www.boxertrix.com

Bugger ! Drained all my fluids last week. Noticed that my final drive oil ( which was replaced exactly 2 years ago) was a dark greyish colour unlike my transmission fluid which was amber. This may be normal but recently my paralever strut pivot bolt nut at the frame needed tightening.

I put the bike on paddock stand and checked to see if the bolt at paralever strut and final drive end was ok. It was. Then I checked the freeplay transversally of the wheel/ final drive assembly and found a considerable amount of movement. The swinging arm pivot points at the gear box end are ok, no side to side movement there.

Funny thing is bike got a good pasting at Hawes and then some on way back home. I did not notice anything unusual with the handling or under braking but I did notice a very mild cyclic resonance on steady throttle. I was wondering if it was surging but it was not a fuelling issue I concluded. Nothing feels wrong but maybe my rear universal joint interface with the drive shaft needs looking at.

I was hoping it was due to the fact that I have no fluid in there at the moment? But then life is never that simple.

Worried. Gonna have to have that final drive off.

Ps I did ride her 2 years ago with a rear wheel that started to loosen

Is the play at the paralever pivots on the bevel box or is it the large ("wheel bearing" ) in the bevel box behind where the wheel bolts on. Removing the large seal is well documented as a means of inspecting the bearing cage.
Removing the paralever arm from the bevel box can make it easier to locate where the play is.
My bike has had that cyclic thrumming on and off for 10 years , replacing the bevel box after failure didn't cure it so as you say it's probably in the drive shaft.. All the uj's seemed perfect to me though

No not the wheel, the movement is at the final drive /swing arm interface.

I am thinking uj pivot bearings area. Its done 27k and it is 10 years old but I am not wanting catastrophic failure especially on our Spain Adventure later this year

So if I hold wheel at top and bottom I can get movement. I will take calliper off tomoz and see if I get more movement which would indicate a problem in the area you are talking about. There does not appear to be any movement in the 9 o clock to 3 o clock axis. The handling is fine, no wobbles, no shakes, no running wide no pulling to left or right under braking. No fluid leaks.

The cyclic resonance is hardly discernible, that could be me just being paranoid about every noise this MF makes

isn't there some issue where the sliding parts of the shaft, seize? Or have I misheard? If the shaft couldn't slide wouldnt that create the type of sensation you're describing?

I seem to recall the guy I bought my cup off saying something about the shaft having to be freed on it when they were replacing some bearing or other?

When you say swingarm pivot points at gearbox end I assume you mean the main swingarm pivots? How about the two smaller pivots at the bevel box to swingarm joint? These look like highly loaded items?

Is the play detectable in a purely axial sense? If you were to push and pull the wheel purely sideways with equal force in both arms?

With the amount of movement you're describing, shouldn't you be able to see movement between the two connecting items concerned?

"Mild cyclic resonance on steady throttle" is the perfect description for what I have always had on my 2006 R1200S. I stripped and rebuilt the swing arm etc a few weeks ago as water had got in through one of the rubber boots and all bearings and drive shaft joints are in perfect condition. "Mild cyclic resonance on steady throttle" remains.

Come on guys, please put your paralever bikes on the centre stand or paddock stands and see just what free play you have, wiggle the back wheel to and fro (9 o clock to 3 o clock) and to and fro (12 o clock to 6 o clock).

There is no water or fluid leaks, drive shaft splined joints are all lubed as per spec and it ain`t main pivot points at frame end, the movement is detectable at final drive and swing arm interface.

Please check yours and tell me what you find?

Steve, if the shaft could not move with the bike stretching out (lowering) or compressing in (raising) Then I reckon you would certainly know something was wrong. Steady throttle, constant rpm, flat road brings on the noticeable cyclic thrumming. Its very predictable and even. You have got to listen for it mind.

I just wonder if it being stuck could be the cause of that rythmic thrumming? Just putting the thought out there?

If the UJ splines seized, how would the suspension go up n down? I'm not saying it won't, just that I wonder how.

Cheers

Boxerscott - I have the same thrumming, it started last month on a trip up to Scotlandshire. (R11s 31k miles)
Nothing loose, no oil drips, knocks or rattles
Will be interested to hear what you find out, good luck!

Phil

Corvus wrote:If the UJ splines seized, how would the suspension go up n down? I'm not saying it won't, just that I wonder how.

Cheers

it's a well known issue on the R11xx's

http://www.ukgser.com/forums/showthread.php?t=262956

I'd guess it stress's all the other components?

There should be no play when twisting/rocking the wheel at either 3-9 and 12-6 o clock.
If your certain its the paralever pivot bearings then you can adjust them without removing the bevel box. In fact you dont need to remove anything, but I would take the rear wheel off.
On the wheel side is the adjustable bearing. (The other side is fixed). You need to slacken and back off the large nut then adjust the central allen screw to remove the play. The manual says to torque this to 7Nm (please check, I think this is correct). In reality you need it tightned until there is no play.
If the big nut has never been removed from the factory heat it with a hot air gun to 'sizzle temperature', i.e the point that when you spit on it., it sizzles. This will melt the threadlock.
I removed all traces of old threadlock (nail varnish remover works well) and didnt put any new stuff back on. The nut has to be torque to 130Nm (check manual again), so its very tight. Put a blob of paint on it after to check its not moving.
Finally, you need to hold the central allen screw whilst torquing up the big nut. You can buy a cut out socket to do this from Laser Tools or make your own.

I adjusted my GS1150 at around 28k miles. Its done nearly 7k miles now and theres no play. If play does come back after adjusting, then its new bearing time Im afraid.

I dont recall reading anywhere of a case where they have failed big time and stopped the bike running.

Hope this helps.

slparry wrote:

Corvus wrote:If the UJ splines seized, how would the suspension go up n down? I'm not saying it won't, just that I wonder how.

Cheers

it's a well known issue on the R11xx's

http://www.ukgser.com/forums/showthread.php?t=262956

I'd guess it stress's all the other components?

Thanks very much for the reply and link.

The first post on the thread you linked answers the question. Very informative.

Yes, I would imagine quite a bit of extra strain would be placed on the various shafts and bearings concerned. It may be that the centres of the UJ at the gearbox end are well placed with respect to the swingarm main bearings. To my way of thinking this would minimise the amount the two halves of the UJ shaft move relative to each other.

Is it possible that when people comment on this cyclic "thrumming" it may be out of phase UJ's? More likely it is just the nature of the beast?

Cheers.

Corvus wrote:
Is it possible that when people comment on this cyclic "thrumming" it may be out of phase UJ's? More likely it is just the nature of the beast?

Cheers.

Could well be an explanation - the only time I ever had a completely 'thrum-free' transmission on any of the several 1100S's I owned it was on my first one which had standard suspension and torque arm (this was in 2000, on a 99 MY bike). Adding a passenger smoothed things out further as the 2 UJ's angles got straighter.

Fitting the GS arm, the thrumming started but it was never particularly bad - still noticeable though. Certainly lends strength to the argument that input and output angles on the 2 UJ's should be equal though.

Gromit wrote:.......Certainly lends strength to the argument that input and output angles on the 2 UJ's should be equal though.

Absolutely. If my understanding of the theory is anything like correct, then the joints should be in phase and the input and output angles equal ie: parallel. The actual angle should be as small as possible and there will be a maximum angle beyond which you shouldn't stray.

This is something approaching if not totally impossible, I guess, on something dynamic, and with other compromises, such is the motorcycle swingarm. Although the paralever must come pretty close.

The original boxers with swingarm suspension seem to break all the UJ design rules, yet they still work pretty good. Somehow!

Cheers.