Shock mount: Re: Temps
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06-18-2008, 16:23
Post: #1
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Shock mount: Re: Temps
The long story: Same shock mount....
Henderson's noticed a crack along one edge of a 'rib' on the left front shock mount. They welded it ... but in reviewing the ultimate much more serious failure, they (Henderson's) didn't know much about proper welding technique. (I'm no expert either ... but after seeing what CCW did vs. what Henderson's did, it is obvious that the Henderson's welder may have had a high-school welding class and was not a certified welder.) I had been noticing a 'popping' noise in the front end -- to my ear, it sounded like it was coming from the curb side of the coach ... but that may have been misleading. The popping noise occurred on heavy dips and on wavy bits of road (as are common on the freeways in the SF Bay Area that were built on fill land). I now realize that it was probably the mount tearing itself apart. The requested inspection found a loose 'fender' (a piece of metal up in the curb side wheel well) that was screwed back in place (OEM was a single screw, which broke. Now there are two screws). That was thought to be the source of the noise. (We hadn't road tested the coach.) Some other work was done and we were about finished with the list when we made a small move (a few feet) and suddenly the left front air line was separated. Upon inspection, it was found that the shock had completely torn away and took out the brake line when it came loose. The shock mount was severely torn and bent. One of the technicians assigned to my coach had actually worked for several years as a certified welder in a shipyard -- and he was supervised (on this job) by yet another certified welder. The prep work they did was significant and impressive compared to the bend it back and tack it weld done at Henderson's. The weld was also given additional gussets to strengthen the area of the crack -- and all the area was completely ground down and all rust was stripped away. (I don't recall seeing that Henderson's did any of the prep work like that.) I note, too, that CCW had the heavy shop equipment necessary to straighten out the bends in the torn off piece -- they must have a heavy press somewhere on their facility as the bent up 1/4" piece of steel that was torn off ended up beautifully flat before it was put back in place. CCW was very careful about the electronics and took everything offline, removing the battery cables, isolating the DDEC unit by removing the wires from it on the engine and similarly isolating the electronics for the transmission. (I don't recall Henderson's doing any of that, either.) Then there was a _lot_ of welding -- with an assistant standing by with a fire extinguisher. All in all, the CCW team did a very professional job of welding and strengthening the shock mount. Unfortunately, the shock itself had been bent at one end during the failure ... and I discovered that Koni shocks for BB buses are not on every auto parts store shelf. As luck would have it, the shock ordered overnight from Hayward (No. CA) was lost by UPS! To avoid keeping me over another weekend, they arranged to remove an identical shock from another coach (which had recently had new shocks installed) and got me on the road. (The shock ordered for my coach went on the other coach when it eventually arrived.) However, this little incident added 2 days to my stay. Since the shock mount had reached imminent failure enroute to CCW, I actually feel lucky that it happened to let go while located in the service area at CCW as compared to any other possibility. (I'm a little surprised that it wasn't seen until the failure occurred -- but I guess they just missed it.) I guess the lesson here is, if you have a 95-97 PT-42, be sure to take a look at your front shock mounts carefully. BB apparently used a variety of designs (from what I hear) and it's probably because they've had some troubles with that component in the past. Oh, yeah. The popping noise is gone. Pete Masterson '95 Blue Bird Wanderlodge WBDA 42 El Sobrante CA "aeonix1@mac.com" On Jun 18, 2008, at 9:37 PM, David Brady wrote: Ouch, another failed front shock mount??? Is this the one that Hendrickson's |
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06-18-2008, 17:43
Post: #2
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Shock mount: Re: Temps
It must feel better to get that off your chest. See what wonderful therapy this list is, and free of charge! you described the work that Henderson's did some months ago. I recall that you had BB in the loop and they suggested "hammering it back in place and welding it". I've had welding work done in the past by shipyard welders and have been impressed. These guys work with heavy equipment routinely and pay attention to stress flows, risers, mitigation, etc. Some people can look at a steel joint or interface and picture in their minds exactly how the lines of stress radiate and how to spread the load with gussets. I wonder if you had shock failure in the CCW parking lot due to them raising the front of the bus with the HWH jacks, and then dropping it w/o first getting some air in the suspension. If so, this may have been the last straw for the mount. We know by now that there's not a lot of tolerance between the suspension bottoming on the air bag bump stops versus the shock bottoming internally exerting "shock" loads into the shock mounts. Ever wonder why you only have this problem on one side of the coach? The reason is that the other shock mount shares it's upper bracket with the panhard rod, which is an extremely stout structure, as opposed to the driver's side upper mount which is a wimpy flange and bolt huck bolted to the vertical flange of the c-channel frame. So everyone: 1) keep an eye on your drivers side upper shock mount, 2) check your shocks to make sure they're not too long in the fully compressed state which leads to the shocks bearing the load of the coach instead of the front airbag bump stops, and 3) air up your coach before you retract your HWH landing gear. David Brady '02 LXi, NC Pete Masterson wrote:
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06-18-2008, 17:46
Post: #3
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Shock mount: Re: Temps
BTW Pete, can you share some pictures of the work that CCW did? David Brady wrote:
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06-18-2008, 20:36
Post: #4
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Shock mount: Re: Temps
The stress crack/tear in the metal was over 7" long, so the problem must have been developing for some time. (The popping noise had been with me for some time, too.)
