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Foretravel Bulkhead Issue

August 01, 2010, 06:27:30 pm

We just pulled into an RV Park in McMinnville, Oregon.

There are two other Foretravels here in the park.  We started talking and got to discussing the Bulkhead question.  Ours had the minor repairs described below and is in perfect condition. One of the others was OK (no separation, no rust, etc), though he has not yet put a torque wrench on the Rolok bolts. The other is from up north and shows signs of a lot of rust.  The bulkheads are the worst I have ever seen-- you can stick your fingers between the sections.

PLEASE, this is an easy (and not too expensive) issue if checked and bolts replaced BEFORE enough fail that the bulkhead separates.  If you have a Unihome or Unicoach,  take a few minutes and check yours (see below from an earlier post).

Brett Wolfe

This is on a 1993 U240, but it is my understanding that most applies to Unibody and Unicoaches.

I am not sure bulkhead is a descriptive term here.  The center part of the coach is built on a
strong grid system with 1 1/2" box beams with 1/8" walls at the ends (front and rear) where they
attach to the 1/4" angle that is part of the frame holding the drive train (rear) and front end
(front).

From the factory, the two "areas" were attached using 5/16" Roloks:
(http://www.semblex.com/files/Rolok-Semblex.pdf)

The Rolok's go through the ¼" angle and torque into 1 1/2" box w 1/8" walls.

After talking with Mark Harvey at Foretravel and an engineer at Rolok, I went under the coach.
First, I looked for any separation in the area of attachment.  NONE-- just some light superficial
rust that I will sand and undercoat.

Next, I put a torque wrench on each of the Roloks.  Check torque to 250 INCH (repeat INCH) pounds.
Check torque CW and CCW. If they don't hold you need to know that.  If it loosens, use that hole
(drilled to 3/8") to install a thru-bolt.

What I found was that 5 Rolok bolt "heads with 4 threads" broke IMMEDIATELY-- at less than 20
inch-lbs. All the rest did not move at 250.  In inspecting the failed Roloks, all had been broken
for a long time-- light surface rust on the sheared surface. The "4 threads" mean they were broken
where they started torquing into the 1 1/2" beam.  Could have been broken at installation or from
sheer stress afterwards.  Not sure it matters.

The fix:  As well described by others, the answer is to thru-drill and install 3/8"X 3", Grade 8
bolts and nuts on either side of the "failed" Roloks.  Yes, you can use shorter ones, but the 3"
ones made the job a little easier. Because I wanted to be able to torque the thru-bolts to 275
in-lbs without taking any chance of crushing the box beam, I made some 1 3/8" X 1 3/8"1/8" plates to
install next to the beam (cost me a piece of steel and $10 at a machine shop).  So on the rear, from
the rear: the 3/8" bolt, washer, 1/4" angle, 1 1/2" bulkhead, 1 3/8X 1 3/8X 1/8" plate, washer and
pinch nut. All hardware grade 8 (except plate). Torque 275 in-lbs.

I used good quality Cobalt bits, progressing up one bit size at a time, using plenty of cutting oil
and keeping the bit cool.  Then, to access the "inside" to install the plate, washer and nut, I used
a 1 3/8" hole saw to cut through the very thin fiberglass bottom of the coach.  Hole was centered on
the bolt left to right and the closest edge of the hole was approximately 3/4" in from the inboard
edge of 1 1/2" beam.  This allows access with a screwdriver to easily remove the foam core, exposing
the beam and also access for the 9/16" wrench to tighten the nut.  When locating the thru-bolts, use
a magnet to locate the other beams in the fiberglass "floor" to the basement.  Since you need access
to install the plate, washer and nut, obviously, avoid areas with beams in the floor.

I wanted a water-proof plug-- driving through rain could "challenge" plugs not designed to keep
water out unless sealant, etc was used.

The largest I could find was the 1 3/8" Heyco plug PN 3837
(http://heyco.com/products/sec_02/2-09.html). This really gave plenty of access.

The other suggestion is that, at least on the coaches I have seen, there is nothing keeping water
from migrating in past the head and threads of the Roloks-- i.e. the 1/4" beam is drilled larger, so
the Rolok threads will torque in the 1 1/2" beam.  That leaves room for water to migrate in along
the side of the Rolok where it goes through the 1/4" beam.  I will solve that by wire brushing the
beam and short metal "skirt" just inboard of it. Then put masking tape on the head of the Roloks
(where a socket would fit) and use automotive undercoating to seal the area, making sure the Rolok
to beam joint is protected.

I suggest to everyone that this is ROUTINE PREVENTIVE MAINTENANCE AND THE ROLOKS NEED TO BE CHECKED
ANNUALLY.

It wasn't a fun project, but neither was it mechanically challenging or expensive.

BTW, Dianne and I will be out of town for the next 4 days, so Internet access questionable.

Brett Wolfe

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Re: Foretravel Bulkhead Issue

Reply #1 – August 02, 2010, 11:27:03 pm

When I had mine checked by Wayne Musser (?), I asked about sealing up the joints - eg. applying undercoating.  (I believe he did many of the bulkead repairs.)  He didn't like the idea.  He told me better to leave unsealed so any water, or whatever, could drain if leak occurred in bay.  His advice was to do thorough and regular washing of the underside joint area.  That has bothered me ever since because any kind of water pressure would probably force water into the joint.  Of course, so would driving on wet pavement, or worse, salted roadway.

What are others' opinions and what have you done with the joints?

