Replacing, speedo cable on my 8HP. Help and advice needed!

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PaulB
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Post by PaulB »

Oh WO is me :(

My new Speedograph Cable has broken :shock:

All was working OK until my speedo stopped working, whilst taking part in a road run today. I checked that the cable was turning, which it was after I UN coupled it from the speedo.

I took my Speedo apart and noticed that there is, a silver, free spinning circle which when you spin it, moves the needle. That was OK. But, there is also another device in-between that and the outlet for the cable, which wouldn't turn. It was seized.

I very carefully sprayed some W D40 and tried turning the instrument using a screw driver. I was able, after a number if turns to spin this "Yellow" looking object by hand and, with my old cable attached I could turn it and see the needle moving.

I then put all this back together and took the car for a road test, only to find that the cable had stopped turning. So back home out with the jack and look underneath. I unscrewed the cable from the gear box and saw what had happened. The wires had unwound themselves.

This must have taken some clout, and I can not believe I had a faulty cable. When I installed this cable my Dad and I both made sure, that there weren't any kinks or bends in the cable. The only thing that I did do, was too tighten the screw at the gear box end with grips. Apparently so I have read, they should all be screwed by hand!

So I have two questions for you.

1 Could a seized speedo cause the cable to brake at the gear box?

2 Or could over tightening, of the locking screw on the gear box, with grips, cause the cable to brake?
Paul A Brierley
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roger young
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Joined: Sat Oct 14, 2006 7:53 pm
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Post by roger young »

Bill purves had a broken speedo cable on his bradford on the way to the NJR he asked me if i had a spare he could have till he got home, but he said make sure the cable is wound the right way, I have not had need to check if there are cables that are wound clockwise or anti-clockwise. Bill Bury got Bill fixed up before he got to me, I think it was through Lancaster spares
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PAUL BEAUMONT
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Given Name: Paul
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Post by PAUL BEAUMONT »

Hi Paul
Fitted my Speedograph cable at the weekenf and had no issues, though only did about 10 miles!! My old one had failed where the cable passed thru the bulkhead. The outer was noticeably kinked there.
I suspect that a seized clock could cause the cable to fail as there is no clutch device anywhere, so if the gearbox end is driving and the other end cannot the result will be a broken cable. I am not sure about the direction of wind. I would have thought that if all is free the torque build up in the cable should be negligible. I have found a inner cable that is about 4" too short for the Bradford. How long was your original cable?
Is your speedo head the same as the Bradford? JCS have several S/h ones available. I guess the alternative is to send your clock to Speedograph. A chat with Tim there might be a good idea anyway.
Paul Beaumont
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PaulB
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Post by PaulB »

Hi Guy's,

What we have decided to do, is wait until our Jowett Bash at the Knott in early September and see what answers the other section members come up with. Then once the rally season is over I will arrange to have my Speedo looked at and re-furbished at Speedograph, I'll also pick up a new cable ether from them or JCS.

Thankfully my Jowett is unlikely to brake any speed limits until I can get it sorted, so in the mean time I'll take it nice and steady.

To answer your question about length Paul. I did notice that the new cable is about 1 or 2 inches shorter than the original cable. But when I attached the cable there was plenty of play for adjustment.

Personally I think I am the victim of bad luck.

And I've just had a silly thought.

Which one should I have ordered?

A RHD cable or LHD cable? I ordered a RHD cable because my 8 is right hand drive. Have I made an error?
Paul A Brierley
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Forumadmin
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Post by Forumadmin »

Having had a lot of experience with speedo cables when connecting multiple devices (speedo, Halda trip and Speedpilot) to cables, I advise checking that everything is moving freely before attaching cable to gearbox. Try turning cable by hand with speedo attached.

It is possible to tighten cable too far on speedo so that it clamps drive. This might also happen if dirt or grease are in the socket or the cable is a little too long. Make sure the square cable goes all the way in, upto the washer (if you have one).

You can also check the other way and make sure the cable turns freely with the speedo disconnected.
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