Just returned today from a 4400 mile mid west ride on my Fatbob (it was my gift to myself after retirng from the AF 22 yrs). Over the past two weeks my attention has been directed to the fact that my Fatbob (now with 20k miles) is not nearly as smooth as it once was. So tomorrow I begin the task of trying to figure out what has happened. Below are the symptoms.

- When going over sharp edged bumps (broken pavement/washboards) I get a thumping noise that is felt in my pegs and butt. Sounds like something is terribly loose but inspections on the road (even with a friend loading up the bike with the brake reveal nothing wrong.
- Especially noticable when using the rear brake only coming to a stop on rough pavement. Nothing felt in the forks what so ever at anytime. Normal road surface bumps do not alter ride qual.
- General motor vibs seems to be increasing in the pegs as well (mid mount).
- It feels as though the motor is fixing to fall out....(maybe not that bad but close)

The only thing that looks amiss is that the front motor mount seems to allow a large amount of movement. I realize that its always been there but there seems to be more now.

At first I thought the rear fork needs to be retorqued but looking at the shop manual, the bearing doesn't appear to be a tapered design (sealed instead). Now I turn my attention to the engine mounts. When loading the bike up, I didn't see much movement at all from the rear (which is what I was expecting). Only the fronts isolator seems "looser" than I remember. I saw posts on shimming the front mount but don't believe that would help my particular issue (I may be wrong).

I have seen auto engine mounts torn apart before and noted how the two halfs of the mount are mechanically interlocked in case of isolator (rubber) failure for safety reasons. My first guess is that the front mount is loosing its effectiveness and allowing the two halves to impact during large bumps in the road sending the thud and vibs to the frame.

Am I going in the right direction? If so, are there heavier duty front mounts available (and recommended)? Is this a normal fail item for a built motor (99hp/112tq since 7k miles)?

I consider my riding style very sporty (prior sport bike owner) utilizing the additional power on corner exits but I do not do burnouts or jackrabbit starts. Any direction would be greatly appreciated. Thank you.

 

at 20k the front motor mount would be my first guess..some go sooner and some last longer.... i replaced mine right at around 20k and cured my excessive vibe problem... ... cheap and easy to change...

 

I'm at 30k and overdue for motor mounts also....

 

Check your front tire, mine is vibrating alot more these days I'm haveing it changed today If half the treads look fine but the other half sorta cuts right down to the tread wear then you are due. It's because the big block tread on those fatbob tires wear out like that.

 

I think you may have 2 issues. One suspension/shock issue and the other a bad motor mount.

I just went through this here https://www.hdforums.com/forum/dyna-...with-pics.html

 

Bet its your steering head bearing adjustment. Mine was making the same noise and after reading of others with the problem I adjusted the fall-away as per the manual and the noise is gone.

 

20,000 miles I was thinking the same thing, mounts and rear shocks. the more the motor moves the more the ride if effected via the swing arm, especially on corners and when riding on a seam in the pavement. Im guessing your main problem is bad shocks

 

Tonygret, Thanks for the link. Very interesting read. I went to HD and picked up a mount after a good look revealed that it has too collapsed. Once I got back home, I went ahead and shimmed the mount (didn't trim the top though) just to see if I felt any difference. Surprisingly, the difference was significantly better. All vibs and thuds are gone except for when hitting very large road ruts. Also, just shimming my mount was enough to separate the upper and lower sections from touching. Simply amazing how much the bike changed with installing 4 flat washers. Crazy stuff.
I still have the new mount in the box un opened. I expect that the shims will only work for a while and end up changing the mount down the road anyway. I may put in the new mount and shim at the same time tomorow.

Thanks to all for the inputs.

 

do you have a part number and price for the front mount?

 

You can use Ronnie's HD parts finder to get the part# and price.