Coachbuilt Motorhome Costruction

[Rayjsj]

Very interesting thread, don't ignore the Great adhesives that are available now, especially from Sika, the joints made with them stand up to being immersed in water until the wood rots away. They can be expensive though. But really do the job. Good luck with the work. Shame Dave Newell doesn't post any more, sure he would have contributed. Ray

[Guest Peter James]

Rayjsj - 2015-04-01 8:31 PM

 

Very interesting thread, don't ignore the Great adhesives that are available now, especially from Sika, the joints made with them stand up to being immersed in water until the wood rots away. They can be expensive though. But really do the job. Good luck with the work. Shame Dave Newell doesn't post any more, sure he would have contributed. Ray

Adhesives are all very well for factory new builds where everything is clean and new in a warm and dry environment. I have felt less confident using them when repairing older materials where the surfaces to be bonded are not as good as new, maybe a damper environment,and may be difficult to hold them together till they set, so I have tended to stick to mechanical fastenings where possible. But then I have little experience of the more modern adhesives.

[Guest Peter James]

..... duplicate...

[Rayjsj]

I have found them to be very good, and they stand the test of time, I bonded a Wind deflector to the roof of my Daughters van, just a rough clean, and on a damp day, it is still there on the roof of her van 5 years later. Also bonded timber together on my outside shed, joint is stronger than the timber itself. Some will now bond together if underwater ! Things have come a long way, and I am a A4 Stainless steel fixings only man, usually. Ray

[Brabander]

Brian,

I always read your posts as they are very informative and knowledgeable.

As you said aluminium does not rust (iron based metals do that) but it does corrode. The surface oxide layer thus produced actually serves to protect the aluminium from further corrosion (therefore do not remove it).

In my experience salt water is particularly conducive to producing corrosion.

Also attaching aluminium to dissimilar metals can cause a reaction.

I am not sure whether timber in contact with aluminium would cause a reaction.

I do however believe that there is a considerable exposure to salt spray on roads in the UK ie the conditions are pretty challenging.

 

Some years ago I was involved in purchasing an office block constructed in the fifties which was built right next to the sea.

Upon detailed inspection (after we had bought it) we found that the aluminium curtain walls were seriously corroded and required urgent replacement.

A simple visual inspection did not show this but in some places you could push a sharp tool straight into the aluminium extrusions (there was as much oxidised material as intact aluminium alloy).

 

The message is therefore that the life of aluminium extrusions is just as finite as that of many other ferrous metals.

 

 

[George Collings]

Smashing thread. I can smell several pages of cheap copy for MMM.

[Will86]

I think a word or two on the corrosion of aluminium surfaces should be said here. There are probably dozens of differing chemical make-ups to suit specific purposes.

 

Pure aluminium is what it says pure. It is soft and easily bendable.(for this thread).

 

It is doubtful if the sheeting on the roof of a M/H is pure, it would contain various elements to make it tougher to suit its job.

 

Yes corrosion will protect an alloy surface to a certain extent but it doesn't stop there. What you see is NOT what you get !

 

The chemical make-up of an alloy will vary and is designed for specific purposes, this variation will change any corrosion progress into the material, on some alloys corrosion will become like a rabbit warren and with thin panels can quickly progress through to the opposite side. (some alloys may have an inhibitor to prevent this). Anodizing a surface is one way of preventing the start of corrosion.

 

What do I base my knowledge on ... I worked on aircraft parts for 20 years plus many industries where corrosion was the cause of major problems, also repairing historic vehicles and their alloy components which are the worst ever.

 

As an example some alloy mixtures are likened to a large currant cake. Corrosion will migrate from one currant to the next and does not stop until all currants and the immediate areas are removed.

 

Even stainless steel will corrode depending on its iron content. If a stainless steel item has been welded its molecular distribution will be changed resulting in serious corrosion at the joint.

 

Will

[Fiat Ducato]

Hi Will

Thanks for your input on this matter, question for you? do you think I've done the wrong thing by putting rust remover on the corroded parts on my aluminium roof. I've used Hammerite Kurust and Hammerite Rust remover Gel.

 

What should I do next? I was planning on giving it a bit of a rub with some sandpaper before applying a motorhome roof leak repair paint.

 

Just come across another problem, I was planning on using a fibreglass to cover an hole from the outside on the side panel of my van, its about the size of a fist, Then bond another piece of aluminium (a patch) from the inside to the existing Aluminium. CAN THIS BE DONE? I've done some research and apparently you can't stick fibreglass to Aluminium.

