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Prevost XLII Skin Delamination Repair
11-15-2014, 19:28 (This post was last modified: 11-15-2014 21:07 by travelite.)
Post: #21
RE: XLII Panel Repair Alternative
CC_Guy,

Bostik 70-03A is what Prevost recommends for XLII panel leak repair for minor leaks when the rivet approach isn't required or desired. It works well because of the UV resistance and especially because it'll stick to stainless steel w/o excessive cleaning or surface prep - no special cleaner, primer, or activator is required as in the Sikaflex 255 case. The tensile and shear strength isn't as good as Sikaflex 255 nor is the elongation, but for sealing a minor leak in panel that's for the most part well attached to the coach, Bostik 70-03A fulfills the requirements.

When Prevost (Nashville) was repairing my H3 panel the tech explained to me that they have a wide selection of bonding products to choose from depending upon the accessibility of the leak, the difficulty in getting cleaning and priming products into the breach, and whether it's anticipated that the panel should be easily detachable for future access. It seems Prevost Service Centers have been well schooled and well equipped to handle our bonded coach needs! Smile

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
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04-28-2017, 10:23
Post: #22
RE: XLII Panel Repair Alternative
Okay, where do you buy Loctite 5590?
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04-28-2017, 10:40
Post: #23
RE: XLII Panel Repair Alternative
(04-28-2017 10:23)CC_Guy Wrote:  Okay, where do you buy Loctite 5590?

Hi CC_Guy,

Looks like the name has changed. A quick search reveals that it's now LocTite 9399. Here's one supplier.

On a side note, Donny Myers at DMRV will only use the old standard SikaFlex 221. He said he wants to be sure that he'll be able to remove the panel without panel damage at some point in the future.

On a double side note, for interior work the only adhesive DMRV uses is Silicon. He's convinced that if you apply it and clamp it properly it's as strong as anything else and again he's able to remove panels at some point in the future.

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
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04-28-2017, 19:41
Post: #24
RE: XLII Panel Repair Alternative
Hmmm, that link goes to a lubricant. Maybe you discovered the root cause of the delamination problem.

Sika 252 would have been my choice in the Sika product family. 221 is the go-to Sika product, so I can certainly see it's use.

There are so many "Silicone" products. I don't think of silicone when it comes to adhesion, especially on some materials. Of course, there may well be a "silicone" product that will work.

I have a friend with a small section of one panel coming loose. Does anyone have a recommendation of how and what to use to prep the surface on the panel that will barely be accessible?
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04-28-2017, 22:05 (This post was last modified: 04-28-2017 22:36 by davidbrady.)
Post: #25
RE: XLII Panel Repair Alternative
It appears LocTite 5590 is now Teroson MS9399, but it doesn't seem to be available in this country. "Prevost Parts Catalog and Pricing" lists LocTite H8000 in the adhesive category, but neither 5590 nor MS9399. H8000 is available at Prevost, part number: N66004. H8000 is a two part structural bus adhesive rated for metal to metal including stainless steel. Hope this helps:


Attached File(s)
.pdf  LOCTITE-H8000-EN.pdf (Size: 72.98 KB / Downloads: 5)

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

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04-29-2017, 22:15 (This post was last modified: 04-30-2017 00:35 by cmillsap.)
Post: #26
RE: XLII Panel Repair Alternative
Prevost decided to convert from attaching the stainless panels to the structural forms with rivets to attaching the panels with an adhesive back about 16/17 years ago on their new XL2 model busses. I would think a lot of feasibility studies, R&D and engineering took place before they decided to switch to glued panels.

Surely, they must have expected the panels to stay securely fastened to the forms for at least 10 years. I say that because when panel delamination started to occur, they were quick to absorb the cost of repairs based on a prorated basis for the first ten years of a bus’s life.

For several years now, panel delamination has been randomly occurring on units of varying ages from near new to all the way back to year 2001 models. Once Prevost became aware of the issue, I’m sure they spent a lot of time trying to alleviate the problem. It’s pretty clear that they are dedicated to attaching the panels with adhesive because they continue to attach the panels on their new models the same way.

But the question of “Why is this happening?” still remains. I have yet to see any data from Prevost regarding answers to the question. So, everyone is left to their own speculation. This is an important question to existing XL2 and XL3 model owners. It remains a serious issue for anyone interested in purchasing one of those models.

