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Harley Speed Wobble, Tank Slap, also known as the Death Wobble

Morning Hoople, your post seems to make the problem/solution to tank slapping/high speed wobble that I have been sold on is somewhat correct. Racers and safety course instructors say the same thing when this subject is discussed. The initial wobble may start at the front or rear of the bike, and may be caused by many issues either with the set of the bike or the surface it is currently on, or rider induced. The main solution when the problem occurs seems to be to give the bike back it's ability to go in a stright line. The hardest part of this is when the wobble starts we all want to tighten our grip and "make" the bike stop wobbling. You have to trust physics and use the lightest grip on the bars you can while increasing throttle, in effect taking the rider out of the equation.
 
occured a couple of years ago on my 07 streetglide at around 110mph in a fairly straight line... scary as all (EDIT) but researched it and applied a stabilizer under the engine (cost about $80us) the bike runs true and no wobbles shudders till around 140mph (and then its fairly minor).... In 08 the engines was stabilized by Harley and then they improved the frames stability 2010 onwards there are no problems at all

Please read this...

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I noticed one day my 07 Heritage wasn't handling as good as it once did, the problem got worse as time progressed....so I got to looking what might be causing this....what I found was loose spokes...the day I took it into the shop I could not get over 55mph or it would start to wobble so bad I could not handle it.
 
I have a question, has anyone had (or heard of ) the front end Wobble without a windshield or Fairing ?
 
RWB, I think you're on to something when it comes to what I call the 'real' wobble. As I mentioned in my earlier post, I get a 'light' feeling sometimes when my windshield is on. Anyone else?
 
karlsbike said:
RWB, I think you're on to something when it comes to what I call the 'real' wobble. As I mentioned in my earlier post, I get a 'light' feeling sometimes when my windshield is on. Anyone else?
Click to expand...

Been almost a day now and no confirmations:

Wow did this thread just go dead, or is there no recorded or remembered occurance of wobble without a windshield or fairing ? For something as fatal as the death wobble, I definitely would want to hone in on this.

Of course not (never) discounting regular and proper maintenance and pre-ride inspections even so since I'm sure they all play together.

But I would like to know the facts on this.
Knock, Knock anybody out there got anything ?
 
Sorry RWB can't answer that.
But a huge thanks to you all that have replied. Chris's brother is compiling all the information from here and a few other sites and is going to write a report and publish on bike forums and hopes it can save someone one day.

Respects to you all.

BaZa from across the pond. U.K.
 
Hoople said:
The more I research the theory about tank slapping and how it happens, the more complex the answers become. There are many theories on how & why it happens and what can be done to reduce the chances of it happening. But what is very interesting is that in several examples during conducted studies of tank slapping, it has been found that if the rider is thrown from the bike, the bike will upright and become completely stable once again. Think about that for a second. If the riders weight was theoretically Zero, tank slapping could not occur. That almost concludes that the fundamental geometry of the bike is correct since once the bike rids itself of the real problem (the rider),, all is well.

It seems to be that once the riders weight goes out of phase with the bikes weight (the bike swings left while riders weight is swinging to the right) it is all over and there is nothing that will stop it. It now becomes a self feeding, positive feedback oscillation, where the riders swinging weight becomes the positive reinforcement.

If the riders weight is high in relationship to the bike frames center of gravity your chances for uncontrollable tank slapping is far greater than if the riders weight was close to the ground.

I truly feel & believe that what we HD riders experience (rear steering wobble) is not the same as true "Tank Slapping" (a violent positive feedback oscillation) that a metric racing bike will experience.
Click to expand...

I'd like to know how you are getting 140 mph on your 2007 streetglide.
 
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