Front wing - I'm going in

[spencerd72]

Morning all,

I'm just about to remove my drivers side front wing to cut out the rusty bits and let in new steel. I'm also planning on doing the same for the inner wing whilst I'm in there.

I've recently learnt to TIG weld and bought a suitable machine. I've practiced welding 0.9 mm steel including making patches and welding them in and got good results. I've got a hammer and dolly set and have practiced using it.

I'm hoping to have it off and the layers of Waxoyl off by this evening. I'm going to use paraffin for the initial cleaning.

Wish me luck chaps - pictures will follow!

[Brucey]

you might well (as I did) find that MIG is the best technique for doing car parts. It is more tolerant to any little spots of gunge/rust there might be ( you need a new tungsten grind with every one you hit with TIG). Contrary to popular belief it is (given that we are not all micro-surgeons) often possible to make a lower heat input weld with MIG vs TIG. MIG is easier to do all-positionally, and the consumables are a lot cheaper too.

You might want to look at my piece in the tech articles section on this repair.

I wish you good luck with it and I'm sure everyone will be interested to see pictures of your work.

cheers

[hornhospital]

+1 on MIG vs TIG for panel work. I have both, and there's no comparison. TIG is perfect for stainless and aluminum, but near useless on corroded panels.

Spencer, where are you? If you're in the US, find a Harbor Freight and buy their little $99 flux-core MIG machine. No tank of gas needed, and it does an excellent job.

Speaking of where you are, you can add that to your profile, so we won't have to ask again when we forget.

Welcome to the madness.

[Chris Wright]

Spencer, where are you? If you're in the US, find a Harbor Freight and buy their little $99 flux-core MIG machine.

If he has a front "Wing" (fender) and uses "paraffin" (gasoline) to clean parts, I doubt he is from the US.

No tank of gas needed, and it does an excellent job.

But I thought the "IG" in "MIG" and "TIG" meant Inert Gas? What does the "M" and "T" mean?

[Brucey]

MIG = Metal Inert Gas

TIG = Tungsten Inert Gas

These acronyms are the ones most people remember but each can be either misleading or not the only acronym used to describe the same process.

TIG was first known (in many places) as 'HeliArc' which was a helium shielded process variant. TIG is also known as GTAW (Gas-Tungsten Arc Welding).

The term 'MIG' is very often applied to other (superficially similar) welding process. Basically any process that is manually applied using wire feed (and does not use a non-consumable electrode) is likely to be applied using a MIG machine variant and may therefore be dubbed 'MIG'.

Anytime you use CO2 gas in a MIG machine to weld steel it is strictly a 'MAG' process, because the gas is Active not Inert. Both MIG and MAG can be known as GMAW.

The term 'Gasless MIG' is widely understood to mean a wire feed weld using a flux-cored wire but is strictly an oxymoron; there is no gas applied. However if you say FCAW (as recommended by the American Welding Society) then it hardly rolls off the tongue and most people don't know what you are on about.

http://www.lincolnelectric.com/en-us/su ... etail.aspx

simply compares MIG and gasless MIG.

All such welding process produce toxic fume; however gasless MIG produces more fume and it is usually considerably more toxic than standard MIG. Gasless MIG welding of stainless steel is arguably the worst of the lot; folk worry about hexavalent chromium in the fume.

Re TIG vs MIG. I know quite a few people who have both (I don't have TIG at home, but have used it plenty) and none of them use MIG on the most delicate clean metal fabrication work on the benchtop, unless they are trying to rattle the parts out using less skilled welders. Likewise none would use TIG on the bodywork under a car.

cheers

[spencerd72]

Dear all,

Thanks for all the replies. Good God - what have I taken on!

I don't have any pics of the outer wing as yet, as I'm concentrating on the inner wing first. So far, progress has been OK. I got the wing removed in about 4 hours on Thursday and then srated developing a philosophy to deal with my initial strategy of putting it all back together and sticking it on ebay! Here is what the wing looked like before I took it off:


I spent most of Friday using the angle grinder with a wire wheel attachment removing the underseal from the ineer and outer wing. Here's what the inner wing looks like when cleaned up:

Here are the main problem area in the inner wing:

There's a bit at the front which I cut out:

Here's the ex-bracket:

Here's another bit that's rusted through:

And here's the sill that I paid someone to supposedly fix:

I'll take some pics of the outer wing soon. There's a big piece i'm going to have to replace, much like the example in Brucey's excellant tech article (Thank you Brucey - I will be digesting that).