 

Can't get hold of Zinc Chromate from anywhere? I've heard this is very very good for Ally and used on commercial air crafts and military vehicles.

 

[Guest Peter James]

Fiat Ducato - 2015-04-02 3:58 PM

 

Can't get hold of Zinc Chromate from anywhere? I've heard this is very very good for Ally and used on commercial air crafts and military vehicles.

 

 

I haven't heard of Zinc Chromate for many years. I thought it had gone the same way as Creosote and Asbestos - it did the job pretty well and was widely used, but now banned by Health and Safety?

[Steve928]

Zinc chromate is still widely used in my other hobby, sailing, between stainless fittings and aluminium mast extrusions.

The trade name is Duralac so try searching on that.

 

E.g.

http://www.seascrew.com/browse.cfm?s=6575000

[Dave225]

I sympathise with the OP and his problems. I would not even know where to start so he is way ahead of me.

 

However, whle I appreciate his feelings regarding Autoroller The photos suggest his van is of a decent vintage and dare I suggest that other makes could just as easily fall into the same category. Most UK vans were made using wooden framework and hardboard panels right up to recent years and many suffered damp issues. A commonn cause was pools of water lyinmgon the aluminium roof and creeping under the sealant where the roof met the wall panels.

 

Autoroller I think are part of the Trigano group which make several makes of motorhome and offer a 10 year warranty on water ingress these days. I am not trying to defend them, merely suggesting that any van of vintage years has a possibilty of damp. My late father had a transit coachbuilt of 1980's vintage and it also suffered damp. His answer was to remove all the aluminium side panels, replace the rotten wooden frame and start again. A long job but achieved the results. However, as he was a qualified shipwright he had skills beyond me..

[Guest Peter James]

Steve928 - 2015-04-02 9:11 PM

 

Zinc chromate is still widely used in my other hobby, sailing, between stainless fittings and aluminium mast extrusions.

The trade name is Duralac so try searching on that.

 

E.g.

http://www.seascrew.com/browse.cfm?s=6575000

 

The link takes me to a Barium chromate jointing compound ??

[Guest Peter James]

Dave225 - 2015-04-02 9:37 PM

 

I sympathise with the OP and his problems. I would not even know where to start so he is way ahead of me.

 

However, whle I appreciate his feelings regarding Autoroller The photos suggest his van is of a decent vintage and dare I suggest that other makes could just as easily fall into the same category. Most UK vans were made using wooden framework and hardboard panels right up to recent years and many suffered damp issues. A commonn cause was pools of water lyinmgon the aluminium roof and creeping under the sealant where the roof met the wall panels.

 

Autoroller I think are part of the Trigano group which make several makes of motorhome and offer a 10 year warranty on water ingress these days. I am not trying to defend them, merely suggesting that any van of vintage years has a possibilty of damp. My late father had a transit coachbuilt of 1980's vintage and it also suffered damp. His answer was to remove all the aluminium side panels, replace the rotten wooden frame and start again. A long job but achieved the results. However, as he was a qualified shipwright he had skills beyond me..

 

Yes , http://davenewell.co.uk/ did a similar job on an Eldiss - I copied and pasted his posting of it to the other thread http://www.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Water-Ingress-Spongy-Ceiling/37732/#M457182

Its long been a problem with caravans, but having only 2 wheels the body doesn't suffer the same torsional stresses so the roof strength is not as important.

 

[Fiat Ducato]

Thanks Peter for your comments, yes the other thread was started by me too, however I can't see any link to any similar work done by Dave Newell. I checked out his website. Be nice to see some pics of a similar project.

 

Thanks Dave for your comments, you are probably right :-)

 

And Steve the Duralac you mention, just googled it and it says its just an anti corrosive jointing compound, nothing about containing zinc chromate or been used for what I want it for??? could you clarify

[Guest Peter James]

Fiat Ducato - 2015-04-02 10:48 PM

 

Thanks Peter for your comments, yes the other thread was started by me too, however I can't see any link to any similar work done by Dave Newell. I checked out his website. Be nice to see some pics of a similar project.

