I have a 94 fxstc. When hit a dip the bike takes it in stride. But if I hit a sharp bump or pothole I get this bang noise coming from under the seat not front end.
Sounds like the Jug is hitting the frame or the swing arm is hitting the frame. I can't find it. And it annoy's the Hell out of me. Any suggestions?

 

Loose gas tank?

 

loose tank is pretty common. Did you just get the bike? suspension bottoming out?

 

Not the tank, had the bike 2 years. It's been doing it, but it's worse since I lowered the rear. Feels like it's under my ***. Tires not bottoming out. Feels like metal to metal.

 

The way the swingarm functions, I can't think of where it would be hitting anything. It just pivots on the pivot bolt freely and the swingarm boss mounts to the shocks which obviously limits it's travel up and down.

How old are the shocks, are the shocks bottoming out, especially given that you have a lowered them? Have you adjusted the shock dampening any since you lowered it? Are your shock mounting bushing still good and in place? Are the shock mounting bolts all tight? Just trying to think what could be banging.

 

Sounds like maybe the shocks or worn out, or they are bottoming out internally. Try tightening up the preload to max and give it a try. When I lowered the rear on my bike with lowering bolts I adjusted the preload to just below max and it was a world of difference. At first after installing the lowering bolts I rode it with the preload in the factory position and I experienced the feel and sound that you are describing.

 

Shocks were just installed, Adjusted 2 turns out towards rear tire. I'm 260lbs. I'll try another turn. 4th turn will be max weight. Ride solo so the only weight is my fat ***.

 

My $.02: After following folks advice about the shocks and such, check the odd things, like license plate mount, passenger pillion mount, inner fender bolts, etc. Perhaps something is tight enough to stay put over small jolts, but the big hits make it/them move.

 

I had a kawasaki vulcan at one point (don't judge) and the rear fender actually hit the chain guard when it was lowered 3 inches. Never seen a Softail do that, but just a thought

 

Thanx all, I have to check further.