The Stovebolt Site Forums The Shop Area General Truck Talk speedometer trouble shoot

I went for a drive in my 1955.1 3600 the other day and heard a screeching noise and my speedometer was bouncing side to side. If it was a broken cable the needle wouldn't move, correct? I am going to take a look at it after I take Christmas lights down. Where should I start ? Thank you, Brian

It still may be broken just pushing enough or grabbing due to lack of lubrication and needle still move.
disconnect from speedo side and spin speedo to confirm all is well on gauge side.
disconnect from transmission side and spin by hand or drill making sure cable is smooth and not grabbing. not connected either end.
if all is well there then it could be the gear in transmission. pull that and review.

Hi Brian, when my '57 speedo started screeching it was very apparent that the noise was from the speedometer itself, the needle was erratic as is your unit. I had lubed the cable prior to the noise and I knew it was probably not a cable issue. Warm weather driving didn't present a problem but in cold weather it would squeal. I removed the speedo and cleaned it and made sure to oil the rear most bushing, that is the input where the cable slips in, the bronze/brass bushing needed oil, I used something light weight, gun oil or clock oil, have not had any more noise and the needle runs smooth.

Bear in mind that if you test the speedo with a drill on the cable, you need to run the drill backwards.

Went for drive after Christmas light removal and noticed the noise is from the unit as per 78buckshot. I removed the speedometer (PITA) and the cable for inspection. The cable seems to be fine. I will get into the speedometer and see what needs attention. Questions I have now are: What to lubricate the cable with? Is marvel air tool oil good for inside of speedo? How to get trim ring and glass off (trim has crimps in ring)? Do I remove screws on back after glass is off? Thank you, Brian

In order to get the speedo itself out of the housing, you'll have to carefully uncrimp the bezel and remove it, and then unscrew the two screws on the back of the housing. That will gain you access to the rest of the speedo, but there isn't much you can do.

I'd try putting some light oil in where the cable attaches (something like "3 in 1" oil - I have no idea whether your air tool oil would be appropriate.) Marvel Mystery Oil is probably the right viscosity, but don't know if their air tool oil is the same stuff.

[on edit] I think that graphite lock lube might be what you should use for the cable.

The air tool oil is pretty light weight, if that is the lightest you have then go for it, it's similar to ATF. I would use some brake cleaner on the rear bushing to dissolve the old lube, keep the speedo face up so you don't get cleaner in the housing, then use a few drops of oil.

Thanks. I'll get at it tomorrow.

Oiled, cleaned, reassembled and installed. The knurled thumb nut thread size is 10-24 for my 1955.1 3600, but my hardware store didn't carry that size. Reinstalled with original nuts. Thanks to all that helped.