Found rot! Advice for welding and repair - Progress

[RobWill116]

Hi all,

After someone knocked my e30 at work I stripped the front end down ready for paint work. Whilst its off the road I thought I'd have a dig around to see what I could find, below are my findings!

D/S Rear Sill


D/S Front floor pan




It has been patched in the past and not sealed properly, the rot goes up to the welding and no further.

D/S inner wheel arch


I will be tackling this myself cutting out the rot and fabricating patches, I'll be learning to weld over the winter.

What thickness sheet metal should I use? Most things I've read so far recommend 0.8 to 1.2mm.

If anybody can give any advise it would be great appreciated.
Cheers

[Speedtouch]

Yes, most car body repairs are done with 1mm thick mild steel. You could use galvanised if you prefer (for better rust resistance), but take care not to breathe in any zinc fumes, as it causes severe nausea and headaches.

http://www.e30zone.net/e30zonewiki/index.php/Rust

[bigbird76]

Not being sarcastic or please dont take this the wrong way but do not use galvanised sheet metal, The fumes will harm you as mentioned above and also when the welding heats up the sheet the galvanisation will pop off and can burn your skin. I know someone with a hole in their face because he did this job. Mild steel sheet is your friend and galvanised paint or epoxy primer afterwards.

Also clean your steel to the extreme to get a good weld.

Leigh

[mcspike]

http://www.e30zone.net/modules.php?name ... c&t=255528

I have a similar issue. The passenger side turned out to be hiding the same demon, but BIGGER.

[Grrrmachine]

Also, I used 1mm as repair plates in some sections, but standard E30 metal is 0.8mm. The thicker stuff is a lot harder to bend into shape.

[Speedtouch]

Not being sarcastic or please dont take this the wrong way but do not use galvanised sheet metal, The fumes will harm you as mentioned above and also when the welding heats up the sheet the galvanisation will pop off and can burn your skin. I know someone with a hole in their face because he did this job.

That's pretty severe, and something I've not heard of before, however, most sensible welders wear gloves, long sleeves/overalls and a face mask when welding, to minimise the risk of weld spatter.

I've done a fair amount of MIG welding using galvanised steel and not encountered any major problems, but it pays to be aware of the potential hazards.

[HairyScreech]

Not being sarcastic or please dont take this the wrong way but do not use galvanised sheet metal, The fumes will harm you as mentioned above and also when the welding heats up the sheet the galvanisation will pop off and can burn your skin. I know someone with a hole in their face because he did this job.

That's pretty severe, and something I've not heard of before, however, most sensible welders wear gloves, long sleeves/overalls and a face mask when welding, to minimise the risk of weld spatter.

I've done a fair amount of MIG welding using galvanised steel and not encountered any major problems, but it pays to be aware of the potential hazards.

As both above.

Don't use galv sheet it's cheep and nasty, you want Zintec or similar.

Yes still the potential for zinc fume fever but only in very high exposure and poor ventilation.

Minimize the risk by running a knot wheel down the edges you wish to weld. (advisable anyway from a weld cleanliness point of view)

Zintec electroplated sheets will resist corrosion in repairs a lot better than mild, I have seen repairs with zintec where the area around the patch has rotten to holes thanks to bad protection but the zintec patch is still intact and untouched.

[RobWill116]

Thanks for the responses. Managed to start cutting some of it out last night and it appears the garage who did the repairs previously, simply welding new plates onto the rust panels

Will get the rest of it cut out hopefully tonight, and can start some welding over the weekend!

[BHadley]

Surprisingly satisfying doing it yourself anyway if you have the resources.

I'm 6 plates in on the passenger side, first real go at it....

All the best

[RobWill116]

Finally got chance to cutting it out over the weekend...



Nice bit of ventilation! Been practising my welding, getting better I reckon welds are more smoother and penetration better.

Not in a rush to get this done, its off the road for winter now so steady as she goes.

Any advice as I go along with it, would be appreciated

[BHadley]

I'm doing the same repair on the passenger side corner....

Knotted wire wheel for your grinder will clean up old metal very well and is good at getting the old seamer off.

Be brutal with it and move wiring out the as much as poss.

Once welded and ground back a good coat of zinc rich primer, when dry seam sealer on the welded area followed by a PU based underseal for under the car ala OEM style...

Bmw do sell this type but 3m sell a similar product and you will need a Shultz style gun and air compressor to spray it

While the carpets up check as much of the bulkhead as you can....

[RobWill116]

Cheers Slideout, had a good look as far as I can with bulkhead and its looks clean as it can be.

Inside it will get all bare metal treated with Bilt Hamber hydrate 80, zinc rich primer, seam sealer welds, top coat in sterling silver then sound proofing.

Underneath, it'll be bilt hamber treatment, primer, seam sealer welds, then stonechip, top coat in sterling and then underseal.

As recommended on the wiki, I won't be replacing the so called 'jacking points' either to prevent future water traps.

Progress is slow, but there's no rush.

[Brianmoooore]

and then underseal. .......... to prevent future water traps.

DO NOT coat your car in schultz (bitumen like) underseal. This stuff is designed to stave off the weighbridge for a few more years on welded up Fords and the like, and has no place on a restored vehicle. After a few years the stuff will dry out and crack, begin to lift, and effectively become one big water trap.

[RobWill116]

and then underseal. .......... to prevent future water traps.

DO NOT coat your car in schultz (bitumen like) underseal. This stuff is designed to stave off the weighbridge for a few more years on welded up Fords and the like, and has no place on a restored vehicle. After a few years the stuff will dry out and crack, begin to lift, and effectively become one big water trap.

What would you recommend?

On my mini I've always used Waxoyl, but I've recently purchased some Bilt Hamber Dynax UC which is a clear anti-corrosion wax. Very impressed with that, non-sticky (like waxoyl), near invisible and provides great coverage.

[BHadley]

3m sell a good PU based underseal that is flexible
Or bmw body shops could sell you OE spec stuff.....

[bigbird76]

Did The whole underside of my M3 with about 12 tins of this stuff

http://www.3mdirect.co.uk/coatings-2/08 ... tle-1.html


The Bilt Hamber is great for inside your cavities with the nozzle supplied as i used Bilt aslo.

Just to add i applied the 3M stuff with a cheapy compressor and a cheap gun to fit the canisters, Warm it up first in a bucket of hot water it goes on really great.



3m Seamsealer



Leigh

[BHadley]

Yeah that's the stuff....

[G-Bear]

Did The whole underside of my M3 with about 12 tins of this stuff

http://www.3mdirect.co.uk/coatings-2/08 ... tle-1.html

Leigh

From reading through many build threads on here. The above 3M stuff seems most successful and gives a nice OEM styled finish.

[RobWill116]

Haven't updated this much, have got quite a bit of progress.





Not the tidiest welding, but it had all penetrated pretty decent. Looks better after being ground back.



Front floor and bulkhead or finished welding and primer





Got the 3m seam sealer and 3m underseal on order.

Here's the next bit I will be tackling...