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Death wobble question

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  #31  
Old 12-06-2010, 11:55 AM
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How about tire condition, wheel balance, wheel slightly bent? I've never experienced the death wobble as it's known, other than my experience with that deer, but I suspect that from tension in the arms and upper body with a death grip on the bars, anticipating impact.. Only other wobble I experienced, was caused from a cupped front tire and letting my hands off the bars at 40-45 mph and up. New front tire cured that.
 
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Old 12-06-2010, 12:13 PM
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Originally Posted by bigdaddy33
Also goes on to say that "stabilizer systems do cause a little more tactile buzzing on the floorboards and handlebars, and will reduce the service life of the front rubber mount". He states that these negatives though are trivial compared to the positives.

The buzzing or increased vibes, has been pretty well documented on this site from a number of riders as well.

I don't have a TT on my bike as I haven't felt the need for one (and was advised of the increased vibes), but if you're having speed wobble problems it may be the solution to the problem.
I have TT kits on both my big twins and have deliberately disconnected the rear stabilizer just to see what the difference is. With my Evo I can tell when it is connected by a change in feel from the bike, but I wouldn't call it vibes. I can't tell any difference with my Dyna.

My Buell has three stock stabilizers and that has always been just great. IMHO that is not an issue!
 
  #33  
Old 12-06-2010, 12:54 PM
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FWIW, I have no more "buzz" than I did before the TT installation.

My completely unproven theory about this is that either

a) there is an engine mount problem that is exaggerated by the TT
b) The heim joints on the locating arms are not adjusted properly causing
either too much "push" or "pull".

I've done a lot of work with heim joints in race cars and a half turn might be
all that's wrong.

Just a thought...
 
  #34  
Old 12-10-2010, 08:35 AM
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Post Here's another aspect

Sputhe Positrac Dyna Chassis Stabilizer, is said to solve the Dyna wobble. They don't sell them for the FL's , funny I thought they had it more than the Dynas.
Anyhow their site is here:
http://www.sputhe.com/index.html
Their email is broken (when I tried it), but they have a phone number. I don't think this product would work with the HD oil Cooler bracket.

I read an interesting write up on it last night but lost the link on it. The Sputhe website is dismal on information. But in any case the write up said that Sputhe got the idea from Buell originally and that the whole stabilizing problem with Dynas is the lateral movement of rubber motor mounts. Of course since the rear swing arm assembly is bolted to the Trans, it directly relays this flexure to the rear wheel and the overall bike alignment.
Just thought I would throw this in.
 

Last edited by R_W_B; 12-11-2010 at 08:02 AM.
  #35  
Old 12-10-2010, 09:52 AM
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Post question for you.

Originally Posted by Mike Horrell
... ........... ...........
a) there is an engine mount problem that is exaggerated by the TT .... ...
I was curious if you had done the front mount washer shim on your setup to unload the rubber stretch? I've heard this helps vibration, but just wondering how it might play in alignment flexure also.
 
  #36  
Old 12-10-2010, 10:13 AM
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Originally Posted by R_W_B
I was curious if you had done the front mount washer shim on your setup to unload the rubber stretch? I've heard this helps vibration, but just wondering how it might play in alignment flexure also.
No, I just did a straight bolt-up. I just wonder if some of the buzz and vibration complaints
are because there's too much "pre-load" on the locating arm(s). I have zero evidence
to back that up beyond the fact that I did a lot of sports car racing and am very aware
of how tension on heim-jointed locating arms can really affect things.
 
  #37  
Old 12-10-2010, 11:29 AM
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Originally Posted by R_W_B
I read an interesting write up on it last night but lost the link on it. The Sputhe website is dismal on information. But in any case the write up said that Sputhe got the idea from Buell originally and that the whole stabilizing problem with Dynas is the lateral movement of rubber motor mounts. Of course since the rear swing arm assembly is bolted to the Trans, it directly relays this flexure to the rear wheel and the overall bike alignment.
Just thought I would throw this in.
I'm disappointed to hear that about the Sputhe website. I recall reading wonderful tales of their over-size Sportster racers, 'aluminium steam-roller', even watched a pair of them at the Isle of Man TT Races many years ago.

