My friend bought a FLD about two weeks ago. He's ridden all his life and has had several HDs to this point. Currently has an Ultra trike to go along with the FLD he just bought, and traded in an 03' Anniversary Dyna on it.

He said the bike had a vibration in a certain RPM range. We werent sure if it was through all the gears or just in one. My son-in-law rode it and said it did have a strange vibration. He took it back to the dealership who had three techs ride it and all said there was no issue. So, I rode it today to check it out.

I've ridden most every bike HD produces right now and ride a wide tire Fatboy currently. What I found was a specific vibration that kicked in just above 3k and ended about 38-3900 RPM. The vibration was different from the smoothness the bike exhibits from off idle to 3k, and then above 4k. It was present in all gears, felt throughout the frame but most predominent in the handlebars. The mirrors were smooth and usable until the vibration started, and then the whole handlebar setup and frame has a distinct "buzz" to it. It is a higher frequency vibration than the rest of the frame and you can see and feel it.

The motor was smooth the whole time but I don't see what else can cause it. Again, it happens in all gears, at any speed, and the only constant is the RPM range it occurs within. The bike feels totally normal, outside of the buzz and I can't say this isn't just what this bike does... I've just never felt one do it like that and neither has anyone else.

Anyone know anything about this?

 

Did he check the motor mounts? I am not real familiar with the FLD but it is a Dyna so I am sure it uses the same engine mounts as all other Dynas. On my '09 Dyna that I used to have and a lot of other people might back this up but then again might not. The front lower mount was put in a bind when the bolts there tighten up causing the mount to not be able to provide ample vibration absorbtion. What I did and others was to loosen the two bolts that go in from the front of the frame into the mount and see if a gap developed. If the mount pulled away from the frame when the bolts were loosened then you would remove the two bolts completely and use appropriate shims such as a couple of flat washers or whatever it took to shim up the gap. Then reinstall the bolts and tighten them down. The majority of the time that got rid of a lot of vibration that was being felt in the bars. If you do this make sure you first have a floor jack under the front of the engine to support it before you loosen the bolts.

 

Plus 1 on the motor mount and the shims. Try the shims first. My motor mount was shot at about 8k miles. I replaced the front mount and added the shims and it was an amazing difference.

https://www.hdforums.com/forum/dyna-...today-wow.html

 

a lot of us are having the same issue, the same with some of the 12 WG owners from what i have read on the web, one site said that HD was aware of the problem and working on a fix. i have also read that it has something to do with the exhaust
but who the hell knows.... would be nice to find an exact cause so it can be fixed.

 

Yea, when I did mine I read the motor mount that came on the bike was crap. Bought the new one that I think the last number/letter in the part number was different. Honestly I didn't notice it till I changed the mount, guess I thought it was normal. I was searching for a wobble and that was the first thing i did reading about all the isolator issues. Turns out that wasn't the cause of the wobble, but smoothed out the bike big time. Wobble was a crappy tire.

Here are the differences between old and new. New on the right. If you look at the two isolators one sits a little lower and that makes a big difference. The problems most had was that round hump at the top would touch the motor with the extra height on the old isolator, which would give you that extra vibration. Some filed off enough of that round part to not touch the motor and the vibes went away. That fix is free! I'd still shim it too.

 

My wrench told me the same thing except he did not say you needed to use a shim. He stated to just loosen the bolts for a minute then tighten them. He said it is a Dyna and that it happen sometimes.

 

i have read that most folks who have changed the exhaust, have gotten rid of the bad vibes

 

That's the vehicle alignment. You have to run the bike with the bolts loose for like 30 secs, shut off the bike then tighten down the bolts. The shims is something else someone figured out that works. When you loosen your bolts to do the vehicle alignment look at the gap that shows up as you loosen the bolts. We fill that gap with the shims. The theory is like a rubber band. You stretch it out and keep it stretched out for a while it's going to weaken and snap or not be as tight. So the shims take that stretch out of the isolator.