'66: Speedometer not accurate...

[bandit2]

My speedometer is not accurate. It hasn't been for a while. My guess is that it's about 10-15 MPH below the true speed. Any ideas how to fix? I don't know if this matters but the transmission was rebuilt in '97.

Thanks,Tom.

 

[iskwezm]

need to know size tires and gears you have.Maybe they changed the gear on the speedo cable.

 

[grego37]

did you recently get taller tires?

 

[SuperDave]

Modification effect speedo

Any changes from stock WILL effect the accuracy of the speedo. (Actually, they weren't terribly accurate in the beginning.) Changes in tire diameter, differential gearing, transmission drive and driven gears, etc. will definitely throw the speedo off.

You can experient with different driven gears as a curative but a shop specializing in speedos is a better source of a solution. The driven gear is available in different tooth configurations and are useful in achueving the desired correction (either to indicate greater speed or less).

You discription does NOT indicate the spwecific problem hence it is impossible to ACCURATELY say which would achieve what you want to do.

 

[gevalia]

Same problem here

I have the same problem here so I'll listen in. Just bught a restored 66 and it's way to easy to see the needle at 100+.

66 FB
16" wheels
T5
3.55 gears

Where would I get this speedo gear? Is it any easy install?

 

[tos]

There is usually a speedometor shop in every city. I would call them or the local tranny shop and tell them your gearing and your tire size and they can probably set you up

 

[Pathfinder65]

Gevalia...for a T5 you can use this site to help figure out which speedo drive gear you need http://www.hanlonmotorsports.com/t5speedo.asp
You probably won't get the perfect match but you can get it pretty close.
You can buy them from any Ford dealership for about $10
Dave

 

[Pathfinder65]

oops, oh yea, the installl is a breeze. Remove the speedo cable from the transmission(drivers side of tranny, one bolt)) Remove the small C clip from the speedo gear and slip it off the end of the cable. Put the new gear on and re-install the C clip. Plug the speedo cable back where you got it and you're good to go.
Dave