Wot, not another '79 Targa resto thread

[PeterK]

So I snuck into the garage again yesterday. A quick bit of trying up turned into a more major reorganisation, followed by a few cups of coffee and an attack on the rear end.

I love the way that to remove the oil tank you really need to remove the OSR lower wing panel first, yet to remove the OSR lower wing panel you really need to remove the oil tank first ! Anyway, after a couple more cups of coffee and following a stern talking to the car, I can report humankind won this particular skirmish

Not many photos to show you today, although I took loads to hopefully give me some clues when it comes time to reassemble.

The only things of note were that both rear inner wings do have some rust (bad news) but only a tiny amount (much better news).
On the offside – just above the oil tank filler
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and on the nearside, around the upper mounting lug for the electrical panel (explains why the panel was waving in the air somewhat !)
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A corner of the OSR lower wing panel, where it meets the bellows, needs a small patch and the both rear lights have lens screws with no desire to leave their comfortable homes. More encouragement will be needed, but tonight is the DDK Xmas meal at the Orange Tree, so not today and probably not this week now.

Current status is an increasing pile of rear end bits accumulating on the garage floor, ready to be hidden in the loft. Another day or so should have the back end fully stripped and time to jet-wash everything again. I’m running out of excuses not to start on the sills and kidneys now

[PeterK]

I do love having a garage now – I can just pop out and play, no matter what the weather or indeed whether it is light or dark. I also don’t need to put all the tools away when I finish for the day. That said, is there really any excuse for my ‘office’ looking like this



I managed a quick couple of hours the other evening. I started on the small hole above the oil filler, which grew as I cleaned the paint off


I decided to explore with my subtle pointy hammer, and the hole grew slightly


so I cut out to good metal


After faffing about trying to make a patch panel for far too long, I decided to make it in three sections. I started with the mid-section


I had all sorts of problems with my welding, I just couldn’t lay a constant bead, although the spot welds were fine. As I played around, trying to work around the poor welding and add the second section, I kept blowing holes and in the end gave up trying to toothpaste the holes away, and just cut the patch out and started again.

I spent some time just watching the weld, and realised that the wire kept burning back to the nozzle, so I checked the wire was feeding properly – it seemed to run OK, maybe just a tad slower than usual. I decided to stop early before I got too grumpy and as I switched the welder off and shut off the gas, I realised that the wire feed switch had been knocked back to 3 instead of a more normal 5 – simples !


I grabbed a coupe of hours again today, with the wire speed where it is meant to be, and finished the patching off


I still sometimes try to make the welds too pretty and end up over-thinning the surrounding metal. I had to cut out some of my new patch and add in a small patch where I made some holes and didn't like the toothpaste patching. Wherever possible I also shine a light from behind the welds to check for pin holes. Grinding these welds back really is an opportunity to over-thin the metal. I would really like some welding lessons (especially before I start on the sills) , but the days of cheap evening courses at the local Tech Colleges seems to be a thing of the past. Any one know of any learning opportunities in north Hampshire / Surrey ?

[PeterK]

Back into the garage for 90 minutes tonight, and a night of highs and lows. Not really happy with the patches from yesterday, so thought b0ll0x, and cut a fair chunk out.


Turned on the welder and realised that failing to shut the gas off at night can get costly . Anyway, nicely fitting patch and some pulse welding got me to here.

Bit of a pain in the ar5e to get to the left hand side of the patch - my welding helmet kept knocking on the underside of the rear parcel shelf and covering my eyes !. There were also a few pin holes just below the patch piece, so toothpaste welding came to the fore .

I'm getting good penetration and strong welds, but if I could weld better I would certainly need less grinding discs ! A rough grind got me to here


and after shining a light behind to locate any pin holes, and a bit more grinding with the 2” disc, and the result is hopefully passable.


I keep over-thinning metal by trying to make my welds invisible, but at the end of the day, this area will be covered by seam sealer and under-shield, so although the welds are visible under the harsh side lighting, they will not be so apparent when the car is painted. Well, that’s my excuse for shoddy work anyway

Remembered to turn the gas off, but as the bottle is pretty much empty now, guess where I'll be going tomorrow (if they're open)

[maxakarudy]

Peter,
You are doing well, if you aren't happy with something, come back to it & do again it's all good practice.
Grinding weld is a skill, like welding, I use an old angle grinder shaft in a battery drill with the 5mm disc, it's slow, so doesn't do damage if you slip off the weld, small used ones are great for tight spaces & I just use the edge of the disc to knock the most of it off, then finish with a flap disc or electric file.
Martin

[sladey]

That sounds like a good idea. I’ve always used flap discs in my grinder - find it’s much better and less harsh than a grinding wheel - are you using flap discs Peter?

