Let me introduce Mathilde, my 1953 Traction Avant. For the record she’s an RHD ‘Onze Normale’ with the ‘Perfo’ engine, dark blue when she came my way but originally silver once I’d delved into the paint layers. I’m going to make this post multi-part (for different subject areas) since it would be too long in one go. This first section I’m going to talk about tools so don’t “stop me if you’ve heard it” rather skip to the meat in later posts. Most of the work here took place some time ago - I'd said I'd write it up "one day," well todays the day.
Confession time - when I got Mathilde my ‘due diligence’ was limited and while I tested the rocker panels in places with a screwdriver it appeared solid although there was loads of surface rust. I’d hoped the worst corrosion was limited to the “bolt on” panels but that turned out not to be
First problem this presented was that I had no equipment to deal with heavy-grade bodyshell fixes. While I was in one of the big DIY chains I spied a ‘MiG’ welder on superspecial knockdown so got that. It was the type that only uses “flux cored” welding wire – there was no separate gas ‘circuit.’ As you’ll likely already know when it comes to joining panels whatever the type of welder you have the basic choice between butt-weld, lap-weld, seam-weld, or plug-weld {OK I left out spot-weld ‘cos that needs more specialist kit}. Butt welding in thin sheet metal is extraordinarily difficult {at least for me} – just about doable if you use oxy-acetylene and go really slow. I went for seam welding where possible and plug-welding elsewhere. I did some experiments on scrap pieces before launching into the main event and found that for a successful plug-weld the hole in the overpiece needed to be 10mm minimum {I’ll qualify this a bit by saying 10mm with my welder and skill level!}, anything smaller the weld appeared OK until ground back to the initial plate thickness when there was a circular microcrack around the circumference. Why was this of interest – well at that stage I was drilling all the holes and the smaller the diameter the quicker you went.
That brings me to grinding – again you’ll know the weld is always stronger if ground back to a flat even surface {concentration of stresses}. Grinding back the welds was a real ‘pita’ – takes waaayyy longer than the welding. Grinding wheels vary considerably in quality – some virtually ‘melt’ away. Somehow in my travels I’d ended up with three angle grinders – each of different size – gave me ‘stockholding’ problems. I’d say minimum two angle grinders needed, one with a stone the other with a cut-off wheel fitted – and make sure the darn things are the same size.
Where possible buy the premade repair panels – trying to make same from scratch is a thankless task – don’t ask me how I know that. Inevitably there’ll be some panel section where nothings available so cutting equipment is a must. I had a couple of sets of ‘tinsnips’ plus the cutoff wheel. Cutoff wheel is quick but radiuses are a problem, tinsnips will do radial cuts but the offcut tends to get mangled and not so useful for your next part. Later I got an air ‘nibbler’ which was well worth it since you can follow complex shapes without damage to the part or the offcut {electric versions of this tool are also available}. Another essential is a ‘deburring’ tool to take off the ‘rags’ that project from the cut edge, particularly if the cutoff wheels been used.
If you go the plug-weld route the first thing you’ve got to do is butcher your nice pristine premade panel by forming lots of holes in it {30 – 35mm centres}. If you have anything more than a single panel then do yourself a favour and get one of these:
Its a lever operated punch - lost count of the number of drill bits I wore out before biting this particular bullet.
When it comes to the “hidden” panels you can be a bit “agricultural” about the joins where one panel laps over the other but for the external panels “on view” you’ve got to do something to recess one edge where the other laps over else you’ll get a ‘step’ at the join. I made a significant investment in one of these:
Its a portable continuous flange forming tool for sheet metal. Not the only way of achieving same – there are ‘joggler’ devices that work like pincers for less coin than the Kings ransom this thing cost. I guess I was {attempting} to think ahead to things such as the doorskin repairs where the smoothest of joins will be needed.
To successfully join panels the welded area’s gotta be 100% clean so a good selection of wire brushes to fit either drills or angle-grinders is a must. As well as clean alignment is super-important {obviously} and indispensable for this is a selection of both pop rivets and ‘self tappers’ to hold panel edges together where you cannot get a clamp around. Clamping’s always preferable where you can so I had a selection of ‘self grip’ and ‘G’ clamps available. Similar to the “more than one angle grinder” argument more than one drill pays dividends {I had three on the go – now one’s burnt out, another busted its gearbox}.
So in summary I learnt as I went along, started with a little bit of ‘Rolls Royce” kit, upgraded others as the lessons kicked in – the welder was probably sub-par to begin with – it broke eventually and I upgraded to a “Unimig 180” gas shielded machine. So much better not to have all the smoke from the flux-cored wire obscuring what you need to be seeing. So there’s the other lesson – don’t skimp on the welder!
