CL77 Speedometer Question

Engineer1 · Post by **Engineer1** » Sun Jul 17, 2011 8:15 pm

While I was riding at 40 MPH my speedometer suddenly swung to a much higher than normal reading--80 to 90 MPH. Even at slower speeds it was still indicating abnormally high. It returns to zero when the bike is stopped. I removed it and checked for loose debris--nothing. Cable and gears turn freely and were recently lubed. Two questions: 1) Can anyone suggest what might be wrong inside the speedometer? 2) Can anyone offer instructions on how to get the speedometer apart without ruining it?
Thanks!

LOUD MOUSE · Post by **LOUD MOUSE** » Sun Jul 17, 2011 8:16 pm

What did ya lube the cable with?. ........lm

Engineer1 wrote:While I was riding at 40 MPH my speedometer suddenly swung to a much higher than normal reading--80 to 90 MPH. Even at slower speeds it was still indicating abnormally high. It returns to zero when the bike is stopped. I removed it and checked for loose debris--nothing. Cable and gears turn freely and were recently lubed. Two questions: 1) Can anyone suggest what might be wrong inside the speedometer? 2) Can anyone offer instructions on how to get the speedometer apart without ruining it?
Thanks!

Engineer1 · Post by **Engineer1** » Sun Jul 17, 2011 8:23 pm

Speedometer drive gears and cable were lubricated with lightweight bearing grease. The cable seems to turn smoothly. The overspeed reading is fairly stable also, not jerking around a lot. By the way, the bike is a 1965 model--no tach.

LOUD MOUSE · Post by **LOUD MOUSE** » Sun Jul 17, 2011 8:42 pm

Thanks for the reply.
May I suggest ya do a really good cleaning of the cable then lube with white grease.
It's at least the easy way to not get into other major parts. ................lm

Engineer1 wrote:Speedometer drive gears and cable were lubricated with lightweight bearing grease. The cable seems to turn smoothly. The overspeed reading is fairly stable also, not jerking around a lot. By the way, the bike is a 1965 model--no tach.

G-Man · Post by **G-Man** » Mon Jul 18, 2011 1:52 am

Hi Engineer1

Welcome to the forum!

The drive to the speedo needle is via a magnetic link ( actually seen as an aluminum drum on the drive shaft) in which the needle is driven against a hair spring. The needle is dragged around only by magnetic force. The faster the drum rotates the more it pushes the needle against the spring. If lube oil or any other debris gets into this air gap, it will alter the calibration of the speedo and must be removed.

CL77 Speedo return spring by graham.curtis, on Flickr

Unfortunately that means dismantling the speedo or perhaps, waiting for the contaminant to evaporate.

I suspect that some dirt or maybe some of your lube has gotten into this part.

Search speedo repair on this site for some good posts on speed dismantling and repair.

Biggest part is getting the chrome bezel off, after which everything is pretty straightforward. If you take time prising up the rim of the bezel you will be able to replace it for an 'invisible repair'.

Removing speedometer Bezel by graham.curtis, on Flickr

Good luck!

G

KJB · Post by **KJB** » Mon Jul 18, 2011 6:18 am

Interesting topic. I’m in NC on vacation now but the morning we were departing I decided to take my CL77 for a quick ride. My speedometer too began to register very high readings when I was only going about 30 mph. I could hear noise coming from the speedometer head that should not be there. I’m guessing it’s the speedometer head and not a cable issue. I’ll be investigating it when we return home at the end of this week.

jgentry425 · Post by **jgentry425** » Mon Jul 18, 2011 8:57 am

I recently had the same problem, only to have the needle stop working completely and rest on zero. Turns out the speedo cable was broken. I've got a new one on the way, and plan to take a look at the speedo assembly as well. Thanks for the pictures and instructions.

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