The True-Track website is spot-on and includes a link to Buell's patent, where you can read all about the THREE stabilizer system he devised. Dynas have just one. No rubber-mount Harley is complete without all three!
 
  #38  
Old 12-10-2010, 12:45 PM
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Originally Posted by Mike Horrell
No, I just did a straight bolt-up. I just wonder if some of the buzz and vibration complaints are because there's too much "pre-load" on the locating arm(s). I have zero evidence .............. .........
Yea after I read the Sputhe report I was wondering if letting the preload loose would help. Not sure why Harley ever preloaded the setup to start with. I guess it sounds good on paper for vibration. Hang everything on rubber and it will dampen it. But it seems to do just the opposite from what I've heard. And the flexure issue sounds even more ominous.
I have in fact just done the washer shim when I put my oil cooler on. But I am still working on other items on my bike and have not test road it yet. But in my case I also replaced the front mount so if it does ride better, I surmise this front mount will last longer not being stretched.
 
  #39  
Old 12-10-2010, 01:36 PM
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Post Another interesting report

Found this report that attempts to further hone in on the motor mount flexure being the primary culprit.

Harley Davidson has been manufacturing motorcycles for over 100 years. Their bikes, known for their distinctive design, are very popular with the general public – and police forces – for which the company supplies bikes. However, many riders are experiencing a very dangerous problem as of late. It’s referred to as “the Harley wobble” and has been linked to serious injuries and deaths.

What is the Harley wobble?

To answer that question, we asked Kevin Liebeck, a California attorney whose practice represents plaintiffs in personal injury, medical malpractice and products liability actions. He explained:

The issue is basically a problem in the manner in which the engine is mounted into the frame and is constrained within the frame from motion. The reason this presents a problem is because the swing arm, the rear suspension member of the motorcycle which is the pivot point, is mounted to the aft end of the transmission on these Harley-Davidson motorcycles. If the engine is not constrained in all three axles, you can develop an elastic relationship between the swing arm and the frame of the motorcycle. While the system isn’t novel, there are a lot of motorcycles that do have some sort of a system to isolate engine vibrations from the rest of the motorcycle. Harley's method is patented.

Liebeck says that the problem has become known as the Harley wobble, the rear steer and even the death wobble – and for good reason as the condition can kill you.

If you have been in a motorcycle accident, click here for a top rated law firm to evaluate your legal rights.

Why hasn’t Harley Davidson instituted a recall?

That’s what many riders and consumer groups want to know. Liebeck explained, “I believe that they haven’t because it would involve recalling tens of thousands of motorcycles. Furthermore, they deny that this situation exists at all. If they admitted that the problem exists, I would expect that they’re going to have a whole lot of people suing them for injuries that they have sustained as a result of these accidents.”

However, Liebeck says that Harley has an advantage in these types of cases. He told us:

Harley is playing with a full deck of cards in these situations, if you will, because I think that many jurors are of the mentality that motorcycles are dangerous and that riders fall off of them all the time for no reason. It's easy to suggest that the rider was going too fast and simply lost control because they were riding beyond their abilities.

This is a situation that is much more likely to occur in a turn or at high speeds. People report it as occurring around 90, 95, or even 100 miles an hour. Well, where can you legally ride a motorcycle in the United States at 95 or 100 miles an hour? Nowhere; so these people are going to be speeding. They're going to be on a canyon road that is real curvy or simply going too fast. I think that makes for a really fantastic defense for Harley in a lot of respects because they can point to what the conduct was and say look, this isn't a problem with our motorcycle; this guy just overcooked it into a corner and ran out of talent. So, don’t blame us.

While that can be a defense for the company, it doesn’t mean that riders can’t be compensated for their injuries. An experienced attorney will be able to determine whether a case exists. If you’ve been injured on a Harley Davidson motorcycle, contact an motorcycle accident attorney whose practice focuses in this area of the law. Consultations are free, without obligation and are strictly confidential.
 
  #40  
Old 12-10-2010, 02:26 PM
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Post Here is a question of mine

At this point, I am noticing a certain data being reported on this as "Pre 2009 issues" in harleys.
I would love to know exactly what HD did to make it not a "post 2009 issue" ?
 
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