removal of MCI inner panels?

busshawg · November 04, 2008, 09:37:44 AM

How many of you have removed your inner wall panels on your MC9s, sprayed insulation without welding in any extra significant bracing. How structural are these inner panels? And if you have done so have you had any problems?

Have Fun
Grant

John316 · November 04, 2008, 09:46:35 AM

In our DL3 those panels, under the windows, are structural (I would assume a 9 is about the same). I could have pulled them off for insulation, but that seemed like a lot of work to grind the welds off, and then re-weld them back on.

Just my .00002.

HTH

God bless,

John

JohnEd · November 04, 2008, 10:03:25 AM

Grant,

My info is only from pictures now. Your best data is at Gumpy's site....A-Z. What I have sen is that the water condensates "inside" the vertical channel and then runs down to the floor behind the panel. The bottom of the vert is a reinforced area and has a couple triangle sections. Some apparently "rust free" buses have a lot of rust in these areas. Replacing the rusted sections is a absolute must and while you are at it you might as well incorporate the diagonal braces. If the interior skin does in fact add anything to the structural strength then adding the diagonals would compensate. Most Knuts are deep into overkill. Don't forget to drill holes in the vert components and squirt a little foam into the channel every 8 inches or so. That will stop the condensation. I think the windows sweat and that water also ends up inside the walls at the bottom of the ribs. I would do the braces if I was doing any welding. I would also put firing strips on the wall and deeply countersink the attaching screws as the heads will become "cold spots" and defeat the insulation in those tiny areas. Small potatoes but countersinking isn't a "big" deal by any stretch. There are lots of sites put up by Knuts to share their work and procedures and I know some readily answer mail with questions. Use this resource cause it was created for you and the likes.

The diagonal BRACES ARE OFTEN NOT WELDED ON THE OUTSIDE EDGE AS THE EXTERIOR SKIN HASN'T BEEN REMOVED. CAPLOCKS! The only universal recommendation among Knuts that have converted a 9 is to
raise the roof at least 8 inches.

HTH

John "with no hands on"

Tom Y · November 04, 2008, 06:53:38 PM

Grant, I did on my 5C about the same as your 9 but 5 feet shorter. I fixed the rottted metal, insulated with foil foam and reinstalled the alumium inner panels. I have not driven it yet but should be plenty strong. Tom Y

busshawg · November 05, 2008, 08:26:22 AM

Thanks for you replies. The reason I was asking was that I am a little confused as to what people are doing. I have read both senarios. I did remove mine, welded in new pieces where the metal was bad, I also welded in horizantal pieces between the window frames where I did remove windows, then had it sprayed in with insulation. Then continued with the strips and lined it with 5/8s plywood. This was done without replacing the interiour metal panels. I'm hoping this will be alright as I was informed at the time that this would be alright. Then the other day I was reading through this site and came across someone saying the interiour panels MUST be replaced. I hope he's wrong but if not I would go back and redo. Better that having a structural problem.

Thanks

Sojourner · November 05, 2008, 11:00:58 AM

About inter panel in MCI 5, 7, 8 and 9 are pop riveted on and which is not structural as the outer skin with solid rivet.
However, inter panel is good retainer under 1/2" plywood wall for sheet metal screws to hold onto.

John316 MCI DL is perhap difference. John said is welded on. That on newer DL. That new on me because not many have them for conversion until now to learn that. Thanks John316.

FWIW

Sojourn for Christ, Gerald

John316 · November 05, 2008, 12:11:50 PM

Gerald, I need to clarify. Inside we started pulling off the fiberglass sheets that were on the walls. In the back I found big steel plates that were welded on (remember this is inside). I thought that that was part of the frame (which it is) and that they ran the whole length of the bus. Since we found out all that metal was behind the fiberglass, why not just leave the fiberglass sheets there. Right? Wrong!!!

Today while we were installing the 5/8 plywood for skinning, we had to pull that fiberglass sheeting off, since it was in the way. Up front we "happened" to find that there was no metal plates below the windows

. We could have taken those sheets of foam insulation out, that was back there, and spray all new foam in (did I mention that we had the foam sprayed yesterday!). I'm not sure why they have the metal plates in the back half (maybe to support the engine and tranny), but I was disappointed to learn about that. We could have had that many more R value. Oh well...live and learn.

The bottom line is, on a DL3 anyways, that the metal plates, that are welded under the windows (again I am talking about the heavy thick metal plates, not the support trusses) in the back half, are structural. If you (busshawg) had to take off those plates (I doubt that your bus has them if it is older that a C or DL3), it would have been VERY memorable. There wouldn't be a doubt in your mind whether those were structural or not. My thought is, you don't have an issue.

