.

[wegweiser]

Simply "pulling the needle off" is not for the faint of heart or the clumsy of fist. Without the needle, the "axle" of the needle will rotate (spring loaded) past it's normal "zero" stop and repositioning it CORRECTLY is NOT easy to do. If you do this, expect a dozen trial and error installations before you get it right...installation in the car over....and over....and over.... not worth it IMHO.

Mine's off by a consistent 3-5 mph according to my GPS using 175-70-13s. Tire size might be your culprit.

[M3M3]

or a diff ratio change will cause a proportional error....just like varying tire size from stock.