On the weekend the speedometer in my 39 ford truck started vibrating the dashboard. The needle was still working and at first I thought I was dragging something underneath the truck. So driving along doing 40 and then thump and a womp womp noise and a vibration. First I thought the fan was hitting the shroud but after some testing I find it’s the speedometer so I disconnected the cable and was able to continue driving with no problems. Tonight I pulled the speedometer down expecting to find the odometer gears chewed but it’s all in good working condition. I am spinning it with a drill on the bench and there is no noise or vibration. Got me puzzled. I figure I would ask here before I put it all back together and go for a drive. 39 truck 60mph speedometer 66 mustang C4 speedometer cable
Depending on what company built the speedometer in your '39 p/u. Rusty @e1956v from Speedometer Service in Colorado might be able to fix it. He rebuilt the Stewart Warner unit in my '39. Reasonable, fast turn around, and fair shipping. JMO And he is an Alliance vendor. Speedometer, Generator And Alternator Repair In Colorado Springs
If you disconnected the cable from the speedometer and the noise stopped, you need the speedometer repaired. Pretty common issue with old speedometers...after sitting for a long time and then going back into service, they work for a little while, then go bonkers. Happens to me all the time. On cars I care about, I send them off for repair BEFORE I try to use them.
I have pulled the cable inner/ drive section out and it is fine. I will pull the drive gear out of the transmission and see if it’s ok. The needle was not jumping at all I pulled it down and reconditioned it before it went back in as a part of the build. I cleaned out the hard grease and put new grease and light oil on the parts.
seems like all my problems are where the square male drive of the cable, goes into the female square of the speedo input or the transmission output....the female square larger then the male one, especially on modern aftermarket cables....check things dimensionally...I've even had to add some material to the male end, using a jewelers torch, and hand file to dimension and/or forge square with a hammer
Everytime im under the dash and accidently bumps i to the speedometercable it starts "chip chip chip" and the needle bumps up and down. Check the cable and bend it in a nice smooth angle, and ofcourse clean it and give it a little grease. And if its not working, remove the cable and put a match in the speedometer and try twisting it, its not ipossible that the speedometer needs a little oil to
Thanks for the replies. I went over everything and found nothing wrong. Put it back together and went around the block. No noise or vibration. Very strange.
I did not see if New or old cable , Most of New cable I use are the Flex steel ,, When New before installing spray WD40 in , I take roll up in coil tight but not to tight Use a drill , spinning drive cable moving in & out of Housing , like honing, Then Remove drive cable , flush /clean both ,,, lube up & instal . Same can be done to old / Original cable.
It was a new cable. Has 40 miles on it now. I put some atf on the cable before installing it and just now I sprayed some wd40 into the liner before putting the inner back in. I don’t have it secured anywhere it’s just draped along the frame rail and has a grommet at the floor. I might cinch it down with some zipties to keep it in a fixed position.
When you removed the speedometer cable, was it fastened securely, or did the cap unscrew easily? If the ends are not engaged squarely and tight they can run at a slight angle and chatter. Also, I'm not sure that WD-40 is the best (or even a good) lubricant for a speedometer cable. Almost any product sold as "speedometer cable" lubricant will be a light grease, or some kind of graphite-based lube.
Back in the day we used Lubriplate (white lithium grease). Put a fat dab on the speedo end of the cable housing and feed the cable through it with a twisting motion, adding as necessary. The last couple of feet were left slightly more than just wet looking to keep the lube from migrating into the speedometer head.
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