Our DL3 has a self supporting truss system like the E series. It doesn't need the outside skin for structural support. Ours is a flat skin bus.

HTH

God bless,

John

busshawg · November 05, 2008, 01:09:48 PM

Thanks again guys, I was told they were NOT structrual. However after reading some posts I was a little concerned so this does ease my mind. I do believe and have been told that the sprayed in insulation will add a significant amount of strength as well. Thanks again.

Have fun
Grant

chazwood · November 05, 2008, 02:55:08 PM

I took off the inside panels on my 82 MC-9, sprayed foam and then drove it around for a few weekends. (about 500 miles)

When I put back in all the some-odd 700 rivets, every single hole lined up prefect.
If the inside panels are structural, don't you think a few of those holes would have become misaligned in all that driving around?

Just a though.

Jriddle · November 05, 2008, 05:29:51 PM

Grant
I am a lot like you. I was told that these panels could be removed. After reading post here found that panels on inside are structural. I did read Craig's web site and added bracing to help make up for structure that may have been lost. I am not a structural engineer but one thing I keep in my mind is that the bus was designed to carry at least 47 people, baggage and any cargo that could be added in bays. The next thing, after I looked at Craig's frame work when he removed his siding and saw most of the main uprights were rotted off. His bus was still driving around before he removed panels and found the damage. There must be a lot of over design from the manufacture. I can't believe that I will add that kind of weight back into my bus when done. I hope that this helps you. I have decided after reading some post here and other places, that many have done what you have done and are getting around just fine.
John

Sojourner · November 05, 2008, 11:29:42 PM

Quote from: John316 on November 05, 2008, 12:11:50 PM
Gerald, I need to clarify. Inside we started pulling off the fiberglass sheets that were on the walls. In the back I found big steel plates that were welded on (remember this is inside). I thought that that was part of the frame (which it is) and that they ran the whole length of the bus. Since we found out all that metal was behind the fiberglass, why not just leave the fiberglass sheets there. Right? Wrong!!!

Today while we were installing the 5/8 plywood for skinning, we had to pull that fiberglass sheeting off, since it was in the way. Up front we "happened" to find that there was no metal plates below the windows . We could have taken those sheets of foam insulation out, that was back there, and spray all new foam in (did I mention that we had the foam sprayed yesterday!). I'm not sure why they have the metal plates in the back half (maybe to support the engine and tranny), but I was disappointed to learn about that. We could have had that many more R value. Oh well...live and learn.

The bottom line is, on a DL3 anyways, that the metal plates, that are welded under the windows (again I am talking about the heavy thick metal plates, not the support trusses) in the back half, are structural. If you (busshawg) had to take off those plates (I doubt that your bus has them if it is older that a C or DL3), it would have been VERY memorable. There wouldn't be a doubt in your mind whether those were structural or not. My thought is, you don't have an issue.

Our DL3 has a self supporting truss system like the E series. It doesn't need the outside skin for structural support. Ours is a flat skin bus.

HTH

God bless,

John

Thank you for answering my question about if the DLs' are truss design or monocoupe.

I do know that using fiber-glass outer skin is not structural. However, it needs to be truss frame type, either using diagonal braces and/or metal plates to control the fore and aft movement and to carry the weight. Your DL with the welded metal plates maybe your substitute diagonal braces. In other words, if it is welded on...don't remove them. But the earlier MCI's are not structural. I know someone a few years ago called MCI about this MCI-8 inter aluminum panel if it is structural....they said it is. Well that has to come from non bridge designer engineer because there is no way it can be structural using pop-rivet fasteners.

Only rivet that are for structural is either solid steel or aluminum or pull type rivet that leave a tight mandrel within to retain it bolt shape.

So there are 2 kinds of purpose of the all rivets:
1) Dual purpose rivet are for structural and holding on type.
2) Single purpose rivet are for holding on type. Such as Pop Rivet

Thank you John316 for the update about DL series construction.

FWIW

Sojourn for Christ, Gerald

busshawg · November 06, 2008, 07:01:04 AM

Very interesting, especially the fact that Chazwood had his inner panels off , put that many miles on it and all the holes lined back up. Good for you for trying it, can't believe you put all those rivots back in. A conversion project involves SO much work as it is!

Have fun

chazwood · November 06, 2008, 04:25:10 PM

Putting back all those rivets (if memory serves me correctly there were over 700) was actually kinda fun. I bought a pneumatic rivet gun from Harbor Freight and went to town with my kids.

It didn't take very long and the rivets were cheap.

The only problem is, after you're all done, you step back .....and it looks like you haven't accomplished a thing.