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Topic: Another bulkhead separate question for the experts (Read 807 times) previous topic - next topic

Another bulkhead separate question for the experts

My 89 GV has total separation on the rear.  It isn't the Rollocks like the other posts I've seen, but the lengthwise square tubing has separated from the cross square tube at the welds.  All of them failed across the rear.

I took it to a local welding shop and they proposed a solution I have not seen addressed here.  If the length wise square tubing goes all the way thru to the front, then they are proposing to drill out the angle iron on the back and front and insert a 3/4" rod the full length with a big nut on each end and draw it up.

This versus opening up the bottom and a lot of welding/cutting, etc.

The appealing thing to me besides the cost is that both the front and back bulkheads will be solved at the same time for longer than I will likely care.

My question to the Forum is if this is a viable solution?  Problems?

Thanks in advance.

Re: Another bulkhead separate question for the experts

Reply #1 –
the thing I would be concerned about would be just crushing the tubing in the area of the 3/4" rod. The large number of Roloks spread the force of the bolt up over a large area not just in two or four locations. Gam

Re: Another bulkhead separate question for the experts

Reply #2 –
I would call James Triana and talk with him.

Re: Another bulkhead separate question for the experts

Reply #3 –
The more I think on this well I'm no expert but. I would call everyone and anyone. With out opening the area up how can they tell how bad it is ?Is the tubing rusted through? The bulkhead holds in all four directions hit the gas put on the brakes turn left and right. To me this is just a very bad idea.But then it's only my thinking. one thing I would look into would be replacing the bad piece of square tubing with a piece of 3/8" x 3" x 3" angle iron with one lip under the fore aft tubing. more area for weld and short bolts through 3/4" of iron. Gam

Re: Another bulkhead separate question for the experts

Reply #4 –
I don't know if you're 89' is the same as our 99', but the longitudinal framing does not run continuously from front to back. On our coach at least, and I suspect on yours as well, it is the tubing that runs horizontally across that is continuous.
Don

Re: Another bulkhead separate question for the experts

Reply #5 –
Even if you could run wires from front to back (I have no idea-- James Triana may know), the "taut wires" might hold front to back, but they would offer no torsional rigidity.  Go over an off-angle dip and you would quickly pull things apart.

Re: Another bulkhead separate question for the experts

Reply #6 –
Thanks Guys!! I knew there would be good opinions- I didn't think about the side to side.

Re: Another bulkhead separate question for the experts

Reply #7 –
Suggest you bite the bullet and replace the tubing that goes all the way across after you are sure that is the extent of the corrosion. If there is any damage to the connecting tubes, you could always weld in a rectangular tubing to make up for any metal you had to remove. No harm in going with a thicker wall on the tubing either. Back side of the angle iron will probably have a lot of rust so will need extensive cleanup with a sawsall to get the chunks out. If it were mine, I would go to 3/8" bolts with nuts/washers at the far end. I consider the Roloks a sub-standard fastener for this application and suggest you use something with galvanic protection in grade 5 or better.

Pierce

Re: Another bulkhead separate question for the experts

Reply #8 –
Rolok screws minimum tensile strength is 135,000 PSI. That far Exceeds grade 5 bolting at 85,000PSI. I think Roloks are taking a bad rap . Has anyone ever found the threads strip on a Rolks.In this type installation the threads should be the weak link.  Then why do the screws break? In the past someone said that they found the head of a broken Rolok screw glued in place. To me that would happen when it was broken when it was first installed.As for the rust what came first , the rust or the broken screw? If the screw is good the joint is tight and water will have a hard time getting in. But if the screw is broken then the joint is open.Has anyone found a lot of rust between two screws that are good. I worked for a long time with very high strength bolting . This type of failure can only be found by a metallurgical lab. Personally I think the failure is caused by the Rolok being install into a pilot hole that was drilled by hand on an angel. When the screw iwas installed the head isn't square to the angel iron of the bulkhead. This causes a cocking of the head and a side loading on the Rolok. The Rolok being a high tensile strength screw it is very strong ,but brittle . So it will crack where the bending moment is the highest. If a high tensile screw breaks under load ,the force is re leasted like a gun shot. The head should come out of the hole and be lost. But if the screw cracks under a cocking force then the head with a short stub will stay in the hole.

Re: Another bulkhead separate question for the experts

Reply #9 –
I'd ask FT for a quote on replacing the entire floor structure.  You may not like the $$, but at least you'd know the cost of piece of mind on your coach's structural integrity.