Shock mount failure

[timvasqz]

I think the lack of flex of the frame adds a greater stess to the
pivioting points . when absorbing the shock of a pothole all the
stress is on the two pins so I guess the violent action and reaction
must be a big force on the cantilivered pin. if you ever see slow
motion footage of a pickup truck off road, you can see the frame and
fenders flexing major. Your "inverse sine" calc sold me, you are
probably right with your theory. (I wrote that down for later use)
Greg ofTim&Greg
94ptca

--- In WanderlodgeForum@yahoogroups.com, david brady
wrote:
>
> Greg,
>
> I don't think the axle tilt puts undo stress on the shock. If you
> consider the steer axle in full droop on one side and full bump on
> the other. The angle of the axle is roughly 5 deg to the horizon,
> and this turns out to also be the angle of the shock.
> (inverse sine of (8 inches / 96 inches)). The rubber bushings
> in the shock can easily comply without transferring
> excessive forces to the mounts. I'm sure Ridewell did this basic
> calculation. If this were the cause then we'd be seeing similar
> failures on the drive axles. The cause could be shocks that bottom
> before bump stops (shocks too long), folks retracting their
> HWH jacks w/o first airing up the suspension, folks raising the
> front off the ground w/o first dumping air, or simply and inferior
> Ridewell design. After year 2000 or so, I was informed by
> the engineering staff at Ridewell that all their suspension systems
> underwent finite element analysis and subsequent redesign;
> consequently the LXi uses a different shock mount system than
> the WB's. Could be that Ridewell addressed an inherent weakness.
>
> David Brady
> '02 LXi, NC
>
>
>
> timvasqz wrote:
> >
> > I think the crack was there from off-camber HWH jack parking in
the
> > past. looks like the temper of the weld proved a brittle spot that
> > under normal conditions would not have issue. Then the new shock
> > absorbed more bounce but reacted equally agressive causing much
more
> > stress on the mount. I think the mount post should have less
strength
> > and be a point that can bend at failure. the tripod gussettes are
a
> > bad idea.
> >
> > I think problems arise when the bus air bags are dropped to be
> > leveled but the spot is too off camber. the HWH push one side up
> > and tilt the axle too much. at that point raising the front is
> > effortless and and the 30 foot lever post all the stress on the
> > tucked tire.
> >
> > If I was to repair that mount I would remove two bolts and make a
> > trapazoid shape cut and replace the plate with a butt weld then
build
> > the post mount back no better than before.
> >
> > If you lose an airline and must drive. there is a screw set in the
> > maxicam to turn off the parking brake. you can then plug the
airline
> > and fold it over then tape it.
> > Greg ofTim&Greg
> > 94ptca
> >
> > ..--- In WanderlodgeForum@yahoogroups.com
> > , "Don Bradner"
> > wrote:
> > >
> > > I'm the latest victim of a driver's side front shock mount
failure.
> > It took out the brake line when it went. I was not far from home
on
> > the way back from Q, so I limped on in (I know, in retrospect it
was
> > too dangerous, but I kept a lonnnng following distance!)
> > >
> > > I've used the local Detroit dealer in Arcata (Trinity Diesel) a
> > couple of times now for service, so I called them, and the service
> > manager said he would swing by for a look, no charge. He ended up
> > removing the shock and the air line, and said that he would come
by
> > the next time he was this way with a new airline. A new shock will
> > have to be ordered (the top bent/caved in) and they will schedule
an
> > appointment to get it welded after they have that. Shock was 17
> > months old.
> > >
> > >
> > > Don Bradner
> > > 90 PT40 "Blue Thunder"
> > > My location: http://www.bbirdmaps.com/user2.cfm?user=1
> > >
> >
> >
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