Tachometer Failure

Started it up this afternoon when leaving work, Tach bounced around like it normally does at idle (100-200 rpm) which I always attributed to warming period for the engine. Than it just quit no bounce no nothing.

I'm pretty sure that this will be self revealing once I look at the cable but has anyone had a sudden Tach failure, that is a failure without any warning? I've had failures of the speedo drive but that at least gave me some warning by bouncing around more and more erratically until failure.

Bike is a 74 Mk II never had the cable off or greased, of course, why would I want to do that. Looks like their are only three likely possibilities, cable, driven gear or Tach. Wondering if this drive is just like the speedo and can I pull the cable and drive it CCW to check the Tach? How would I determine if the driven gear needs to be replaced or just the cable if the Tach works fine? Obviously, if cable broke that will be a real tip-off.

Driven gear is pretty expensive so would much rather have it be the cable.

My tach quit suddenly 2 years ago. Turned out it was the tach itself. About $150 to fix/rebuild.

Jim,

Last year I bought an NOS tach for my Victor: new, in its original box. I lubed the cable and installed it; it failed after a few miles on the road. The cable, still well lubed, had sheared at the lower end. The CAUSE of shearing was the tach internals, which had completely locked up. I had failed to appreciate that even a new part, after 40 years on a shelf, was as dry as a bone. Fortunately, carefull lubrication with Teflon spray over several days restored the tach, and with a new cable, I was back on the road. The point here is that, even in the presence of a sheared cable, the cable may not be the root cause of the failure. If you find that the tach drive is not turning freely, try some carefull lubrication before sending it off to Nisonger; you might get lucky. If you botch the lube, you can always send it off then. Nisonger will charge the same 150 bucks in either case (they do a very professional job of rebuilding).

Rick

Unless I missread your post, you said that in the last 37 years you have never lubed the cable? I think you found the root cause. Owner neglect. I think back to how many miles I put on my Nortons as a kid in my teens / twenties & I realy think it's amazing they survived my neglect. I guess I just didn't think about stuff like wheel bearings, or bearings at all? Cables were just,,, well I don't remember ever lubing a tach cable back as a punk kid. Then again I think I ride harder and I know I ride much farther & longer now so perhaps maintanance is more pressing now. Hope you get it svedberg & sorry for going off on a tangent.

Unless I missread your post, you said that in the last 37 years you have never lubed the cable? I think you found the root cause. Owner neglect. I think back to how many miles I put on my Nortons as a kid in my teens / twenties & I realy think it's amazing they survived my neglect. I guess I just didn't think about stuff like wheel bearings, or bearings at all? Cables were just,,, well I don't remember ever lubing a tach cable back as a punk kid. Then again I think I ride harder and I know I ride much farther & longer now so perhaps maintanance is more pressing now. Any way, hope you get it solved & sorry for going off on a tangent.

gtsun,
you didn't misread my post. No maintenance, on tach, for 37 years. My mechanical skills are slightly better than my carpentry skills (measure twice, cut once, get more wood at home depot) but I tend to be careful not to fix what I haven't broken yet. The good thing (?) is once I break something and fix I pretty much know how to do it right. Look at it this weekend and figure out what the problem is.

Rick,
Will take your advice. If cable in tact, I'll try turning Tach with a drill and see what happens. I never thought about lubing the tach or speedo itself but if it doesn't work right I may try it before sending out clocks for refurb (intended to do this anyway).

In mean time, as long as speedo works (new speedo drive last year) not that much of an issue without a Tach. Sound will pretty much tell you when to shift. Speedo tells you when you might get pulled over.

what does careful lube mean?

Use a q tip maybe? Lube exactly where, don't just shoot lube in there and hope?