Lash on bevel drive Oldhams couplings query

[machten]

I've been diagnosing today what I've considered excess noise in the top end of my 450 Mark 3. There was another problem contributing to this, but one of the things I discovered along the way was some lash on the bevel drive oldhams coupling that results in about 0.5mm of circumferal "slop" in the upper camshaft bevel gears. it is definitely contributing to some "rattle". Ducati specified 3 undersized oldhams coupling sleeves (0.02, 0.04 and 0.06mm undersize internal diameter). I can see some wear on the upper bevel gear coupling but it doesn't seem particularly excessive....





Intuitavely, this approach of using an undersize sleeve feels like a bit of a "bodge", but that being apparently the factory solution, I have a few questions:

1. Anyone know where you can get these from?
2. I'm assuming the sleeve should still be able to rotate freely on the shafts. Is that correct.
3. I may need to have some made up. Anyone know what steel they are made out of?
4. Has anyone used undersized sleeves and what has been your experience with their effect?

Regards,

Kev

[LaceyDucati]

Best fix is usually to restore the flat either by hard chrome or by Nickel stelite or similar facing, then surface grind it back flat to size. I have done both successfully with no problems in use. It's best to do both shafts if they are both worn as that will give the best long term solution. I have used nickel stelite to face quite a lot, but you have to be very carefull not to get to much heat into it, by heat sinking etc. Hard Chroming is better but is more of a specialised (out sourced) solution, that's for me more costly and time consuming. I've run both these solutions in road and race bikes over many years.

Your bevels actually look quite good compared to a lot, so maybe your sleeve is worn or oversize. I've never found any undersize sleeves myself but I would think their use would be limited if you did get one. However there is a lot of variation in used sleeves so worth a look first. Picture is of another dustbin recovery.

IMG_2397 (1000x750).jpg

[Ventodue]

And there was I, already to post ...

"Kev, I reckon your best bet would be to stay up late one night and give Nigel a call ...."

[machten]

Indeed, Craig!!! I remember comparing the engine noise of mine with your Scrambler on our rides in France and thinking at the time, "I'll have to look in to that at some stage". Finally got around to it!

Thanks for that Nigel. I'd become a bit concerned that the lash in the oldhams coupling would be causing some unnecessary repeated strains on the same teeth of the upper bevel gears. The shimming of the upper and lower bevels is good and they are in good condition, so all the lash is from the coupling.

Your bevels actually look quite good compared to a lot, so maybe your sleeve is worn or oversize

I'm not seeing what I would identify as any obvious excessive wear in any particular component, but I didn't really know what was "reasonable" prior to your post, so thanks for your thoughts on that. I'll see if I can measure accurately the bore of the sleeve and get a better look at the lower bevel coupling face too.

Then I'll see if I can get a few other sleeves to try and go from there as you suggest. If worst comes to worst I'll probably pursue the hard chroming option as I will have to outsource either option anyway. Hopefully, it's the sleeve!

Thanks.

Kev

[Harvey]

Kev in your first picture, you can see that the lower section is not just driving the top on one side. It is hitting one side as the lobe pushes the spring down, then as the valve starts to close, the spring rotates the cam, to hit the other side of the D section. So as you are running at low rpms the coupling clacks back and forward, hitting each side. Certainly the cause of the noise.

[graeme]

Hello Kev,

I've seen a worn Oldham coupling worn like yours that had the "non flat" area ground flat and a piece of feeler gauge surer glued in place to make up the slack.
This worked for years, but I wouldn't recomend doing it.
Bushmans fix?

graeme

[machten]

From harvey:

Kev in your first picture, you can see that the lower section is not just driving the top on one side. It is hitting one side as the lobe pushes the spring down, then as the valve starts to close, the spring rotates the cam, to hit the other side of the D section. So as you are running at low rpms the coupling clacks back and forward, hitting each side. Certainly the cause of the noise.

Yes, that's my diagnosis too. I haven't attempted to liberate the lower bevel yet to have a good look at it (I'm kind of hoping (rather forlornly, I suspect) to avoid that), but I expect to see the mirror image. I put a straight edge across the upper bevel coupling drive surface and I can detect a tiny bit of curvature on the face, but only tiny. Possibly when you multiply it x 2 taking into account both surfaces, it's enough. I'm going follow up on Nigel's suggestion of different sleeves first though, as if I turn the current sleeve the other way around, there seems to be marginally less play around the top bevel coupling (not that is is by any means "sloppy" as it was)

I've seen a worn Oldham coupling worn like yours that had the "non flat" area ground flat and a piece of feeler gauge surer glued in place to make up the slack.
This worked for years, but I wouldn't recomend doing it.

Bushmans fix?

I must confess Graeme, that such a thought had come to tempt my mind too, but the thought of potentially getting shredded metal finding it's way down the bevel tube and into the lower bevel bearing (and not knowing if it was happening) was too much to bear!

Kev

[Jordan]

Someone told me he had noise from his single's bevel shaft, that was tracked down to being caused by wear in the head. The place was the metal surrounding the top bearing housing.

Jordan

[machten]

Yes, I've seen that before in one of my twins. I've found tracing noise sources in the 450 springer to be often particlarly challenging as the barrel really seems to reverberate the noise around - much moreso than my 250.

In this particular case, I've positively isolated it to the oldhams coupling by removing the case covering the lower bevel and wiggling the upper bevel whilst securing the lower bevel. I can generate the tapping noise by hand on demand.

Kev

[ecurbruce]

Kev,
Put it together once without the shroud tube installed, it gives access to the oldhams joint so you can get your hands on it and feel what it's doing...
You may have already done that, I don't know?

Bruce.