 

Thanks Dave for your comments, you are probably right :-)

 

And Steve the Duralac you mention, just googled it and it says its just an anti corrosive jointing compound, nothing about containing zinc chromate or been used for what I want it for??? could you clarify

 

I didn't see any photos from Dave Newell either (except his tiny avtar photo of the finished job), and don't think there is anything about it on his website. I don't think he is looking for any more jobs like that, which was just one he did for himself. Sorry I can't help with the Aluminium Primer either. The last stuff I used was Zinc Chromate. But even if it hasn't been banned now I would be concerned about the health implications of working below it spreading the quantity needed to paint the underside of a ceiling in the confined space of a motorhome. I just used to touch things up with it outside in the open air.

This was Dave Newell's post which I saved and pasted to the other thread;

QUOTE FROM DAVE NEWELL;

Being an elderly Elddis its stick built, that is to say the frame is 1" square softwood with polystyrene infill for insulation, a thin plywood skin on interior with decorative coating and a thin aluminium skin outer with thin paint finish.

 

Rebuilding a motorhome of this type with such extensive damp is a huge task; I know I was that soldier! I re-skinned a 1990 Autohomes Highwayman a few years back and had to reframe a quarter of the entire structure.

 

There are three main areas that water gets in and whichever is the one (or more) in your case will need dealing with or you'll just end up with a damp motorhome again.

 

The first point of water ingress is poorly fitted window seals.

Second is roof to wall joints.

Third is the worst, when water has got into the structure the wooden frame will eventually rot. Wet rot in soft woods as used for motorhome framing releases chemicals that will eat through aluminium skin in short order and will appear as tiny dots on the outer skin in line with the framework sections (often referred to as aluminium cancer).

 

One and two are easily dealt with but three is a bugger as it means the rotten timber will need removing and the skin replacing. Replacing the frame timbers is difficult if the damage is extensive as once you start to remove the interior or exterior skin and rotten timber the strength of the body just evaporates. I did mine one stick at a time after removing the entire outer aluminium skin (not an easy job in itself) and replaced all rotten timberwork with 1" square aluminium box section screwed together with stainless self-tappers. For the roof I fabricated a TIG welded framework of 1" alloy box section, which was placed on top and screwed to the sidewall frames.

 

Re-skinning was the most challenging part and took four of us three days to do the two sidewalls, rear wall and roof. Trust me when I say handling a 5 metre by 2 metre sheet of 0.8mm alloy without kinking it is not fun and spreading twenty odd tubes of sikaflex over the surface by hand is no easy job either!

 

Sorry if this sounds negative but I write from personal experience of a similar project. Cost wise I spent over £3K at trade prices and took nine months to do it!

 

DAVE NEWELL

 

 

 

 

[Guest Peter James]

daven - 2015-03-31 7:56 PM

 

Depending on the position of the hole what about placing a grill over it & after painting the van it could look like its always been there ? it would also ventilate the cavity of the wall

 

The cavity of the wall and roof needs to be kept sealed for good thermal insulation, and to seal out damp to prevent rot of the timber and wallboards. It is normally filled by some sort of foam to improve insulation and structural strength.

[Guest pelmetman]

Will85 - 2015-04-02 11:41 AM

 

 

As an example some alloy mixtures are likened to a large currant cake. Corrosion will migrate from one currant to the next and does not stop until all currants and the immediate areas are removed.

 

Even stainless steel will corrode depending on its iron content. If a stainless steel item has been welded its molecular distribution will be changed resulting in serious corrosion at the joint.

 

Will

 

Makes you wonder whether motorhome builders should fit sacrificial anodes like boat builders? :-S......

 

 

[Brian Kirby]

Peter James - 2015-04-01 7:05 PM

 

Brian Kirby - 2015-04-01 6:42 PM

 

Peter James - 2015-04-01 6:31 PM

 

Brian Kirby - 2015-04-01 6:13 PM

Construction industry, but design/technical, not site based.

 

As in 'I just have the ideas, its your job to make them work' ;-) .............

Of course Peter! :-D But, if you keep serving up ideas that don't work, folk complain, and then you have to start looking for a new job! Besides, everyone needs a bit of a challenge from time to time. It's what gets them out of bed. Easy, is boring. :-)

 

Oh I dunno, I think I have had enough challenges to last me (lol)

If the roof panel is released, its possible the body could twist as easily as the food container when you take the lid off. It may be necessary to jack up one of the wheels a little to twist the body back into its original shape so the roof panel fits again.

An excellent point Peter. It would need to be on level ground to start, and would probably be better supported on axle stands under the chassis to true it up before releasing the existing roof, or measuring for, or fitting, any of the new panels, or re-fitting the aly roof.

