Dyna Shake on Decel
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Joined: Mar 2011
Posts: 85
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From: Midwest
Dyna Shake on Decel
So I've put about 650 miles on the FXDF I recently aquired, the bike now has 32xx miles on it. Rides great except for an annoying chatter / shake on decel. You feel it in the front. I've searched around but not found any specific answers, but possible culprits seem to be the engine mounts.
Is there anything in the front end I should check?
Or any other suggestions?
The first front brake app (usually low speed leaving driveway) seems to make it dive pretty hard, too.. is this 'cause of the 2 disc FXDF system or something to do with the forks?
Thanks for all the input!
Is there anything in the front end I should check?
Or any other suggestions?
The first front brake app (usually low speed leaving driveway) seems to make it dive pretty hard, too.. is this 'cause of the 2 disc FXDF system or something to do with the forks?
Thanks for all the input!
Road Master
Joined: Nov 2010
Posts: 1,115
Likes: 69
From: Bay Area, NorCal
Check the two bolts that secure the front lower mount to the frame; maybe they've just loosened up and need to be snugged up. Other possibility could be out-of-adjustment top stabilizer link. Whatever the cause it should be investigated soon.
As far as front-end dive on braking, changing the std fork oil to SE oil will improve handling and reduce fork compression; if you need even more control then you'll have to go with different fork springs. Hope you get it all worked out.
~
Road Warrior
Joined: May 2010
Posts: 1,382
Likes: 4
From: Kennewick, WA
Is that 3,200 or 32,000 miles that are on the bike? What year bike?
If it's just 3,200 miles, then yes just tighten things up. Check your static sag up front. If it's diving that hard, consider changing to heavier fork oil or raising it's level. Also check the preload tube length to see if it's been shortened over stock or if weaker springs were installed. If you can contact the previous owner, all the better.
If the bike has 32k miles, then the recommendations change a lot.
If it's just 3,200 miles, then yes just tighten things up. Check your static sag up front. If it's diving that hard, consider changing to heavier fork oil or raising it's level. Also check the preload tube length to see if it's been shortened over stock or if weaker springs were installed. If you can contact the previous owner, all the better.
If the bike has 32k miles, then the recommendations change a lot.
Road Warrior
Joined: Apr 2009
Posts: 1,360
Likes: 4
If you are applying brakes during the decel, there is less front end movement to absorb the engine vibration, so you will feel engine vibration more. More noticeable when coming to stop and at a standstill.
Your motor mounts may be out of adjustment (or soft) and reaching their limit on decel. There is a pretty simple realign procedure posted somewhere, something like loosening the two bolts, pull the bike upright and run the engine for something like 15-30 seconds. Stop engine and tighten the bolts (keep the bike upright until the bolts are tightened).
Many riders do not like the FatBob brake dive, which appears to be a characteristic of the stock bike. There are several solutions, the one that worked for me is the RICOR fork inserts.
Your motor mounts may be out of adjustment (or soft) and reaching their limit on decel. There is a pretty simple realign procedure posted somewhere, something like loosening the two bolts, pull the bike upright and run the engine for something like 15-30 seconds. Stop engine and tighten the bolts (keep the bike upright until the bolts are tightened).
Many riders do not like the FatBob brake dive, which appears to be a characteristic of the stock bike. There are several solutions, the one that worked for me is the RICOR fork inserts.
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Joined: Mar 2011
Posts: 85
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From: Midwest
The bike has 3200 miles on it. I'll perform the factory alignment procedure Cold Case mentioned. The front end is all stock, I know the original owner and he didn't do anything to it. Rotors are true. Should have some time later this week to tinker, I'll report my findings.
Thanks everyone!
Thanks everyone!
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Road Warrior
Joined: Nov 2006
Posts: 1,699
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From: Deltona, FL
While you're checking stuff, be sure to verify the fall away of your front end and retorque the fork stem. I'm about to do the same on my '09. Supposedly they fixed the problem of the fork stem losing torque before the '09 model year, but I'm starting to question that. I'm getting a lot more slop than I used to feel up there.
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Joined: Mar 2011
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From: Midwest
Update:
Finally had a few minutes to check things out, and did the Harley engine "realign" process - loosen front mount, run engine for 15 seconds, retorque mount... and that made a HUGE difference. Big improvement. I still get the rattle, but now only when it's a very hard decel, using brakes and downshifting, but it's not where near what it was. I'm looking into a new mount next, but this is acceptable. Happens very seldom now. Thanks for the advice!
Finally had a few minutes to check things out, and did the Harley engine "realign" process - loosen front mount, run engine for 15 seconds, retorque mount... and that made a HUGE difference. Big improvement. I still get the rattle, but now only when it's a very hard decel, using brakes and downshifting, but it's not where near what it was. I'm looking into a new mount next, but this is acceptable. Happens very seldom now. Thanks for the advice!
