Vibration, just wondering.....

milleplod · Apr 29, 2017

.....if it could be FD related. I serviced my 1200ST 6 weeks or so ago, including dropping the FD and putting fresh oil in. I've noticed a vibration that I've never noticed before (had the ST 6 years now), and its enough to deaden my right hand, and give me tingly feet, over a 120-miles or so cross-country ride - the only time it used to bother me prior to this year was on longer m'way runs.

Is the shaft balanced at all ....as in, should I have put it back together exactly the same as it came apart, or doesn't it matter if its been rotated before sliding it together? On previous services, and I've done the FD every year, the splines have gone back together easily....this time I had a right old job. :confused:

I can't think of anything else that could be causing it....TBs balanced, tappets done, PR3s just fitted, Jim Hill gave it a quick once-over and said all was good. P'raps its just me with another year under my belt and I'm less resilient than I was... :nenau

Feel free btw to launch scathing and vitriolic criticism!

Pete

Bendy toy · Apr 29, 2017

On my bike engine vibes do the handlebars. My transmission has a coarse vibration but which I notice only through the footrests more than handlebars. It can be at worse at speed just after shutting throttle.

My driveshaft had a new rear UJ fitted by MikeyBoy because the old one was notchy. Front UJ was OK.

I'm yet to open it up. So -
(1) the back UJ is failing again
(2) the front UJ is failing
(3) the FD splines are fecked.
(4) it's an entirely different problem.

Check the wheel lateral play at rim. More than 3mm is a worn but not yet failed wheel bearing.
Take the shaft out and check the UJs are both smooth.
If they are fine simply disturbing it again might just sort it out.

Don't bother running it in gear on centre stand. The clatter will scare you to death & back. But saying that it might just shake things up and change any symptoms caused by worn parts.

My gearbox is noisy in neutral so this year I'm planning a rebuild or more likely low miles used replacement. Drive shaft and clutch friction plate will also be renewed.

milleplod · Apr 29, 2017

Thanks for the reply.

Yep, I did wonder about a quick re-dismantling at the back just to see if it was improved after reassembly. I took it for its MoT yesterday, I could feel the vibes even at low speeds riding through our estate - its definitely an 'open throttle' thing, on a closed throttle it disappears. There's no play at all at the rear rim.

I'll whip it apart on Monday then report back after its back together. Off to Spain at the end of May, so it'd be nice to get it sorted!

Cheers, Pete

Mac One · Apr 29, 2017

I would think the shafts would be balanced when they are manufactured, I don't see how they could do it on each individual motorcycle and although there probably is a sweet spot vibration wise for mating it to the FD, it would be a lot of trial and error. As for your difficulty in mating the shaft to the FD, that's normal, for me anyway, sometimes a piece of cake other times a pure :forry

.

(RIP) trickytree · Apr 29, 2017

Driveshafts are phased and should go back on the same way.....but I think later bikes had a odd spline so they could only go back one way? Try a search in the oilhead section, Steptoe posted about it not that long ago.

Edit....Here you go....

milleplod · Apr 29, 2017

Mac One said:
I would think the shafts would be balanced when they are manufactured, I don't see how they could do it on each individual motorcycle and although there probably is a sweet spot vibration wise for mating it to the FD, it would be a lot of trial and error. As for your difficulty in mating the shaft to the FD, that's normal, for me anyway, sometimes a piece of cake other times a pure .

Having had 5 x piece of cake, this last time had me ****ing and ****ing for about 20 minutes!

Then it just popped in. Bastard thing.

Pete

milleplod · Apr 29, 2017

trickytree said:
Driveshafts are phased and should go back on the same way.....but I think later bikes had a odd spline so they could only go back one way? Try a search in the oilhead section, Steptoe posted about it not that long ago.

Edit....Here you go....

Now that's interesting! It seems a bit more than coincidence that when I did the FD the last 5 times, I simply dropped the unit and changed the oil, then it slid back together nice and easy....but this time I had to do a lot of rotating to get it to go back. Hmmmm.

Pete

Bendy toy · Apr 29, 2017

Mine went back easily when I refitted the overhauled shaft. I use two zip cable ties. One is zipped around the shaft spines end trapping the 2nd tie's buckle. It's then easy to align the male & female parts.
Assuming it's possible I will try to re fit mine turned 180 degrees.

milleplod · Apr 29, 2017

Well, I couldn't wait till Monday, the suspense was killing me.....would it/wouldn't it sort it?! :nenau

It only took 15 mins to do it.....I rotated the shaft just by 2 or 3 splines (very scientific method), it went back together in an instant this time. Just had a 10-min ride out......bugger me (don't, but you get my drift), I reckon its done it....no buzz as I rode through the estate, got it up to 70/80mph on a local back road and all I could feel was the 'normal' vibes through the bars that I always used to get, nothing at all through the pegs.

