bulkhead blues

Topic: bulkhead blues (Read 12047 times) previous topic - next topic

Re: bulkhead blues

Reply #150 – July 13, 2012, 08:09:05 pm

Quote from: Dwayne – July 13, 2012, 05:41:06 pm

Pierce: you are talking about a coach that already had airbags right? Fabricating airbags over the torsilastic spring is going to be an interesting project. James Triana told me that he'd heard it has been done but didn't have details.

No, I installed it on a 26 footer with big leaf springs. They had flattened out over time. The ride was so soft, everyone on board got sea sick.

No idea what your suspension looks like or how feasible the installation is. With the airbags, you can adjust the pressure to control height and firmness. Some owners have installed an air regulator to adjust while driving. Mine installation was the rear only. They were only about one third to one half the size of the Foretravel airbags. They had generic mounts on each end that I modified for my installation.

Pierce

Re: bulkhead blues

Reply #151 – July 14, 2012, 02:34:16 pm

Inspected every bolt today. 3 total are broken. The second one in on the left front and the second one in on the right rear and the sixth one in on the left front. I am going to remove them and order some new roloks. I really don't want to drill for larger through bolts. Some spray foam and an aluminum cover siliconed on should do for quite a while.

Re: bulkhead blues

Reply #152 – July 15, 2012, 05:15:55 pm

Successfully diverted fresh water overflow through bottom of bay. Went just left of water manifold and next to black water tank. there weren't too many choices due to metal beams detected with a magnet. Thanks to Rudy and Brett Wolfe for the suggestions. Actually there were the thin fiberglass skins and a thick layer of plywood that I had to drill through.

Re: bulkhead blues

Reply #153 – July 15, 2012, 06:04:13 pm

Question to all the experts on this saga--
If the concensus is that the Retarder is the culprit (mainly, and not rust jacking) for the rear Bulkhead, what causes the front one to have same problem? Fast take offs in reverse??
Am I missing something/ I believe the rust problem more than Retarder as I have used mine a LOT over the years and I do not have 1 bolt broken.
Another thought, would it be of interest for one of the moderators to make a table that we can add our info to see which models and years are most affected. Say yr/length/and engine size. My thought is there are more 40ft units with the problem than say 36'.
Just a thought.
John H

Re: bulkhead blues

Reply #154 – July 15, 2012, 06:14:33 pm

My front bulkhead is perfect. Had 8 bolts rear bulkhead that came off with much less than 20 ft lbs of torque. Very minimal separation rear and none in front. No explanation except for water intrusion rear bulkhead. Bolts that sheared off were on both ends. middle bolts were good.

Re: bulkhead blues

Reply #155 – July 15, 2012, 06:42:12 pm

I'm no engineer and although water is always a problem with steel, I have to think that unanticipated forces on this junction is a major part of it. I think they were thinking in two dimensions: push/pull and up/down. When the coach is going over bumps or turning there is probably some twisting or lifting force on one side of the connection and downward force simultaneously on the opposite side. If not exactly this, something like it. As with anything, it is always when several things come together at the same time that causes failure (perfect storm). Poor design + water intrusion through the larger hole in the angle iron + fresh water being dumped across from above + road salts + unsealed union. I'll bet if they'd have just put something gummy like undercoating between the angle iron and box beam before roloking it up it might have prevented the problem.

Re: bulkhead blues

Reply #156 – July 15, 2012, 07:10:17 pm

John
While not claiming to be an expert on the matter, I am at least someone who has spent many hours contemplating the subject (many of those hours camped underneath!), I do have some ideas about it. I don't think that the retarder is the main cause, but it is perhaps the strongest force directly acting to separate the joint. The front bulkhead on our coach has just one broken bolt and that one is the outer most on the curb side. I removed all of them and wire brushed them for close inspection (one at a time of course... there has to be something to hold up the 1/3 tank of diesel!) It is broken off about an inch and a quarter in, or right before it goes into the back wall of the square tube. Moisture is definitely implicated since all of the Styrofoam in that area was pretty well eaten up by diesel exposure, creating an opportunity for condensing moisture.

