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crack on body panel, Chausson Welcome 76


Mick Bajcar

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Mick Bajcar - 2017-03-26 11:54 AM

 

Andrew,

 

Firstly, thanks I had a good day. I photograph aircraft as a hobby (I even have gold braid on my anorak) and the weather was nigh on perfect!

I have attached another photo and taking all of the advice I have had so far into account, I think I can see the way to do it.

 

I think I will drill out that top rivet so that the gap in the panel can really be tightened up and then put another (or perhaps a self tapper to allow some adjustment?) right at the top before replacing the one drilled out. I feel that I can then probably get away with either using a scratch repair service or put some white film over the whole top section.

 

Further suggestions will be welcomed :-)

 

Mick

Drill out the rivet. carefully peel back the edges of the fairing so as not to start another crack from the next pop down, work in a good quality construction sealant behind the edge of the fairing, press back into place so that the stress in the panel is relieved, clean up, allow to cure, and then set about getting the crack fixed as suggested above. The pop rivet is the cause of the crack.

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It must be April 1st or I'm looking at a different set of pictures.

 

Brian

 

if you are referring to the latest picture ref the pop rivet and the crack. The large head of the pop rivet was probably used to level up the two sides as it had obviously 'jumped' out of level, and I cannot in all my wildest dreams see how such an application can cause a crack.

 

ps. I'm working right now this afternoon with all manner of rivets, copper, alloy etc, all with a variety of heads including the pop variety. Please come and visit me, just off J10 on the M20 and I'll show you some real riveting.

 

Someone's been at the Mothers Day sherry for sure.

 

 

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Will

 

That pop rivet is used to fix that panel to the cab and it was done that way by Chausson (there are six or seven holding it in place and I have not touched it all yet. The split is very clearly from the pop rivet hole and there is a very minor one on the other side that I had not noticed until Friday. No riddles at all !

 

Brian,

 

thanks, that seems a good way to go and I might even drill the next one down out (if it seems a good idea) so that I can get a patch on the back too. Never heard of STIXALL but will look into that too.

 

Mick

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Please ... the split is not FROM the pop rivet hole(s). A fracture will start from the edge of a material, here it was caused in all probability by rivets that prevented the body from flexing.

 

I see the situation differently now, the rivets were applied to hold the bodywork in place. A damn daft idea.

 

A subtle difference in description here me thinks. I should have gone to Specsavers.

 

Will

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Mick Bajcar - 2017-03-26 4:53 PM

 

 

 

Brian,

 

thanks, that seems a good way to go and I might even drill the next one down out (if it seems a good idea) so that I can get a patch on the back too. Never heard of STIXALL but will look into that too.

 

Mick

 

Mick,

 

It's fantastic stuff and Brian has made a very good suggestion by using this first. We use between 5-10 tubes per week on house projects but it will bond your panel with amazing strength.

 

It should cost £5.50 for the mastic plus your dispensing gun so the basic fix could be achieved for less than 10-quid.

 

STIXALL grips incredibly well but if the daytime temps are reasonable then it will set in place at the 3-hour point with solid fix achieved at 24hrs. It does retain a very small amount of flexibility so great for what you need on your cab. The remaining mastic can be used to seal your windows on your house :-)

 

A great idea from Brian.

 

Cheers,

 

Andrew

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Will86 - 2017-03-26 3:51 PM

 

Brian

 

if you are referring to the latest picture ref the pop rivet and the crack. The large head of the pop rivet was probably used to level up the two sides as it had obviously 'jumped' out of level, and I cannot in all my wildest dreams see how such an application can cause a crack.

..................

But just look at that last picture, Will. There is a clear depression around the head of the rivet. That indicates that the substrate was not in contact with the back of the fairing when the rivet was set, and that the operative used the rivet to pull the two materials together. That process will have stressed the fairing (in all probability, as others have said, ABS), and the stress will, over time, have been relieved over time by the development of the crack.

 

Pop riveting a material such as ABS to steel is in any case a bad practise. ABS has a far greater coefficient of expansion than steel and will move more than the substrate in response to temperature change, so stressing the point of attachment.

 

In addition, the ABS is thin and flexible relative to the steel but, unlike the steel, is un-stressed structurally. So, vibration and flexing of the cab structure when the vehicle is in motion will not be mirrored by similar movements of the fairing, whereas the thinner ABS will be prone to flex in the vehicle slipstream, which the steel cab will not mirror.

 

Stress around such rigid attachment points is therefore inevitable, IMO, as is the consequent cracking.

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WORK IN PROGRESS

 

Well, I bit the bullet and drilled the top two rivets out and that enabled me to see inside and that, contrary to expectations, the panel was not actually glued on it is clipped on. The only sealant was at the top but that had cracked indicating that the panel must have been moving. Contrary to the advice , I took it off which was surprisingly easy and the panel fairly rigid too. I took it to a very local glass fibre place where they advised me that glass fibre would not bond and stay on but they suggested that I bonded a piece of plastic on the back using a solvent adhesive. I found a piece of perspex and using a heat gun, bent it slightly to a very rough approximation of the contour of the panel then used Floplast solvent cement (which I had in already) and clamped that over the back of the break. I had tested this on a bit of the back and perspex first to make sure they did dissolve. A couple of hours later it is rock solid.