Thanks for the input chaps! :thumb2

Pete

Bendy toy · Apr 29, 2017

Great news. I have a week of motorways coming up so will have a fettle tomorrow.

Alan R · Apr 29, 2017

Am I missing something here? The video refers to the relationship - the phasing - between the two uv joints on the shaft which is fixed unless a uv joint is remove from the shaft. It doesn't mean when the final drive unit is pivoted down to grease the splines and then offered back up and snicked back into the female splined socket on the uv joint. That's the way I see the video anyway. I've greased the splines on my bike and fiddled about lining up the spline and socket: very unlikely that it slid back onto the same splines that were previously engaged.
Alan R

milleplod · Apr 29, 2017

Regarding my ST, on the last 5 FD services, I've dropped the drive down to drain the oil, then its (literally) gone straight back up and re-engaged with no need to rotate the unit. This time, I had to do a lot of rotating, and cursing, to get it to re-engage....I assume I'd inadvertently moved the disc round at some point, suffice to say it was a real pain! Anyway, my new vibes were certainly real....and they're now gone after a quick 'adjustment'. So....I assume I've put it back to how it more-or-less was, and its now sorted! :nenau

I get what you mean regarding the video. But, if BMW started to produce bikes with a 'keyed' spline setup, they must have done it for a reason....ie it made a difference not reassembling the shaft how it came out of the factory. Perhaps. :confused:

Pete

Alan R · Apr 29, 2017

I made a point of looking at the splines for wear when I greased them- I didn't notice any keyed area that would prevent engagement in any position and your experience of 'adjustment' seems to bear that out. Also, the BMW repair manual makes no mention of the splines always having to be engaged in just one position.
Alan R

milleplod · Apr 29, 2017

I was referring to trickytree's mention of later bikes having an 'odd' spline, meaning the shaft could only go back one way. Mine certainly hasn't, and I've no idea if others have. Yep, I checked my CD-ROM, no mention of a particular way of reassembly. Doesn't really matter - my 'fix' might just be my imagination, but I don't care, the vibes have gone!

Alan R · Apr 29, 2017

Mine is a 2011 twincam. How much later can the legendary 'odd spline' bikes be? I think it may be myth or a different model/manufacturer altogether. Glad yours is sorted.
Alan R

Bendy toy · Apr 30, 2017

My bike has had this vibration for a very long time. I'll try doing the fix & see what happens.

The UJ phasing is built into the shaft. No adjustment possible even if you fit new hardy spicers.

Mac One · Apr 30, 2017

Bendy toy said:
My bike has had this vibration for a very long time. I'll try doing the fix & see what happens.

The UJ phasing is built into the shaft. No adjustment possible even if you fit new hardy spicers.

Thanks for clearing that up, I've never marked the shaft / FD when separating them, I'm always just thankful when they go back together any way.
I hope the fix works for you and you finally get rid of the vibes, keep us posted.

(RIP) trickytree · Apr 30, 2017

Alan R said:
Am I missing something here? The video refers to the relationship - the phasing - between the two uv joints on the shaft which is fixed unless a uv joint is remove from the shaft. It doesn't mean when the final drive unit is pivoted down to grease the splines and then offered back up and snicked back into the female splined socket on the uv joint. That's the way I see the video anyway. I've greased the splines on my bike and fiddled about lining up the spline and socket: very unlikely that it slid back onto the same splines that were previously engaged.
Alan R

Guilty of misleading you then...sorry. The rear UJ on a 1150 isn't fixed to the driveshaft, when you pull the bevel drive off the UJ slides off the driveshaft with it. So when reassembling a 1150 it needs to be phased. I'll check if there is a odd spline the next time I take it to bits.

VAL. H. · May 7, 2017

This is interesting stuff. I have an 05GS with 60'000+ miles had it from new. Never had a problem personally. However my wife Jill has just said to me that she gets the same vibration issues through the bars on her 1992 R100gs. When I ride her bike I don't get any such problem. Now. Jill does have some Carpel Tunnel issues. Or it could simply be that I don't really hold the bars I ride very loose just resting my hands on the bars.

Adding to this my brother t4camper has just bought a very nice 04GS with full history. He tells my of this same problem. I haven't ridden his bike so I can't say if it's him or the bike. could be an interesting comparison. Has anyone thought of doing this? My brother is 200 miles away so not easy for me to do a comparison ride.

I'd be interested too to hear more about the final drive possibility. Whether anyone else has tried re rotating he FD and got or got rid of the vibes.

Val.

Bendy toy · May 7, 2017

It's simple enough to do.

Drop the FD back turn the wheel enough to move the input by 120 degrees and box it up. If there is any change, repeat at different positions.

BUT drive vibration is a lower frequency more coarse feeling. On mine it's felt though footrests but never a problem.

It has zero effect on the handlebars buzz, which for me is a problem.

Vibration, just wondering.....

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