I firmly believe that the retarder, and to a lesser extent on the older coaches, exhaust brakes are just a contributing factor and perhaps one of the more dynamic forces acting on the joints because of the trailing arm connection from the drive axle, which isn't a factor on the front bulkhead. I can imagine that more of the northern and eastern coaches that travel the winter roads are more prone to front bulkhead failure from exposure because of the pretty direct exposure to water etc. coming right off of the front tires. Our coach has virtually no rust on any of the exposed frame work front or rear, just plenty of dirt... LOL.
Just my one cent... I would give two, but I am trying to pay the mortgage!
Don

Quote from: John Haygarth – July 15, 2012, 06:04:13 pm

Question to all the experts on this saga--
If the concensus is that the Retarder is the culprit (mainly, and not rust jacking) for the rear Bulkhead, what causes the front one to have same problem? Fast take offs in reverse??
Am I missing something/ I believe the rust problem more than Retarder as I have used mine a LOT over the years and I do not have 1 bolt broken.
Another thought, would it be of interest for one of the moderators to make a table that we can add our info to see which models and years are most affected. Say yr/length/and engine size. My thought is there are more 40ft units with the problem than say 36'.
Just a thought.
John H

Re: bulkhead blues

Reply #157 – July 15, 2012, 07:14:45 pm

Nothing to do with retarder, jake, towing, or fast acceleration/braking. Rust jacking from water intrusion and lack of rust preventative coatings like galvanizing, etc. is the cause for Rolock failure in my opinion with plenty of strength in the factory structure if the fasteners have not been compromised and only after they have been, do the retarder, jake, towing or anything else come into play. Rust proofing, diesel resistive foam, no plywood, drains, etc. could also have been used in the center section and would have prevented Don and Tys damage.

Not a vehicle out there on the road that does not have a problem area(s). Most SOBs have so many issues that forum posts must take an hour to read each day. So much is good with our coaches, we just have to deal with it and make sure it is on the list of preventative maintenance items. And it is such an easy thing to check.

I am a not a believer in sweeping this under the carpet but rather keeping this active as members encounter bulkhead issues. It has been around two months since a forum member had a major problem. If keeping this topic occasionally in the forum posts can keep future and present owners aware and prevent another occurrence, great. I know this is an old, boring topic for a lot of us but not so if you are a new owner.

Pierce

Re: bulkhead blues

Reply #158 – July 15, 2012, 08:34:42 pm

Is every rolok accessible by drilling the hole through the fiberglass bottom...even those first two or three at the street and curbside? I can't tell from Don's great photos if there is a box beam perpendicular to the bulkhead on the sides and perhaps at very points across that will interfere with accessing the roloks at those locations.

Re: bulkhead blues

Reply #159 – July 15, 2012, 08:59:41 pm

I was just making some comments re-possible problem(others many opinions) as I am sure it is a rust problem. The truck industry for one is having a heck of a time with the road anti-icing compound they have used the last bunch of years.So we feel it as well maybe. Sure glad I cleaned and sealed mine up after I bought it and do not fill my tanks ever.
John

Re: bulkhead blues

Reply #160 – July 15, 2012, 09:01:15 pm

Dwayne, have you considered abandoning the broken Rollocks, leaving them in place and sistering in a few new ones?

Re: bulkhead blues

Reply #161 – July 15, 2012, 09:02:16 pm

Dwayne,
The two outermost Roloks (one on street side and one curb side) are smack dab in the middle of the outer most longitudinal (perpendicular) square tubes on either side. Additionally, the next four on the street side are in the area of the doubled up horizontal tubing. So you have a total of six with no access from the basement side of the joint, at least on the rear of our 99' WTFE U270. It is probably similar on other years because I believe they used the same framing scheme on several different floor plans on the unicoaches. Also on our coach, there was one other Rolok that went into a longitudinal frame member and one other that was so close there wasn't even room to get a nut on the broken bolt from the basement side.
Don

Quote from: Dwayne – July 15, 2012, 08:34:42 pm

Is every rolok accessible by drilling the hole through the fiberglass bottom...even those first two or three at the street and curbside? I can't tell from Don's great photos if there is a box beam perpendicular to the bulkhead on the sides and perhaps at very points across that will interfere with accessing the roloks at those locations.

Re: bulkhead blues

Reply #162 – July 15, 2012, 10:07:01 pm

Dwayne, et al,

To determine how far toward the center the beams go (i.e. where to drill to access the back of the Rolock to remove it and/or to access the area where you will install the large washer and nut if through bolting) take a magnet and "map out" where the steel structure is in the fiberglass floor just toward the center of the coach from the bulkhead area. I use blue painter's tape to "map out" the bulkheads and then just drill toward the center of that. VERY simple.

Brett

Re: bulkhead blues

Reply #163 – July 15, 2012, 10:29:39 pm

Dwayne,

Why not pull a couple of good Rolocks and check for rust on the threads between the two sides of the 1 1/2" rectangular tubing it goes through? If no rust on the middle approx. 1 1/4" inch of threads, the tube probably is not damp inside. The broken Rolock will have sealed both sides of the tube so after cleaning the rusty area and giving it a phosphoric acid conversion treatment, drill a new hole and install a new Rolock. Drill should be perpendicular as you can get it to the face of the angle iron. After drilling the hole, you could inject several ounces of boiled linseed oil. It will climb all the walls inside. Would be careful for the amount of protectant (no thick undercoat) on the outside so you can get a torque wrench on the nut head in the future. Repeat for as many broken bolts as you have.

