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Topic: bent shock mounts (Read 1407 times) previous topic - next topic

Re: bent shock mounts

Reply #21 –
I would bite the bullet and find a welder to beef up the mount and or add more metal and strenthen the mounts,will be better in the long run,every time you bend metal it gets weaker,and please let us know where you got this coach if from a dealer so we can avoid them like the plauge,if your in an area of Mich. that has oilfield work you can find a "rig welder" that will come to your location .

Re: bent shock mounts

Reply #22 –
Quote from: wolfe10 –
Not sure I understand.  Have you measured ride height the way the factory describes?

I should have been more clear.  Ride height is 8" between plates.  At max. height there is 12" between plates.  At min. height there is 4" between plates.  That's what I meant by "half way between max and min suspension height".
Yes my coach is at correct ride height.  The question of what would cause my shock mounts to bend from overextension is still a mystery.  If in fact by design the shocks are intended to be the limiting device, what could cause the suspension to max out with enough force to bend all of the lower shock mounts?  It seems to me that only the force of the air bags could do this and that would be true regardless of if the shocks were the (slightly longer) Koni's or the shorter Gabriel's.  In either case the shock would be the limiting device and when it reaches its maximum extended length it would transfer the force to the shock mounts (or break) which only one did.

Re: bent shock mounts

Reply #23 –
Good chance that a shock stud , with fixing nut to the mount , plus the shock retainer nut , would reduce the bending moment arm of the shock .
As it is with one bolt and nut through the shock, the bushing and bolt just want to sag .
I added a set of front shocks. . I welded the 3/4 in bolt to the bracket to avoid the load path issues that you are experiencing.

Re: bent shock mounts

Reply #24 –
Quote from: Geodmann –
The question of what would cause my shock mounts to bend from overextension is still a mystery.
I know we are talking about different year and model coaches in this thread, so what applies to my older coach may not apply to newer models.

We have owned our '93 U280 for 10+ years, and in that time I have raised it to max height (to insert safety stands) on innumerable occasions.  As I mentioned up above, my standard procedure for "raising" is (engine running) to depress the RAISE button until I hear and feel the mechanical KLUNK noise indicating the suspension has topped out, and then I STILL hold the button down until my air dryer purges indicating the air system is at max pressure (130 psi on my coach).  At that point my air bags should be exerting the maximum possible force against whatever it is that keeps the suspension from extending any farther.

I can only say that none of the bottom shock mount brackets on our coach are bent, and we have never had a shock absorber fail.  Early in our ownership I replaced the 20+ year old original red Koni shocks with the gold Koni FSD's.  I can see no signs of stress (in the gold shocks or in the shock mounts) that might have been caused by my "raising" technique.  Other members may have had totally different experiences.

Re: bent shock mounts

Reply #25 –
Same here Chuck. I've fully extended the airbags on my 01 on more occasions than I can count. I just recently replaced all my shocks and all my mounts were in good, square condition.

Re: bent shock mounts

Reply #26 –
George. Double shearing all the mounts would resolve issue, but I think it can be resolved by straightening and monitoring.  Because they are stretched up from overextending would recommend not getting your Coach airborne in the future. Monitor  your leveling (personally I think this is how this happened) Joking aside with poor rebound of worn out shocks would allow the suspension to top out with a lot of energy causing the same results. It's hard to imagine this happening but at Hiway speeds it can and does happen although non of us would want this Intentionally. Big bump in the road. I admit I overthink most of these problem and personally I would straighten and monitor. If it come back double shear the mounts, but that's a lot of work. Adding a backer to the back side of the angle may be sufficient also. On my project bronco I have limit straps. Would be another option, and another can of worms.
Scott

Re: bent shock mounts

Reply #27 –
Looking at the pictures again,it looks like the mount bent from compression not over extension,if overextention the bolt would be angled the other way,from the picture it's like he hit a big hole and that bent the mount,like I said before,fix the mounts then
worry about ride height.Agree with Brett,never heard of a Gabriel on a Foretravel.

Re: bent shock mounts

Reply #28 –
Quote from: John44 –
Looking at the pictures again,it looks like the mount bent from compression not over extension,if overextention the bolt would be angled the other way,from the picture it's like he hit a big hole and that bent the mount,like I said before,fix the mounts then
worry about ride height.Agree with Brett,never heard of a Gabriel on a Foretravel.
Over extended, really hard impact would push the mount bolt downward if the shocks were functional. Slamming over extended would also rotate the fastener this way with bad shocks no rebound all the unsprung weight dropping freely then slamming the mechanical limits of the shocks (axle,brakes, tires and carriage. Half the weight of the airbags)

Re: bent shock mounts

Reply #29 –
"you describe the exact same experience I had pulling out of my campsite.  I'm amazed that the shock itself is stronger than the shock mounts welded to the subframe.  Did your mounting bracket bend at all?"

