2008 Dyna Fat Bob vibration problems

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Apr 16, 2025 | 09:05 AM

Pedro Amado

Thread Starter

5th Gear

Joined: Feb 2025

Posts: 9

Likes: 1

From: Lisbon

2008 Dyna Fat Bob vibration problems

So, A few weeks ago I posted about vibration after changing the mufflers. Bad vibration started that wouldn't allow me to ride in peace. the foot pegs vibration numbed my feet and the mirrors were completely useless.

Changed the exhaust again, torqued and retorqued the mount bolts and when I released some torque of the exhaus mount that is bolted to the frame and gearbox, and the vibration is gone.

Now, the question is: Can I keep those bolts without the proper tightening torque? what is the risk? should I use some rubber washers to try to reduce the vibration?

I'm completely lost and in the meatime, one of the bolts broke and I need to use those extractor tools to extract it. Also read somewhere that these bolts break often, maybe due to vibrations...

All comments welcome.

Thanks.

Apr 16, 2025 | 09:09 AM

pgrchaplain

Road Master

Joined: Dec 2014

Posts: 820

Likes: 705

From: N/E Indiana

I'd check the Motor Mounts to start with. You can't leave the Exhaust Mounts loose. Google Switchback Clevis Pin Fix, you may try something like that.

Apr 16, 2025 | 12:41 PM

Pedro Amado

Thread Starter

5th Gear

Joined: Feb 2025

Posts: 9

Likes: 1

From: Lisbon

Quote:

Originally Posted by pgrchaplain

I'd check the Motor Mounts to start with. You can't leave the Exhaust Mounts loose. Google Switchback Clevis Pin Fix, you may try something like that.

The mounts are new. I mean 2 weeks new and they were destroyed before.

I don’t mean to have them loose, I mean to leave them slightly less tight than the 24Nm Harley’s manual recommends.

Engine is rubber mounted and vibrates without affecting chassis but the exhaust vibrates and is directly mounted on the chassis. Doesn’t make sense to me.

Maybe some washers with rubber “lining” could help and I could tighten the bolts a bit more while avoiding vibration or blue loctite the bolts.

Apr 16, 2025 | 09:08 PM

John CC

HDF Community Team

Joined: Aug 2018

Posts: 3,016

Likes: 1,194

From: New Hampsha

Quote:

Originally Posted by Pedro Amado

the exhaust vibrates and is directly mounted on the chassis.

It shouldn't be! It should be fastened to a bracket that attaches to the transmission. If it is really connected to the chassis it will break in short order.