Old car body repairs - advice sought...

[Reuben]

I have a 1983 VW Passat GL5 which is in reasonable condition barring some serious rust on the training edges of the doors and the tailgate. Professional repairers seem reluctant to take on repairs like this - they want to replace the doors (possible) and the tailgate (not possible to buy new tailgate now). I'm considering doing the repairs myself and I'd like to hear from anyone who has experience of this kind of job in relation to materials and methods. I'm realistic about what I can expect to achieve - I just want a passable job to keep the car legal. If it turns out really well, that's a bonus.

Thanks.

[mrcheerful]

Haynes do a body work repair manual that used to include these sort of repairs from the american angle, basically they suggest cutting away the rusty stuff and reforming the edges as closely as possible in steel or aluminium and fill to make it look ok. amking it look really good is very difficult though, which is why pro body places don't take it on here, the labour costs get ridiculous.

mrcheerful

[Set Square]

Have you tried breakers yards for second-hand doors and tailgates which might be in a better condition than yours?

By keeping the car legal, I presume you mean remove sharp rusty edges which could be dangerous. What is written below is ok from that perspective but does *not* apply to anything structural - like chassis members - which would need to be welded.

If you want to repair the panels, you need to:

• remove paint and flaking rust from the affected areas

• treat the rust with phosphoric acid to stop it spreading

• indent the edges of any holes, and stick sheets of fireglass matting, soaked in fibreglass resin, on the back of the panel [disposable gloves essential for this!]

• once the resin has hardened, spread filler over the front surface

• when the filler has hardened, sand it to shape, blending in with surrounding metalwork

• prime and paint the finished surface [It really needs spraying, for which you *might* get away with aerosols provided the areas are fairly small and you do it on a wind-free day].

[Paper2002AD]

This is all excellent advice. After spraying, rub down with wet'n'dry paper (wet of course) and spray again. Repeat until you get a reasonably even paint finish. The rub hard with brasso to get a glossy shine.

[Mike Mitchell]

First, you should forget about using fibre glass, resin, filler, and suchlike. It's okay for surface dents and blemishes, but not where structural strength has been compromised by rust. The most fun you can have with a welding torch is brazing! You can inset pieces of sheet metal and braze them in, thereby restoring (and probably improving) the original structure - although be aware of any designed-in crumple zones. Brazing is easier to learn than welding, and it really is a pleasure seeing the molten brazing rod pool out and flow into the join. DON'T do any welding/brazing in situ (or in an enclosed space) unless you have someone to watch out for fire hazards. Be careful about petrol and oily rags. Treat oxy-acetylene bottles with the utmost respect. They are like bombs.

Obviously you have to have some solid metal to braze on to! It depends how far gone a panel is. When I was doing my apprenticeship (forty years ago now) we didn't even use Isopon at all. The correct way was to melt large bars of solder on to the panel, then smooth it down with a rasp. Stopper on top, then primer surface etc.

MM

[Cicero]

================== These are cosmetic repairs and the simplest and cheapest method is to cut away the rusted sections and replace with new metal pop rivetted into place. Basically use a pair of tin snips to cut away the damaged material and then cut a cardboard pattern to cut replacements from new metal. Most car spares shops sell sheets of suitable repair metal - Zintec is the best if you can get it. Make sure that there is sufficient overlap on the replacement metal (at least 1") and feed it *under* the original metal. Clamp the new to the old as well as you can and drill 1/8" holes through both layers for your pop rivets (stick to 1/8" rivets). If you need to put a lip on - e.g. for a door edge prepare a bend in the new metal before starting the clamping / rivetting. Finish off the new door edge by hammering or crimping with pliers or mole wrench.

When you're sure that your new patch is securely rivetted clean the whole area and do a cosmetic finish with body filler and spray with aerosols to finish off. If possible try to hammer in the heads of the pop rivets so that the body filler covers them.

If the rusted areas are quite small you can use thin mesh instead of metal. You can buy this with 'Isopon' etc or separately. Clean the area to be repaired - remove all paint and rust. Then use a little body filler (Isopon or similar) to hold the mesh in place. Allow to set and then use more filler to complete the job.

Don't be tempted to use either of these methods on anything structural - they're for cosmetic use only.

Cic.

[Paper2002AD]

I just happen to have an oxy-acetylene kit here in the sideboard - been wondering what to do with it.

Really - let's keep our feet on the ground, shall we?

[Grunff]

They are nothing like bombs.

[Grunff]

As others have said, by far the best result will be obtained by replacing the doors and tailgate. Phone around your local scrappies. Someone will have a suitable donor with reasonable panels.

[:::Jerry::::]

Well the oxygen one is, in the wrong hands.

As for using oxy-acetylene on car body repairs, forget it, Mig (or Tig) is the only way to go - unless you like sorting out distortion.

obviously if you now what you are doing that, yes, oxy-acetylene can be used but then the OP would not be asking here....

[Mark]

Did you really mean brazing ? if so, its an MOT failure in anything considered structural.

[dp]

I'm surprised anyone would even consider anything else. With a bit of luck and a bit of searching, it might even be possible to match the colour. One big draw to driving an old car is that you don't need to feel bad about using second hand parts. If you have the space to keep it, you could buy a complete vehicle (for spares) for the cost of a new door.

[Dave Plowman (News)]

Brazed repairs aren't allowed in structural areas. They must be seam welded if a patch - or if replacing a complete panel, spot welding is ok if that was used originally.

[Rob Morley]

Door skins are hardly structural, are they?

[Rob Morley]

You will need: angle grinder with a selection of disks, MIG welder tin snips, hammer, pliers, workbench sheet(s) of steel rust treatment, filler, paint, sanding block and abrasive sheets

First run a coarse linishing disk over the crusty areas to remove all flaking paint and rust until you reach something vaguely resembling steel. If the edges of the frame are still mostly there you can just treat them with Kurust, if not you will need to weld in patches to restore the shape of the edge. Tidy up the hole in the skin with snips, cutting back until you reach something that looks like it will weld. Make up a patch using similar weight steel (something like 26SWG?) and fold the edges that sit on the frame to about 90 degrees so it sits snugly. Tuck under the cut-away skin and tack-weld securely in place - don't try to run a seam weld as you'll probably end up with lots of distortion and burning. Linish any blobs of weld so you can hide them under a thin skim of filler, but be careful not to go through the skin. Fold the edges tightly around the frame (no need to weld). Treat all the exposed edges with Kurust. Wipe a thin layer of polyester filler over the weld and sand it smooth. Paint.

[Jim Warren]

You could try asking in uk.rec.cars.maintenance. They might even know of a professional repairer in your area that will take on the job. If not, then you will get advice form someone who has done it before. There is a lot to be wary of if you are dealing with serious rust.

Jim

[Mike Mitchell]

Alternatively, tie yourself to the bottles, and whoosh! ;)

MM

[Mike Mitchell]

You don't have a clue. The fire brigade are always warning of hazards like oxy-acetylene bottles in workshops everywhere, especially when they are called out to put a fire out. How do you think a fireman feels to be told that in the conflagration there will be a couple - maybe several - of such bottles? The fireman typically play water on them for ages to reduce the risk of explosion.

MM

[Mike Mitchell]

Nonsense. Oxy-acetylene welding and brazing have been used for decades on car and truck bodies.

MM

[Grunff]

That doesn't make them 'like bombs'. By your reasoning a can of deoderant is 'like a bomb', and should be treated with utmost respect. Many things are perfectly safe in everday use, but become dangerous under extreme conditions.