Speedo Drive

Quote GIR.

The most annoying part that I would update is the speedo drive. What piece of junk. 3700 miles more or less to Lumby and back. Just over 3000 miles on the clock even after repairing it once.

I don't know how long it's going to last but after replacing speedo drives regularly for many years I took the last low milage used drive apart before I used it and packed the large gear in Casite [case hardening compund] and baked it at 1750 for a half hour before a water quench. I didn't have a hardness tester at that time but my file said it was harder. And it's been on my bike for around 15 thousand miles now which is longer than any have ever lasted before. Jim

Interesting, a vast mileage increase by hardened cog. The weak link in my speedos has always been the rivets working loose, then the rest goes to trash.
Only upgrade I've read that helped was to re-do these rivets with squat bolts before the rivet slack got to eating its speedo meal.
I'd be interested to try to preserve the slightly used spare awaiting its turn or Trixie
Combat. I do so like to see the steady direct indicating speedo and tach needles.

hobot

Steve. I have always removed the tin plate and rivets and replaced it with a machined steel flange after boring the hole in the center out about 1/4 inch larger. That way the pinch from tightening the axle does not squash the pot metal and cause the side to bow out. But even after that I generally wore out the large gear regularly. The more I think about it I believe the hardened gear has been in there since it failed on the way home from LOP four years ago. So it has lasted pretty good. Jim

If you replace the rivets with #2-56 flat heads and just tap the holes left buy the rivets you will have no problems. If you use the grease nipple to top it up you’re going to lunch it every time. The drivers need to be taken apart cleaned and by hand lubed. I never use the grease nipple. New grease on top of old grease is no good. I use a white lithium grease engineered for 90 degree drives the metal never touches the metal and the only way to have that happen is to replace the grease before it degrades. Blackened lube showing up on the outside is you’re first and last warning. I keep a stable of six or so running bikes with a 1974 being the newest one. Also never remove the spindle gear or anything that keeps it in place it can be cleaned in a shallow pan of solvent with a broken end of speedo cable and a drill motor. That’s what I have found YMMV. I wrote this up somewhere on here a year back or so with pics.

The Indian made replacements are complete and utter s**t. I was lucky to get a used Smith's original from an autojumble and the tolerances are so much better, a good clean and new rivets and it's fine.

The difference shows itself particularly in the quality of the gears, the Smiths ones are very precise and hardened, the Indian ones seem to made of some kind of grey cheese that round off

Why not go electronic? yes I know some would like to keep the bike completely original, but for day to day use, an electronic gauge makes a lot of sense. The gauges made by Motogadget http://www.motogadget.com/ may be pricy, but top quality.

Jean

No question the electronics are the way to go for longevity. Maybe when I get some equipment payed for in a couple years I can treat myself to a set. Jim

Here is a picture of a Motogadget gauge, this is a chronoclassic and it will replace the tach and the speedo as well as all the other indicators.



Jean

Jeandr said:

Here is a picture of a Motogadget gauge, this is a chronoclassic and it will replace the tach and the speedo as well as all the other indicators.

Jean

Click to expand...

$527? Maybe one day.

does it fit in the instrument cups ok?

Delicious Nortoneer gemstones in this thread on self consuming hobby horses.
I'm humbled to keep one factory Cdo going - so avoiding all its weak spots in another project I can handle better and maintain. I'm split between which I like best.

In for a penny down for a pound eh. Ok will attempt to learn hardening process and rivet replacement in two speedo drives on Trixie, one mounted still intact and another un-installed from mystery source. May be way better if I just pay extra for a modifed one and ride more informed on a real Combat. Peel gets digital meters but she only looks Norton from a distance.

My bud Wes uses digi bicycle speedo's, which work well and don't hardly mare the look of no gages at all, until on lookers react. On back burner this season as still a cam and some doo-dad to buy for Peel's engine and Trixie hangs w/o an engine but all the parts on hand. Just lacking will power and other tasks to resolve into real progress. Got to stop asking wife for tasks to catch up on, ugh.

Also realize what ever I put into hobby I can expect to be ruined in a season or two going by history lesions.

speirmoor said:

does it fit in the instrument cups ok?

Click to expand...

Damn close. Diameter is 80mm = approx 3.149 and I measured the Smith speedo at 3.140-ish.

Remember that this one dial replaces both the tach and speedo so it would one need one cup.