Slack in the differential?

  • Thread starter Thread starter extenso
  • Start date Start date

extenso

Guest
When I testet a 1200 GS, i couldn't help to notice a "clunky" sound when disengaging the clutch taking off from standstill. Is this due to slack in diff or gearbox in some way? Please explain this sound for me, I'm on the virge to buy a 1200 GS, and need some psychological support! :-)

Pardon my english, I'm norwegian...
 
Hi! extenso

don't worry about that, I'm sure you mean the muffled 'ka-lunk' as the clutch engages / disengages... every one I've ever seen / ridden does that... if I'm not mistaken it's due to the design of the clutch being partially dry or something suchlike... I only noticed it after I'd bought one... scared the hell out of me until I found out it's normal...

BTW Norway has some fantastic GS territory to ride on, I have to visit Oslo every year for business and I'm always impressed by how much fantastic riding terrain there seems to be, from Oslo out towards Skarnes and the surrounding area look fantastic... pity I never have my bike on these trips...
 
Yes I concur with Plasmatron, the clunk & crunch is normal for BMW, it’s almost a trademark. I understand the sounds are a combination of “stepped dogs to gears”, ”zero dragging clutch”, ”thin walled cast gearbox” & “shaft drive”! . All of which, can and will be improved in coming years. But for now ….it is what it is. :ukgser
 
Yes, they all do that sir. I've been riding a works 1150 RT for weeks, with exactly the same clunks etc.
To be honest if your light of clutch,brakes and throttle, you won't hear anything. It's only when your ham fisted it shows itself.
 
Hi Extenso, like the good folks have already said, they all do it.

For someone used to wet-clutch Japanese tackle it seems worrying but is nothing to be afraid of. A typical dry-clutch, inline geared, shaft driven trait.

Also be aware of the difficulty in engaging first gear from standstill, there is a posting on here about it, it is a knack you need to learn and something that worries the new GS rider till he learns they all do it.

Simple to do: Clutch lever in, HOLD pedal down in 1st position, EASE OUT (not release) clutch lever till she slips into gear with a 'ker-lunk', lift foot off pedal........signal, lifesaver, ride off.

I think they call it 'character', something a lot of Japanese stuff seems to have lost in their quest for perfection.
 
Thank you, all three of you, for your answers. I wasn't to worried, and now I'm not worried at all anymore! When you invest as much as € 25.000 (price in Norway, ughhh!), you have to bee sure about things like this.
To plasmatron: Yes, we do have some fantastic GS territory to ride in. It's almost like the GS was made for the place I live in, in the middle of Norway. My favourite trip is from west coast Norway, to eastcoast Sweden (Molde (N) to Sundsvall (S)). I also have great days on gravelroads. Looking forward to try out the GS on these. But GB also have a lot of candy for GS-riders, I presume?! :-)
 
I know that supposedly they all do it, but on my bike there does seem to be an awful lot of drivetrain slack, to the extent that when trying to trickle along at slow speed on an almost closed throttle, the bike lurches forward and backward, making some very nasty clunking noises. This is even more apparent when riding on an unsurfaced road, as the bike goes over dips and crests.

I am guessing this problem is due to a combination of poor fixed throttle response by the fuel injection, but the slack in the drivetrain can only make it worse. Has anyone else found the problem to be this bad?

The bike's due a service this week so I'm going to try and ride the dealer's demonstrator and see if that shows the same problem.
 
I've ridden 4 12GS's so far... one early production Januray '04, two Sept. '04 and one November '04... all had roughly the same amount of drive train slack, but interestingly the more recent build model seemed to have the same stuttering on/off fueling at low throttle openings, but with much more 'smoothed edges' to describe it badly... that is most likely down to the revised firmware updates that some BMW dealers (like mine) claim do not exist...

bar something being properly broken / way off operating tolerances I don't see how there could be too much variation between bikes in terms of how much drive train slack there is... which is worrying if some people seem to have more drivetrain slack than others... :confused:

i'll be interested to hear your verdict on the status of the dealer's demo GS's drivetrain slack Mouse...
 
When measuring the drive train slack by putting the bike in first gear onto the centre stand and rotating the rear wheel, I found that the slack on my 1200 was just the same as the slack on my Pan, a bike that is a byword for reliability. The difference seems to be that the Pan had three different shock absorbers in the drive train, and at the end of the slack in either direction it hit rubber, not steel as the 1200 seems to. The whole thing is exacerbated by fuel injection which is very much on/off and a big lumpy high compression engine.

Got to the point where I dont notice it any longer, but my wife complains that the ride is much more jerky than on previous bikes. Mind you, she blames the rider's lack of skill.
 
Doesn't wifes always blame the rider? :-)
PS. My won't even ride......
PPS. On the bike, that is!
 
I sometimes pull in the clutch right as I am about to throttle off and just before the FI cuts out. Eliminates the clunck, but requires more work. I am do for 12K service in two weeks and am supposed to get the new fuel mapping/sowftware update.

Cheers
 
Agricultaral gear changes on the 1200 GS

Having tried to smooth out the bang's and crunches within the drive train, I was pleased to hear that the noises that I have on my 1200 GS are normal, So with the lack of "Cush Drive" "Multipull plate wet clutch" "Chain" "single hellycut gears" "11.1 compression" it is becoming no surprise, However with the ongoing effort to smoothout the gear changes I have noticed how quick the engine is at shutting down its revs due to the absence of any substantial flywheel and the 11.1 compresstion. So I have found it very effective when changing up, to change gear as quickly as you can by barely closing the throttle and holding your clutch hand in very close to the pivot this has the effect of the clutch not totally dissengaging and acting like a syncroring in the gearbox this upward change is un natual at first but with a bit of practise it works very well (So my passenger tells me) as for changing down we need a neutral between gears so as we can double "D" clutch :driving
 
Drivetrain

Mouse said:
I know that supposedly they all do it, but on my bike there does seem to be an awful lot of drivetrain slack, to the extent that when trying to trickle along at slow speed on an almost closed throttle, the bike lurches forward and backward, making some very nasty clunking noises. This is even more apparent when riding on an unsurfaced road, as the bike goes over dips and crests.

I am guessing this problem is due to a combination of poor fixed throttle response by the fuel injection, but the slack in the drivetrain can only make it worse. Has anyone else found the problem to be this bad?

Hi Mouse

Yep.........5000 miles and mine is exactly the same especially when in slow traffic. Hoping that the 6000 service sorts it out. Let me know how your bike fares after the service........Would appreciate the feedback.


Regards
Click to expand...
 
Just to report back, bike had the service today and the various electronicy bits were updated. Result is that the bike is much smoother when the throttle is nearly closed. It's not perfect, but definitely a massive improvement :)
 
Mine clunks really badly - either at slow speed on/off throttle, or off-road. The dealer agreed, and put a new gearbox in some while ago, but it made no difference. As my final drive also was changed on another occasion, I've sort of given up now! In fact, you can tell it's not the final drive, as you can feel the drive shaft rotating through one of the rubber gaitors, even with a very small wheel movement.

I don't like it - clunking of metal against metal surely can't be good?
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
You must log in or register to reply here.


Back
Top Bottom