Speedo and Drive Issues

Hello All, as part of my prep for the upcoming Vintage Rally I'm onto all the niggly things I have lived with for ages....
The speedo used to go but at 60 to 70 it used to call it a day and stop..... eventually it stopped altogether indicating it was time to do some maintenance...
I found the guts had fallen out of the speedo drive.....easy fix, just get another one, got one of the repro ones and fitted it.
I had high hopes of a resolution with this......nope.
Just the odd blip...
So I did a thread search and gleaned all your good info on how much sticks out the speedo end, cable lube, testing with drill .....
passed the drill test....the Black and Decker battery drill can do over 50 mph.
Ran the bike with the speedo head off and the cable turns.

I suspect the cable inner is not long enough and is riding off the drive at the drive end....any thoughts? :idea:

My local testing station guy has not yet twigged to the speedo...just thinks I don't use it much

That drive end is a little bizarre. I think I remember someone had a fix for it, but my brain is freezing at the moment. Make sure your cables are good and lubed too, that can make a big difference, as well as routing. I found I could slip a piece of tubing over the end and pour oil in the tube, let it drain out the other end. I use moly lube.

Dave
69S

I pull my cable out, lube it, and slide it back in. Maybe the cable isn't sticking out the bottom enough to fully engage the drive. If you undo the top, there is enough cable sticking out you can twist it with your fingers. If you can spin it, its not locked into the drive. Either the cable is too short, the square drive in the unit is rounded or poorly formed, the nut on the speedo drive is not seated, or the little brass stop at the top of the cable isn't in the correct position.

I would think the nut isn't seated fully on the drive unit or the drive has issues. The threads on the drive neck may be a little malformed. You can check to see how far the nut should go on - it should go the full number of threads visible inside the nut, snugging the flare of the cable sheath to the unit. The square drive inside the unit is pretty far in - but if the bottom nut is snugged down and you feed the cable into the unit from the top, you should feel a good 1/2" worth of engagement.

From what I've gleaned, the inner cable should not stick out any more than when you pull the nut all the way to the end, it should be flush, that's when you have the engine/gearbox end installed. More will damage the clock, less will not engage enough, maybe. It's just what I've heard and mine seem to work fine on the original cables and clocks with that situation.

Dave
69S

Ugh finally find out why Trixies speedo went loopy then died this summer, thinking the worse, only the cable was broken when pulled out but strangely spinning the wheel drove cable to turn at top aginst oiled finger resistance. Yes...
The installed drive seated cable should leave the speedo end flush with the to clock fasten nut, with nut pulled to cable end.

Thanks guys, I think the outer was a bit too long, filed a bit off the drive end of the cable outer and put it all back together.
Got the Rally on tomorrow so seeing as it was such a nice day I did a couple of test laps round the block and the speedo worked .
So headed into the city , stopped for a coffee with the bike parked up on the kerb ....a young chap asks me if the bike is mine, how nice it its and have I ever had it on the track.....no...... I have a BMW I use for thrashing on the track......
What do you race I asked......a 350 Manx he replied.......then introduced himself ...James....Jamie........
....( me) ....as in Jamie McIntosh....?
Yep....Dads Ken....
Sure is a small world here in NZ.....
So finished in the city and rode down the motorway to the data centre.......70 mph......sweet........could see one of the exhaust nuts needs a tweek......

come off motorway......throttle getting a bit stiff......then about 100 metres from work.....throttle stuck open.....eeek.....cut the gas and stopped.

Damn.....the top cable was frayed.....good I got a new one this week......was last item on to-do list.....bugger.

As usual everyone sees you pushing your old Brit bike.....LOL LOL LOL........

" wheres ya BMW....and your Scooter.....LOL LOL" GRRRRR.

So I phone up the missus...." Hello Darling"
" What do you want..."
" Do you have the van today....."
" Y...e....s..."
" Can you pick me up after work.....I have hoppy beer in the frigdge.."
" ok"


Still the speedo works fine......

Life time events to fill in old age memories and reads like an extension to Norton Tunnel of Love... Suspect clutch cable next young man and electrical grimlims after disturbing the loom. Not bad id to keep eye on on cable end recuse kit.
Fix em all at one go or fix em many piece meals at a time.

CanukNortonNut said:

72Combat said:

Hello All, as part of my prep for the upcoming Vintage Rally I'm onto all the niggly things I have lived with for ages....

I suspect the cable inner is not long enough and is riding off the drive at the drive end....any thoughts? :idea:

72
Make sure that the speedo cable runs between the engine and the frame cross brace for the side stand spring (just under the Engine timing case) and not under it. That’s how the outer sleeve gets pulled apart.
CNN

Click to expand...

Click to expand...

Thanks

Ive found that the pattern drives have a slightly different size square drive hole
than the genuine. Found this out by buying a new cable from the fellow who bought
the Smith's tooling. His cable will not go into the pattern drive but goes in a
genuine one beautifully. So Im stuck using a Venhill cable in the pattern drive.
It wobbles a bit below 35, fine as you go faster.
Id also try light oil for lubing. Not grease.
I really wish somebody would run up a repair kit for the genuine drives.

I did about 200 miles over the weekend on a vintage bike run and although the needle moves around a tad it works ok.
I suspect its a combination of pattern parts and worn original speedo head.
Rode it to work today 45 km round trip on motorway....get some funny looks. :roll: