Author Topic: Is the speedo drive servicable?  (Read 2588 times)

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ge0ff

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on: November 10, 2013, 02:50:07 am
I've had some problems with an erratic speedo needle that start to present after a few straight hours on the bike and gradually gets worse as the ride gets long. Starts off fine but after about 2 - 3 hours of riding the needle starts to wobble and gradually worsens. On the way home last night, it wound off the clock past 160 all the while still flailing about. If my C5 could actually do that speed, i'd be very happy but I was being overtaken by other traffic so I suggest it was a little misleading.

I've deduced it to be the speedo drive box on the front wheel not due to certainty but merely process of elimination as everything else is in order, lubed and checked sufficiently. I pulled it off and spun it by hand - very stiff, grinding a little. Didn't feel "right" and didn't spin very freely. Can i pull it apart and pack it full of high temp wheel bearing grease? It seems permanently pressed together but I could be wrong so I thought i'd check.

Failing that id prefer not to replace it with another flimsy plastic piece of junk - the replacements for older bullets look similar and are made of alloy.....are they compatible? What is the ratio on a metric C5 speedo drive?


Alan LaRue

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Reply #1 on: November 10, 2013, 03:24:30 am
You don't say how long it's been since you either lubed or replaced the speedometer cable.

The flailing is what happens when it dries out, or when it's worn out and needs to be replaced. Mine started that at about 2500 miles. I lubed it then, then 1000 miles later at the 2nd oil change, and again once and it didn't really help much so I replaced the cable. Haven't had much trouble since then, possibly because I lubed the new cable really well before I installed it. (I soaked it really well with Liquid Wrench chain and cable lube.) It has recently started being a little wobbly after 30 miles or so on the highway, so I just lubed the second cable tonight for the first time since I installed it. (Not sure how many miles that's been, but I think about 5000, so a lot better this time.)
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singhg5

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Reply #2 on: November 10, 2013, 06:13:41 am
I've had some problems with an erratic speedo needle that start to present after a few straight hours on the bike and gradually gets worse as the ride gets long. Starts off fine but after about 2 - 3 hours of riding the needle starts to wobble and gradually worsens. On the way home last night, it wound off the clock past 160 all the while still flailing about. If my C5 could actually do that speed, i'd be very happy but I was being overtaken by other traffic so I suggest it was a little misleading.

I've deduced it to be the speedo drive box on the front wheel not due to certainty but merely process of elimination as everything else is in order, lubed and checked sufficiently. I pulled it off and spun it by hand - very stiff, grinding a little. Didn't feel "right" and didn't spin very freely. Can i pull it apart and pack it full of high temp wheel bearing grease? It seems permanently pressed together but I could be wrong so I thought i'd check.

Failing that id prefer not to replace it with another flimsy plastic piece of junk - the replacements for older bullets look similar and are made of alloy.....are they compatible? What is the ratio on a metric C5 speedo drive?

If cable is lubed well, then lube the speedo hub drive at two places - shown in pictures below.

The inner plastic piece with two tabs on it rubs hard against outer piece. A silicone spray lube all along circular contact area between the two will help (picture 2).

The speedo needle jumping and flailing may be due to intermittent contact and no-contact between speedometer and top end of the speedo cable, as the cable moves up/down inside the sheath.
 
« Last Edit: November 10, 2013, 06:20:46 am by singhg5 »
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Craig McClure

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Reply #3 on: November 10, 2013, 07:58:39 pm
I have heard that the PLASTIC speedo drive can be replaced with an ALLOY unit. Not sure which one, but I have decided to do it at first opportunity. I will probably write the BULLET WALLAHS in India about it. They would be a reasonable part source for this elective surgery project.
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barenekd

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Reply #4 on: November 10, 2013, 08:20:09 pm
But you have to make sure the gearing is the same. It varies with models. The old English ones were metal, but, as I said, the gearing may or may not match the current gearing. the plastic ones are actually quite durable as long as they haven't been crushed during a wheel removal operation.
Your bike should have come with a new speedo cable.
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ge0ff

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Reply #5 on: November 11, 2013, 12:47:01 am
Thanks for the replies.

The bike only has 3100km on the clock (1900mi approximately). I bought it at 2000 and lubed the cable the day I picked it up and again before the trip in question. I'd be very disappointed if the cable was flogged out.


wildbill

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Reply #6 on: November 11, 2013, 05:53:37 am
why not try the new cable which came with the spare part kit


barenekd

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Reply #7 on: November 11, 2013, 07:12:44 pm
What are you lubing it with? You need a very light grease like a white lithium or a speedo cable specific grease. Heavier greases can bind it up.
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