Another Speedo Question....

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jsouthard

jsouthard

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Mighty Norton Knowledgeable,

I have recently been trouble shooting my speedometer. It doesn't work at all.

I purchased a new drive from Phil at Fairspares along with a new cable just in case. I had hooked up the drive end of the cable to my drill (in reverse) and the speedo works fine. the needle is steady and moves along with the speed of the drill. At the same time when i hook up the drive side of the cable to the drive and ride the cable does spin at what seems to be a balanced smooth rotation that changes as i advance speed.

Both sides seem to work but when i hook the entire assembly together i get nothing. An occasional flick from the needle and the odometer will track on and off.

Any ideas?

850 commando Roadster 1973.

Thanks for your help in advance
 
It might sound daft but try swapping the tacho and speedo heads over. You should still get a progressive movement and it might give a clue as to where the problem lies.
 
Just a few ideas.

How much of the inner cable actually projects from the outer cable at the speedo end when the cable is fully connected at the drive box end?
As there may not be sufficient length of inner cable to fully engage with the speedo drive slot? Or the squared drive end of the cable could be undersize or the speedo spindle slot could be worn?
 
jsouthard said:
Mighty Norton Knowledgeable,

I have recently been trouble shooting my speedometer. It doesn't work at all.

I purchased a new drive from Phil at Fairspares along with a new cable just in case. I had hooked up the drive end of the cable to my drill (in reverse) and the speedo works fine. the needle is steady and moves along with the speed of the drill. At the same time when i hook up the drive side of the cable to the drive and ride the cable does spin at what seems to be a balanced smooth rotation that changes as i advance speed.

Both sides seem to work but when i hook the entire assembly together i get nothing. An occasional flick from the needle and the odometer will track on and off.

Any ideas?

850 commando Roadster 1973.

Thanks for your help in advance
Click to expand...

I think LAB has got it. One or other end of the cable is not sticking out far enough to engage when the assembly is all together. It's a fine line between sticking out too far (and damaging the speedo) and not far enough. There should be about 7/16 inch sticking out past the threaded housing at the speedo end with the ferrule fully seated. The drive end seems less critical but you do need enough sticking out and into the drive mechansism.
 
After measuring i found the cable to be to short (3/16th outside of the sheath) i had just ordered the cable and phil at fairsparesamerica.com has the entire assembly right now to see where the disconnect happens.

So far i couldn't find a cable long enough to engage the speedo.

I had ordered three?

I'll let you know what phil says.
 
Hello!

I had touble with my tachowire when the driveside got rounded off.
I then repositioned the bush on the topend with a circulardrift to get a new portion of the square to engage at the drive end.
Perhaps this might be applied to your speedowire to make it reach the speedo?

Benton
 
I just heard from Phil,

Turns out 4th times the charm. He found a cable that was long enough to engage the speedo. Says it seems to have fixed the problem and has already sent the assembly back.

1- My original cable "worked" (meaning it spun inside the sheath) But wouldn't engage. Ordered a new cable from britishonly.com. Didn't fit at all.

2 - Replaced speedo gearbox (drive). Now the cable spins from the drive but still won't engage speedometer.

3 - Ordered new cable. No Go.

4 - Sent to Phil. Fixed problem by trying a different brand cable.
 
thanks for that, i'll strip my one down and have a gander. The Tacho wouldn't work but a new cable sorted that out so i will try the same source for a new speedo cable. (RGM if i remember).
 
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