| Author |
Message |
Malcolm
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 11, 2006 - 11:12 pm: | |
We are trying to find out where to block the frame on our '81 Prevost Le Mirage, so we can safely cut and raise the roof 8". We read that the coach chassis bend if you dont do this. We heard something about jacking points, But as this is a new bus to us, we can't even tell were they are yet! Any help would be apreciated. Anyone know where to get slideout mechanisumes at a resonable cost. Thanks in advance. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, February 11, 2006 - 11:40 pm: | |
(*GASP*)
Malcolm, your question takes the breath out of me. I can't
imagine anyone that isn't familiar enough with their bus to know
where to place the blocks, is going to undertake a roof raise
and add a "slide out"...... by themselves.
I wish you much luck and safe travel through your dream.
Your trip is just beginning.... go it one step at a time. Think
"safety" with each and every step. Ask here, about safe work
procedures, and ask at the local bus garage as well. Do not take
what you are about to undertake, lightly. Iron and steel do not
apologize after crushing your body.
There will be many posts to follow, to help guide you..
I am a novice myself; know nothing about Prevost; I can
only wish you well. |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 12:30 am: | |
Malcolm,
I picked up a dozen screw jacks, much like trailer supports, for this purpose.
My approach to the roof raise will be as follows.
I have the floors of my MCI-9s removed. I will repair the underfloor structure associated with the wheel wells and air beams, install the fresh water tanks in the subfloor area above the bays - ala Gumpydog, install braces for seat mounts, wall supports, etc., and prepare to raise the driver area and ramp at the same time I raise the roof. Some additional structure in the bays to support various items of equipment will also be planned and/or laid out. The permanent floor will be installed, but not permanently (no tar tape) establishing a flat floor surface.
After airing up the bags (but not all the way), I will "cat's cradle" string the floor with 1" standoffs, using a 6' level and a 1" spacer to verify the floor for flat and absence of twist.
I will then position the jack stands and screw jacks at various structural points at the front and rear suspension hard points and below the various verticals between the bay doors. The bus will be dropped on the jack stands [first], lightly, the cat's cradle checked/verified, and the jack stands shimmed as necessary to establish a level, untwisted floor.
The screw jacks will be positioned and adjusted under the bay door verticals (You'll have to verify on your Prevost how to best do this), finally, with, [for example], 1" spacers for all, the bags are raised fully spacers installed and the bus lowered until it contacts all support points simultaneously (I hope!). Once again, checking the cat's cradle for level, twist, and now, slide a 1" spacer around the perimeter of the cat's cradle to verify no "bow" or "dip" in the floor between the four corners of the cradle (not attributable to variations in the floor structure (stringline the supports first, before laying the flooring, if in doubt)).
I forgot to mention, I'm fortunate enough to have a shop with a 8" concrete floor large enough to park the bus inside. You don't want a soft floor that will settle - (saves adjustments)
Sometimes stresses are built up in the chassis that "relax" when the roof is separated from the bottom. If you pull a string line on the upper section and mark with spray paint, you'll see a difference between the string and line (don't forget roof may sag when lifted! - I'm talking about weird variations not a progressive sag between supports) Check the "cat's cradle" string line for the floor also, if so, adjustments will have to be made on the fly - use your judgment or consult someone with more knowledge. Adjust spacers to match, or use "come alongs" to make the roof confom to the bottom. I don't think I'd try to releave stress in the roof to make it conform to the bottom, too many variable and most likely a waste of time.
As for the rest of the procedure, Dave Galey's "Bible", Gumpydog's excellent site or various issues of BC magazine.
Excuse the long winded post. I can't recall anybody going into this detail on roof raise set-up previously and I felt it was an unaddressed issue.
As Luke says, Hope this Helps!
