BMW E30 Wheel Well Rust Repair & Underseal Removal | Welding Thin Metal With A DIY Copper Block | 034

In this BMW E30 Build video, I turn my attention to the wheelwells which are the last area of the car I need to strip the underseal from. I'd already noticed a few ugly looking rust patches within the front wheel houses that needed attention so I was expecting to find a few rust holes to weld up.

Here's what I use in this video:
Clarke Weld MIG 150 TE Turbo: https://ebay.us/jbdfE8 (this is the newer version)
0.8 Welding Wire: https://ebay.us/eQWqWx
Argon/CO2 Welding Gas & Regulator: https://ebay.us/7BOngD
Angle Grinder Wire Brushes: https://ebay.us/sSJjtM
Dewalt Angle Grinder: https://ebay.us/CmsNuW
Safety Goggles: https://ebay.us/2Dvt5C

I got to work using an angle grinder with a wire brush on to strip the E30s underseal away and reveal what was underneath. It's worth noting that on the BMW E30 there is an additional factory coating on top of the typical BMW factory beige underseal and body colour spray. The additional coating is a black substance applied only in the wheel-wells to give them some extra protection from grit and stone chips.

After a few hours of grinding away at the underseal I had cleared the areas of rust and worked back to bare metal, and also resurfaced the larger solid areas of underseal ready to take on a new coating.

Continuing with my previous train of thought, I decided not to strip the wheelwells to bare metal and remove the factory e-coat. It's my belief that stripping away the original ecoat would only enable the chassis to rust more readily on the car. If something has been solid for 30 years, why disturb it and start it off rusting?

The areas of rust I feared would become rust holes turned out to be just areas of surface rust, the worst of it being some pitting. However in the passenger side wheel well I found that one of the studs which a plastic retainer for the fuel breather line screws onto had completely rusted away and needed replacing.

The worst of it however was a series of holes drilled into the top of the wheel well by a previous owner of the E30. These holes were drilled to fit an aftermarket alarm system, but this old system was no longer functioning so I ripped it out along with the wiring when I first got the car and it was driving.

Unfortunately, these holes were really poorly positioned to allow for future rust or grit to be flung into the engine bay, so I knew they needed to be sealed up. The good news was that I had great access to both the top and bottom side of this thin sheet steel, but the bad news is it was some of the thinnest sheet metal I'd ever needed to weld, and it was suffering from a little bit of pitting and surface rust too.

A previous commenter, and someone who clearly knows a lot more about how to weld thin sheet metal than I had informed me of the neat trick of using a copper block to aid with the welding of thin sheet steel.

I decided to try and fabricate my own small copper welding block DIY style with a length of old copper pipe which I cleaned up and hammered flat into a small copper welding block successfully.

How to use a copper welding block consists of pressing it against the back side of the thin sheet steel you're trying to weld, and it helps in these ways:

- It draws heat out of the thin steel, reducing the chance of warping
- It helps prevent blow-through by keeping the weld pool in place
- It prevents wire shoot-through when the weld current disconnects

I think this trick really is a game changer and combined with a simple MIG welder like my Clarke MIG150 machine you will be able to undertake all types of thin bodywork welding on the lower settings.

Needless to say, the repair went very well and once ground down with a flap disc the fix is almost invisible.

I've not got the areas sprayed up in etch primer to prevent flash rusting ready to apply my new underseal and seam sealer in a future video.

For more helpful how-to guides and restoration project logs, visit our blog: https://www.spannerrash.com/

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#bmwe30 #welding #rust #repair #restoration #bmw #e30