[Will86]

Fiat Ducato - 2015-04-02 3:58 PM

 

Hi Will

Thanks for your input on this matter, question for you? do you think I've done the wrong thing by putting rust remover on the corroded parts on my aluminium roof. I've used Hammerite Kurust and Hammerite Rust remover Gel.

 

What should I do next? I was planning on giving it a bit of a rub with some sandpaper before applying a motorhome roof leak repair paint.

 

Just come across another problem, I was planning on using a fibreglass to cover an hole from the outside on the side panel of my van, its about the size of a fist, Then bond another piece of aluminium (a patch) from the inside to the existing Aluminium. CAN THIS BE DONE? I've done some research and apparently you can't stick fibreglass to Aluminium.

 

 

Apologise for the delay. The only observation I have regarding 'what have I done wrong' ... is ... "That you have unwittingly taken on a major bodywork repair problem". As an example, if this were a car floor the only answer would be a complete new floor. From what I see in your first and third pictures ... all that is dark in colour should be replaced. I don't see any solution in applying small patches neither in attempting any filler material applications.

 

Applying any paint-on material I see of little use, the panel in that area will already be devoid of much of its thickness and corrosion will continue under whatever is painted on. Some of the corrosion appears to be in corners or shaped areas and nigh impossible to cure.

 

One of the benefits of modern day vehicles is the access to replacement parts. Unfortunately Motorhome panels such as we see here are not.

 

My answer is brief ... for I do not see one.

 

Will

 

[Guest Peter James]

pelmetman - 2015-04-03 7:38 AM

 

Will85 - 2015-04-02 11:41 AM

 

 

As an example some alloy mixtures are likened to a large currant cake. Corrosion will migrate from one currant to the next and does not stop until all currants and the immediate areas are removed.

 

Even stainless steel will corrode depending on its iron content. If a stainless steel item has been welded its molecular distribution will be changed resulting in serious corrosion at the joint.

 

Will

 

Makes you wonder whether motorhome builders should fit sacrificial anodes like boat builders? :-S......

 

 

I've found a thread you may find more useful ;) http://www.telegraph.co.uk/men/thinking-man/11512160/Eight-tricks-to-make-you-appear-more-intelligent.html

[Guest Peter James]

Brian Kirby - 2015-04-03 12:42 PM

 

An excellent point Peter. It would need to be on level ground to start, and would probably be better supported on axle stands under the chassis to true it up before releasing the existing roof, or measuring for, or fitting, any of the new panels, or re-fitting the aly roof.

 

Yes I'm sure that would be a good idea. I should have added that, Thank You.

[Guest Peter James]

Will85 - 2015-04-03 4:42 PM

 

Fiat Ducato - 2015-04-02 3:58 PM

 

Hi Will

Thanks for your input on this matter, question for you? do you think I've done the wrong thing by putting rust remover on the corroded parts on my aluminium roof. I've used Hammerite Kurust and Hammerite Rust remover Gel.

 

What should I do next? I was planning on giving it a bit of a rub with some sandpaper before applying a motorhome roof leak repair paint.

 

Just come across another problem, I was planning on using a fibreglass to cover an hole from the outside on the side panel of my van, its about the size of a fist, Then bond another piece of aluminium (a patch) from the inside to the existing Aluminium. CAN THIS BE DONE? I've done some research and apparently you can't stick fibreglass to Aluminium.

 

 

Apologise for the delay. The only observation I have regarding 'what have I done wrong' ... is ... "That you have unwittingly taken on a major bodywork repair problem". As an example, if this were a car floor the only answer would be a complete new floor. From what I see in your first and third pictures ... all that is dark in colour should be replaced. I don't see any solution in applying small patches neither in attempting any filler material applications.

 

Applying any paint-on material I see of little use, the panel in that area will already be devoid of much of its thickness and corrosion will continue under whatever is painted on. Some of the corrosion appears to be in corners or shaped areas and nigh impossible to cure.

 

One of the benefits of modern day vehicles is the access to replacement parts. Unfortunately Motorhome panels such as we see here are not.

 

My answer is brief ... for I do not see one.

 

Will

 

Reluctantly I have to agree that although anything is possible it sounds beyond economic repair. I am sorry to be so negative but I think its better than a drip drip of bad news and throwing good money after bad. Are there any bits on it you could take off and put on ebay? Otherwise I would cut my losses, call the scrap man, and write it off to experience.

