speedo just started spinning wildly...

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Sep 26, 2007
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Yesterday i looked down at my speedo as i was putting along in 40 mph traffic to see that Mr Smith thought I was going 130 mph.

The speedo was swinging wildly beyond my real speed, whether i was going 20 mph or 60.

The cable is fine. And i think the drive is fine too.

I disconnected the cable from the drive, checked that it was in the speedo firmly and turned it by hand at the drive end - the speedo showed 50 Mph. I put my drill on the cable - same crazy result (yes with the drill in reverse).

I took the speedo off, went over to the bench, and turned it manually with an allen key. Again, spinning the allen key between my fingers shows up at 20 to 50 mph per Mr Smith.

However, if it do the same thing with the speedo and the allen key but hold the speedo upside down, the needle barely moves. Turn it right side up - problem is back.

Should i mount it upside down on the bike and put a mirror under it to see my speed that way? Or does someone have a theory or suggestion for speedo repair.

Note: it is the Smiths SSM 4003/00 1000 model, with the NVT logo.

Google helped me find a speedo repair shop here in San Diego, Foreign Speedo, plus there are lots of others.


Try Nisonger Instruments. They do only Smiths and I've heard that they do excellent work and the cosmetics look as new. I have Veglia units and they won't work on them, so I had to go somewhere else but for Smiths, Nisonger should be able to help you.

Keith, Inside the speed o is an alum. disk that is spun buy the cable. The faster it turns the more it influences the magnet the magnet moves the needle against a spring. Adjustments to the air gap between the alum. disk and the magnet calibrate the needle to a corrected speed. The gages are very simple to work on once you have figured out the bit about removing and replacing the metal bezel.
By the way have you read the last post on your thread "Awesome ride! - It's worth all the sweat!"
Hello Keith,
are you sure the cable is fine. Does the cable have some smooth worn spots. I have found inside the outer tube is wrecked and causes the speedo cable to grab and coil up hence you get the wild speedo dance. It feels fine when its laid flat give it an arc and you might find it rubbing. Anyway a quick check if you haven't done it.
Nope, it's definitely the instrument.

There is also Joel Levine in Atlanta, GA that does good work.

There was just another post on this subject last week with at least two other sources for rebuilds besides Nissonger & Levine.
Foreign speedo off University Ave. does high quality work. They have rebuilt several Smiths' instruments for me, though not for ten or fifteen years--everything has held up pretty well.
Thanks Mike for the confirmation on Foreign Speedo, and Grandpaul on the confirmation that it's the speedo itself.

Since i can reproduce the problem with the speedo in my hand at the kitchen table with an allen key, seems like the speedo unit to me.

I called Foreign Speedo this morning. It's got the advantage of being driving distance for me, and I see a couple of other Norton owners on this forum are OK with their work.

The guy says he has a bunch of Smiths instruments in the shop now and is very familiar with their issues. (He suggested that a frequent issue is a slightly too-long cable, that gets overtightened and ends up pushing up on the mechanism in the speedo. I guess he's insinuating that I overtightened my cable, such as when I had the wheel off the other day to get the fender off to get at something.... who me!?)

Anyway, he quoted $85 to $110, so I'm going to drop it off to him today - with expected 2-3 week turnaround.

Thanks again,
Keith Kelly
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