Dyna death wobble?
Stellar HDF Member
Joined: Aug 2009
Posts: 3,212
Likes: 212
No, it's not done to keep them from failing prematurely. Have you ever replaced wheel bearings on a trailer? They are set up with clearance/lash, and are subjected to much harsher use than our headstock bearings. Nor are bearings in general set up with preload very often. Zero or negative clearance interferes with maintaining a lubricant film.
I emphasize stiffness because that is the primary reason headstock bearings are preloaded. A trailer bearing is not the same operational environment as a neck bearing in the least.
However, the stiffness of the neck of a motorcycle and accompanying front end is high importance. You can't have any play there for the chassis and suspension to work as intended. They are designed to be a stiff unit so that the frame and suspension take up all the forces in a predictable, smooth way. That is why the neck bearings are set with a small preload.
SKF has a good article showing the importance of preload in bearing systems as it regards deflection of the component. http://www.skf.com/caribbean/product...ems/index.html NSK also has a great white paper on the benefits and uses of preloaded bearing setups: http://www.nskamericas.com/cps/rde/x...en/Preload.pdf
Last edited by Scuba10jdl; Apr 15, 2016 at 02:27 PM.
6th Gear
Joined: Sep 2018
Posts: 13
Likes: 1
From: Corona ca.
I have motor mount stabilizers front and rear.
Done the steering head bearings.
Adjusted upper motor mount to make the rear wheel plumb .
And have new tires.
Tightened spokes and balanced wheels.
Wheel bearings seem ok when on a center lift...
And the wobble is worse than when I started.
Bout to sell it.
Done the steering head bearings.
Adjusted upper motor mount to make the rear wheel plumb .
And have new tires.
Tightened spokes and balanced wheels.
Wheel bearings seem ok when on a center lift...
And the wobble is worse than when I started.
Bout to sell it.
Last edited by MikeMikeMotorbike; Jun 3, 2019 at 02:33 AM.
Do you have saddlebags? Are they possibly sitting too far back, or unsupported possibly?
I'm seeing lots of death wobbles reported because of that...
Sort of like having your passenger sitting too far back, they will split your center of gravity an cause all these symptoms. Not to mention the harmonic flapping unseen to the naked eye that aggravates the situation further.
I'm seeing lots of death wobbles reported because of that...
Sort of like having your passenger sitting too far back, they will split your center of gravity an cause all these symptoms. Not to mention the harmonic flapping unseen to the naked eye that aggravates the situation further.
6th Gear
Joined: Sep 2018
Posts: 13
Likes: 1
From: Corona ca.
I do. I'll have to take them off and see.
I kinda think it's the new tires. Seemed to get worse when I put them on.
Oh also have progressive 490 shocks and mono tube fork kit.
I kinda think it's the new tires. Seemed to get worse when I put them on.
Oh also have progressive 490 shocks and mono tube fork kit.
Last edited by MikeMikeMotorbike; Jun 3, 2019 at 03:06 AM.
Seasoned HDF Member
Joined: Aug 2011
Posts: 11,814
Likes: 5,120
From: SW Ohio
No, it's not done to keep them from failing prematurely. Have you ever replaced wheel bearings on a trailer? They are set up with clearance/lash, and are subjected to much harsher use than our headstock bearings. Nor are bearings in general set up with preload very often. Zero or negative clearance interferes with maintaining a lubricant film.
Last edited by Campy Roadie; Jun 3, 2019 at 04:18 AM.
Road Captain
Joined: Jun 2007
Posts: 632
Likes: 86
I have never had this sort of issue with my '12 FXDC. Several years ago I changed out my cheapo stock H-D wheel bearings for brand name (Fafnir/Timken) pieces due to a slight wheel bobble at some speeds. After that, everything is rock-solid. I do have a Sputhe stabilizer, front and rear, Ohlins +2inch shocks and Racetech emulators.
I can lay mine down low in tight curves. Had to install V&H Upsweep for exhaust clearance. No wobbling.
I can lay mine down low in tight curves. Had to install V&H Upsweep for exhaust clearance. No wobbling.
Last edited by leafman60; Jun 3, 2019 at 07:25 AM.
Road Warrior
Joined: Jun 2017
Posts: 1,705
Likes: 1,017
From: Lawrenceville Ga.
No, it's not done to keep them from failing prematurely. Have you ever replaced wheel bearings on a trailer? They are set up with clearance/lash, and are subjected to much harsher use than our headstock bearings. Nor are bearings in general set up with preload very often. Zero or negative clearance interferes with maintaining a lubricant film.
Neck bearings are set up more like pinion bearings , light preload.
Neck bearings set up with preload and are not going to fail because of preload, more likely to be damaged from being too loose.
Road Master
Joined: Sep 2015
Posts: 1,020
Likes: 130
From: Vancouver
Without taking this thread sideways, I just want to note I just experienced the death wobble. At 70 mph on sweeping curves using a HD windshield caused this. The wind going around the windshield as I aggressively lean the bike wobbles my front end like mad. I wont be using a windshield ever again besides straight line hwy rides.
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