A while back, I bought a new speedo cable, made to measure by Venhill. I wanted a slightly longer cable than the old one (it died when I tried to remove the inner cable to lube it, and .... )
The new cable lasted very few miles, before the inner failed. As did the second. The next one got fitted, and the bike didn't get used over lock-down. I have just given the bike a few day rides - and the new cable has failed.
The bike is a very standard 1955 model 88 with chronometric speedo and standard drive gearbox. I run the speedo cable along the lower frame rails for softer bends and easier cable life,
I find it hard to believe that Venhills have screwed up totally with three speedo cables all lasting fewer than 500 miles. So what is wrong?
Paul Standeven
What failed with the cable?…
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fails....
On the first cable, the ferrule at the speedo end was not crimped and caused the inner to break. The speedo end of the inner broke off on the second. This time, the speedo stopped working 3 miles from home, with lots of speed cameras in 20mph zones etc. I got back from a bike club meeting at midnight, put the bike in the garage and left it. I will be able to check the failure on Thursday.
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The lower frame route was…
The lower frame route was the Norton way, I think the upper frame route was the AMC way.
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Speedo cables
The Speedo cable problem with them breaking was because they were routed along the lower frame rails, or under the engine. The factory changed this to the cable running over the top of the engine, and this stopped the speedo cables from breaking. I have always done this on all my bikes, and i have not had a speedo cable break.
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preventing failure
Hello Anthony,
Can you explain to me how routing the speedo cable along the top frame rails prevents failure?
Thanks
Paul
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Speedo Cables
I've always routed my cables under the engine as the suspension movement then has less effect. The only time I had an issue was when I was being too clever with my routing and managed to get the cable trapped by the centre stand. Could that by your issue, Paul?
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the failure
I routed the speedo cable under the engine, because it avoids the sharp flexing under suspension movement, and avoids the tight bend immediately at the speedo itself. Instead there is soft flexing with suspension movement, a large radius bend at the front of the motor, and a slight bend at the speedo. No, the cable is not being crushed at the centre stand.
A few minutes ago, I did some tests on the cable. The inner spins with the wheel, but does not spin the speedo. I tried a spare chronometric, and it likewise fails to spin it. It did spin a pre-WW2 bike speedo, non-chronometric. The tip of the cable inner has a rough end, it is broken off,
This is the second time that a Venhills new cable has broken at this end, after a very few miles. I haven't tested the speedo to verify it is at all stiff in its movement. Next question, if a chronometric is a little stiff, can it cause a cable to break its tip off?
Paul
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A plug for JJ Cables
Hi Paul,
May I suggest that you give JJ Cables, Warminster a try? They make their own stuff, even bespoke cables.
Have used their stuff on several bikes and it just fits and works.
Only cable I have had from Venhill was a clutch cable kit that I used to make my own cable up with, so that one was ok. Venhill seem to have a mixed reputation - either total satisfaction or peed off customers with incorrect fitting cables being supplied.
Good luck,
George
PS: I use the 'up and over' route on my 650 and it works OK, but I agree the lower route would appear to be better for the cable.
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I have used JJ for cables…
I have used JJ for cables too. Check that the inner cable protrusion is the right one for your speedo head and that you have the short nut detail at the head end . Cable length changes with clock mounting position. If your bike really IS standard 55 featherbed then the spec will be known. Avoid E_Bay sellers and Chinese crap.
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JJ Cables,
I have used JJ Cables for a number of years. I normally send them the old ones as patterns and have never had a problem. Today I sent them 4 cables for the Manx following my off. The gentleman looks at them and then rings me with a price. He also made a set for my Aermacchi.
FYI he is no longer at Warminster but has moved to Fir Tree Farm, Warmington, Banbury, OX17 1JL and his contact number is 01295 971170.
He always seem happy to discuss your requirements.
I have no connection with the company but am a very satisfied customer.
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To see what a cable should…
To see what a cable should look like WWW. Vintage British Cables Item DF1110/22 . You need to specify length if JJ does not know.
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sourcing a correct speedo cable
I just looked at the Vintage British Cables website. The item DF1110/22 looks good. They offer lengths 5' 2", 5' 5", 5' 7", 5' 9" without saying what each length may be correct for.... I presume that this measurement is to the end faces of the ferules. Mine is 5' 4 3/8" and fits perfectly on the bike. I just need an inner.....
RGM offers speedo cables 5' 7" for Dominators. The RGM page on speedo cables says that a chronometric speedo should accept at least 3/8" of inner. That's how long the broken inner projects on my cable. It's not long enough to drive either Chrono speedo I have.
When the on-line information is imprecise and incomplete, how are we supposed to sort our bikes out?
Paul
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stiffness?
I did a test today using a cordless drill. The speedo head end of the drive cable is just under 1/2" long, not long enough to drive the speedo, so I put that into the drill chuck. The other end I used to drive the speedo. The Dominator speedo went up to 10mph. A spare speedo for another bike went up to 15mph, not sure if that is due to different gearing. At any rate, it is not seized.
So, is there any fault with the bike that caused the fractures?
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Cable lube
Always use a light oil, too much drag with grease
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I got JJ to make me 2 new…
I got JJ to make me 2 new inners to my dimensions, Might be you have damage to the speedo head.
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speedo at fault, not the cable?
I sent it to Phil Woods at ChronometricSpeedos. He says the main shaft is worn and caused the cable fracture. Cost £92. Next job to call JJ Cables about a new inner, or maybe a whole cable.
According to data on the RGM website the cable needs to project 7/16" from the ferule at the head end. Mine does that, still, yet it does not drive the speedo. That tells me that in fact the Venhills cable is not faulty. It just does not drive the speedo. When I get the speedo back, I will have to check how long the cable inner has to be for it to work.
This is not as I expected it to be ....
Paul
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Be happy that by the time…
Be happy that by the time you have got it sorted you will be almost an expert on the subject and well able to pass on valuable info to newcomers !!. PS, the outer needs to be the short nut type.
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Bodger
You blokes will probably think of me as a terrible bodger by now, especially after this post.
I have had quite a bit of success brazing the broken inner cables back together.
The last, on my ES2 broke where the square bit becomes the round bit where it connects to the speedo drive. It's worked for the last 300 km or so...
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What failed with the cable?. There can be an issue with the inner cable projection which is different between chronos and magnetics . I guess a short one will chew up the ends and a long one will seize in the outer and damage the speedo.. I didn't like the cheap look of replacements, so I found an orriginal outer with the long heavy steel sheilding at the top with a short nut fitting and ordered a couple of new inners from a specialist .made to my measurements Fitted fine works well. I have a spare and it cost less. And looks a proper.job. Sometimes you have to go the extra mile even if its a headache.