Speedo repair?

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Jul 18, 2004
Can any one tell me if my speedo is garbage (or not) based on the picture below.
I removed the felt and de-gunked it. It appears that the worm gear is seized and was the cause of the destruction. Were those bits part of the drive gear ? Am I missing dowels?

Are parts available - I only see the unit listed as a whole.
Speedo repair?

Sorry to bear bad news, but it's junk. My original Smiths unit suffered a similar fate, losing all the teeth in its drive gear. Parts are not available and Smiths went out of business years ago. Repops are available however. I bought one from Phil Radford and all is well again. So that's the good news. A phone call, another $100 charge to the credit card, and you'll be good to go :)

ahh well - thanks Debby, I had an feeling that was the case.:cry:

I will search the swapmeet next weekend - just so I don't buy another piece of junk or an incomplete unit.... are the two tabs the fit into the wheel, square like the pic below?

Speedo repair?
Yes the tabs are square and fit into the square holes on the rear wheel bearing lockring.
When looking for a speedo drive at the swapmeet, make sure you get one that is 15/12 ratio and has the number BG 171 (some one help me out here because this is from my feeble memory). Also make sure you use the axle spacer that I see in your picture of your old drive if there is none in the replacement. Better yet, buy a new one as these tend to get crushed causing the drive to grind into that nicely polished wheel disc you just spent 2 hours on!

Ditto Ron's comment regarding being aware of the different speedometer drive ratios. An identical looking Smiths drive gear was also used on BSAs and Triumphs, which had different ratios. Like Ron, I can't remember what the ratio should be for your bike.

I purchased a used, reproduction speedo drive gear from Rabers Parts Mart in San Jose for use on my MK III. It cost about USD 35.00 and it's worked flawlessly for some 6,000 miles now.

By the way, great looking photograph you took of the drive gear!

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