What to use after welding repairs?

[Lurch320i]

Hi all

I'll be doing some welding on the floor and bulkhead
Just wondering a few things
1.what thickness steel to use
2.which underseal, primer, paint etc
3.how to stop it happening again

I'll post some photos up soon

[Lurch320i]

Drivers front corner

Passenger front corner

Under passenger front seat

Bulkhead

[Grrrmachine]

1) 0.8mm steel, but you can use 1mm if you have it to hand (I did).

2) Depending on the amount of work you're doing, you can spray on a zinc primer immediately after welding if it's a work-in-progress, or use a brushable seam sealer if you're finished/it's a hidden repair. I prefer to coat fresh welds in an epoxy anti-rust layer such as Brunox, but it isn't really designed for painting over so I only use it on welds in hidden areas.

3) Use the proper paint process of panelwipe-tackcloth-primer-base-clear if you're repairing panels. If it's sills/bulkheads, use seam sealer and non-bitumen based underbody coating. Spray inside all cavities with a zinc primer followed by cavity wax.

The restore thread in my signature outlines how I tackled repairs in exactly the same rust spots, and what chemicals I used during the process. It's also worth going through the other Restorations for other tidbits of advice:

http://www.e30zone.net/e30zonewiki/inde ... storations

[Lurch320i]

Thanks grrr I've been through your thread a few times

I was after actual products people like yourself that have done this work
Like any particular brands to look for or stay away from

[DanThe]

After welding clean off all the soot/burned bits and paint with an acid etch primer, in my experience zinc primers are shite, dont put seam sealer directly onto bare steel either, its meant to be put over primer

[Lurch320i]

Ok I'm gonna order few bits
Any brands I should stay away from?
Is there anything considered a must have?

Regarding inside the wheel arch.which is best?hammerite?

[Brianmoooore]

Any brands I should stay away from?.................hammerite?

Far too brittle and other paints, etc. don't stick to it.

[Lurch320i]

Thanks Brian

So anyone have links to specific products they would recommend?
A full list would be nice
From primer to paint to the finishing underseal stuff

[Lurch320i]

This is what I'm looking at so far
Etch primer
http://pages.ebay.com/link/?nav=item.vi ... 1632854558

Seam sealer
http://pages.ebay.com/link/?nav=item.vi ... 1635839633

Lachs silver paint
http://pages.ebay.com/link/?nav=item.vi ... 0640981040

Stuck on which underseal to het
If someone could provide an actual product name or a link that'd be great

[Grrrmachine]

dont put seam sealer directly onto bare steel either, its meant to be put over primer

Plenty of products out there that go on bare metal, although it's good to wash the steel with a touch of phosphoric acid first. If you brush sealant onto primer there's a risk it'll lift off in some cases.

It's mostly a case of "read what it says on the tin". The one I use (AutoPlast Seal 10) is for both bare and primed steel.

[Lurch320i]

That's the thing
Ive read so many conflicting articles about what order to do things in
This was another reason I thought id ask

So does anyone have a difinative order/method to prep, weld and aftercare including products that I should definitely avoid and some that is a must

Also any hints/tips that people did that made the job a tad easier

Appreciate all your input alreafy

[BHadley]

Here's what I do......
For floor sill and under body out of sight items

After welding grind down to reasonably even thickness everywhere.

Aerosol zinc primer welded area and any bare metal

Brush able seam sealer or PU type sealer (tiger seal being one of many brand names for it), best applied with a cut down 1/2" paint brush to work in seams.

3m flexible PU based underseal
http://www.3mdirect.co.uk/coatings-2/08 ... tle-1.html

Can be bought as an Aerosol too I think but a Shultz style gun and air compressor is the best way.

All the above are ready avalible from car refinishing style motor factors...

[HairyScreech]

For internal/hidden panels and suspension components I am a fan of a good quality (not rustoleum) long chain oil based paint. If you get good quality marine grade paint then you can seal things up practically for ever.

[Lurch320i]

Thanks guys that's the kind of stuff I was aiming for
Any tips or tricks?

And how many of those 3m cans would I need to do both wheel arches including the backs of the new wings I need and the front half of the floor?ill do the rear half at a later date (when I get around to looking for rust at the back)

[DanThe]

dont put seam sealer directly onto bare steel either, its meant to be put over primer

Plenty of products out there that go on bare metal, although it's good to wash the steel with a touch of phosphoric acid first. If you brush sealant onto primer there's a risk it'll lift off in some cases.

It's mostly a case of "read what it says on the tin". The one I use (AutoPlast Seal 10) is for both bare and primed steel.

Like you say it depends on the product, im just talking 'generally' as thats how the old school stuff thats been about for years is supposed to be used, obviously if it says on the tin [straight to steel] then fair enough

[BHadley]

Thanks guys that's the kind of stuff I was aiming for
Any tips or tricks?

And how many of those 3m cans would I need to do both wheel arches including the backs of the new wings I need and the front half of the floor?ill do the rear half at a later date (when I get around to looking for rust at the back)

Guy on here did the underside of his m3 with five of the 1 liter cans....