Pierce

Re: bulkhead blues

Reply #164 – July 15, 2012, 10:38:46 pm

Rather than coating the heads of the bolts which, as Pierce points out will prevent future torque checks, you might put some urethane sealant on the underside of the bolt head before tightening it down. Ditto for the other bolts if you're going to loosen them.

Re: bulkhead blues

Reply #165 – July 15, 2012, 11:11:55 pm

I'm having trouble imagining how, if avoiding the area directly behind the bolt when a perpendicular beam is present, getting to it with the beam in the way. Wouldn't you be beside the beam with the broken bolt inside it and inaccessible? Brett, are you saying you've done the through bolt operation on bolts near the street or curbside? And it does sound like a good idea to put some sealant behind the bolt before tightening down leaving the heads clean. I am too scared to back out any of the unbroken bolts though.

Re: bulkhead blues

Reply #166 – July 16, 2012, 10:35:02 am

Dwayne,

The Rolocks are long enough that they go through the box beam (toward center of coach) far enough that you can double nut them from a hole you drill in the fiberglass. The hole should start (i.e. for rear beam just FORWARD of the box beam), The dimensions of the box beam are very easy to determine with any magnet.

And, as my original writeup suggested, soak them for a couple of days with a good penetrating oil before attempting to back them out. I use 50/50 acetone and ATF and apply with a long Q tip to both the angle (broken) end and liberally on the inboard end you will double nut.

Brett

Re: bulkhead blues

Reply #167 – July 16, 2012, 10:38:44 am

when these bulkheads are in the construction stage, are the roloks
individually torqued or are they put in with an air gun in rapid
succession? in other words is it possible some bolts are stripped or
broken right from the get go?

Re: bulkhead blues

Reply #168 – July 16, 2012, 01:05:36 pm

I recommend that whatever you do--chamfer the hole where it would be under the bolt head.
Many SAE standard bolts come with a specified radius under the bolt head. This radius can cause problems such as incorrect torqueing values (altho minor--errors in reading are present) Also, improper seating that can put a "canting" pressure on the bolt head. With additional force being exerted by rust jacking makes failure more likely.
Example: A Holo-Krome 3/8-16 grade 8 socket head cap screw has a callout of .023 R max under the head. Also, all bolts up to 5/8 dia shall have a max of 2 imperfect threads under the bolt head.
In the machine building industry we found failures if we did not account for the radii and the imperfect threads in assembly.

Re: bulkhead blues

Reply #169 – July 16, 2012, 01:53:12 pm

that is an important note about chamfering the hole before installing any bolt as it COULD hold the inside face of head away from plate face and allow moisture etc to build up. Another good suggestion was to put some Polyurethane caulk under the head before bolting tight. 2 good points to note.
John

Re: bulkhead blues

Reply #170 – July 16, 2012, 02:07:46 pm

John,

After cleaning off the angle and bolts with a wire brush on a drill, I masked off the bolt heads, then undercoated. No problem with being able to re-check torque and no possibility of moisture migrating in through the over-drilled angle/serrated head on the Rolock.

Brett

Re: bulkhead blues

Reply #171 – July 16, 2012, 04:04:28 pm

We're not alone in Rolok/bulkhead problems. Metal and Metallurgy engineering - Sheared Fastener

I personally believe the analysis suggested is preferable to guessing though pretty strong suggestions were made to just increase size/strength of fasteners.

Chuck

Re: bulkhead blues

Reply #172 – July 16, 2012, 04:41:20 pm

Chuck,

That's my photo. Who grabbed it, uploaded it to Picasa and linked it to the engineering site?

Pierce

Re: bulkhead blues

Reply #173 – July 16, 2012, 05:03:10 pm

Finally had a chance to check all mine and not one is loose-phew!! I will re-clean the areas and spray more undercoating crap on them to make sure all voids are sealed.
John

Re: bulkhead blues

Reply #174 – July 16, 2012, 06:07:16 pm

Water...it's everywhere you don't want it to be.

When I had the bulkhead repair done at Xtreme. there were two drain holes made at the corners of the rear bulkhead floor to enable any water spilled onto the utility bay to run off and not stagnate in unseen areas of that compartment. I think that's a real good addition to the "fix the bulkhead repair" protocol. I know I'm always spilling water onto the bay floor when using the faucet on the street side. And spilling water when I empty the water heater tank on the curb side. It's inevitable.

Any thoughts?

Peter

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