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johncrosby
 Senior Member
256 Posts
Sevenoaks, Kent
United Kingdom
BMW
GSA 90 Anniversary
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 Posted - 07/06/2013 : 2:23 AM
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I'm the proud owner of a new bike (90th anniversary edition BMW R1200GSA) and have noticed some oscillation of the front shocks at speed. It's a slowish slight shimmy , it doesn't seem to travel up to the bars.
My concern is suffering a tank slapper. I'm getting a bit paranoid about especially after the UK bike journalist Kevin Ashe died test riding the new liquid cooled GS earlier this year.
So my technical questions (sorry for the preamble I do get there eventually).
Will a properly set up suspension (this bike has ESA and is set up for 1 rider plus luggage preload and normal damping) always exhibit some lateral movement of the front shocks or should they be absolutely static apart from their vertical shock absorber movement?
I could just be noticing something I really shouldn't bother about but it only occurs at high speed, above 70mph. It's not progressive, just maintains this slight movement. If you look at the top of the two shocks they appear to be moving a few degrees clockwise in a circle, then back again anticlockwise and so forth.
My useless BMW dealer isn't interested, probably thinks I'm mad to worry about these things.
Could fitting a steering damper (or is it dampener?) be a solution or insurance against anything like a real tank slapper happening.
Best regards
John
Edited for terrible spelling and grammar.
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Edited by - johncrosby on 07/06/2013 9:15 AM |
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greywolf
Moderator
1484 Posts
[Mentor]
Evanston, IL
USA
Suzuki
DL650AL2
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Posted - 07/06/2013 : 8:22 AM
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| A steering damper is excellent insurance against a tank slapper. I lived through one that threw me off and I feel much better riding with a damper. It stops large, high speed displacements but not the little wiggles you report. I would check the model specific forums about that if I were you. |
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rkfire
Advanced Member
1714 Posts
Stratford, CT
USA
Suzuki
Bandit
Peer Review:
Blocked
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Posted - 07/06/2013 : 11:06 AM
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Something seems off to me. The telelever forks are designed to be supported, and fixed in position better than convenional forks. There is only the one shock and spring, so there should be no difference from one leg to the other.
Seeing any movement at all laterally or at the top at the triple tree would cause me concern. It sounds to me like things aren't tightened up properly, and to spec.
Find another dealer, that will actually take a look, and check the torque at all the front end bolts. |
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scottrnelson
Advanced Member
6918 Posts
[Mentor]
Meridian, ID
USA
Honda
XR650L, 1090 Adv R
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Posted - 07/06/2013 : 12:23 PM
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Is there any chance this is related to a front tire that is out of balance?
I just noticed that my KTM gets some unwanted vibration from a mis-balanced front wheel when above about 90 mph. 
I already know that the answer is that I shouldn't be riding that fast, but sometimes you just have to get around traffic to get to the big gaps where it's safer. 
I'm due for some new tires on that bike anyway, so it will be fixed soon, one way or the other. |
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Discussion Topic |
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High Speed Wobble