It's going to take time. I;m also weather dependant as I don't have a garage. I just have to keep telling myself not to panic and to take my time....

Regarding my chioice of welding process.. I've also heard that MIG is the way to go with automotive work, but TIG is the process I've invested in by purchaseing a machine and consumables, so I'm going to continue with it, angle grinder and spare tungstens at the ready, for now!

More soon.. cheers.

[Brucey]

I have fixed worse than that; my inner wings (on two cars now) just had lumps of rust instead of brackets (both sides) and by the time I'd cut out all the bad I had holes the size of a paperback book to fill in.

Just keep plugging away at it and you'll get there OK.

BTW cleanliness is super-important for TIG. You may find that some de-rusting gels are handy for cleaning awkward pieces (that are not too badly rusted) that you need to weld to.

cheers

[olympia57]

It looks bad but could have been a lot worse. As Bruce says take a deep breath and approach it logically .
'Tis a pity that the gusset/triangle plate rear of the trumpet has rusted ,that could be tricky to repair properly, get a flexible drive for a drill with a metal de burring bit up into it to remove the worst of the rust .
Removal of the rubberised underseal is so much easier if you use one of these with a sharpened blade ,


I had to remove a little more than you at the front but the rear gussets were perfect , most of the metal removed was replacing a very poor previous repair.


And to boost your mojo , everything's repairable , epoxy applied awaiting stonechip, wing mount bracket will be bolted on.


Good luck with it and PM me if I can help in any way .
Don

[ron]

.... "paraffin" (gasoline)

Paraffin is kerosene in UK terminology Chris.

[ron]

The bracket you show in your first pic. is #6 below and available from dealers.

http://www.realoem.com/bmw/showparts.do ... g=41&fg=10

[spencerd72]

Thanks all for you encouraging messages. I thought I'd post some pics of my progress so far. The first bit I tackled was the bit of flange rail at the front. I had to make the piece twice and getting the fit up right was a bit of a nightmare. The welding is bloody awful - my technique was 'developing' whilst doing this piece. Should have done something simpler to start with. I got the holes filled in in the end though..





Next, I looked at the piece behind bracket. I made lots of measurements and notes and marked the inner wing with punch marks to allow me to reproduce the position of the bracket. I was more careful cutting out this time, but the fit up still required a lot of dollying and I had a few holes to fill with the tig torch, which is a waste of argon. I made the piece geometrically perfect, but the hole was less so. I think in future I will concentrate of getting the hole nice and straight / square so that making the piece form a good fit is easier. Here's the piece as good as I could get it before the process of tacking /dollying began:



Here's after it's welded. The nice smooth bit's that have been ground were ground down for a reason!


Here's the inside:


Here's a test fit of the bracket with one tack and the wing in position with bolt holes aligned - should be OK!



Here's the bracket welded up. I ended up using 308 SS filler rod, as the 0.6 MIG wire I have for the thin steel was a bit too thin for this job:




Now to get another coat of epoxy mastic on before the rain starts and order some more bloody argon!

[olympia57]

Great job and looking good , well done

One suggestion I'd make is to apply seam sealer over the ground down weld run after the zinc primer but prior to any top coat of paint /epoxy . I do this to ensure that all welds are watertight and protected and also to tidy up the overall finish .

I normally run a bead of polyureathane PU sealer smoothed with a spatula and then a brush on sealer applied with a rough stiff brush to replicate the factory applied sealer.

[Brucey]

good work so far!

Some points;

1) easiest way to make repair sections fit is to cut the repair section, then mark round it carefully and cut to the line. Or vice versa.

2) Gap filling is so much easier with MIG; you can go flush to ~1mm gap and using the right (burst weld) conditions you can cope with it all. There is only a bit more grinding required.

3) Using stainless filler material is a bit of a no-no on cars. You end up with an uncontrolled weld metal composition which might be strong, but then it might be brittle too. In addition to this if the weldment is exposed to any corrosion conditions in the future the HAZ in the mild steel will corrode like fury; think x10 faster than normal corrosion. Even Zinc-based coatings won't protect the steel if the water gets into this mix.

