Tequila Mockingbird - 1992 AARE w/ 24" roof raise

[JDecker]

Hello Skoolies,

JDecker here. My wife and I just got out of the USAF and back from Korea, and have started on my/our dream of many years. She was an eBay find back in april, and having searched long and hard for a full length AARE with a Cummins ISC in the back, we picked her up sight unseen for the princely sum of $4500. Flew a friend out to drive the bus back from PA for us, and while he had a breakdown (excess water in the fuel) en route, my friend(of many years and many colorful co-capers) handled everything well and figured everything out no sweat. Insurance lady wouldn't insure it with seats in it, so my uncle and brother pulled the seats out for me. I was in korea the whole time, feeling thankful to have such a great bunch back here at home.

So here's when I first found her, this past December. The seats were out already, and she ran like a champ (after a pair of new batteries.)





So we immediately set to work stripping the interior. We also laid out our Floorplan in blue painter's tape. It will surely change.



Then my brother cut some square tube and some allthread for me, out of my dad's scrap pile. Forgive the gorilla welds-- it was the first time I'd welded since before I enlisted. I used to be pretty decent on MIG.




Today we finished cutting the roof, enough to raise it anyway. If you look closely, you'll notice the cuts aren't the same all the way around. I took the path of convenience to get it raised today, but the rub rail immediately below the windows and the two rows of rivets above the drip rails are all getting removed. We're going up 24" all the way around, which puts us at about 8'1" in the center inside, and right at 12' externally. With low profile A/C units I should be comfortably under 13'6".



If anyone wants to see more pictures, there are more here:

Full Imgur Album

Steel is on hand for the new ribs to be welded in this week. 20 GA galvanized sheets are in, as well, but no rivets ordered yet.

[JDecker]

So, question for the community on this section of the build:



1. As pictured above, I have left the inner skin on the roof for structural integrity.
I reason that: A. We are doing long slides so the roof will need to be strong, and I believe the roof is many times stronger as a 2 layer sandwich. B. Raising the ceiling to 8' means we will have a little headroom to spare for insulation on the inside. C. Even without the inner layer of steel, the ribs would seriously compromise the roof insulation without at least a bit of foam between them and the interior, therefore I'd have to lose some space(we value insulation) either way. D. All those overhead 3/16" stainless rivets would be a lot of work to remove.

My question: would it be feasible to rip the existing fiberglass out without cutting the steel or rivets and fill the space with closed cell spray foam? I know a lot of foams need moisture to dry, but would a 2 part type work?

[claydbal]

found your wife on ebay for $4500 ? cool!!!!!!!!!!!!!!!1

your work looks great. im thinking the roof may deform if you follow with the idea of filling the "sandwich" with expandable foam.

tell us more about getting the insurance.
thanks

[EastCoastCB]

Welcome back the the states. My ex is living in Korea! I hope they have enough to feed her! JK
That was nice of your friends and family... getting the seats out is a pita. You got a sweet bus there!
These roof raises are starting to look easy you guys are doing such great jobs of them!
I wouldn't skip insulating the roof, though. And I agree with claydbal.

[Tango]

Welcome home & thank you for your service --- Looks like a great find at a reasonable price (the bus). What tranny is hooked up to the Cummins?

I looked into injecting foam into my shorty roof and was told by supposed experts to forget it. The urethane does not flow that well, sets too quickly and would at best be spotty.

And I am in total agreement regarding keeping both the inner & outer skins intact (a subject of more than a few heated exchanges here). However, the inner skin can be pulled, the roof sprayed and leveled, then the skin replaced. And don't forget to make accommodations for any electrical that is or will be routed up there.

Congrats on a great find and please do keep the pix coming.

PS...LOVE the name !!!

[The Nebuchadnezzar]

Welcome! Good work so far, love the underbelly storage.

[aaronsb]

If I wanted to retain the steel skin without removing it, I would figure out a way to use a hole saw to cut a number of 4-6" round access holes throughout from front to rear, and use a hook, crook, and vaccum cleaner to suck out all the old fiberglass batt.

Do whatever prep for wiring or whatever, then get your spray foam contractor to shoot foam back into the gap between the lower and upper sheets through your access ports. Use the inner sheet metal as a support for whatever "nice" headliner you end up installing.

I elected to remove the inner sheet on mine, because it was a bunch of weird perf steel.

I felt the following things outweight the benefits of leaving the inner metal there:

* Significant cold bridge contact surface
* Opportunity for reduction of an "expensive" moment arm mass after a cab lift (approx. 600 lbs)
* Based on experience I have working with other cab structures, the inner steel does not massively improve the performance of the structure, but is there more from a regulatory conformance standpoint than anything else.

Originally Posted by JDecker

So, question for the community on this section of the build:



1. As pictured above, I have left the inner skin on the roof for structural integrity.
I reason that: A. We are doing long slides so the roof will need to be strong, and I believe the roof is many times stronger as a 2 layer sandwich. B. Raising the ceiling to 8' means we will have a little headroom to spare for insulation on the inside. C. Even without the inner layer of steel, the ribs would seriously compromise the roof insulation without at least a bit of foam between them and the interior, therefore I'd have to lose some space(we value insulation) either way. D. All those overhead 3/16" stainless rivets would be a lot of work to remove.