[Brian Kirby]

'Strewth, Paul, I've only just seen the pictures above, and rather wish I hadn't!

 

There is a suitable primer sold under the trade name "Guard". It is a chromate free etch primer that can be applied by brush, made by Newguard Coatings Ltd, named Guard Single Pack Etch. Seems my zinc chromate info is out of date, and H&S has indeed, as stated by Peter, fallen to H&S, (which is probably for the overall good).

 

I agree with what I think Will is trying gently to say, I really think this aluminium skin has gone beyond realistic repair. Until I saw the pictures above, I'd no idea it was that bad. The rotting wood has eaten the aluminium, and it will be down to the thickness of aly foil in a lot of areas that aren't yet holed. What is left is an aluminium filigree, and I think the only solution to that will have to be to re-skin the van in the affected areas. That is going to be a massive job, and not one to undertake in the open. It is also not a job to tackle single handed. Dave Newell was very honest when he described the job he did to me, and admitted he got close to giving up at times - and I think he had a fully enclosed heated workshop in which to tackle it.

 

Time to take a big stap back, I think, and a very deep breath. This is going to get expensive, and very, very, time consuming. You could get quotes from a repair workshop, but would have to set that cost against the value of the van when repaired. The problem will be, as is already emerging, that much of the frame needs re-building, and to get at the sound parts so that new can be joined to them, I think much of the outer skin will have to be removed and replaced.

 

Generally, when a van is built, the floor is laid over the bare chassis. Next the furniture is placed onto the floor, and the fridge, toilet, cooker etc fitted to the furniture, then the external walls and cab door fairings are added, followed by the rear wall, over-cab fairing, and finally roof. From what I can see in the pics, I really, really, think the only way to re-build that supporting frame will be to fully expose what is there, and I strongly suspect that can't be achieved adequately with the external skin still in situ. It first has to be "unmade", before it can be re-made.

 

So, being brutal, but based only on what the photos show, yes it could be done, if under cover, but at considerable time and expense. At the end of that process what you would have, would be a largely re-built but ageing Auto-Roller worth little, if any, more than any other similar van of equal age. I think you should ask yourself whether you will be able to complete this task, and if you do, what you will end up with, and what it might be worth. Might it be time to cut your losses and walk away from it?

 

My only alternative thought concerns where you bought it, and when, and whether, in view of its condition, you could get your money back? It must have been in that condition when bought so, if there was any doubt at all about its repairability, you should have been warned. To be honest, I looks to me to be not far short of a wreck, and fit only for scrap. I am so very sorry.

[pepe63xnotuse]

Paul..

Was the van supposedly straight and sound? and all of this has come as a shock?...

or was the van bought as a.. *cough*... bit of a dog/fixer-upper?...

 

If it's the latter, as in it's current state it'd probably be worth very little, I'd say that a bundle of softwood battens, a few ply/hardboard panels,some sheets/rolls of insulation and a couple of weekends fettling could "tidy" the interior..

As for the external panels, maybe cut out the bad and/or slap on one of the coatings/potions that others have Googled ( ;-) ) and then just overlay/bond/rivet on a decent sized ali sheet (sized appropriately, so as it's edges correspond with existing panel seams, body lines etc...and helped blend in with decals?..).

 

Yes, it'll be a bit of a bodge-up but if you can retrieve it enough to at least get a few holidays out of it, that's got to be better than just writing it off straight away....

 

[Guest Peter James]

pepe63 - 2015-04-03 6:27 PM

 

Paul..

Was the van supposedly straight and sound? and all of this has come as a shock?...

or was the van bought as a.. *cough*... bit of a dog/fixer-upper?...

 

If it's the latter, as in it's current state it'd probably be worth very little, I'd say that a bundle of softwood battens, a few ply/hardboard panels,some sheets/rolls of insulation and a couple of weekends fettling could "tidy" the interior..

As for the external panels, maybe cut out the bad and/or slap on one of the coatings/potions that others have Googled ( ;-) ) and then just overlay/bond/rivet on a decent sized ali sheet (sized appropriately, so as it's edges correspond with existing panel seams, body lines etc...and helped blend in with decals?..).

 

Yes, it'll be a bit of a bodge-up but if you can retrieve it enough to at least get a few holidays out of it, that's got to be better than just writing it off straight away....

 

 

Is that going to withstand wind forces and the vibration and torsional forces driving over uneven surfaces?