I have a 71 f250 with a speedometer issue. It had a broken speedometer gear. So I replaced it and the cable. But when I accelerate it goes straight to 100, when I reverse it goes because to 0. Could it be the speedometer gauge it self Or the gear in the tranny? I don't believe it's the gear in the tranny since it moves the speedometer any help is appreciated.

 

Those gears are all color coded, so did you replace it with the same color & tooth count?
Mind was bouncy and tried to smooth it out by lubing cable checked the tranny gears.
So after 30+ yrs I was feed up and made a custom dash, plus switched over to a electric speedometer
Orich

 

Yes I bought the proper tooth count. My broken one said 19 r on it plus you could count where they broke off so I replaced it with a 19 tooth and lubricated it well still nothing

 

You probably just need to trim some off the cable at the transmission end. It is likely just binding because it is too long. I have just recently replaced the cable in mine and had to trim about 3/8" off in order to get the gauge to work properly.

Marty

 

Could I maybe have to trim off the gear it self because at the end of the plastic tip it's black

 

I have not had to make any changes to anything other than the cable, so I can't really speak to making any sort of alterations to the gear itself. Maybe some else out there will chime in.

 

When you trim the cable how does that help it. Just wondering. To educate myself more.

 

One size does not fit all. There are several different lengths of 1971 F250 speedo cables, which cable did you buy? 2WD or 4WD, 3 M/T, 4 M/T or A/T?

 

I'd say what Marty69 has done was trim off a little kink/shape bend of the outer cable housing where it goes into the cable end to the tranny adapter end.

But really should have replaced the whole outer & inner cable to have may a longer term fix..
orich

 

Inside the speedo cable housing is a woven steel core. It supposed to be lubed every so often, but most people are unaware.

When the lube dries out, the woven steel core binds up inside the housing and snaps.

Instead of replacing the speedometer cable and housing assembly...

Auto parts stores sell a 'universal' woven steel core kit. Cut it to length, coat with a fine film of graphite, install in the housing.

 

More specifically what I had to do was trim the inner steel core driving part of the cable (the squared end). Without doing this, the cable was bottoming out in the transmission speedometer drive gear when the outer cable nut was tightened up. This caused excessive flutter of the speedometer needle and failure to return back to zero when I stopped.

 

It's a brand new cable less than 4 months old

 

Thanks a lot I'll have to try that today. Did you just use simple wire cutters to remove the piece you cut

 

That's nice, but for what application did you buy it for? One size does not fit all, see post 8.

 

How exactly does one go about lubing the speedo cable? I gave 'er a look and it seems like I'd need to pull out the gauge cluster to remove the cable from the speedo.