Speaking of Death Wobble

[Cruzen]

A friend of mine had a wobble problem with a used Harley his neighbor had purchased.  In doing research on the subject he found and sent me this link which I found to be interesting.

http://delcurmudgeon.wordpress.com/2011/05/19/chainsaw-opines-on-the-harley-death-wobble/

After reading this I have often wondered about the Valk swing arm bushings.  I've not seen much dicussion about them.  It would seem that Valk riders are not the only ones to overload their bikes like a pack mule.  Check out the weight limits he is discussing.  I like this guys attitude.

[da prez]

  I read his reply,and am not arguing, but what I posted was the comparison of my streetrod to the bike. I think it boils down to the tire and the inertia.  MC tires on my car are the same when the wobble hits, but I did as much of a comparison as I could to the two vehicles. The only common factor is the tire. As far as I know, road race bikes use chain drive as it pulls down on the rear suspension , while shaft drive has a tendency to lift up. Forward my post to chainsaw ( I am still learning to use this computer thing) please. I have never seen this comparison brfore.
                                   
                                                                da prez

[The Anvil]

  I read his reply,and am not arguing, but what I posted was the comparison of my streetrod to the bike. I think it boils down to the tire and the inertia.  MC tires on my car are the same when the wobble hits, but I did as much of a comparison as I could to the two vehicles. The only common factor is the tire. As far as I know, road race bikes use chain drive as it pulls down on the rear suspension , while shaft drive has a tendency to lift up. Forward my post to chainsaw ( I am still learning to use this computer thing) please. I have never seen this comparison brfore.
                                   
                                                                da prez

Sort of. The effect the chain's tension under acceleration has on the geometry has a lot to do with the swingarm pivot point in it's relation to the coutershaft and rear axle. It tends to try and shorten the distance between the two and that results in the swingarm "triangulating" which is similar to shaft jacking (the phenomenon of the rear rising with shaft drive) but because of other dynamic forces at work with chain drive bikes the triangulating effect is overcome by squat. But the triangulation can also be tuned out almost entirely with strategic placement of the swingarm pivot.

This might make it more or less clear. http://en.wikipedia.org/wiki/Shaft_effect

[Fritz The Cat]

A wobble at 80 mph. would end my riding career one way or the other. this just isn't acceptable behavior.

My ex Goldwing would wobble at around 25 mph. when the tires reached 12k or so. I understood it to be caused by the rear wheel cupping. I could speed up or slow down and the wobble would stop. i never gave it much thought because I never felt threatened by it knowing what caused it. But at 80 mph, now that's a totally different story.  Ain't gonna go there if I can help it.
 

[Cruzen]

  I read his reply,and am not arguing, but what I posted was the comparison of my streetrod to the bike. I think it boils down to the tire and the inertia.  MC tires on my car are the same when the wobble hits, but I did as much of a comparison as I could to the two vehicles. The only common factor is the tire. As far as I know, road race bikes use chain drive as it pulls down on the rear suspension , while shaft drive has a tendency to lift up. Forward my post to chainsaw ( I am still learning to use this computer thing) please. I have never seen this comparison brfore.
                                   
                                                                da prez

Sorry prez, this was not a reply to your post.  I replied to your post.  Basically I suggested that you find someone who runs a front engine rail and they will help you sort out your street rod wobble issues which can be caused by a lot of factors as I mentioned. 

This posting was a separate issue that came up a couple of months ago and your post reminded me about it.  That is why I did not hyjack your post.   

Reading this dissertation written by chainsaw got me to thinking about the wear factor on our swing arm bearings as I do not rember seeing it discussed before.