Thread: An amateur attempts some rust repair (upper windscreeen)

Originally Posted by admiralranga

...hey I've welded before how hard can rust repair be...Need to go buy some steel and I'll be picking up a friends welder and press brake tomorrow. Might buy a joggler (weirdly the air one is cheaper than a hand one at hare and forbes), I'm hoping my patches are all small enough I'm not going to need a shrinker to get a curve on them but will see, there's a few small holes that going to be sensible start/practice points.

Flat or shaped pieces of copper can be used behind small holes to support the weld metal being deposited. Iron will not stick to copper. Double skinned situations will add complications ie access to the rusted sheet. If your sheet around the hole is thin then you will be chasing the hole and may be better off cutting new steel to shape. If you make the copper plates long enough you can use super magnets to hold the copper to the steel ie hands free. You can get the copper from splitting a piece of copper piping. Did a lot of rust repair on a Range Rover classic, Disco 1 and LandCruiser and from memory all the steel is 0.9 mm thick. Used solid mig wire with gas. Flux core explosiveness just makes delicate work too difficult.

Never used a joggler, but looks useful. Always had trouble with vertical spot welds.

I usually cut and shaped replacement steel such that it was a gap fit ie not a perfect tight fit - magnets again come in handy holding the part in place until a couple of spots have been applied. Lots of practice before hand with scrap to set the machine to the right power level such that each dot had flow to the back of the weld joint. Avoid weld runs...just lots of dots...and a torch to shine from the back to pick up remaining pin holes. Lots of youtube stuff on this.

Found the dremel thin disks extremely useful, for both cutting out segments, and while your probably not supposed to, as a mini grinding wheel to shape a hole (with care). Tungsten tipped probe for popping black hematite rust spots. Found oscillating fine tungsten toothed cutters useful for tight spots or for reaching down past gutters etc.

Curves made around bolts or other appropriate shapes, hand bending etc. Steps made by clamping sheet between scraps of plate steel (steel plate thickness dependent on depth of step required), hammer and chisel to get sharp corner in the fold.

Look forward to the thread. Good luck.

Appreciate all the advice, unfortunately access is rather limited. Absolutely spots over runs, I had quite a bit of fun till I realised the machine had been left on pull to start, pull to stop so just releasing it wasn't enough (aren't fancy welders dandy). Did manage the first hole, initially was basically plug welding it till I blew the backing bit out so it's just a bunch of tacks ground down.

Some updates now it's all (mostly) back together. After much swearing and cursing attempting to use 0.9mm wire and big welder (ENVY MULTI 230), I went out and bought some 0.6mm wire. That was significantly easier to use but because the torch was too big it birds nested at the drop of a hat. Next step was buying a sensible sized torch for tin work which really made things go well (minus that I bought a 5m one so still ended up with the odd birdsnest). Got it all welded up to a good enough standard, it's all sealed but it's just not the most perfect visually.
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Nothing some high build and bog can't fix (plus the rubber finisher hides most of it)
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Somehow managed to fill a hole without actually welding the backing bit in.
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Being aggressive with cutting bits out also is something that I was stubborn about not doing and it made my life harder than it should have been till I stopped being silly.
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I really didn't want it to rust again (norshield red oxide primer x3, coat of norglass 2 part undercoat/primer, their epoxy bog, 2 more coats of undercoat and then a final 3 coats of 2k Chawton White mixed into a spray can), long term I need to do something to the rest of the roof the gloss is gone and both I'd like to go white and frankly I'm not going to get a seamless result imho a "feature" looks better than failing to match. So much masking off for the spray coat tho
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The entire reason I started this little side adventure - replacing the front plenum cover and giving everything around it a spruce up (scope may have ballooned)
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Did also fit new wiper arms etc but did draw the line at new wiper nut covers as they're somehow $40 each. Unfortunately I did snap the gutter trim finisher's while installing them, think it was a combination of the extra thickness of the paint on both the (new 3d printed) gutter trim finisher's and the gutter trim. I have ordered some from aliexpress ($40) so I'm waiting on them before I install the A pillar covers (still the originals somehow if the date sticker's are to be believed) but hey she's at least able to move*. Also swapped the snorkel fasteners to the A pillar with nice wafer head ones (because while you're there). See also the extra roof insulation as it was on special at repco on one of many visits.
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*If someone git hadn't gotten bored and pulled the intake manifold off while waiting for a coat of paint to dry so I could troubleshoot some intermittent starting issues. Turns out the starter motor wasn't well bolted in and would occasionally fall out. Close as I can figure when I swapped the engine out previously I used too long bolts and tightened them down onto their shoulders still leaving the starter loose. The top nut held on for a while but eventually went AWOL and so occasionally wouldn't be in postion to engage with the flywheel. Have bolted it back in with correctly sized bolts/nut and now just need DHL to deliver the new intake gasket (plus some other miscellanous bits I'd either forgotten to order, couldn't find or broke in the process.

