What is allowed and what is not allowed in bodywork repairs?

Currently, I occasionally work in a body shop, where I deal with rusted metal panels. No matter what my boss says, I still want to inquire about this again! I just didn't study that particular subject, but I did become a plumber.

1. What materials can be welded, and what materials cannot?
2. What can be hard-soldered, and what cannot?
3. When is spot welding sufficient, and when and where is it a necessity?
4. What can be glued? So, without a weld point?
5. If I need to achieve a particularly high level of detail, I also weld the sheets together edge-to-edge, but always ensuring the seam is tight. Is there a regulation regarding butt welding?


Perhaps someone will take the time and address this...

Hi.

To explain that, you would need to write at least a master's thesis!

And then you have to distinguish between the manufacturer's specifications and what the inspectors expect during the main inspection...

And one must not forget one's own expectations.

It's important to do the job properly and then apply rust protection afterward!

I've been doing this kind of work since 1986, and I always determine the best approach for each project individually... because you have to consider whether the car is intended to become a classic or just needs to pass the next technical inspection.

Well, I've talked to a few bodywork specialists here and there, and none of them mentioned any regulations. That doesn't really satisfy me... even the expert here never complains.

"For example, if I were to cut a hole in the middle of a threshold and then weld it shut, I've always used spot welding to ensure a tight seal. I've never welded a seam in one continuous piece because of the risk of warping. However, I've also seen cases where this was done with spot welds, spaced about 3cm apart. Personally, I wouldn't do that on my own car, mainly for rust prevention. But is it permissible to spot weld it like that? How about brazing?" I mean, a sill is a load-bearing component these days...

Soldering has the advantage that the joint, especially when using galvanized sheet metal, won't rust.

Body shops typically repair cars involved in accidents and do not weld rust holes, as it is absolutely uneconomical given the hourly rates.

You should get in touch with a specialized company that restores classic cars.

What kind of car are we even talking about?

If you can prove, through a strength analysis report, that the solder joint complies with the manufacturer's specifications, then there should be no problem.

I once had to hard-solder a car, specifically the connection between the roof skin and the A-pillars after the roof skin was installed.

Yes, in the company where I occasionally do this, removing rust is a real pain! Now that people have less money, these kinds of repairs are becoming more and more common.

I'm just a little skeptical about the methods and techniques being suggested for how certain things should be welded. That's why this thread.

Hi,
For passenger cars from the last 20 years or so, there are relevant repair guidelines provided by the manufacturers. B. von Audi already used the RLF code "Body assembly work" for the Audi 80 models manufactured before 1996.
When it comes to structural parts, there's no getting around it, but with simple repair panels, the key is at least to ensure the proper treatment of the surfaces.
I remember that any damage to load-bearing parts identified by the TÜV (German technical inspection authority) had to be presented before any coating was applied.
hg
Herbert.

Hello!

The TÜV and Dekra inspection companies in my area are refusing to inspect the welds.
If no one asks, and there's paint and underbody sealant covering it, and it looks reasonably decent, then no one has complained.

I know, however, that this is required differently elsewhere.

It's probably also a matter of the trust relationship between the workshop and the inspector, but in my experience, that was always very good when I still owned my workshop.

Otherwise, yes, I didn't really learn that properly either; I just observed what my older colleagues were doing when I was younger and working there. So, basically, everything was done using the MAG process.
There were welders among them who used to work on the assembly line at the Trabant factory in Zwickau (some individual seams, which the robots couldn't do, were done manually), and these people were actually able to weld, which is hard to believe.
They welded 20cm-long seams overhead in a single pass, and it looked like it was done by a machine.

I'm far from that.

In the weeks leading up to my vacation, I also managed to fix up my two old cars.
A front bumper and wheel arch trim for a T4, plus some additional parts. For the Golf, only the front fender edges.

Okay, so for the butt seams, there was no other way with the Golf, so I welded it in short sections using MAG welding. That is permitted in the bodywork construction.

Mostly, I translated the text, punched holes in it with a hole punch, and then welded the pieces together through the holes.
With a spot welding nozzle, properly adjusted equipment, and a little practice, it actually worked quite well. As always, it worked best when I was almost finished.

To be honest, I'm not really interested in soldering.
I don't have/can't do laser or TIG welding.
A lot of damage can be caused by using a welding torch and a flame.
If half the car doesn't catch fire and burn through the underbody protection, at the very least, the metal will glow red hot. And it brings about delays and, eventually, endless rust.


You have to be careful when doing MIG welding if there's underbody sealant or wax present. It should definitely be kept away from the seams, but if it gets hot, it will become liquid and run everywhere.
That's going to be a real mess, and if it gets to the weld seams, it will only make things worse. It can also cause fires.

So, that's not exactly a glamorous job you've chosen.
And the dust that comes off when you remove old paint and filler isn't exactly healthy either...


Otherwise, regarding soldering:

When performing high-quality repairs on valuable cars,
Can you use solder as filler instead of the usual two-component filler?
"An old car body builder once showed me something like that."
While it's also essentially a form of craftsmanship,
But with a little practice, you can achieve some really great results.

Steffen G wrote:

Hello! To be honest, I'm not really interested in soldering. I don't have/can't do laser or TIG welding. A lot of damage can be caused by using a welding torch and a flame.

