76 Dodge 440 model 821F ---leaping speedometer

My speedometer needle leaps at every turn of the cable.  At about 55mph the needle reads a constant 100mph.  what do I need to do to smooth out the reading and get an accurate reading at all speeds?
Chris

[LARRY RAY]

THE BEST AND EASIEST WAY TO FIX THIS PROBLEM IS MAKE SURE THE CABLE MAKES NO SHARP TURNS. DISCONNECT IT AT THE TRANSMISSION, PULL THE CACBLE OUT, CLEAN AND GREASE WITH LIGHT GREASE WHILE REINSERTING IT. THAT SHOULD DO IT UNLESS YOU HAVE OTHER PROBLEMS.

I took boothe cables out and lubed well with a can of aerosol white assembly grease, made certain that there were no kinks in the cable housings, and then checked out the speedometer head itself.  Upon close inspection I discovered that the "whirlygig thingy" that is spun by the cable actuallt was rubbing (not supposed to) on the part attached to the needle.  I tried to adjust things a bit and the speedometer worked fine for about 40 miles.  When I hit the gravel mountain roads again I think the vibration put things out of whack again because I got the old leaping needle back.  I think that I probably need a new speedometer head.  Are these abvailable at any known location?  NAPA struck out on the 76 vintage.
Chris

[DCI]

Mine did the same thing. I took the cable loose from the speedometer and trans. Then I took the wire out and greased the entire thing well.(It had nothing on it) Stopped the needle from jumping and it has been 1.5 yrs since I did that.


Tom

Tom, Thanks for the reply.  What did you use to lube the cables with?  I have alrady removed both cables , cleaned, and lubed them well with the aerosol white assembly grease from NAPA.  I suppose I could replace both cables but they did seem to be ok.  Chris

[DCI]

I used a white grease as well. My cables also looked to be in good shape just dry. This stopped my problem.

Tom