I don't know if the raising/lowering the coach was the last straw, or what ... (might have been) But airing the coach before raising the jacks is tough (on my coach) since the air bags are dumped automatically when you lower the jacks, so I don't know if they'll refill until the jacks are raised. (Does someone know precisely how that is set up?) I know I've forgotten to dump the suspension before I started the jacks ... but then they dump anyway. Pete Masterson '95 Blue Bird Wanderlodge WBDA 42 El Sobrante CA "aeonix1@mac.com" On Jun 18, 2008, at 10:43 PM, David Brady wrote: It must feel better to get that off your chest. See what wonderful |
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06-18-2008, 20:53
Post: #5
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Shock mount: Re: Temps
It's difficult ... they put a coat of black paint over everything when they finished. Can't get a particularly clear photo -- and the darn thing is hard to get to as it is.
The huge list of other stuff they did isn't particularly photogenic. (e.g. New muffler (it's all inside); rebuild air dryer; etc.) By the way, one of the things on my list was to find the dryer vent outlet. CCW was not successful in finding it. (I suspected it was clogged and wanted to (try to) clear it from the outside.) My coach has the "diagonal aisle" (that the "DA" in the WBDA below). This creates a hallway past the bathroom to one side. Since the bath is rearranged from the "walk through" type, the combo washer/dryer ends up on the centerline of the coach. Searching from the underside proved futile, so I had to remove the Splendide to get to the vent. It turns out that the vent outlet is simply a hole cut into the floor, just off center, but inside the frame rails, way up above and just to the front of the drive axles. The doors to the closet that holds the dryer are not quite wide enough, so they have to be removed. About a dozen screws on each piano hinge (BB does love those piano hinges). Then two screws must be removed from a felt-covered board that runs along the back edge of the washer. (That's what really holds the washer from sliding around while underway.) Finally, I was able to wrestle the thing out of the closet and push it mostly out of the way. I then had to remove the bottom of the closet, and there was the air-operated vent device (actually a surprisingly siimple thing) and once the flexible dryer vent hose was removed, I discovered a "pad" of lint, about 1/4" thick completely blocking the vent exit. The exit is simply a hole in the plywood/steel coach interior floor with an expanded mesh screen (holes of 1/2 x 3/4" or so). Obviously this is to keep larger vermin from entering the coach. Once the "pad" was removed, I could easily see through it, past the frame, to the street below. (But I can imagine how difficult it might be to see from the bottom, looking up.) Besides, I doubt I could have cleared it from the outside, anyway. When I first had access to the vent hose, I tried running my shop vac hose down in it, but I couldn't get past the vent door thing. I also tried the reverse direction air, and all the air went back into the room. Once the "felt pad" of lint was removed, the dryer hose then handled the full blow pressure of the shop vac with ease. I plan to run a modest load of laundry later this week to see just how well the washer/dryer (especially the dryer) works, now that it is vented. Pete Masterson '95 Blue Bird Wanderlodge WBDA 42 El Sobrante CA "aeonix1@mac.com" On Jun 18, 2008, at 10:46 PM, David Brady wrote: BTW Pete, can you share some pictures of the work that CCW |
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06-19-2008, 01:39
Post: #6
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Shock mount: Re: Temps
The LXi is set up the same way. If the front end is lifted high off the ground by the jacks, the front ride height valve wants to dump suspension air. Usually, if I start the motor, build up air pressure, then throw the switch to raise the suspension, then retract the jacks, by the time the jacks are "almost" completely retracted, the front ride height valve is starting to allow air to flow into the airbags and it just catches, landing softly on the airbags instead of crashing on the bump stops. If it doesn't appear that things are going to work out this way, I'm not above retracting the front jacks manually and then stopping them at a point where the ride height valve is willing to pump some air into the front air bags. I then let the front airbags fill up then continue with jack retraction. These cases usually occur due to someone wanting to raise the coach sufficiently to remove a tire, or work underneath (with proper blocking/cribbing). At campgrounds, the coach will typically raise on the suspension allowing the jacks to be retracted without incident. David Brady '02 LXi, NC Pete Masterson wrote:
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06-19-2008, 01:48
Post: #7
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Shock mount: Re: Temps
Me and the rest of the gang are probably only interested in the gusseting and welding of the shock mount area so that we can fix ours similarly if need be. Just reach around the wheel with your digital camera and take a blind shot. I think you'll get it! It should be right there! Come on Pete! Fascinating story about your dryer vent. Usually BB does a good job of making things accessible, but not in this case with the DA. My home dryer has a screen that's about a yard long with a handle at the end. I wonder if you could arrange something like that: basically a screen on a long handle that rides in tracks allowing you to pull from the bottom front floor area of the dryer. The screen would block the floor opening and catch the lint. I know, in your infinite time! David Brady '02 LXi, NC Pete Masterson wrote:
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06-19-2008, 03:04
Post: #8
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Shock mount: Re: Temps
Interesting. I usually start the engine (and close the suspension dump switches) before lowering the jacks when I'm getting ready to leave a campground. Since I don't have an auxiliary compressor, I need air pressure to open/close the dump valves so that is the basis behind my normal practice -- I need the air to complete my un-hook procedures and I may as well raise the jacks while the air is coming up. As you say, this probably puts at least some air into the suspension before the coach is lowered.
