Speedometer maintenance

[RGrayson]

I recently disassembled a 65 CL77 speedometer as the two screws holding the face plate were loose. Since I have it taken apart, what maintenance should be done prior to reassembly. The bike has less than 7K original miles and is probably a 7 or 8.

[conbs]

No expert here, but I did look into this quite a bit at one point and disassembled a couple of speedo's. There is some pretty good info online if you take the time to look. One site was very instructive to me. magnetic-speedometer-repair.com The Dream service manual also has a good cross section of the speedo guts.

The function of a magnetic speedometer (and any cable-driven tach) is amazingly simple. A spinning shaft with the magnetic cup on it pulls on a second metal cup on the needle shaft that pushes against the little watch spring. The faster the first shaft spins the more pressure it puts on the needle shaft and the higher the MPH reading.

There are 3 main lube points that you will see in the cross section diagram and from studying which pieces move independent of each other. Above web site suggests synthetic oil for lube. I got some cheap on ebay. You don't need very much.

The first lube point is the bushing where the cable connects. The second is right under the needle. The third lube point is more difficult. As you can see in the cross-section diagram, it is down inside the magnetic cup so there is not a great way to get at it. IF you do take that mechanism apart to get at it, BE CAREFUL or you will break the little watch spring. There may be a way to put a little oil inside the magnetic cup with the idea that it will work its way down to the 3rd lube point, but I don't know. You would need to make sure any excess oil was removed. The other option is you can lube the other two points and leave the third hoping there is enough original lube in there to let it operate well for a time. You will know there is a problem in that area if your needle starts reading higher than it should due to increased friction at that point.

As you have found, it is not too hard to get a speedo apart. You can always leave the 3rd lube point for another day. Final word, the chromed trim is brass, I think. The lip will bend to get the ring and glass off, but don't try bending too much at one time or the brass will split. Work it slowly a little at a time and be patient. I hope you didn't figure that out the same way I did. The good news for me was I was working on parts speedo's that had beat up trim. If yours needs to be straightened, remember it is brass, so you should be able to remove dents fairly easily.

Best wishes and let everyone know how it turns out.

[RGrayson]

Thanks for the quick reply. I have the speedo apart and am now looking for the oil. I will let you know how it goes.