Speedometer Bounce

LOL, Oh man keri I need to hear tales like yours time to time to be able to forgive my own similar fixing senseless annoyances to death before finally understanding the real issues. My Trixie got like 5000 miles on Peels used cable, then got erradic and then quit, I farted a fair bit with everything listed here then pulled on cable but only half of it came out, yet it did turn if either end twisted by hand. ugh. Smiths speedo is very accurate steady indicator when all up to stuff. Part my fascination of vintage actaully fully grasping its parts and doing something about on my own, eventaully - often with hand holding. Since I quit following the over tight trq listed for long axle I've been rather amazed at the mileage the axle drive has lasted and no real signs of decay after 10,000 plus miles on two Combats. Btw do speedometer clocks make any sound?

Like Dave says the cable has to locate in the gearbox and head properly. Now I know that sounds like an obvious statement but having repaired my Veglia a couple of times in 30k miles I had similar issue develop last year. For some reason the cable had taken to creeping further into the gearbox and dropping out of the head. The cable stop was not effective so the cure was to measure the correct stickout at the head end, check the stickout at the gearbox, measure the depth of the hollow pinion and insert a spacer (a piece of electrical cable insulation) to stop the inner cable entering too far. Problem solved.

Hi,

I have same symptomes after overhauling my speedos by an experienced shop. It doesn't bounce, but it isn't completely steady as well. At a constant speed on a flat road it is almost steady. But on acceleration or on an uneven road it can tremble a bit. But it is still possible to read the speed reliably.
I stopped greasing speedo (and tacho) cables after it destroyed one clock. The cable works like a pump and presses the grease into the clock. That can't be avoided. Now I only apply a thin coat of motor oil on the inner cable just enough that the cable is not dry.

Ralf

Thanks for revising this thread Bonwit. My first project on my newly purchased, nice running Commando was to get the speedo working. Figured that would build my confidence to tackle bigger projects. HA!
Replaced the drive unit with one from Taiwan. No luck there. Cleaned and re-lubed the cable. No sign of life. Took the speedo instrument to local repair guy who thoroughly cleaned and adjusted it to work flawlessly on his tester. When connected to my bike it worked for about 30 seconds then gradually stopped. Discovered the cable was too short in the head, so I added some washers under the collar to move it into the head further. Now have signs of life but a VERY wobbly indicator.
Will try some of the cable fixes listed here (dry lube first, then heavy grease / fussing with length / flatten the ends / new cable). Appreciate all the help.
As to my confidence at fixing and upgrading the old girl - guess I will move on to installing electronic ignition and new carbs which will arrive this week.
Thinking the engine re-build is a long way off. :mrgreen:
tomas

tomspro said:

... (dry lube first, then heavy grease / fussing with length / flatten the ends / new cable). ...

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I would start with new cable !

pete.v said:

After some time the bearing and bushimgs get dry internally. Eventually your needle will break. Your need to send it in for service to one of the many places that do this. Not much else to say but to bite the bullet. $170 to $220.

Click to expand...

Gidday All. A question about a clock that has done a few miles. after removing the chrome bezel, for replacement only, then the guts is removed for replacing the 6 mounting rubbers. at this time it would be prudent to lube the internals, (bearing and bush or whatever is in there.

What is a good lubricant to use and where exactly are the lubing points for the internals. Does the guts require further dismantling to allow internal lubeing. Maybe needle and dial face need to come off to internally lube. I dont know enough about the internals to go spraying silicon, or any other lube around willy nilly. lube in the wrong places may do damage ?. the clock is fine, just mounting rubbers and bezel need replacing. I thought that while it is dismantled, it is a good time to lube the internals, as they probably never had lube since new. maybe a drop of sewing machine in the right place does the job??.

Any advice is greatly appreciated.
PS Snorton, this is not your old clock. this is off my 70 fastback.
Ride safe Bradley

It ain't rocket science, so i'm told. See if ya find some clues here
https://www.google.com/#q=smith+motorcy ... nts+repair

Yes , cable wind up / spring . Wash out the outer . No KINKS . wash inner . Oil . hang up to drain overnight . No dry spots whatsoever .

mine bounces and the worm gear drive is pretty worn so I thought that may be the problem I didn't expect it to work at all but holds a pretty accurate read albeit bouncy. Sounds like could be something to do with the cable although it was a new part - so another puzzle to ponder!

I was going to let this thread die again, but since Jed did a post...
I finally I got mine working, if not perfectly smooth.
While not rocket science, there are a large number of variables that that are critical to proper functioning.
Including: cable length, amount of cable inserted into the head, shape (not rounded) and width of the square ends, condition of the head internals, amount of oil/grease/dirt in the cable housing, etc.
After spending nearly the cost of a new electronic unit on new parts and speedo head tune-up, if I could start over I would buy a new electronic until and be done with the hassles.
Which is what I will do the next time it quits.
tomas