Welding Body Panels - Thickness and Tips?

[Baldchap]

I need to do some repairs to the shed Jag and I'm going to have a stab at patching the rusty wheel arches. Does anyone know roughly how thick the existing body panels are likely to be, and therefore what thickness sheet metal to go for?

I've never done much beyond basic straight welding before, so if anyone has any tips for this job, they'd be appreciated.

Thanks.

[E-bmw]

0.8mm is normal but I suspect Jags of a certain age might be slightly more, so anywhere between 0.8 & 1.0mm should be fine.

I am assuming you are going to Mig weld it.

If at all possible "joggle" the last 1/2" of good metal to give greater volume of metal to handle the heat better and "stitch" the edge until you end up with a full weld.

I generally use a slower wire feed to allow the weld pool to give full penetration, but the key is good clean surfaces and have a practice on similar metal first.

[paintman]

As above.

Don't know what your welding experience is so this might be worth a read:
https://www.mig-welding.co.uk/

Might be a bit problematic given the lockdown but I can thoroughly recommend an auto darkening mask. Used in conjunction with a good light source means you can see what you're doing!

Important to have the surfaces as clean as possible.
Don't try & do long seams - esp butt welds - in one hit by starting at one end. Tack at intervals then fill in the gaps between, reduces heat distortion.

If you are replacing an item that was originally spot welded then you can plug weld, if repairing holes in panels the patch must be seam welded.
"10. Acceptable methods of repair
Repairs to structural components must be properly carried out and appear to be as strong as the original structure. This requires the use of suitable materials and any plating or welding extends to a sound part of a load-bearing member.

You can only pass spot welded repairs if the original panel was spot welded and the original panel or section has been removed. Stitch or plug welding can be used instead of spot welding.

In all other circumstances, patch repairs must be continuously seam welded.

Some vehicle manufacturers have recommended repair methods that use MIG brazing, a combination of adhesive bonding and riveting, or amalgamations of these with other joining methods. Such repairs are therefore acceptable unless they are clearly inadequate."
https://www.gov.uk/guidance/mot-inspection-manual-...

[Baldchap]

Thanks both. I have a little experience (years back) but both posts above are very useful, so thank you. I actually read the link yesterday and ordered a self-dimming mask last week (I think).

The car is going to be used for a banger rally, so never needs to pass another MOT, though obviously I'd like it to be safe and pass a roadside check. The big home made spoiler might make that difficult though!

I'll grab some 0.8 mm sheet metal and wire and have a practice first.

Thanks again.

Edited by Baldchap on Tuesday 14th April 12:52

[Matt_E_Mulsion]

The back of my mind is saying that 18 gauge sheet steel is what what we used to use for panel repairs many years ago. A quick look online says that equates to 1.2mm.

What I can remember is that if the steel is too thin you'll just blow it away with the welder, and if it's too thick you can't bend easily to form the shapes you want.

[VanDiesel99]

Couple of Tips:

Use a Heatsink where you can: this can be copper or Aluminium, my Ali Heat Sinks were once part of a Shower Enclosure

Seam Welding is the most difficult: use a Plug Weld in preference where you can

Don't under-estimate how big a hole you could end up with once you start nibbling away at rust.

Keep the Torch at a shallow angle to the metal where possible

Start in the spot that'll notice 'least' if it all goes horribly wrong

If you're not looking for a 'wonderful' or structural repair, consider Body Filler and/or Fibreglass also