Speedo cable wrapped around axle

Cable wrap story

Had a trifecta of failures day last week. I was cruising along on the HWY when I felt a little wiggle for no apparent reason. Looked down to see what my speed was and noticed the speed just dropped to 0. No doubt I had a cable issue. Rode another 3 miles into a town and pulled over in a vacant parking lot to see what was going on.

The speedo drive ring that screws into the rear wheel hub had backed all the way out. The speedo gearbox was spinning at the same rate of speed as the wheel, and the drive ring was pushing on the speedo gear while it was backing out. Also noticed my steering damper bracket had snapped. So I had a distorted busted speedo gearbox, a busted steering damper bracket, and a snapped off speedo cable wrapped around the axle. It was a long day getting back home.

I took a pic of the speedo gearbox after I got it off and cleaned it up some. I'm little surprised it didn't lock up and force me into a low side slide. Paint bubbled up on the speedo gearbox. It was hot, so was the entire rear hub.



All fixed now with a new speedo gearbox, a 30 year old NOS speedo cable I had, some new spacers, and a bearing check. Fixed the steering damper bracket too.

And as always, the video. Thanks to @Mike T for helping me put this together.

The drive depth of the '71-on gauge spindle (below) is approximately 0.735" so should have been fine with an inner cable of 0.45" as the inner cable only needs to be just less than the drive depth of the gauge.


Chronometrics and pre-'71 magnetics (the one below), however, have less drive depth (approx 0.546")...


...'71-on, therefore, are 9/16" (0.5625").

L.A.B. said:

The drive depth of the '71-on gauge spindle (below) is approximately 0.735" so should have been fine with an inner cable of 0.45" as the inner cable only needs to be just less than the drive depth of the gauge.

Chronometrics and pre-'71 magnetics (the one below), however, have less drive depth (approx 0.546")...

...'71-on, therefore, are 9/16" (0.5625").

Cables

Click to expand...

Gauge did not work at .45”. I’ll go with what @bmepkid says, no offense.

swooshdave said:

Gauge did not work at .45”. I’ll go with what @bmepkid says, no offense.

Click to expand...

No offence/offense taken if it worked for you but I fail to see how shortening an inner cable that's already under length could have solved the problem.

I've just run up 6 gauges (out of the 8 shown as 2 are faulty actually they also worked but the needles went wild) with a 0.525" inner cable and all 6 worked normally including one pre-'71 with the shorter spindle depth.

In the last couple of hundred miles, I've noticed my speedo no longer holds steady, but wavers a bit. Is this usual or an impending problem? (I think I may have hypochondria by proxy with my Commando )

Mart UK said:

In the last couple of hundred miles, I've noticed my speedo no longer holds steady, but wavers a bit. Is this usual...

Click to expand...

Not particularly.

Mart UK said:

...or an impending problem?

Click to expand...

Difficult to say. Smiths or Veglia?

Have you greased the cable (not the top 6 inches)?

Mart UK said:

In the last couple of hundred miles, I've noticed my speedo no longer holds steady, but wavers a bit. Is this usual or an impending problem? (I think I may have hypochondria by proxy with my Commando )

Click to expand...

It's generally a cable issue

L.A.B. said:

Not particularly.



Difficult to say. Smiths or Veglia?

Have you greased the cable (not the top 6 inches)?

Click to expand...

L.A.B. said:

Not particularly.



Difficult to say. Smiths or Veglia?

Have you greased the cable (not the top 6 inches)?

Click to expand...

I don't know which type of speedo. May not be original. Picture attached.

I have not greased the cable. I looked for it in the service manual this morning and can't find it. Do I just give a couple of pumps of usual grease to the nipple on the underside of the speedo gear housing at the back wheel? Or do I remove the cable and oil it?

Mart UK said:

I don't know which type of speedo. May not be original. Picture attached.

I have not greased the cable. I looked for it in the service manual this morning and can't find it. Do I just give a couple of pumps of usual grease to the nipple on the underside of the speedo gear housing at the back wheel? Or do I remove the cable and oil it?

Click to expand...

That's an aftermarket instrument.

Mart UK said:

I have not greased the cable. I looked for it in the service manual this morning and can't find it.

