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Vibration Issue

Started by 71R/T, August 02, 2021, 10:14:14 AM

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71R/T

I have searched through pages on the internet about vibration issues relevant to Dynas and I have not been able to solve my issue. 2003 FXD with big bore kit 98" that has about 5K miles on it now. Recently I started noticing increased vibrations in the handlebars, seat and foot pegs. I went ahead and replaced both motor mounts, the rear with an OEM Harley, front with a Drag Specialties as there were no OEM front mounts in stock within 500 miles of me. No shimming was necessary as there was no gap in the front. My vibration problems are just as bad as before replacing the mounts. The issue seemed to come on suddenly too. Belt tension is correct. I was in the primary last year to replace the stator so I know the primary chain tension was done correctly. Also the compensator was torqued correctly to 165 ft.lb. with red locktite. This vibration is more than normal as my hands go numb on the bars after a few miles. The only time the vibes aren't as bad is at about 70mph. I can feel a much worse shaking in the handlebars during deceleration at around 30 mph too. At idle though nothing seems bad and I do not see any excessive engine shaking either? Any ideas? Thanks

Hossamania

Check for loose exhaust mounts, or exhaust shifting and touching somewhere, loose bags if present, loose pegs, loose fasteners of any kind. Check for loose air cleaner mount, cover.
If the government gives you everything you want,
it can take away everything you have.

Armin

What happens at standstill with the gears in neutral if you rev the engine to about 3200 RPM, that would be the engine state cruising around 60 to 80 mph in 4th and 5th gear. If no abnormal vibration is noticed I would focus the examination on drive train parts including wheels. Another inspection of the proper engine mounts might be important. Another aspect is improper cylinder filling causing imbalanced engine action. Check for leaks at the intake side.

Armin.
Nothing can ruin a Man's day faster than an Almost-Takeoff!

koko3052

Quote from: Armin on August 02, 2021, 11:17:18 AM
What happens at standstill with the gears in neutral if you rev the engine to about 3200 RPM, that would be the engine state cruising around 60 to 80 mph in 4th and 5th gear. If no abnormal vibration is noticed I would focus the examination on drive train parts including wheels. Another inspection of the proper engine mounts might be important. Another aspect is improper cylinder filling causing imbalanced engine action. Check for leaks at the intake side.

Armin.

On the other hand, if it is vibrating bad while in neutral, then you had better get into the cam chest & check runout on the crank. My first lead was the "98" kit.  :smileo:

71R/T

Thanks for all of the replies. It turns out it was the new Drag Specialties front mount. I believe that the rubber is too hard in this mount. I put the old front mount back on and the vibration is much better. I believe that the rear mount was bad and I did replace it as well, after changing the front mount initially.

guido4198

Glad you appear to have found the "issue".  :up:
I'm a little confused however. You said the vibrations became a problem BEFORE you put the new Drag Specialties front mount on the bike, then after trying the Drag Specialties mount...putting the original mount back on solved your problem..??
Hmmmm.... :scratch:
There's a LOT of information and opinion out there on Front mounts and the proper way to install one. I believe the motor company has gone through 4 or more material changes over the years for my old ( 1985) FXR.
At the end of the day then...did you just toss the Drag mount, reinstall the original and feel like your problem magically went away..???
As I mentioned above...I'm riding an old, High-mile FXR and am always interested in any conversation about rubber mounts on these bikes. Mine is currently in great shape "mount and vibration wise". All of the previous suggestions are pertinent by the way...especially exhaust fasteners.  :banghead:
Best advice I ever got:
"You gotta keep everything HAPPY..."
Thanks Red.

71R/T

Quote from: guido4198 on August 03, 2021, 01:30:01 AM
Glad you appear to have found the "issue".  :up:
I'm a little confused however. You said the vibrations became a problem BEFORE you put the new Drag Specialties front mount on the bike, then after trying the Drag Specialties mount...putting the original mount back on solved your problem..??
Hmmmm.... :scratch:
There's a LOT of information and opinion out there on Front mounts and the proper way to install one. I believe the motor company has gone through 4 or more material changes over the years for my old ( 1985) FXR.
At the end of the day then...did you just toss the Drag mount, reinstall the original and feel like your problem magically went away..???
As I mentioned above...I'm riding an old, High-mile FXR and am always interested in any conversation about rubber mounts on these bikes. Mine is currently in great shape "mount and vibration wise". All of the previous suggestions are pertinent by the way...especially exhaust fasteners.  :banghead:
Best advice I ever got:
"You gotta keep everything HAPPY..."
Thanks Red.

I did notice more vibrations with the original mount, but after changing to the Drag Specialties mount they were worse. I still think that the original mount needs to be replaced but it still does not vibrate as bad as the Drag Specialties mount. I did not toss the new mount.

mkd

motor mounts are designed to reduce vibration in most cases. as ther mounts wear and become weak they tend to let the motor shake more and less vibration is transmitted to the frame.i had a front motor mount fail with 30,000 mikes on my 05 eglide and it was caught during a dealer service. they replaced the mount and the bike had increased vibration because the mount was new and more rigid and the motor mounts themselves had a design change.

71R/T

Quote from: mkd on August 03, 2021, 03:20:29 AM
motor mounts are designed to reduce vibration in most cases. as ther mounts wear and become weak they tend to let the motor shake more and less vibration is transmitted to the frame.i had a front motor mount fail with 30,000 mikes on my 05 eglide and it was caught during a dealer service. they replaced the mount and the bike had increased vibration because the mount was new and more rigid and the motor mounts themselves had a design change.

The Drag Specialties mount probably had 3 times the the vibration as the original mount and it clearly is made from a harder rubber compound. I just couldn't get used to the increased vibrations in the bars, seat and pegs.

guido4198

The last time I replaced the front motor mount on my '85 FXRS, I did a lot of research on this forum and across 'net. I found a lot of information and recommendations. I didn't need to find the cheapest/least expensive item so I decided to try something new and went with one of these:
https://www.kineticstructures.com/harley-engine-motor-mount
I've put 20,000 mi on it so far and have to say I'm perfectly satisfied. My memory is that just the new front mount provided a great improvement over the one that was on the bike at that point in time. It was somebody's black rubber product but I don't remember who I got it from. It was in very poor condition and needed to go.
In the interest of full disclosure I have to add that right around that same time frame, I replaced the factory original rear isolators as well, pulled a crappy pair of Progressive shocks, replaced them with Pro-Action shocks and replaced the old  "Velva-ride" stabilizer links that I had put on a lot of years back( and have been satisfied with) with new ones of the same manufacture.
At the end of the day....I have a 36 yr old FXRS that will run 90 mph down the interstate and be smooth enough to read the front license plate in my rear view mirror on cars coming up next to me.  :bike:
Happy Guy.

Jobie

FYI...... If changing all the rubber mounting bits and still have vibes that aren't normal, check the run out on the crank or a bolt touching the frame like a heat shield bolt.  To think.... Harley would make a bike that vibrates.  They have their nerve!