Shock mount failure

[David Brady]

Pete,

I note that Koni shocks have zero or close to zero dampening
in the bump direction. All of the dampening control is exerted
on the rebound. I had discussions with Justin at Koni regarding
this and he said this is how they are able to achieve the ride
that Koni's known for.

In the case of rebound where the front end is bobbing over
Ca roads, the accelerations and velocities of the shock body
are such that Koni calculated 4000 pounds of force that can be felt
by the shock mount at the frame. Mostly in the downward direction.

When I spoke with Ridewell, they were most concerned about
folks lifting a tire off the ground, via hwh jacks, while still having
air in the air bags. They calculated a force of up to 13000 lb in
the downward direction in this case.

So, the forces are predominantly in the downward direction,
unless the shock is too long, and the issue seems to be metal
fatigue of a Ridewell component that is probably underdesigned,
or mounted incorrectly. I say this cause just one additional bolt
adjacent to the brake air line and next to the shock mount might
have been a good idea.

David Brady
'02 LXi, NC

-----Original Message-----

From: Pete Masterson

Sent: Feb 19, 2009 1:11 PM

To: WanderlodgeForum@yahoogroups.com

Subject: Re: [WanderlodgeForum] Re: Shock mount failure

I'm inclined to agree that the left shock mount was a less robust component than is ideal, possibly due to a Ridewell error or miscalculation of stresses. The tear starts at the top and works down. That suggests that the force causing the stress is the fully extended shock absorber. This is in the opposite direction of stress caused by lowering the jacks when the air bags are deflated. Indeed, in that situation, the bumper stops ought to be taking the brunt of the weight rather than the shock mount, if the shock is of the correct length.