Disclaimer - Other than a customer I’ve no connection with any of the brands mentioned above.
Happy fixing
Rob
Confession time - when I got Mathilde my ‘due diligence’ was limited and while I tested the rocker panels in places with a screwdriver it appeared solid although there was loads of surface rust. I’d hoped the worst corrosion was limited to the “bolt on” panels but that turned out not to be
First problem this presented was that I had no equipment to deal with heavy-grade bodyshell fixes. While I was in one of the big DIY chains I spied a ‘MiG’ welder on superspecial knockdown so got that. It was the type that only uses “flux cored” welding wire – there was no separate gas ‘circuit.’ As you’ll likely already know when it comes to joining panels whatever the type of welder you have the basic choice between butt-weld, lap-weld, seam-weld, or plug-weld {OK I left out spot-weld ‘cos that needs more specialist kit}. Butt welding in thin sheet metal is extraordinarily difficult {at least for me} – just about doable if you use oxy-acetylene and go really slow. I went for seam welding where possible and plug-welding elsewhere. I did some experiments on scrap pieces before launching into the main event and found that for a successful plug-weld the hole in the overpiece needed to be 10mm minimum {I’ll qualify this a bit by saying 10mm with my welder and skill level!}, anything smaller the weld appeared OK until ground back to the initial plate thickness when there was a circular microcrack around the circumference. Why was this of interest – well at that stage I was drilling all the holes and the smaller the diameter the quicker you went.That brings me to grinding – again you’ll know the weld is always stronger if ground back to a flat even surface {concentration of stresses}. Grinding back the welds was a real ‘pita’ – takes waaayyy longer than the welding. Grinding wheels vary considerably in quality – some virtually ‘melt’ away. Somehow in my travels I’d ended up with three angle grinders – each of different size – gave me ‘stockholding’ problems. I’d say minimum two angle grinders needed, one with a stone the other with a cut-off wheel fitted – and make sure the darn things are the same size.
Where possible buy the premade repair panels – trying to make same from scratch is a thankless task – don’t ask me how I know that. Inevitably there’ll be some panel section where nothings available so cutting equipment is a must. I had a couple of sets of ‘tinsnips’ plus the cutoff wheel. Cutoff wheel is quick but radiuses are a problem, tinsnips will do radial cuts but the offcut tends to get mangled and not so useful for your next part. Later I got an air ‘nibbler’ which was well worth it since you can follow complex shapes without damage to the part or the offcut {electric versions of this tool are also available}. Another essential is a ‘deburring’ tool to take off the ‘rags’ that project from the cut edge, particularly if the cutoff wheels been used.
If you go the plug-weld route the first thing you’ve got to do is butcher your nice pristine premade panel by forming lots of holes in it {30 – 35mm centres}. If you have anything more than a single panel then do yourself a favour and get one of these:
Its a lever operated punch - lost count of the number of drill bits I wore out before biting this particular bullet.
When it comes to the “hidden” panels you can be a bit “agricultural” about the joins where one panel laps over the other but for the external panels “on view” you’ve got to do something to recess one edge where the other laps over else you’ll get a ‘step’ at the join. I made a significant investment in one of these:
Its a portable continuous flange forming tool for sheet metal. Not the only way of achieving same – there are ‘joggler’ devices that work like pincers for less coin than the Kings ransom this thing cost. I guess I was {attempting} to think ahead to things such as the doorskin repairs where the smoothest of joins will be needed.
To successfully join panels the welded area’s gotta be 100% clean so a good selection of wire brushes to fit either drills or angle-grinders is a must. As well as clean alignment is super-important {obviously} and indispensable for this is a selection of both pop rivets and ‘self tappers’ to hold panel edges together where you cannot get a clamp around. Clamping’s always preferable where you can so I had a selection of ‘self grip’ and ‘G’ clamps available. Similar to the “more than one angle grinder” argument more than one drill pays dividends {I had three on the go – now one’s burnt out, another busted its gearbox}.
So in summary I learnt as I went along, started with a little bit of ‘Rolls Royce” kit, upgraded others as the lessons kicked in – the welder was probably sub-par to begin with – it broke eventually and I upgraded to a “Unimig 180” gas shielded machine. So much better not to have all the smoke from the flux-cored wire obscuring what you need to be seeing. So there’s the other lesson – don’t skimp on the welder!
Disclaimer - Other than a customer I’ve no connection with any of the brands mentioned above.
Happy fixing
Rob