4) You will go through (very expensive) argon like it is going out of fashion on this job. I dunno what size bottles you are using but check the weight of gas you are getting. Typical disposable bottles have about 300g of argon gas inside them. At best an hour's welding, if you set the gas flow right. Typical CO2 bottles cost about the same and have 600 or 700g of gas inside them. Even allowing for the slightly higher molecular weight of CO2 vs Argon the CO2 is a better deal for MIG welding. I use an Argon/CO2 mix only for stainless MIG welding. For standard MIG welding in the workshop I use CO2 and a medium-sized bottle costs about £25 for a refill; this gives me about 7 or 8kg of gas. I need to do a LOT of welding to use a full bottle; the current one has been on the go for about five years. For work out of the shop I use CO2 from smaller bottles and this is almost free (PM me if you want to know what I use here). Generally for any given bottle size you get between two and four times as much CO2 gas in it (and at much lower pressure) as either Argon or Argon CO2 mix; CO2 is (high density) liquid under pressure and the others are not.

Keep at it, I'm impressed with how you have got on so far. BTW if you get a chance to try a spool gun, do it! (one-handed TIG welding, how cool is that...! )

cheers

[spencerd72]

Brucey - cheers for the tips. I'm going to have to stick with TIG, as I can't afford to buy something else and I also don't have a workshop, so storage for two machines would be an issue. I've found a local supplier for Argon and will be getting 20 liters at 200 Bar tomorrow which should keep me going for a while! I worked out that this is 3 times the amount of gas compared with the 9 L / 137 bar bottles I have been using. It's only £30 more for the larger bottles!

I'm worried about the Stainless filler rod I used now - thanks for the info though - I wont make that mistake again. Unless I suddenly feel like re-making this bit, I will have to make it as waterproof as possible, using PU sealant on the welds as recommended by Olympia.

I did some more exploratory work into to the next two areas today and in both cases I feel I need to stop and think (and seek the knowledge of this forum!) before proceeding any further. The first one looks like I'm going to have to chop into the 'trumpet', as the is a layer of rot between the healthy inner and outer layers. Is the trumpet some sort of crumple zone? I don't think my metal forming skills are going to be good enough to re-create it if I have to chop it out.


You can see the bit of rusty metal more clearly here, sandwiched between the start of the trumpet section and the healthy-ish inner lip:





Then, there's the sill. Here's what what under the sodden soundproofing:













I suppose logically, I have to chop out the rot until I have clean metal and then build it back up one layer at a time. Are there any caveats to just chopping it all out? I'd be really grateful for any tips!

[olympia57]

I'm repairing the same part of the floor right now .
Mine was just as bad ,

Which doesn't look too bad once you get rid of the rot.It looks more dramatic than it was as I am removing those dreadful plates from my floors and it was easier to do it all in one section, well two actually ..

Now this is a sketch of the profile of the front section of the sill,

Without seeing what yours is actually like I can only describe the way I have repaired mine .
Looking at the second photo you will see that I have marked out a black line on the sill flange . I removed this flange and made up a new one from 18swg and welded it onto the inside of the existing sill , I then ran a weld along the underside . The photo also shows that I have cut out a section of the rotten inner sill leaving a gap . This allowed me to make up a new jacking point support and weld it in too. I will now spot weld a new inner sill section onto the new flange along the bottom and seam weld it along the top edge of the gap adjacent to the two inspection holes.
The lower wing mount flange on both sides were very good and did not need to be replaced , you won't know until you have dissected yours .
Have a look at page 5 on this thread ,you'll find it better explained there. I would add that Tony , the guy who created the thread , is a perfectionist and repairs to factory spec but the end result is similar to my method .
http://retrorides.proboards.com/thread/119596
I still have to finish weld mine which will be done this weekend but will post up some photos if you wish .
I hope this helps you a little but believe me it's not a difficult section to repair , you'll do it .
Don

[Brucey]

Olympia, I like your drawing!

Spencer; glad you have a better deal on the Argon. It still seems expensive vs CO2 for MIG of steel to me but I can understand if you want to try and carry on with the kit you have. BTW are you sure you have the flowrate set right? Even 9L @ 137 bar should be enough for about four hours of welding.

It is easy to set the flowrate too high; in a breeze it is tempting to try and 'shield the weld better' this way but it can be counterproductive; a fast gas flow goes turbulent and this turbulent flow actually drags in air and makes the weld worse.

If you have not tried it yet just turn the flow down on a testpiece until the weld or the tungsten start to suffer badly. You may find that your can gas last x3 longer if you reduce the flowrate.

