BULKHEAD REPAIR - drainage around box beam?

Topic: BULKHEAD REPAIR - drainage around box beam? (Read 1247 times) previous topic - next topic

BULKHEAD REPAIR - drainage around box beam?

May 19, 2015, 04:22:45 am

I finally started on the autopsy for the rear bulk head repair.
As I posted in another post my rear bulkhead looked fine UNTIL I jacked up the rear of the coach to do maintenance (air bags- I had a hole in the old bag and could not raise the rear right wheel area. I had to jack up the upper frame to allow clearance to R&R the new bag) I also had the rear jacked up for brake work.
After this stress it appears that ALL the Rolok bolts failed.
I cut about a 6" strip of the fiberglass under-covering that covers the inside of the box beam. After I removed the insulation I could get a good look at the entire box beam and the failed Roloks bolt.
To my surprise the right outside area was wet under the water pump area. I drained all the fresh water out last fall so I don't know where that wetness originated. I'm surprised that with the fiberglass cover and the insulation right up next to the box beam that nothing was rusted out. The box beam looks to be in great shape despite the trapped water being held against it.

Every Rolok bolt is broken with the pointed end exiting the box beam. In most cases the bolt head is still on the outside of the box beam. This leaves me to believe that even if it looks like your Roloks bolts are there, they could be broken inside the box beam.

I Tried to remove a couple Roloks out by double nutting and hitting with penetrating oil and bringing them all the way through the box beam, as Brett has suggested, but those Roloks all snapped.

I have to add my name to the hat that says Foretravel dropped the ball on the way they chose the attach the bulk heads together. Probably should have been welded together or a much better bolting solution used.

I plan to replace the roloks bolts with 3/8" Grade 8, Zinc coated bolts with nuts and washers. I will also add a 1/8" x 1 1/2" backing plate to the inside of the box beam for extra support on the box beam wall. I will drill out any Rolok bolt that won't come out by double nutting and use the existing hole, and enlarging to 3/8" for the new bolt.

My question;
After seeing the water captured by the insulation and held against the box beam should I leave an air gap between the box beam so water can drain away from the box beam? I do plan on coating the box beam and bolts to help them repel moisture.
I would like to think I could seal the area above and below to keep the box beam dry, but in practicality I think this approach will eventually fail. My current thinking tells me to except water intrusion and allow a way for it to escape.

IDEAS? - SUGGESTIONS?
Thanks for your input!

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #1 – May 19, 2015, 08:03:43 am

For what it is worth, I worked in the machine design industry and I had a policy regarding chips and coolant that I think you should apply here. "If you can't keep it out, then let it out." I would design outlets for the coolant and chips so they could exit the fixture and provide clean, accurate placement of the succeeding part.
I think you should do everything you can to protect all the parts, but do allow egress for any moisture that gets in. The moisture is what causes your problem so let it escape or provide a means of allowing it to evaporate.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #2 – May 19, 2015, 08:06:28 am

If possible, could you take some photos of the "opened up" area showing the damage? For new members of the Forum, it is sometimes hard to visualize this "bulkhead" problem. Don, Brett and others have fully documented the various methods of repair, but every additional photo added to the archive helps "Those who will follow...".

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #3 – May 19, 2015, 08:20:04 am

From what I've read, there seems to be 3 possible sources of water (moisture) in the bulkhead area:
1. Water draining from the "stock location" fresh water tank overflow pipe.
2. Water leaks in the wet bay from one of the holding tanks, or the fresh water tank, or the water system plumbing pipes.
3. Water splashed up by rear tires when driving in heavy rain.
#1 and #2 can be addressed by modifying the drain pipe outlet, and repairing any leaks. Not much you can do about #3 except never drive in the rain or snow (or through big puddles). The "drain holes" you propose might help, or they might add to problem #3. Good luck with your repair.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #4 – May 19, 2015, 11:15:23 am

You seem to have a handle on most of the causes. Yes, Foretravel dropped the ball on the design and choice of materials, especially using the Roloks, a fastener totally out of it's element for the application and environment it is being asked to work in. No corrosion protection so it rusts, is susceptible hydrogen embrittlement and rust jacking from the large amount of rust build up on the back side of the big angle iron. Just as bad was the choice to install the angle iron where moisture and road chemicals could collect behind it.

You can't drill out the Roloks. Just drill a 1/2" inspection hole and use a very inexpensive ($20) USB borescope plugged into a laptop to view the inside of the rectangular tubing and view, video or take stills of the inside. Space and drill between the existing Roloks either matching the number or double up. Since I bought a box of stainless bolts, I have been doubling up. Fasteners on eBay are less than half the price at Fastenal.

