BANG go the forks. Gl1500

[dingdong]

This problem just recently developed when on our trip to Utah (93 1500). When I ride through a rut or off a shallow drop off (say at least 2 inches) at slow speeds , about 10 to 15 mph, the forks go BANG. And I mean BANG. Sounds like hitting a boulder with a sledge hammer. I can't think of anything that could make this loud of a noise in the forks. When hitting a raised bump or at speed there is no problem just a drop off. I service the forks at regular intervals. Progressive springs with 10 weight fork oil and bushing have been replaced around 20k miles ago. What's up???

[virgilmobile]

My noise up front was the caliper bushing missing.
Perhaps the bolt up under the axle is loose?

[dingdong]

My noise up front was the caliper bushing missing.
Perhaps the bolt up under the axle is loose?

Virgil are you talking about the bolt that has to be removed to separate the forks?
This started all of the sudden. One day good the next day bang.

[WingAdmin]

I can think of a couple things right off the top of my head to perhaps cause this:

- low fork fluid (extension orifice is flowing air instead of fluid, so no damping taking place)
- broken compression orifice valve, so both compression and extension orifices are open, allowing fork to extend with little damping

[virgilmobile]

Possible.....Even one rebound spring broken
And yes I was referring to the Allen bolt under the slide that holds it together.
Anyways..I'm just speculating...It's still up to you to do the hard part... Disassembly...identify and repair...I'm sure sense you've serviced the forks you are familiar with the inspection testing and disassembly.

[virgilmobile]

A picture may help visualize what we're taking bout.
#16 is the piston...it is held to bottom of the slide by #40 bolt...this is all that keeps the slide on the fork...On the downward stroke there is a "rebound" spring..#11
Its there to keep the piston from slamming into the bottom of the fork.
A problem in this area(including the Admins suggested) could cause a extension bang....
I'd even go as far as loose or broken top head steering bearing.
Get the front wheel up and start messing with it...I have every confidence that you'll find the trouble.

[dingdong]

Yeah I'm just looking for some magic solution. Was hoping not have to tear down the forks. Oh well, here goes nothing. lol

[virgilmobile]

Unless it's something external do replace the slide bushings and seals while your there.
Keep us posted as to what you find.Take pictures...We wanna see...

[newday777]

20,000 miles. Rebuild is due.