 

I have ordered Stixall and I will follow Brian's suggestion for gluing it back on when that arrives. I think the pop rivets will go back in as 'belt and braces' but feel that they should be less problematic when bedded onto the slightly flexible adhesive rather than direct plastic to metal. I am hoping I can then get the crack repaired cosmetically and re-seal with Sikaflex at the top

 

Thanks for all the advice

 

Mick

 

Photos are attached

panel_lamp_small.thumb.jpg.3d7775949c6a101eedb938a8ea34c7c9.jpg

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Brian,

 

Thanks for the comments, the whole saga was nothing like I originally thought and as time passed I became even more confused, and still am over the way all the parts are / were assembled and why.

 

The second line on Mick's original post ... "that has run from a pop rivet hole on the door frame" ... was not the description I would have used. However he appears to be winning.

 

Will

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Mick, looks good! I can see only one problem, which is the use of pop rivets to re-install the panel. I suspect you're right that they are the most practical solution, but they bring the potential for the same problem being caused again.

 

The problem with all plastics is that they are just that: they are not solids, so tend to flow and distort under stress. Pop rivets exert considerable local stress on materials when they are set - which is why they work.

 

My suggestion would be to first do a dry run with the panel to see how much clearance there is between it and the slam edge of the door and, if possible, add washers to the rear of the panel at the rivet points(possibly on a dab of sealant to hold them in place while you get everything lined up) so that thy create a small gap between the back of the panel and the door frame. That gap will be filled with the sealant, but will be beneficial to it, as it needs to maintain some depth to retain its resilience. If you can't you can't, so will have to replace as before. The point however, would be to allow the washer to take the force of setting the rivet without causing local distortion of the fairing panel. I'd also suggest you look for larger headed rivets so that the force is spread over a larger area front and rear, in a further attempt to reduce the local stress on the panel when the rivet is set. Good luck.

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pepe63 - 2017-03-28 2:25 PM

 

Good work Mick! ...and from the initial quote, the thick end of 800 quid saved! :-D

 

Crazy money indeed. He will be able to buy a few bottles of 'red' with his £795 saved.

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Bop

 

More likely to spend it on Belgian beer :-) (Vive La Chouffe)

 

Brian

Thanks for those ideas. There will be a degree of trial and error, I am sure but I am convinced that simply bedding the panel onto some flexible adhesive will be better than it was before. It will however be a real pig if it ever needs to come off again! It's just a pity that the customer has to find out problems like this rather than the R and D people at Trigano.

 

I will update further when I go to finishing the job, hopefully at the weekend.

 

Mick

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Only my opinion - I think the pressure when the pop-rivets were installed will be the source of the problem.

A heavy handed installer, maybe using too much sealant & then trying to squeeze out the excess when fitting the pop-rivets ??

If you replace with St. Steel Self Tappers they can be screwed in without putting too much pressure on the panel.

It's not unusual for pop-rivets to cause cracking in many materials, when fitted under too much pressure & ABS isn't good for it's strength qualities.

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flicka

 

There is no sealant at all between the panel and the door frame and I am sure that has exacerbated the problem. Brian's suggestion to put a sealant adhesive in does seem to be the way to go but I am sure you are right, it has come from heavy handed pop riveting in the first place. I doubt they did them by hand as I will be doing ! Self tappers and adhesive would allow a very precise control of the pressure but the holes are quite big and I might struggle to get them. I will probably end up with pop rivets again but with washers under the panel and bigger heads.

 

Mick

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Good call on those "plastic snap-rivets" Dave...!

 

I was thinking along a similar lines (having removed/refitted the ceiling panel of our Hiace, which has similar fixings) but I hadn't a clue what such fixings were called.....

 

So, "plastic snap-rivets" now saved in my " Useful Stuff " favourites folder... :-D

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I am worried what sits behind this panel. Are we in the cabin or habitation or both in regards to water ingress. The crack can propagated longer than you think.First ask your dealer for the lay out of the panel attachment details in 3D. And all bits and pieces. This will give you an idea how L/R is fitted. Normally you will get the full lay out of all side panels which can be easily replaced. Including front and rear bumpers. But not the side walls and the roof. Remove and replace this panel original and claim Chausson. And water damage if any they have 10 years. But of course you do what you want whit your motorhome.
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Mick

 

Although you have probably completed the panel assembly now I favour self tapping screws as suggested by flicka. You will have plenty of control over any pressures exerted, whereas pop rivets are designed to operate at a maximum and the larger diameter even more so. A rubber washer or pad under the panel may also have a softening effect and still allow some flexing, which (the lack of) was part of the original cause.

 

A little late perhaps but filling the original pop rivet hole in the panel and making two new ones may also be an advantage.

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Will

 

Thanks for that.

I have not yer re-assembled it as the Stixall has not arrived but I have ordered some nylon washers to go under the panel. I had already thought about not re-using the hole that had split. and, in fact, when I did a dry run for re-assembly by offering the panel up to the door it pulled up absolutely perfectly a few mm further over than where it had been drilled on assembly. I am pretty sure that that panel had never been aligned properly and the stress of movement has caused it to crack over time.

I am going to put Stixall on along with those plastic rivets and see how I feel and see if I can get some stainless self-tappers in case I am not happy with them.

 

Mick

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