From a purely speculative standpoint, it seems to me that there may be so many variables in the total application process as to cause it to be extremely difficult to duplicate the exact procedure as required from unit to unit as each bus travels down the assembly line.

By “variables” I mean things like variations in proper cleaning and preparing the bonding surfaces from bus to bus. Then there’s the need to apply the adhesive correctly and uniformly from bus to bus. Is there an acceptable and exact period of time between applying the adhesive and attaching the panel to the forms to attain the best adhesive coefficient being strictly followed from unit to unit? Add varying weather, ambient temperatures and humidity during the application process into the mix. I could add several other variables not mentioned here. So, it’s pretty easy to make a case that variables within the assembly process could be a possible reason why we have seen random delamination over several model years.

If variables are ever found to be the culprits and Prevost can’t eliminate them, we’re destined to live with possible delamination for years to come.


Chuck & Tela Millsap
Arizona
2003 Marathon XLII S/S
2000 Wanderlodge LXi S/S
2004 Wanderlodge M380 D/S
2000 Wanderlodge LXi N
/S
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04-30-2017, 08:06
Post: #27
RE: XLII Panel Repair Alternative
I once read that this problem was corrected in 2010. Does anyone know of a 2011 or nearer with delamination?
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04-30-2017, 11:41 (This post was last modified: 04-30-2017 14:14 by travelite.)
Post: #28
RE: XLII Panel Repair Alternative
(04-30-2017 08:06)CC_Guy Wrote:  I once read that this problem was corrected in 2010. Does anyone know of a 2011 or nearer with delamination?

There was a guy on PC who said he saw delam on an X3 at a show in Indio, but who knows??? Certainly far from a confirmed case.

If you go to http://www.scholar.google.com and google for "adhesive steel frp fatigue" you'll get a feel for the current state of the research and testing. Methyl Methacrylate (MMA) is often cited when structurally gluing FRP, steel, and concrete. Loctite H8000 is an MMA. An interesting side note is that MMA is often used to glue bone, dental caps and veneers. You can imagine the service life expected in medical applications.

One of the interesting things about MMA is it requires very little, if any, surface prep. However, the researchers in the attached paper got much better adhesive performance if they first sandblasted or grinded steel surfaces. Perhaps Prevost bought into the manufacturers' hype and they didn't prep the stainless steel. I would have expected Prevost to run their own strength tests given what's a stake.

One thing's clear, there's no way bus manufacturers are going back to rivets. There are just too many advantages of a glued on panel: it simplifies manufacturing, reduces time and cost, simplifies paint prep, cleaner look, waterproof interface, stresses are evenly distributed - no stress concentrations at the rivets, etc. Panels provide chassis stiffening; adhesives provide damping. Once they settle on the right adhesive, and the correct prep (even if in addition to the adhesive manufacturers' recommendations), and if they can keep stresses in check, bonded panels should last 30+ years.

Even with rivets, it's fairly common to see busnuts reskin their old buses.


Attached File(s)
.pdf  ConMat-BondCharacteristics.pdf (Size: 1.21 MB / Downloads: 4)

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"there is no perfect forum there are only perfect forums"
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04-30-2017, 14:44
Post: #29
RE: XLII Panel Repair Alternative
Well, I didn’t mean to imply that the level of delamination remains at the same level as it was in earlier models of the XL2. I’m sure that the efforts applied by Prevost have resulted in substantially reducing the numbers of panel delamination. If the new bus in Indio suffering from delamination is accurate and I see no reason to doubt it, one must assume that it is still happening. I hope it is an isolated case but I doubt that also.

I also certainly didn’t mean to imply or dissuade anyone from purchasing a bus with SS panels. I am only suggesting that anyone interested in purchasing one be aware of the issue and have the bus inspected before they purchase it.


Chuck & Tela Millsap
Arizona
2003 Marathon XLII S/S
2000 Wanderlodge LXi S/S
2004 Wanderlodge M380 D/S
2000 Wanderlodge LXi N
/S
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04-30-2017, 16:59
Post: #30
RE: XLII Panel Repair Alternative
If the problem still exists, how can anyone think they have a viable repair? If they did, wouldn't they implement it in new builds?

Maybe motorcoach converters should buy entertainer shells. Entertainer shells don't have the problem, at least I haven't heard of it.

Did I tell you I iove my H-3?
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