Interior trim is all in my living room waiting for the enthusiasm to clean it before refitting it.

Having waited the required time I got in inside and got my fiancee to hose over the windscreen and oh look at that there's water coming in. Glad I did check because it was both a spot that would have been covered by the a pillar plastics (inside and out) and it was really obvious the issue was not enough sealant under the windscreen (I'm hoping they don't need to remove the windscreen start from scratch but also dunno how I feel about a "patch"). No issues from what I could with my repairs and was very satisfying watching the water run off the plenum as it should.

Did notice the carpets were still wet (from like originally) so went through and pull them out (plus the seats and way more trim) to both let dry and to give a good clean. Didn't actually realise how much you had to remove till I was too far in but such is life. Spent the evening glue some of the damaged trim back together.

Carpets were too wet this morning so instead of doing the sensible thing and go enjoy breakfast somewhere nice I ran down my list of things that need fixing on the car and landed on heater core piping. Seemed sensible enough given I was basically half why there. Not so when attempting to remove the dash and discovering just how many fasteners need removing and also that I'd manage to pin the dash in with some of the wiring I'd added.

Swapping the pipes was pretty easy once the dash and heater assembly were both out (would it have been too hard to flip the bracket so you don't have to pull the heater box), it's back in now will see if the car starts without the instrument panel etc attached, I'd like to make sure it's not leaking first but also will see.

A bit of hard won info that may help in future. I've spent years with old cars and decaying plastic and this is the best way I've found :



The issue is with age the plasticiser leaches out of the plastics and they become terribly brittle. Epoxy will make a mechanical bond, but it eventually breaks off (whether peeling or shearing on the bond line). I found "Bunnings gift cards" were the perfect reinforcing material. They are a generic PVC plastic card, so I got on the net and bought a pack of blank security ID cards (same but I didn't have to beg at Bunnings to get them). They work great for reinforcing the break.

Prep involves cleaning thoroughly and then wiping the surfaces with PVC priming fluid (from Bunnings, it's about a 50/50 mix of Acetone and MEK). That really softens things up.

The glue I use is Devcon Plastic Welder. It's an MMA (Methacrylate) epoxy. Has a pot life of a couple of minutes and smells something terrible, so work fast.

Nothing I ever repaired failed anywhere near the repair. The best part about the MMA adhesive is it makes a chemical bond with the plastic so it's not reliant on sanding or roughening the surface, and it'll pretty much glue any plastic to any plastic (with the exception of low surface energy plastics like H/LDPE or some impregnated Nylons). The epoxy is also good for building, so can be shaped (with a bit of a makeshift mould), drilled/tapped and filed. Having said that it's a ton more flexible than normal Araldite style epoxy, so it handles a bit of movement.

For the ABS/PVC often used in cars it's perfect.

I reckon the 740 I sold a few years ago was probably 20% PVC ID cards. Looked good and held together.

I ordered 10 tubes from E-bay about 15 years ago. Keep them in the fridge. I've run out, but just found it in stock at Blackwoods and have some more coming.

Appreciate the recommendation, I've used other Devcon stuff and it's been bloody good. Unfortunately I was working with whatever Bunning had available at 6pm on a Saturday, was meaning to order some of the tubes of metal stuff anyway so will get some of that as well.

Carpet and some of the trim around the doors back in, it's odd how much of a difference carpet/no carpet makes to it looking like a car not a money pit (and if I'd have thought about there would be a before/after).

Dash has had some glue and TLC applied, currently waiting impatiently for auspost to deliver a cage for the radio as I suspect it'll be worth installing in on my lounge room floor over in the car.

Windscreen mob insist on me driving it to their office to inspect the leak, which I get but also annoying. They're also complaining I got it wet after 24/36 hours, both that's longer than the installer said when I asked and from what I can it's more high pressure cleaners that you need to wait longer for.

Originally Posted by BradC

I found "Bunnings gift cards" were the perfect reinforcing material. They are a generic PVC plastic card, so I got on the net and bought a pack of blank security ID cards (same but I didn't have to beg at Bunnings to get them). They work great for reinforcing the break.

That's not a bad plan. I collect "rewards" cards, and the old defunct officeworks print cards. Never thought of just buying them......