I don't think you need worry too much about the trumpets; they just stiffen the wing assy up, they don't provide a significant crumple zone or anything. I wouldn't do this, but I've seen cars repaired where the very ends of the trumpets were not replaced at all! Anything that looks about right will probably do the job well enough

Also I agree if you use enough sealant you shouldn't get bad corrosion in a small length of stainless weld in the inner wing. In the sills though? Hmmm. I'd stick to conventional filler there.

cheers

[Ubercoupe]

Thanks for the link to tonybmw olympia57. His work is truly awe inspiring, even to the untrained eye. I remember getting the call from the body shop after they removed my e24 wings ..."You better come over and have a look at this"

I hope to see you at the classic BMW open day this summer olympia57.

Best of luck with the restoration to you and spencerd72.

[spencerd72]

Olympia - many thanks for those pics and the diagram - I've transcribed that into my notebook and also the description of how you are going about the repair. That Tony fella's good isn't he! What I'm worried about is how to build it all up. I suppose I can't start to plan this until I've cut the rot out though.

Brucey - thanks for the note about the trumpets. Regarding the gas, I'm using 7 l / min, measured on the flow meter. I'll try reducing this a bit to get more time out of the gas.

Right, so I need to get in and chop it all out. I'll post some more pics when I get to clean metal.

Cheers,
Dominic.

[Brucey]

re the gas flow; with a smaller shroud size (as normally used for tight access jobs) you can turn it down lots from there ; 3l/min is plenty. Even with a standard shroud and stickout you can usually go to 5l/min or a touch less; remember that 'perfect' shielding is an impossible goal in any event on this job; for that you would need a backside shield too.

If you have enough gas that the tungsten is OK (even if the weld top blues up a bit) then it is usually enough for the weld too on a job like this. You really need to go some to get porous welds from lack of shielding with TIG; if you do get weld porosity it is much more likely to be a speck of rust or something.

One reason for using CO2 with MIG is that it decomposes in the arc to give CO and this yields an active (MAG) reducing atmosphere; even if the cleanest welds are not as clean, small amounts of contamination as are typically found in car welds are tolerated far better in this condition.

BTW I expect the sills and floorpan to be a greater challenge than the inner wings, but keep at it, you are doing well so far!

cheers

[spencerd72]

I've now chopped out the rot. The pictures aren't that good as the sun was a bit bright.. but here's the hole in the floor.. Unfortunately I managed to break the plastic hinge on the accelerator pedal when moving the carpet.





I need to tidy up the cutting out quite a bit. I've got some re-inforced Dremel cutting discs on the way, which should give me more precision than the angle grinder.

Luckily, the outer sill seems to be sound on the inside but the bottom flange looks a bit dodgy and I might need to cut and replace:



Now to start making the replacement pieces!

[spencerd72]

Wish I'd have taken this week off work as well.

The weather's not bad and work is a pain!

Progress is going to be a bit slow now with all that her indoors has planned for my weekends.

[olympia57]

Enjoy the journey Dominic , don't rush it you'll get there .
Don

[Chickie the Shark]

It is really great to see the level of help provided in these forums. I just found a small leak into my trunk and thought I'd look at this thread to get an idea of what I would be getting into by cutting out the rust and welding in new steel. Between your pictures, Dominic, and the ton of welding info shared by members of this forum, I believe I can handle the job myself.

I'm following this thread with great interest, keep the info flowing.

Good luck with the project, looks great to me so far.

[Horsetan]

If ye have a look at E12 welding guru TonyBMW's website, he tackles an E24 which is as bad as any.

Tony regularly gets rave reviews on classic car forums for the quality of his metal forming and welding work - I seem to recall he's almost entirely self-taught.

Click here

Also here

Me, I'm only any good with a soldering iron.

*sighs*

[spencerd72]

Hi veryone,

A bit of progress today - I cut out some of the outer sill that was seriously pitted and welded a piece in. It went surprisingly well since it was my first experience of welding upside down!

I bought some proper 1mm welding rods for Tig. AR15 is the specification I found these a lot better than the mig wire I had been using.




The lumpy bit is where I blew a hole - I'll tidy that yp tomorrow.

I've also med the piece for the inner wing. However TonyBMW I am not. I've had to leave out the concave bit with the inspection holes in, i.e. my piece has a slightly bigger inspection hole! I'll post some pictures tomorrow.

I've been thinking about what to treat the bare metal inside the sill with after I've welded. Phosphoric acid and then acid etch primer? Hammerite? Ultimately, it will be getting a good dose of Dinitrol.

Cheers,
Dominic.