Onward and Upward
Marc Bourget |
Pat Bartlett (Muddog16)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 8:29 am: | |
Malcolm
Bryce Robson, used a method of raising his roof, that for Prevosts was the only one I found when I was getting ready to raise mine. Bryces method was simple and easy. I actually spent more time thinking about it than doing the roof raise. I'm sure Marcs methods are just as good! One point Marc raised was, are you indoors or out. I don't have a large shop to bring mine inside, I know that Bryce did his indoors also. What I did was purchase a small laser level from Lowe's, ($80). One evening after dark armed with this laser level I proceded to shoot the concrete the bus was sitting on from front to rear. I knew when I built my house that I sloped the driveway in two directions away and from the house. With the laser at the front of the bus I took measurements at the rear of the front wheel wells(there is a major support beam located there on both drivers and passengers side). Then I moved to the rear drive wheels on both sides and took measurements again (using the laser which I could see on my measuring tape) I recorded all of my measurements on a drawing of the bus. I now knew how much cribbing I needed at each point. At the rear I used the rear axle support for leveling the rear of the bus. I used good oak cribbing it will not crush as will pressure treated lumber. After leveling my bus I checked with the laser in the main cabin to make sure it agreed. I put the laser in the front of the cabin on the floor the laser beam was 2 inches off of the floor,(that is the way it was made) I just made sure that I had the same two inches on all four corners inside the cabin. I didn't block in the middle I could not find any sag at all. But, if you find sag, place your cribbing at the walls between each baggage compartment there is steel structure at each of those locations. My prevost is an 82 and should be the same as yours. Under the flooring in your bays are two 2"x3" supports that run the length of your baggae compartments front to rear. These beams are about 27 inches in from the outside of the bus on both sides. You do more measuring than work and its easy just take your time!
Slidouts, I'm pretty ambitious but I couldn't bring myself to try it. I spent a lot of time finding the stuff to do it with. Unlike an MCI, Prevosts baggage compartments are not tall. HBIndustries has a complete section on doing a slideout. He also has the mechanical parts you would require. I believe he is on the west coast. Good luck Malcolm if you have any more questions just send me a email. Good luck!
Pat
http://prevostlemirage.blogspot.com/ |
Pat Bartlett (Muddog16)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 8:48 am: | |
John your comment about being new and ambitious brought a lot of memories back to me, I was too at one time. Experience is what we get when we do these projects, You always have good points to offer, not to mention that great sense of humor!
Pat |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 10:07 am: | |
"Experience is what we get when we do these projects,...."
We get experience from our mistakes, and we make our mistakes due to lack of experience.
The cheapest and best way to design a slide for your Prevost is to go to any converter and study their brand new Prevost designed and engineered slides. Unless, of course, you like pain. |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 11:20 am: | |
Pat,
Agree with your comments on the laser level. Great technology that I first used in the mid-80's. I have access to professional models used for T-bar ceiling installations, etc. but didn't use it. (I had better uses for the $$! LOL!!)
The "cat's cradle" is a string line pattern made from four (4) 1" stand off posts I machined specially on my lathe. I place them in the farthest corners of the wood portion of the floor about 3-6" in from the wall(depending on where/how you placed your jacks for raising the roof).
I run the perimeter and an "X" crossing the center with a high quality string and stretch it really tight. (The reason why I made "custom" standoff's) The perimeter lines are for level, sag or bulge. The criss-cross tattles on warp. If the crossing lines just touch and arent' "kinked" (or separated, a "gap") the floor is flat enough for our purposes. You can check for bulge or sag anyplace with a 1" spacer on the perimeter or through the cross.
Re-establishing the laser with "stuff" like roof jacks in the way is sometimes problematical. I just leave the stand-offs in place and just re-tension the string when I need to check things.
The "painted" string line on the upper portions above the cuts is not necessary, it just gives me an idea of what might be "going on" with the roof (which carries a significant portion of the structural load) upon cutting it free. But I've done large steel fabrication(s) before and if you don't pay attention, somethings things sneak up on you and "bite" you in the rear! IYKWIM.
I'm sure many have raised their roofs without needing this attention to detail. It's a matter of choice, not necessity, and nobody should feel that the "have to" do it my way.
I choose to go to the little extra effort cuz I fear a little factor missed in the beginning can "snowball" , and to mix metaphors, put me in a position of "painting myself in a corner", -having to undo a lot of work to "make it right".
Onward and Upward |
KC Jack
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 11:45 am: | |
I am under the impression that, unlike an eagle, that the skin is part of the structural integrity in the Prevost. In the new factory slides that Prevost offers, the slide is “locked” in and “locked” in the out position so it again becomes a rigid part of the frame.
jack in KC |
Jon W.
