Death Wobble on turns (2008 FXDB)
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Joined: Apr 2010
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From: SoCal
Death Wobble on turns (2008 FXDB)
Hello all. I have a 2008 FXDB and the bike just started doing a crazy death wobble around turns at highway speeds. The wobble or flex was there before but is now much more extreme since I have installed progressive 440's in 10.5 inch. I also have progressive drop in springs up front, stock length. But the front helped and was installed a year earlier. I know of true-track and believe this is probably the answer but why? Why does a half inch lower shock cause an excessive wobble through highway speed turns? On the straight roads and bumps the suspension is seriously better but the twisties have got me in a twist now. What gives?
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Joined: Dec 2011
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From: Dandridge,TN
You might want to check the front tire for balance or being out of round. I had a softail and it begin to have wobble in turns. The front tire had about 14k miles on it and really didn't show bad signs of abnormal wear. I had the tire changed and the problem went away.
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From: SoCal
I have no preload notches. Just use your hand on the top to adjust amount of preload. I will have to stiffen them and see if that helps. I have ordered a true-track, hopefully that will alleviate my problems all together.
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From: SoCal
I am inclined to think it has something to do with the rear end and its geometry changing since this became a pronounced issue after the new shocks were installed. Irritating, I just want to ride and when I want to ride I dont want to fart around.
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Joined: Jun 2007
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From: Richmond, VA
Theres a whole laundry list of stuff to start checking. First, the simple stuff like tire pressure and wheel balance. My bike liked more pressure when I lowered it. 38-40 respectively. Then theres the steering head bearing. Have you checked the fall away? Then the front and rear axle bearings and of course the swing arm bearing. Lastly, new motor mounts are probably a very good idea. The rubber mounts do not last forever. I don't know how many miles your bike has but mine are trashed within 10K....... but, I ride two up most of the time and thats a large contributor to wasting the rear mount. As you can see just by looking, the swing arm is NOT mounted to the frame. Its mounted to the trans and motor mount which is in turn mounted to the frame. Having a worn out rear mount can only exaggerate swing arm movement. At the very least, if you do the True Track, do the rear motor mount at the same time... JMHO.
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Last edited by bikerlaw; Dec 25, 2011 at 09:09 PM.
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Road Warrior
Joined: Apr 2010
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From: Suffolk, England
Theres a whole laundry list of stuff to start checking. First, the simple stuff like tire pressure and wheel balance. My bike liked more pressure when I lowered it. 38-40 respectively. Then theres the steering head bearing. Have you checked the fall away? Then the front and rear axle bearings and of course the swing arm bearing. Lastly, new motor mounts are probably a very good idea. The rubber mounts do not last forever. I don't know how many miles your bike has but mine are trashed within 10K....... but, I ride two up most of the time and thats a large contributor to wasting the rear mount. As you can see just by looking, the swing arm is NOT mounted to the frame. Its mounted to the trans and motor mount which is in turn mounted to the frame. Having a worn out rear mount can only exaggerate swing arm movement. At the very least, if you do the True Track, do the rear motor mount at the same time... JMHO.
Bolting on a Truetrak to overcome a major problem like this doesn't seem sensible to me. They are for reducing vibration and improving the handling a bit, not for fixing a major instability issue like you have.
If you eliminate faults with the front end and still have the problem then you may have to think about backing out some of your mods. You could have a bad combination of too hard front end, too hard rear end and too low a bike now. All these can lead to wobbles, especially on bends.
Road Warrior
Joined: Dec 2006
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From: Douglasville, GA
I was looking at a 2003 Dyna service manual and there is an alignment procedure for both the chassis and the power train. Either might be contributing to the problem, as well as the other items members have brought up.