Speedometer bounce

[70ford1]

I have replaced my speedo cable three times because it wasn't working. The orginal cable seemed fine but it gave no response to the needle--the first cable I cut to the same length as the old one, which was working fine then one day it bounced a bit & quit working. The first one didn't work so I cut a 2nd one, longer, thinking it might be too short. The needle would bounce a bit at times but didn't work--I cut a third one even longer & this time I could get the speedo to go up to 20-25 mph & hold steady but I was doing in excess of 50 mph but that has now stopped. I read somewhere where you need to lube the speedo head on occasion with a drop or so of cable lube. Has anyone ever tried this. I haven't yet but I am thinking of it. It seems, if my memory serves me, that the head works on a magnetic rheostat type of system & without some lube the magnets hang up therefore the needle doesn't advance. Something on the order of a fuel gage sender. I wanted some feedback on this if possible before I try it & maybe ruin a head that may be repairable. Comments please. Thanks

[fordman]

the inner cable is supposed to be greased. the speedometer head should spin by hand and read properly. if it feels dry or sticky. you could try oiling it. but not very much. oil attracts and catches dust and dirt.

[bluej7]

I have the same type of issue with my 71, every time I hit a bump it bounces around a 10mph span...very annoying

[fordamericana]

I had to replace my speedo cable along with a bunch of things on my truck that were rigged to work, but didn't really work... I had a bounce problem after that, and I discovered the gear on the end of the cable had some worn teeth on it, replaced the gear and the speedo ran fine after that...

[cdeal28078]

I think bouncing is usually due to not being lubricated and not working at all is not being connected on one or other end.
Clint

[woods]

Mine was bouncing so bad that the needle would clank against the pin. I pulled out the cluster, removed the speedo, cleaned up all the gears really well, then lubed it. Cured the problem. Maybe you have the same thing going on.

[70ford1]

Thanks to all for the info. I still haven't made time to lube the spedo head but when I do I may pull the whole cable & housing & give it a thorough cleaning & lube. My driven gear may be the wrong one--I put in a white one & thought that was the probable color--the original one was a blend of tan, white, & cream, If you can picture what that color might be. There was no color to match it so I figured it had "tarnished" in the years of use. Still don't know what color to put in. My truck came from the factory with an NP-435 and married in-out transfer case, 350:1 diff. & 700x15 tires. I have tried to check the drive gear, short of pulling it out, but I can't tell if my little finger is moving the gear or just sliding on it. I know the white driven gear has the right number of teeth, & it was the samr size & shape of the old one so it is the one I settled for. May be a while down the road before I get to it but when I do I will post my findings.
Thanks again--------

[Aussie_1970]

I had a wierd speedo bounce as well, and found that where the cable screws in at the back of the speedo was loose / about 1 turn loose...I tightened it up at the problem went away. Not sure why but it did