I would do a 2 foot or so section at a time, drilling and even doubling up on the number of holes. You can force the angle iron away from the rectangular tubing, remove the rust on the back side of the angle iron with a Sawzall, sandblast the backside and then use various primers to protect it. Spacing the angle iron away 1/16" from the sheet metal and rectangular tubing will let it drain and will stop the accumulation of trapped moisture and chemicals from road salt, etc. Stainless or galvanized washers can be placed between the angle iron and the sheet metal at each new bolt location. You can either open up the belly to get to the other end and install the nut or cut the belly open all the way across and then install several short strips to cover the repaired area.

You can use grade 5 or 8 or stainless fasteners (Roloks are grade 5). I bought a big box of long 3/8" 316 stainless bolts and 316 nylocks /flat washers bolted all the way through. There are special galvanized bolts available that pass underwater installation saltwater tests and would also be a good choice. The grade 8 do require higher torque than the 5 or stainless but won't crush the rectangular tubing unless it has been weakened from interior rust. It does not take many to hold the structure together as you have little strength remaining on yours and have not had a catastrophic failure YET.

Fore

the naysayers worried about the galvanic potential between the steel and the stainless steel, it is extremely low and of zero consequence.

If you have leaks from the tanks, water soaked foam, etc, your repair may be more involved, much more involved. The torque wrench test is not effective in my opinion as the fasteners may have rusted in place and no longer have much strength left. If you can back the bolt off a half turn and then torque, it is a better test. Trouble is that many will fail when you try to back them off a half turn. Coaches with a clean underbelly and angle iron are not an indication of the remaining strength and health of the Roloks.

See my old posts and photos for the amount of rust that collected behind a very short section of a very clean angle iron. I was amazed.

Pierce

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #5 – May 19, 2015, 03:08:27 pm

I am quite surprised that you were not able to double nut the "inboard" end of the Rolock and remove it AFTER using a couple of days of a good penetrating oil. I used 50/50 ATF/acetone.

Remember, the Rolock is a grade 8 bolt. It is only held by two mild steel 1/8" thick walls (that are probably somewhat compromised).

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #6 – May 19, 2015, 05:36:01 pm

Brett,

Where did you get the information that Roloks are grade 8? The manufacturer only claims that they exceed Grade 5 specs.

Rolok fasteners roll-form their own mating threads. The result is a stronger, more uniform thread. The 360° thread-forming lobes preserve the grain structure of the mating threads, rather than cutting them and weakening them. Of course, stronger mating threads also enhance overall fastener performance. All Rolok fasteners are engineered at a minimum straight tensile strength of 135,000 PSI, which exceed grade 5 requirements.

Pierce

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #7 – May 19, 2015, 05:48:07 pm

Pierce,

I certainly could be wrong. But, even if it "just exceeds grade 5", I would expect that the bolt itself would be stronger (in terms of being able to remove it by double nutting) than the two (likely compromised) 1/8" thick wall sections of the box beam. And, in most cases, the Rolocks break just into the outer box beam, the grip there should not be as strong.

As I mentioned, applying a good penetrating oil to both sides of the box beam/Rolock is how I, and others have done it. I used a long Q-tip soaked in penetrating oil over a couple of days.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #8 – May 19, 2015, 10:06:51 pm

While I am not an engineer my limited experience is grade 8 bolts are brittle. Grade 5 are not.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #9 – May 19, 2015, 10:58:35 pm

Ductile vs strength. PSI (stress) is a measure of strength the material can handle before deforming/failing. Yield, elastic deformation, etc are all parts of the material properties. PSI * surface area = clamping force. More bolts or bigger bolts means more clamping force. A bolt is just a spring.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #10 – May 19, 2015, 11:22:35 pm

Chuck said that item 3 is something you cannot do about--well.

I do not know if this is part of the problem with water intrusion getting into the front and rear bays but a few years ago I found a large area that allows water to "pour" into those bays and did something to stop it. Alongside the curved arms for the operation of the bay doors on our coach is/was a vertical vent that allowed water to be thrown from the tires right into the bay. It is slightly shielded on the outside by a piece of angle welded to the panel I guess to try and stop water coming right thru. I have put another "baffle at each one and siliconed them in and since then no water intrudes. I had a feeling that this could have been a problem especially if the inside caulking was broken.
I see in many pictures of coaches that these bays are not in the most clean condition and wonder why the owners have not fixed and cleaned them up so a good watch can be kept on moisture.
JohnH

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #11 – May 20, 2015, 03:52:04 am

Thanks for the advice.
"Coaches with a clean underbelly and angle iron are not an indication of the remaining strength and health of the Roloks."
I can testify to this Pierce, Mine all looked good until they were stressed.
I like the idea of the washers between the angle iron and the box beam. I'm not going to kid myself and think water won't find its way in, I will give it a route back out.

