Speedo problem (any ideas, please?)

[Jacqueslemac]

Last Autumn the speedo on my RD04 stopped working suddenly. The cable looked pretty corroded, so I replaced it.

All was fine for a couple of hundred miles and then it stopped again.

I removed the front wheel and took a look inside the little gearbox thingy. Everything looked fine, but following advice on here, I bent the lugs on the circular drive that sits against the wheel hub, just to make them sit up a little more. I also noticed that the leading edge of the lugs on the nylon drive were worn.

I assembled everything, but no joy.

I had a spare wheel, so I dismantled that and noticed there was an o-ring inserted behind the circular drive ring (with the lugs). Working out that this must push the lugs closer to the nylon drive cog, I swapped it onto my original wheel. It worked for a couple of hundred miles and then the speedo stopped again.

(I keep a record of fuel economy based on miles between fill-ups, so you can imagine how annoying this was, completely buggering up my stats!)

This time I bought a complete gearbox unit from eBay and installed that. The nylon cog looked like new, with no wear on the lugs at all. I took the o-ring out at this stage.

Everything was fine for a while and then, guess what, it stopped working again.

When I stripped everything down, I found the nylon cog completely stripped bare.

So I took the original nylog cog, pared the leading edges of the lug down so they were now at right angles, stuffed everything with grease and put it into the newer gearbox unit.

Again, everything worked for a while. Until yesterday, when it stopped again.

I've forked out nearly £21 for a new nylon cog, so before I strip the speedo drive down yet again and fit the new bit, has anyone any idea what might be causing the problem?

Bear in mind I've used two different gearbox units, two different nylon cogs, two different metal drives (with and without o-ring), plus one new cable.

Thanks in advance for your words of wisdom and experience.

[taffy]

i had the same problem, what grease are you packing it with, when done this i packed it with axel grease and it didnt like that then i found out i had to use light white greas for plastic, all works fine now.

[Jacqueslemac]

Yes, I put axle grease in the last time. I didn't put any grease in all the times before, though.

Why would the wrong grease make it stop working so suddenly?

[btbloke]

viscosity and operating temperature is your answer to that question. some greases don't become thin and lubricant till under high pressure or temperature and the speedo drive will not get very hot so the grease would cause extra resistance/strain on the drive.
Another option is,have you moved,re-installed the speedo cable the correct route and did you oil it? If the cable is causing resistance it could be forcing the drive to work too hard.

[Jacqueslemac]

Makes sense, BT, thanks.

I didn't oil the new speedo because it felt smooth and free-running, but it's worth a go. I think I've got the routing right...

Thanks for the suggestions so far.

So, new thinner grease, check routing, remove, oil and refit the cable.

Any other suggestions while I've got the thing apart?

[btbloke]

vaseline.



















for the speedo that is,I pack mine with vaseline,and oil the cable with 3 in one oil or olive oil.

[BobA]

Jack the Lad!


Some thoughts.


My last speedo drive failed on my RD04 because the wheel bearing on the front right hand side was knackered. It meant that the speedo drive was actually being put under stress. This was accomponied by a strange squeeking sound (that you may or may not have) as the bearing dust seal was being driven against the speedo drive. Might be worth getting the front wheel in the air and checking for play.

Next, when you screw the front axle into the left fork, your not doing it up too tight are you?? This might squeeze the speedo drive against the hub too much. I just snick mine up before I do up the clamp on the right fork leg.

Have you got the speedo drive in the correct orientation, so it abutts the lug on the front of the right fork leg?? ( I think from memory)

[BobA]

vaseline...




for the speedo that is,I pack mine with vaseline,and oil the cable with 3 in one oil or olive oil.

AND obviously, being Italian, the engine is filled with sun-dried tomatos (to mask the whining gearbox!!)

[btbloke]

organic, no chemicals to eat in to the plastic sheathing/self lubing material,never let me down in fact when I forgot to put the screw holing the cable to the drive on the way to the 2008 national the cable fell out of the sheath by the time I got 20 miles from home so the olio olive definitely lubes................got a few other lube uses for it but this is a family forum.

[Jacqueslemac]

I fitted the new plastic speedo drive thingy on Thursday night (only took an hour, all in, in the drive, in the dark. I'm getting the hang of it).

Didn't have Vaseline, but I cleaned all the grease out and lubricated the new assembly with thin three-in-one oil.

So far, so good (hope I haven't talked up yet another failure). I've done a couple of hundred miles and all is still working.

However, I did notice that the new drive is a good millimetre taller than the old (original) one. The lugs should engage better with the drive that sits by the wheel bearing. I wonder if Honda makes them bigger now to prevent the lugs in the drive skipping over the lugs in the plastic thingy (apologies for all these technical terms)?

Thanks to one and all for your words of wisdom, as always.