Click to expand...

Well, you don't always find absolutely everything you might need to do in the manual.

Mart UK said:

Do I just give a couple of pumps of usual grease to the nipple on the underside of the speedo gear housing at the back wheel? Or do I remove the cable and oil it?

Click to expand...

To grease the cable (not the speedo drive gearbox) you need to disconnect the upper end from the speedo and pull out the inner cable). Should only be a 5-minute job and why not do the rev counter cable too?
Speedo is aftermarket as TS says.

Mk3 Smiths:

Mind you, AN said to use light oil only on the new one I purchased..

EstuaryBoy said:

Mind you, AN said to use light oil only on the new one I purchased..

Click to expand...

A speedo cable?

My experience of greasing the speedo cable is that it causes too much drag and makes the speed needle fluctuate. It may also contribute to speedo drive failures as there is almost 6 feet of cable to turn. I have had best results using "dry" lubricant. I use some stuff for cycle cables that is quite thin when you apply but dries out and still provides lubrication. Need to wash out the outer cable first and clean inner too. I disconnected both ends of the cable and poured petrol through the cable a few times.
My speedo needle is rock steady when moving and I can turn the cable easily with my fingers.

OK, well thanks all. I guess I'll take the middle line, I use 20W50 in my clutch cable, I'll do the same on the speedo cable (and tacho drive). Sorry to take the topic on a detour. And I'll write it into my service manual

EDIT: I greased them. That's what it looked like was on there.

Mart UK said:

I guess I'll take the middle line, I use 20W50 in my clutch cable,

Click to expand...

Control cables are a different matter and I wouldn't recommend greasing those as they are often nylon or Teflon lined so need no, or only minimal lubrication.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwi_29q4-vHyAhVQzqQKHeEHDuAQFnoECAIQAQ&url=https://www.venhill.co.uk/cableinstallation&usg=AOvVaw07ZQvXx6_mgZq4EE2tjiz0

"• Road bikes – At the beginning and end of the summer, remove the cables and flush through with a light lubricant spray such as "WD40". You do not need to lubricate Venhill cables with oil as this will increase friction between the inner wire and the Teflon tubing."

I've never had any problems using LM grease on instrument inner cables as that's what I've always used although I'm not saying there isn't something better.

L.A.B. said:

Control cables are a different matter and I wouldn't recommend greasing those as they are often nylon or Teflon lined so need no, or only minimal lubrication.

file:///tmp/CableInstallationRecommendations-1.pdf

I've never had any problems using LM grease on instrument inner cables as that's what I've always used although I'm not saying there isn't something better.

Click to expand...

I always use grease too.

I make sure the inner cable is completely clean and the outer is as clean as I can get it and then feed the inner in while applying a thin coating of grease and making sure that the last few inches near the instrument have no grease. Too much grease is a problem in the cold and will cause needle jumping. Too little lubrication will cause needle jumping at any temp. The problem with oil is that it will migrate to the speedo drive where it is not wanted.

So, IMHO, use grease but don't pack with grease.

marinatlas said:

http://vintagebritishcables.com/images/ServiceInformation2.jpg

Click to expand...

That's a great link. Thank you. I edited my post above, before I saw the replies! I used grease, that's what was already on the speedo cable, by the look of it. I cleaned them, rubbed it on lightly and refitted. The tacho cable (which has been fine) was dry. I'll see if it's made any difference.

Sorry Dave!

L.A.B. said:

A speedo cable?

Click to expand...

I said:

Many thanks for speedo cable now received. A question or two before I fit same (sorry I couldn't access technical queries from your website)..

Will it need lubrication before install? If so, with preferably what? Also, was there a factory preferred route to fixing these, or just 'play it by ear?' Contemporary photos show some machines with cables below the bottom yoke, others above. Any suggestions/recommendations for the least stress free fix?

Thanks in advance...

They said:

Apparently, you do not need to oil the cable but if you want to, then use a light lubricating oil. I use 3 in 1.

The best route for the cable is under the yoke, if you go over the lower yoke it makes it a tight turn to get into the head.

Regards,


Ashley Cutler IEng MIET