Sorry for the late reply , all I can tell you is that the bottom mount is what broke.

Re: bent shock mounts

Reply #30 –
Yesterday I noticed two broken lower shock mounts on the drive axle. One broke on each side. A couple of years ago I had broken mounts on the driver side, tag and drive axles. The coach has Koni FSD shocks.  Koni replaced the two shocks on the drivers side but they did not say what caused the shock failure. Did the shock fail and then the mount broke or the other way?

We are in Kerrville, TX for a few days and looking for a shop to weld the mounts.

I looked at the post from Barry from several years ago. Foretravel added bump stops. I will need to look at what stops and size of stops are on my axle.

Re: bent shock mounts

Reply #31 –
I looked at the rear suspension today and observed that there are no bump stops present to prevent bottoming out. I should have taken a picture but did not. The two frame rails that sit perpendicular to each other are actually touching each other when the coach is deflated.

In the post from Barry several years ago they welded what appeared to be washers in the contact space, thus keeping the shock from bottoming out. I plan to have a welder look at the coach tomorrow. I think I will have him weld something in the contact position. He said they would make a new and stronger bottom mount. My concern there is that if the bottom is stronger and the top mount breaks next time the top mount is more difficult to get at. Maybe the bump stops will prevent future breakage.  The coach went 16 years without breaking a mount, I cannot figure out why I get the breaks recently.

Comments are appreciated.

Thank you,
Ed

Re: bent shock mounts

Reply #32 –
I looked at the rear suspension today and observed that there are no bump stops present to prevent bottoming out. I should have taken a picture but did not. The two frame rails that sit perpendicular to each other are actually touching each other when the coach is deflated.

In the post from Barry several years ago they welded what appeared to be washers in the contact space, thus keeping the shock from bottoming out. I plan to have a welder look at the coach tomorrow. I think I will have him weld something in the contact position. He said they would make a new and stronger bottom mount. My concern there is that if the bottom is stronger and the top mount breaks next time the top mount is more difficult to get at. Maybe the bump stops will prevent future breakage.  The coach went 16 years without breaking a mount, I cannot figure out why I get the breaks recently.

Comments are appreciated.

Thank you,
Ed

Re: bent shock mounts

Reply #33 –
Ed, when you say broken shock mounts are you referring to the eyelet breaking off of the shock body or the tabs that are welded to the suspension frames broke off the frames?  In my case the "shock mounts" or brackets are securely welded to the suspension frames but the lower brackets are bent because shocks themselves limit the maximum extension of the suspension.  I'm in the process of fixing this all now and I will provide a more complete report once I'm done to wrap up this thread.  In the meantime i've attached a photo of the process.

Re: bent shock mounts

Reply #34 –
Also if you look in reply #5 you can see the "bump stop" which limit suspension compression.  My coach has these as well and as long as the shocks don't bind up in maximum compression you should not have a problem with that.  My problem was during maximum extension.

Re: bent shock mounts

Reply #35 –
As pictured in reply #5, I have no bump stops. Doesn't look like any were ever in place. The tabs for the bottom shock bolt broke. Let's see if I can attach two pictures.

Re: bent shock mounts

Reply #36 –
I'm speechless.  Those brackets are 1/4" steel.  I can't imagine the force required to break them in that way.

Re: bent shock mounts

Reply #37 –
Ed is there any indication on which directional the failure happened? I would want to see the actual length of the collapsed shock. Im betting you will find they still have travel left when fully your suspension is at full travel up. Installing bump stops wont resolve your issue. You may find that this is from overextending or just hard working shocks. Im starting to think that they were a poor design and double shearing them would be a permanent resolution. Being single sheared every time they move there is a flexing on the tab/bolt. My coach when resting on the frame also has contact with the tires to the lower sheeting in the fender well. I recall be told Foretravel did this to make the coach more stable. I thought the 2002 had a built in clearance of the tire not to touch the sheeting.
Scott

Re: bent shock mounts

Reply #38 –
Quote from: Geodmann –
I'm speechless.  Those brackets are 1/4" steel.  I can't imagine the force required to break them in that way.
I can with thousands of flex cycles every mile. No triangulation

Re: bent shock mounts

Reply #39 –
Scott I can confirm that (my) 2002 does have clearance above the tires when the suspension is fully compressed and sitting on the "bump stops/steel washers"  and that the shocks are not fully compressed at that point.  I agree with your point about metal fatigue but that assumes that the suspension regularly droops to full extension (with force) during normal driving.  In spite of your (previous) implication that I have jumped my coach and gotten airborne... lol... I can assure you that I have never subjected it to that kind of abuse.  I'm glad that my shock mounts bent instead of breaking.  I'm not done fixing my problem or completely studying the geometry of the suspension at full extension/compression but I am well on my way (pesky day job) and I will provide a full wrap up and conclusion once it's done.