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Tank slapper discussion

  #1  
Old 03-11-2010, 08:57 PM
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Default Tank slapper discussion

In case you don't know what one is
http://www.youtube.com/watch?v=LZ1srcQMa_0

So what causes them? What can you do to prevent a wobble from becoming one? And if it's too late to prevent one, what do you do (besides the obvious involuntary bowel movements)?

I know I got lucky when I had taken the bike out after fixing a carb problem. I ripped the throttle, causing the front end to pick up by suprise (it had never had power like that before). Front end started skipping across the pavement and I kept landing the front crooked each time. Near as I can figure it was that same skipping that saved me, giving me enough chances for luck to land the front back in line with the rear.
 
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Old 03-11-2010, 09:10 PM
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Never had tank slap happen to me, but my friend who rode for a long time told me that when you start to feel the wobble coming on that it's best to pull on the throttle. My guess is that the wobble gains momentum and the shakes are transmitted all the way to your rear wheel through the frame so if you try to put your bike's weight bias to the rear, you could technically cut away some of that momentum? I dunno, never really studied physics.

I say just get a steering damper and be done with it. When I first test rode my latest bike, I brought the front wheel up a couple inches by accident and the thing came down crooked as my teeth.. weaved for a sec and then everything went back to normal, which I'm guessing I can thank the damper for.
 
  #3  
Old 03-11-2010, 09:18 PM
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Yeah, I know steering dampers can be a godsend. But what do you do without one? I figure if people know the causes, they can avoid them entirely. Or react properly to prevent a wobble from getting worse. Or if the worse does happen, what to do at that point.
 
  #4  
Old 03-11-2010, 09:21 PM
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my old 88 cane like to act like it was gonna tank slap. I think alot of it had to do with the rake the forks had, that and when the front lost weight on it.

My F4 has never even gave a hint of trying to do it.
 
  #5  
Old 03-11-2010, 09:36 PM
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Might be a duh question... what do you mean by pull on the throttle?
 
  #6  
Old 03-11-2010, 09:41 PM
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Guessing he means more gas to transfer weight to the rear cause me yanking on my F3's bars will just add a back strain to the injuries from the tank slap
 
  #7  
Old 03-11-2010, 11:24 PM
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yeah, like kuro was saying, he felt like he got a few lucky chances because his front wheel was skipping. i'm assuming my friend meant that if you can manage to make your front lighten up by accelerating, you can straighten out the front wheel while it's momentarily off the ground. i remember a long while back that you could get a tank wobble when going over train tracks... maybe it has something to do with uneven road surfaces, i don't think i've ever seen a bike get the wobble at a track.
 
  #8  
Old 03-12-2010, 07:36 AM
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I had actually read somewhere (on these forums I think) that a tank slapper was the result of a loose front end (read: light) and that our steel-framed bikes -- being heavier in the front -- were less prone to them. That's why it's not as much use on our bikes for a steering dampener. If that is true, which I can't say either way, it seems like pulling the front up would only exacerbate the problem.

Need more info.
 
  #9  
Old 03-12-2010, 07:46 AM
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There was something someone brought up about tank slappers: if the bike ejects the rider or they bail before the bike goes down, the bike almost always straightens itself out and continues riderless stabilized (till it hits something)

So the rider is contributing to the slap. Motorcycles under load are self correcting. So the rider is probably over correcting for the problem
 
  #10  
Old 03-12-2010, 07:49 AM
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http://www.600rr.net/vb/showthread.php?t=17074

Here's some good info. Nothing on how to respond, but I think I'll stick with my initial opinion on it.
 

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