My question: would it be feasible to rip the existing fiberglass out without cutting the steel or rivets and fill the space with closed cell spray foam? I know a lot of foams need moisture to dry, but would a 2 part type work?

[JDecker]

All,

Thanks for the warm welcome! We want to full time, so insulation is of course a BIG priority. My wife is very excited for our adventure, but gave me the condition that she must always be warm. I can live with that!

Nebuchadnezzar,

Thanks! Have plans to expand that basement!

Tango,

Believe it's a MT643 based on engine and model year, but have not confirmed. Fingers are crossed for an MD3060, but I don't believe they go back that far. I don't think they ever used the AT545 behind the 8.3. Regarding the ceiling, I don't see the benefit of removing the 3.4 million rivets (I counted) as long as I plan on putting it back up there. If there was an easy way, maybe, but the rivets are 3/16" stainless: impervious to our air chisel, and awful tough with a regular hammer and chisel. I'm afraid I'd weaken the rivet holes grinding them out. HF in our area doesn't stock a larger air chisel.

I therefore plan to take what I can get for insulation in the top layer -- as a "bonus" -- and plan on about 1.5-2" of closed cellspray foam under that, and then electrical traces in the center under that.

EastCoastCB,

Hope your ex likes spicy, fermented cabbage!

claydbal,

Our family has worked with the same 'insurance lady' for years. I had motorcycle insurance through USAA(Progressive), but called and was denied by them and about 6 other places for bus insurance, calling from Korea in the middle of the night. Still waiting for a bill for our temporary coverage, it's been 9 months! Hopefully it's easier after the title says 'RV.' PM me if you want contact info, but she's in Missouri.

aaronsb,

How was your ceiling fastened on, and how did you remove it? Relative difficulty of removal is a undoubtedly a factor I wish I didn't have to consider. I do believe the structural difference may be noticeable with 15+ foot slideouts. Word on the moment arm and thermal bridge, though. Perhaps a very 'open' version of the hole pattern you suggest would be a good compromise.

[aaronsb]

edit: I forgot to add it took me two 8 hour days of chiseling rivets with an air chisel to remove all the panels from my ceiling. They were all painted stainless steel rivets.


I'm pretty squarely in the camp that while the interior sheet metal helps in it's purpose as a school bus, it doesn't really do much as an RV conversion. There are always many caveats, ipso factos, and quid pro quos of course.

I did some research in the way the boxed structure gets formed from the two sheets, and I think removing all the windows and replacing them with riveted sheet skin (attached to the ribs, tops, and bottoms) adds back most of the rigidity you've lost by removing the interior skin.

The ribs are subject to torsion and fore to aft lateral forces in normal and emergency situations, and the factory window frames preclude any sort of way to communicate the stress from the roof to the lower chassis. To compensate for that, the interior steel skin forms a full box structure that keeps the roof rigid.

If the interior skin is removed, and the windows replaced with sheet metal as mentioned above, the roof flexing forces are fully transferred to the lower structure, and rigidity is retained without the need for the inner ceiling panel.

I would imagine that if you're building slides (and thus cutting large holes in the bus) you could benefit from the interior skin. I considered them with great scrutiny and ultimately decided against it, since it goes contrary to my reasons for selecting a school bus chassis platform. If I had picked perhaps an MCI chassis or similar I probably would have built slides.

Some questions and observations in my mind about slides:

How are you transferring the stress and weight from the unsupported ribs to the supported ribs?

Are you bolstering the framing and lower floor support ribs (the horizontal ones that bolt to the truck body frame) to carry the additional point loads?

If the slide system is bolted directly to the frame, and thus the body/cabin "floats" around the slide and structure, is it really necessary to overbuild the cabin then?

The body of the bus is designed for torsional flex fore to aft. Perhaps it would make sense to retain the inner skin only in the sectors where the slides are at, especially if you'll be skinning and riveting the non-slide sections.

Originally Posted by JDecker

All,
aaronsb,

How was your ceiling fastened on, and how did you remove it? Relative difficulty of removal is a undoubtedly a factor I wish I didn't have to consider. I do believe the structural difference may be noticeable with 15+ foot slideouts. Word on the moment arm and thermal bridge, though. Perhaps a very 'open' version of the hole pattern you suggest would be a good compromise.

[MuddaEarth]

Looking good.....I'm preparing to do a raise on mine also.

I drilled out all the smaller rivets on the side walls and started to drill all the ceiling rivets, about 2 rows in and 7 drill bits later, I chose to chisel them off. I used a Snap-On PH3050....It chiseled them off in no time. I did walls and roof in a weekend by myself. There's a link to a short video of the process on my thread if you'd like to watch it.