[PeterK]

Hi both
Generally I use a 80 grit 115mm flap disc (where I have access) to knock the tops off the welds (it puts in less heat and is quicker) before switching to an 80 grit 50mm roloc sanding disc - using the edge. I sometimes use 80 grit 50mm flap discs but find they need to be used flat and access here was not that great.
Peter

[aston]

Hi Peter - before you leave that area just check that the big rubber gasket that goes around the oil filter and filler neck fits nicely, as that aperture has a taper on it. I had a really difficult job fitting mine and actually had the cut and glue my gasket in the end so I didn't damage paint.

[911hillclimber]

And if that rubber gasket is crushed or distorted it can make replacing the oil filter incredibly difficult!

[PeterK]

Thanks Kieron

With my patch (part 1) I actually left the original edge on the aperture, although on patch part 2, I remade a small part of it, so good shout on that check. I'll trial refit the oil tank - another job for the ToDo list

[jjeffries]

Peter, since you're asking, here's my two penneth:
- Do a more comprehensive job of prepping your area to be repaired, stripping further back, so you're not getting dirty welds and the fumes they create (your health);
- spend more time shaping your patch. This is likely the area we all eff-up...too much of a hurrry, we wanna lay down some bead, haste makes waste etc.; you can get excellent results without all the cool specialist tools with patience and ingenuity; leather shot bags are good for blokes like us;
- create your patch so that it has a good 1mm gap all around. This may seem counter-intuitive but that gap is where the weld belongs, too little gap and the weld sits atop the joint and you're having to grind ad nauseum. You can hold the patch in place with magnets if you cannot get clamps in there.
- look at Barry's work and note how he rounds the corners of the hole to be filled and the corresponding patch. Also look at the total cleanliness of everything Barry works on; ditto Jon Miller's shop. They may be masters but we can all do the same work needed to get that sort of surface prep; when we don't our work will look amateurish.
Offered constructively....John in Connecticut

[PeterK]

Thanks John
My new patch for the other side - presumably rust here was caused by crap sitting on the engine hood release cable tube - is currently a perfect interference fit, pending the arrival of new gas. Before I weld anything, I’ll relieve it to give a 1mm clearance as you suggest. I use magnets to hold my patches in place while I get initial tacks done.
All comments always taken as constructive
Peter

[DustyM]

I agree with John's point above about spending more time making the repair section out of one piece rather than trying to make several smaller sections and weld them together, also (and perhaps you have) but make sure you clean the reverse side of the area you are repairing just as carefully.

Above all though, make sure you are enjoying it, if it becomes frustrating, walk away and come back to it later.

[PeterK]

So, after feedback from Sladey and Martin, I had another go at grinding the patch above the oil filler. Found a couple of more pinholes between my pulse welds, so touched them up, and went as far as my brave pants would allow with the small flap wheel. Where access was better (the top left area), the finish is not too bad, but where access was less good, I haven’t risked grinding away metal beside the weld bead, so more of the weld remains slightly proud.

As John & Jon suggest, if I spend more time with my sandbag trying to make a larger single patch, then I would have less awkward welds to grind - especially next to areas of high curvature.

Very low on gas – content gauge says nothing left, although the flow meter shows gas, and when I took the regulator off, there was certainly a good whoosh of gas when I cracked the valve. Didn’t want to risk starting and running out part way through, so no welding on the other side yet. Assume that the rust here is caused by grot building up on top of the engine hood release tube (not that I have much of that left now).

So, first to another clean up – incredible how many tools you can get out and use once then leave on the floor. Also quite a pile of rubbish.

Judging by this pile, plus the amount of grinding dust I vacuumed out of the engine compartment area, it’s rather like body filler - spend ages putting it on and then even more ages taking most of it off again.


Bit of time left before I have to scrub up and head off to an Xmas party, so made a start on the patch for above the electrical panel. Slowly, slowly here and I ended up with a patch that fits slightly snugly – more of an interference fit at the moment.

But, and with thanks to John and Jon for their input, I’ll make sure that the edges are cleaned up and that I have as consistent gap all around as I can – target is 1mm (but don’t hold your breath) before I break out the welder again

Merry Xmas all

[maxakarudy]

Hi Peter,
Patches are looking better.
A few things I do when patch repairing.
1. I don't use metal grinding pads to remove paint or rust, I use strip discs, as this doesn't thin the metal that you want to weld on, like this..https://www.ebay.co.uk/itm/Strip-and-Pa ... SwaSZZ8gfu
2. I always make the piece before cutting out the rusty metal, make the patch touch the whole surface, that way you know it matches the contours.
3. Radius corners as this causes less distortion.

Personally I don't leave a gap between panels, too much penetration means more grinding ( no innuendo intended )

Hope this helps, have a great christmas
Martin

[jjeffries]

Peter, please try my gap suggestion on some clean scrap before the car itself. May be good for you but maybe not. Could result in holes being blown in the metal and you shouting "Who's that w_nker in Connecticut?". Works with heavier gauges of metal but may not be appropriate in this case. Best of luck, John