Mike Spitz
2003 U-295

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Re: Foretravel Bulkhead Issue

Reply #2 – August 03, 2010, 12:43:32 am

We use a spray can of undercoat, repeated every once in a while, especially after we recently put in several more bolts and nuts ourselves.

When Wayne did our first bolt prevention, he used and recommended spray can of rustproof.

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Re: Foretravel Bulkhead Issue

Reply #3 – August 03, 2010, 10:42:23 am

Mike,

See my post above for how I treated this issue.

Clearly, one of the causes of bulkhead separation is a leak in the wet bay.  The water WILL get down to the bulkhead area and can cause rust and in severe cases rust jacking, broken bolts and bulkhead separation. And, even if the bottom is not sealed, there is clearly no "safe" path for water in the wet bay to exit without wetting the beam.

So, if you are conscientious about not allowing water to leak onto the wet bay floor, definitely seal the bottom with undercoating as the other source of water is from the road.  I masked off the head of the Rolok and replacement bolts and sealed the beam to bolt area, as you sure don't want water migration into that area.

Brett Wolfe

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96 Bulkhead Repair

Reply #4 – September 24, 2010, 07:01:10 pm

Although my bulkheads seem to be in good shape, I have decided to install the larger grade 8 bolts.  Here is what I have found so far.  The tube in the basement floor just in front of the rear piece of angle that extends all the way across the coach is 1 1/2" x 1 1/2" as has been stated in previous discussions.  The bolts do indeed pierce both sides of the tube.  The tube that is in the front behind the piece of angle is 3" x 1 1/2" so the bolts only pierce one side of the tube.  In addition in several places there is extra tubing just behind the 3" piece.  They may be there as support for the large propane tank and batteries.  My fuel tank is not against the front bulkhead as in later models, but it is in the front compartment.  So far I have drilled a few access holes  with a hole saw in the fiberglass skin, just to see what is what being very careful not to drill through the floor and into a tank.  I did manage to remove a few bolts that are not broken.  Also could not budge some with an ordinary socket and ratchet handle.  Have not tried to remove all the bolts, but 2 more that had passed the torque test were found to be previously broken (rusted at the break).  Due to this I now plan  to drill holes for new bolts in between the existing bolts using a jig to guide the drill bit.  Just seems like a waste of time to try to remove the broken pieces of bolts.  Will give the double nut technique a try on one just to see if it works.

Hear is a surprise, took one of the "rolok bolts" to a bolt supply  and was told that it was not a Rolok bolt, just a pointed hardened bolt 5/16 x 18 thread of indeterminate manufacture.  He said that a Rolok bolt has a some what triangular cross section and these bolts are just round like most bolts. 

Between the suspension frame and the bulkhead is a piece of sheet metal.  It is tack welded to the angle where the bolts are and to other pieces about every 2".  My plan is to apply CorrosionX in the joint area.  Should I apply ospho or phosphoric acid or similar first?  Should I spray some CorrosionX in the tubing before installing the bolts?  Opinions requested. 

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Re: 96 Bulkhead Repair

Reply #5 – September 24, 2010, 07:52:42 pm

Where we put bolts and nuts, I cut a piece of 1-1/2 wide steel to a length that would fit into our 2" bottom drilled access holes to be used as a flat washer against the 1-1/2  x 1-1/2 metal tube.  This flat washer puts pressure on the stronger edges of the square tube.  We painted the cut steel white and placed it in the access hole after the new bolt hole was drilled. Then ran the drill bit back it to mark my white steel, which then went to a drill press to make the hole in the proper place.  Widening the inside of the 2" access hole against the square tube will allow for a longer piece of white steel.  Important to add some new bolts as close to the outer edges to help hold parts together.
 
To locate the in-floor steel square tubing (both side to side and front to back) is located, I used a good magnet to slide along the bottom of the fiberglass and marked the open spaces with a magic marker.  We then know where to not drill due to front to back steel interference and where to drill our 2" access hole.
 
Between the top and bottom surfaces of the floor is blue Styrofoam and what looks like two stacked pieces of 3/4" marine plywood.  We used a hole-saw where I put a thick washer between the mandrel and bottom of the hole saw to reduce how much the hole saw drill bit stuck out, to prevent puncturing the top of the floor and potentially a tank on top of the floor.  I finished removing the foam or plywood just under the floor with a wood chisel.
 
I don't understand your finding of 1-1/2" x 3" tubing.  Maybe it is two pieces of 1-1/2" x 1-1/2".

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Re: 96 Bulkhead Repair

Reply #6 – September 24, 2010, 08:30:20 pm

Jerry,

CorrosionX is for metal you are NOT going to paint.  You can not paint over CorrosionX until it is removed by a strong solvent or sanding.

Your application appears to be needing paint.  So, use Ospho to kill surface corrosion and prime the metal.  Then paint for long lasting protection.

James Stallings at Xtreme Paint and Graphics used Ospho in the cleaned gap on my coach and then painted to protect the metal surface.

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Re: Foretravel Bulkhead Issue

Reply #7 – September 25, 2010, 12:24:41 am

Thanks for the advise about not being able to paint over CorrosionX, I did not know that.  The piece of tubing in front is 3"x 1 1/2" as I was able to remove a bolt there and probed around in the hole with an ice pick as I too thought it could be 2 pieces of tubing.  I did use a magnet to locate the tubes, and plan on backing the tube with a flat piece of 1 1/2" steel.  I also found some wood above the blue foam at the rear bulkhead. 

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