Since my coach is parked in the street in front of my house, I have done no work on it at home that involves using the jacks to lift it to work underneath. Indeed, I do not generally ever put the jacks down while at home for any reason -- early on, I discovered that it dents the pavement. (I'm no mechanic, so there's little that I can do under the coach anyway.) While the long-term parking isn't an issue where I live, there is an ordinance against doing mechanical work on vehicles in public streets. However, while at CCW, the coach was raised and lowered several times, with and without blocking under the jacks to make room for the technicians to work underneath. As you describe, these activities may have been the last straw, but the length of the support crack also indicates that it was working toward failure for some time. Pete Masterson '95 Blue Bird Wanderlodge WBDA 42 El Sobrante CA "aeonix1@mac.com" On Jun 19, 2008, at 6:39 AM, David Brady wrote: The LXi is set up the same way. If the front end is lifted high |
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06-19-2008, 03:13
Post: #9
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Shock mount: Re: Temps
I have some other matters going on now... but I'll try to get a shot or two as you suggest in the next few days. I'll post 'em if I can get anything that's understandable. I will say that the gussets are not installed as I might have thought... but I know nothing about welding and how stresses propagate through metal.
(I note that 3 gussets were prepared, but when the welding was done, they only used two of them.) Modifying the dryer vent access is probably much more work than it's worth. Assuming that the dryer is worth a damn now (I was ready to just take it out), I suppose that it will take some time for it to degrade again -- I'll probably notice that before the vent becomes entirely clogged, and now I know what to do to clear it. My home dryer -- that gets far more use than the Splendide will ever get -- only requires a vent cleaning every two or three years -- so this one ought to be good for a longer period. (Who knows, I may sell the coach before I need to service the dryer vent again.) Most of the really important things are easily accessible, once you figure out where they're hidden. It would have been nice if there were a 'port' from the bedroom side of the bulkhead to reach the back of the washer. But there's a pocket door there that is in the way... Pete Masterson '95 Blue Bird Wanderlodge WBDA 42 El Sobrante CA "aeonix1@mac.com" On Jun 19, 2008, at 6:48 AM, David Brady wrote: Me and the rest of the gang are probably only interested in |
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06-19-2008, 04:12
Post: #10
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Shock mount: Re: Temps
Pete & PT-42 guys,
My left front shock mount was also torn up. My BB guru said it's a known problem???!!!&@$%^&*WHAT THE !@#$%^9)_. The fix, just weld it back up! What the F@#$! After installing new shocks a few months latter I replaced all the airbags. When they lifted the front end up with jacks and the front axle was hanging with all it's weight and no air bags attached the shock must have just pulled everything down, ripping the mount off the frame. Of course the new Koni was toast. The mechanic was under the coach and I queried him, Hey DUDE, I think you missed something here. Well it got fixed, he was a certified welder, they did add some gussetts as I recall. I'll try to get some photo's of mine as well just to compair notes. The work on my coach was done at Prevost Nashville. If this is known problem. I would say anyone with a PT-42 95 to 97 might want to check for a potential problem. Dang Pete 10 days in the parking lot! I think I might have rented a car and gone home. I've been there to and sometimes you think well their almost done and bang, you find something else to get fixed. My coach has an air compressor although it's not really very good, well it's just loud. I can air up the bags befor hitting the STOW/STORE button. So I either air up from Aux. compressor of from the engine compressor before I let her down. I never had a problem doing it that way. In my coach it doesn't matter if the jacks are up or down the air bags will inflate or deflate on command. Kurt Horvath 95 PT-42 WLWB 10AC |
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