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 12:28 pm: | |
I don't know about the H3 or the XLII, but the skin is not structural on the XL. |
Rob King
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 3:11 pm: | |
Hi Malcolm
I finished the roof raise on my 91 MeLirage XL about a year ago. I like Pat, used the same technique as Bryce Robson in Las Vegas. His web site is http://www.collinburnell.com/thebus/index.htm
The system worked well except I didn't use the roof jacks. The heart of my system is welding up two supports that lift the front on the shell and the rear of the shell on two 3 ton hydralic jacks. The supports spanned from side to side inside the bus just under the "over the window header", creating the cross member. I then welded small up supports from the cross member to support the roof longitadional braces. I then welded two diagnional supports from the distal end of the cross member to the center support. I then welded a disk to the bottom of the center support and welded it to the jack screw on the top of the jack to prevent movement at that point. Then I cut 2" X 4" blocks and nailed them to the bus floor around the jacks. One thing that SHOULD BE done before lifting is to weld "guide supports" to the outside of the window supports in the 4 corners to help keep the roof aligned while lifting. I used 3/4" steel rod running inside steel tubing as my guide supports with good success. Another tip, raise the jacks "a few strokes in the front then go to the rear and raise a few strokes then back to the front" i.e go slow in the raise.
If this doesn't make sense, I would be happy to do email at skykingrob@hotmail.com.
I wasn't confident enough to try a slide so can't help there. The "locked in and locked out", according to Prevost engineering, is to maintain the same structural rigidity as a non-slide coach. I found this little pearl when I spoke to a factory engineer about doing structural drawings for me to add a slide. The cost "estimated at $18-20K US". That's without the thing built!! To rich for my blood.
BTW, the skin isn't structural on the XL as Jon says.
Hope this helps
Rob
91 LeMirage XL
Missouri |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 3:13 pm: | |
Specifically, with regard to "Locked In", one purpose is to maintain, while underway and within acceptable limits, the "harmonics" properties of the chassis that means so much to structural engineers and is rarely appreciated by lay persons.
The "bean counters" would win the "delete" argument if it wasn't significant, i.e. detrimental if deleted.
FTMP (For The Most Part) it matters little whether the skin is stressed in the main structure. Any "hole" in the structural pattern will tend to affect chassis harmonics.
It may be beneficial in the scheme of installing a slideout in an H-3, (for instance), to stress the skin of the slideout.
(Caveat: Not having scoped out one of these installations in detail, these comments are simply logical observations in the absence of accurate facts - I'm simply sharing an opinion, not "preaching" )
Onward and Upward |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, February 12, 2006 - 3:40 pm: | |
Rob posted while I was composing mine.
The design quote of $18-20K is realistic, considering the level of expertise and comlexity of the work required.
That being said, once the work is done for one coach, it can be safely duplicated in others, provided virtually no changes are made.
I'll be putting a front slide in my "81-MCI-9" but I doubt anyone else will want to go to the diligence and work to duplicate the effort involved in this design. (revisit Rob's post!) |
Ray D
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 13, 2006 - 4:27 pm: | |
I used Bryces method also, I wanted the drivers seat up with the co-pilot. Dave Galley's Book on slideouts covers the Prevost, the book appears to only cover Eagles. If you read close, you will use the version that uses the diagonal bracing. I put two slides in mine and am very happy with the results and will be glad to answer any questions if needed.
P.S. I didn't know where to put the jacks either when I got mine, and you are qualified to do the work, you were smart enough to ask. I have these jack points explained on a pdf. if you want it.
Ray D |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 13, 2006 - 8:42 pm: | |
Re:
"P.S. I didn't know where to put the jacks either when I got mine,
and you are qualified to do the work, you were smart enough to ask. "
Thanks for waking me up with a boot to the ass, Ray. I hadn't
meant it the way I typed it. I deserved that kick.
Cheers! |
Ray D
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 13, 2006 - 11:50 pm: | |
Didn't mean it as a kick, I just didn't want to see him get discouraged, same thing happened to me when I was looking how to jack the darned thing up. Taking on a bus is a huge undertaking.
I owe ya a beer,
Ray D |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 14, 2006 - 12:40 am: | |
HAR!
Appreciated! But my sentiments are the same as yours!
These old gals are a major headache waiting to happen.
"Menopausal MCI's", or "PMS Prevosts", they're all the
same at the age they are.
(Oh holy *#^%#@&* I musta' been nuts to type that).
(there goes six months of promises) |
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