You probably don't know what soldering is, just like I do. I mean, it's just like welding. It is "soldered" using a MIG/MAG welding machine, and argon is used as the shielding gas.
I would never use a flame near a car. (I once had an old Jeep that caught fire just from having a welding machine nearby...)

I know people who solder everything, even where there's rust underneath. For me, that's shoddy workmanship.

Quote:

TÜV and Dekra, the inspection companies here where I am, don't want to inspect the welds. If no one asks, and if there's paint and underbody sealant covering it, and it looks reasonably decent, then no one has complained.

Here as well. At first, the inspector would still walk past me skeptically, but now he's happy whenever I'm there .

Quote:

So, the seams were butted together, and with the Golf, there was no other way; I welded them in short sections using MAG welding. This is allowed in body construction.

That's actually what I've always done with my cars, and what I enjoy doing the most. It just takes longer, and that's not always desirable.
To reproduce something as faithfully as possible is what's truly "beautiful."

Quote:

So, it's not exactly a glamorous job you've chosen.

Luckily, I also have the opportunity to do some filling and painting of smaller parts. It's a welcome change, but it's actually a lot of fun! In reality, that's my dream job. Car repairs are sometimes included.



But thank you for your words. I was able to get a few helpful tips from it!

What do you think about welding it completely shut, or welding tack welds every 2 to 3 centimeters?
Am I correct in assuming that I should repair it in the same way as it was originally? At least, to the extent that it's possible, especially when it comes to overlapping panels. "I weld in the same spots where it was previously spot-welded, like the edge of the sill as shown below, and I weld continuously along any areas where there is a continuous piece of metal."
However, for non-structural parts like a door, for example, I usually leave it as a spot weld or a soldered joint, as intended. For myself and my family, I still completely reject such things.



Okay, and what wire gauge do you use?

Herbert wrote:

Hi, For passenger cars from the last 20 years or so, there are relevant repair guidelines provided by the manufacturers. B. von Audi already used the RLF code "Body assembly work" for the Audi 80 models manufactured before 1996. When it comes to structural parts, there's no getting around it, but with simple repair panels, the key is at least to ensure the proper treatment of the surfaces. I remember that any damage to load-bearing parts identified by the TÜV (German technical inspection authority) had to be presented before any coating was applied. hg Herbert

Is there a resource where I can find information about which manufacturers have specific guidelines or requirements? Is there a book or software that contains everything about this?

"There probably isn't a single book that covers all manufacturers; instead, there are likely books specifically for each model and manufacturer."

And then, all of this relates to the repair of accident damage.

However, not every workshop adheres to this. Crushed longitudinal beams usually need to be replaced according to the manufacturer's specifications. However, workshops often only remove them and then often only replace parts, if at all.

In your case, you should contact an experienced expert from a recognized testing organization, such as TÜV or DEKRA.

I once had a Golf 3 where the rear axle mounting was rusted through. There were no repair patches available, so I discussed it with my Dekra inspector and repaired it accordingly.

[quote="Martininii"]

Steffen G wrote:

Hello! Oh yes, and what wire gauge do you use?

Hello!
This question is still open.

So, I use 0.8 mm welding wire.

There might also be 0.6 mm wire available.
If that's the case, then he would probably be better suited for those types of metalworking tasks.

However, I only have a relatively large MAG welding machine that can weld wires with a diameter of 0.8 mm and 1 mm.
This is more suitable for metalworking and thicker materials.
Unfortunately, there aren't many settings for the current strength available, even in the lower performance range.

What I can also add is that the type of welding wire used makes a significant difference, as there are noticeable variations in how easily it can be welded.

For cost reasons, I currently use pure carbon dioxide; in the past, I used an argon-based gas mixture.
I didn't really notice much of a difference.

I can't really judge that.
The poor connection and the mixed gas made things quite difficult.
Then, with carbon dioxide and the poor connection, it gets even worse.

Now that I have a good understanding of copper wire and carbon dioxide, I'm doing quite well.

The success of the entire welding process depends entirely on the settings.

Welding with 0.8mm wire is a good compromise.

[quote="Steffen G"][quote="Martininii"]

Steffen G wrote:

So, I use 0.8 mm welding wire. There might also be 0.6 mm wire available. If that's the case, then he would probably be better suited for those types of metalworking tasks. Okay, I'm ready. Please provide the German text you want me to translate. What I can also add is that the type of welding wire used makes a significant difference, as there are noticeable variations in how easily it can be welded. For cost reasons, I currently use pure carbon dioxide; in the past, I used an argon-based gas mixture. I didn't really notice much of a difference. I can't really judge that. The poor connection and the mixed gas made things quite difficult. Then, with carbon dioxide and the poor connection, it gets even worse. Now, I'm getting along quite well with copper wire and carbon dioxide.

At home, I always use 0.6mm wire. You can even weld very thin sheet metal with it. I would much prefer that, but in my part-time job, I only have 0.8mm wire and a huge welding machine...
I've noticed that you have to adjust the settings differently for the welding wire to get a good result. The other day, I had to change the spool, and I didn't realize it was a different type of wire (all-purpose). At first, I kept getting holes in the weld, and it wouldn't stop. With more gas and less wire feed, things improved again.

Is there a hole there? If so, were there too many...?