When I replace the strip of fiberglass on the belly in front of the box beam I will leave a way to give a full width inspection so I can see and re-torque the new bolts and nuts in the future.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #12 – May 20, 2015, 11:39:08 am

FT is using a different system to repair bulkheads then Rance over at James. Does anyone know what FT is using and how effective it is?
Or anyone that has FT do bulkheads with pictures

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #13 – May 20, 2015, 01:07:05 pm

Need to verify this is what they are still doing, but in the past, they have used huck bolts (giant rivets). Which to me is a poor solution, as it concentrates the load in the dead middle of the box beam (which in most cases is already compromised). It is quicker, as you do not need to drill holes through the thin fiberglass covering the bottom of the basement. With a through bolt with large washer to spread the load to the horizontal parts of the box beam, you must drill through the thin fiberglass to fit the washer and nut.

Please let us know if this is still their method.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #14 – May 21, 2015, 11:38:11 am

I think I am finally going to add this to my list. When I was speaking with Paul Yasbeck, he told me that often times the bolts are still threaded into the outer angle and are compromised internally such that even if you put a torque wrench on it it will seem to be okay. He said he has seen cases where two failed and then the rest opened up like a zipper almost instantly. The problem is one I see often on motorhome design that is very different on for instance my BMW or a house. In the case of the BMW the sunroof has a rubber seal but right underneath it is a tray leading to tubes that drain the water out. They simply know and expect it to leak over time. In the case of the FT, the floor should be mildly sloped and there should be drains. My fresh water pump sprang a leak and my overflow leaks. I spotted both quickly but I could see how you could miss it. The tanks are all sealed up behind non-opening panels so you can't inspect in there very easily. I saw in a Newell that these cover panels are often hinged or removable so that you can inspect. Seems like a good idea. In the case of a house roof, there is tar paper underneath and even under that is often exterior grade plywood. Belts and suspenders and such.

I worry extra much about mine given that it is the same Roloks as a shorter smaller model but yet my bays hold more stuff, more weight, more fuel, bigger tanks. I have 200 gallons of fresh water capacity. All on the same Roloks. Scary.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #15 – May 21, 2015, 12:00:35 pm

Let us know if you find a broken Rolock that is not broken as it starts threading into the closest wall of the box beam (about 5 threads in from the bolt head).

With the break in this area, a torque wrench WILL tell you very quickly if the bolt is broken. It will either torque up or keep spinning with very little torque applied. When this happens, merely back it out and see where it broke.

I check 100% of bulkhead bolts on every Foretravel mechanical inspection I do. Have had owners/sellers get excited that I was "breaking" the bolts. Standard answer is that I am not only good enough to break them, but good enough to rust the broken end. Yup they had been broken a LONG time.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #16 – May 21, 2015, 12:10:09 pm

The dealer where I bought my coach from was absolutely terrified when I got out the torque wrench.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #17 – May 21, 2015, 04:42:12 pm

Here's a photo of one of the broken bolts from our coach. Notice how the end is rusted - as Brett says, it was broken for a long time (probably since the coach was manufactured) to look like this.

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #18 – May 22, 2015, 12:08:39 am

I sent a broken Rolok in for metallography examination at the company I worked for. What I was told was that the Rolok was a case hardened screw with the case hardening aprox .030 thick. They said the reason the screw I sent in broke was because it was installed at an angle. When it was tightened there was a very high load put on one side of the head and the screw was made to bend where it entered the box frame . This side load cracked the case hardening at the box frame. The soft center of the screw was unable to take the torque load and it stretched to the point of pulling apart. That is why the broken ends of the screw look the way they did. This can explain why some of them broke when they where installed by Foretravel. Someone in the past said that they had found a broken Rolok that the head had been stuck on with silastic rubber , done by Foretravel ? Gam

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #19 – May 22, 2015, 01:29:41 am

Quote from: bogeygolfer – May 21, 2015, 04:42:12 pm

Here's a photo of one of the broken bolts from our coach. Notice how the end is rusted - as Brett says, it was broken for a long time (probably since the coach was manufactured) to look like this.

That is exactly the way all of our broken bolts looked. They start going downhill as soon as water and chemicals get trapped behind the angle iron. Easy fix so no big deal unless you let it go.

Pierce

Re: BULKHEAD REPAIR - drainage around box beam?

Reply #20 – May 22, 2015, 07:43:02 am

Easy fix for the misangled bolt holes. Purchase the two piece washer made just for that type of problem. It has a spherical half that mates with a concave half. Probably available at Grainger or Fastenal.

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