As far as insulating, My bus had doublers that ran forward and aft the entire length of the bus between the ribs. They are overhead, roughly in line with the outer edges of the escape hatches. Yours may not have them, but if so, you'd have to cut access holes to blow in insulation in the center sections of the roof. You can see them clearly in the video, I believe it's on page 5 of my thread.

If it were me......I'd go ahead and takes the inner skins off. It would be a much easier task of fully insulating the roof well.

[EastCoastCB]

You guys and the root raising... I'm about talked into it now...

[JDecker]

I did some research in the way the boxed structure gets formed from the two sheets, and I think removing all the windows and replacing them with riveted sheet skin (attached to the ribs, tops, and bottoms) adds back most of the rigidity you've lost by removing the interior skin.

The ribs are subject to torsion and fore to aft lateral forces in normal and emergency situations, and the factory window frames preclude any sort of way to communicate the stress from the roof to the lower chassis. To compensate for that, the interior steel skin forms a full box structure that keeps the roof rigid.

If the interior skin is removed, and the windows replaced with sheet metal as mentioned above, the roof flexing forces are fully transferred to the lower structure, and rigidity is retained without the need for the inner ceiling panel.

I'm in agreement. IMHO the inner panels should be retained over the slideouts, at least, as that area is without the box structure provided by the skin over the sides. Where the side is skinned, the effect is the same. It's probably overkill, but that's why we like school buses in the first place. I'm on the look out for a 6" hole saw, I think the perforations would sacrifice very little in terms of strength, and having it set in dense, sticky foam would somewhat offset that. They would also negate any issues caused by the 'doublers' MuddaEarth mentions-- haven't probed for them yet.

I'm also on the hunt for a Snap-On-PH3050-equivalent air chisel to borrow, as the $400 they want for one is outside my budget. Our craftsman 875 weighs about 1/4 what those do.

How are you transferring the stress and weight from the unsupported ribs to the supported ribs?

We're using 1.5"x2"x.125" rectangular tube to extend the supported ribs. There will be a box around the slideout made of the same stuff, and the header piece will extend to the first supported rib. The roof will spread the load.

Are you bolstering the framing and lower floor support ribs (the horizontal ones that bolt to the truck body frame) to carry the additional point loads?

If the slide system is bolted directly to the frame, and thus the body/cabin "floats" around the slide and structure, is it really necessary to overbuild the cabin then?

There will be 2 large male/female square tubes that support the extended slide, similar to the pirate4x4 build that Nat often links(don't have a link handy). It'll have a supportive wear rail along the bottom outside chassis edge, as well. The slide will essentially be a floating box, so the bus will be slightly overbuilt to support it from the bottom and also so that it will keep its bus shape around the slide-- in the event of a collision, as time and gravity take their toll, or if I ever want to drag race her with the slides out .

Also, EastCoastCB, I can't speak personally for the ease of the roof raise, seeing as mine is yet to be supported by anything but 2 tiedowns and some allthread!

No progress today; rebuilding my parents' (korean made) GE dryer. The wife and I are under contract on a house, but until we get it we have to pay our rent somehow!

[skoolie_n00bie]

Hold on a sec.... Are you telling me that if I want to raise the roof and remove the inner skin to replace the insulation, I either put back the inner skin, or cover my windows?!? What if I want to cover my new insulation with plywood? Isn't that what most ppl do in these cases?

Sent from my SPH-L710 using Tapatalk

[EastCoastCB]

I like the use of the allthread. I can get that cheap or free.

[JDecker]

EastCoastCB,

For lift hardware, we used 3' of 1" x 1/8" square tube, 18' of 3/4" allthread, 18x 3/4" nuts, 6x 3/4" washers, 2 ratchet straps(in an 'X' for stability after ~12" of height), and some welding wire. Pretty economical.

skoolie_n00bie,

Regarding leaving the inner skin or skinning the windows, the difference in performance (that aaronsb and I speak of) would likely only be apparent in a serious accident. It's important to me that the roof be exceptionally sturdy, but even with no skin and no inner roof layer, you're still worlds ahead of the average sticks and staples. And as always, our armchair engineering degrees may have come from different universities.


Back on the subject of my build, I took some measurements for the slides today and hope to get the frames and ribs roughed in by the middle of next week. I also took measurements and did some brainstorming for the basement and radiant floor heating. Saturday we judge a regional science competition(balsa wood bridges!) and then Sunday we're going to pick up 1200 board feet of kilned lumber (mostly walnut) cut from my parents' land, some of which will become my interior cabinets! Talk about a birthday present!

[EastCoastCB]

Thanks, any and all info and pics appreciated! Especially related to roof raising!

[skoolie_n00bie]

Understood
Thanks!

Sent from my SPH-L710 using Tapatalk

[bansil]

Originally Posted by JDecker

All,

Thanks for the warm welcome! We want to full time, so insulation is of course a BIG priority. My wife is very excited for our adventure, but gave me the condition that she must always be warm. I can live with that!

welcome, and far enough south a convertible could be warm...beautiful sunrises/sunsets and fresh air and the stars at night all from your bus