I agree @bricol but only to a certain extent. I know I'm teaching my granny to suck eggs as far as you are concerned but for the newbies this is what I do.
By far the best option is grit blast to SA2,5 and that's what I do when it's practical and necessary. If possible pressure washer or wash with something like "Chlor-x" to remove any salts and allow to fully dry before blasting.
It's not always practical though and I'd rarely blast "good" steel on body panels but I do certainly follow the manufacturers instructions which means remove all contamination and flat back both the steel and feather into any existing paintwork.
For the shiny bits on the top I use a Sherwin Williams epoxy and for the under side I use Jotamastic 87A.
The 87A is surface tolerant meaning it can be applied to a less than perfect substrate (I fully accept it will preform better if it is) however that doesn't mean it can be slapped on over any old junk.
I'll send a link to the 87A Application Guide when I get home which is full of good information and if followed will give good results.
I've started scraping and cleaning the underside of the 75 witn a wood chisel and a wire brush in a grinder (what fun)
I don't have the facility or inclination to fully blast to SA2.5 but I will blast the scabby bits, the bits that were polished by the wire brush and will sweep blast the rest of it before stripe coating with the 87A.
Hopefully I won't need to report back in less than 10 years.
@Exuptoy only thing to watch with pouring epoxy into the doors is the coating will be way too thick which can cause cracking which can then let the water in. Better to keep to the recommended thickness (which is still dam thick)
Also I haven't used the 121 but suspect RustBuster only put other manufactures products in their own cans. Not saying it's not good stuff, just you can probably get better for less.
I'm a sucker for a quick fix and I've tried lots of the converts and magic potions over the years but have never stuck with one and it's always difficult to show what worked (or didn't) without really stringent testing.
I've Jenolite and Rustbuster fe123 in the cupboard but who really knows if they are any better than good paint on top of clean well abraded steel (or rust)?
I've also got a almost full tub of Bonderite 1455 pre-treatment wipes (too miserable to use them) which are supposed to be good on aluminum and galvanized metals before applying epoxy primer.
I thought they were expensive until I saw the price of the rc900
Yea the rc900 is very expensive....yea this isn't for a quick fix....there is no such thing of course!
But it's good stuff and a single can goes a very long way because I clean the steel thoroughly with a wire wheel and only use a couple of very light coats to prep the steel.
I wire brush one area at a time generally...without the RC900 I'd end up leaving areas overnight or a week or two and they'd get surface corrosion so the RC900 basically stops this until I get the final epoxy on.
Other converters seem to require washing off which in my mind is nuts....why would I want to add water to my nice clean unprotected steel!
It dries with a purple tinge....which is handy as you know when you have covered everything. I think it took a couple of weeks to wire wheel this underside so needed something on there (my garage is a bit damp for sure in the winter...so not ideal!)
@Pigeon_Droppings2 your photo has shamed, inspired, suckered (insert as appropriate) me to take all the under-seal off.
I have the luxury of a 2 post lift and I still don't want to do it.
I know this is a bad idea because it will make more work and delay the "back on the road" date.
It's a good idea because it will make more work (which needs to be done) and I won't have to do it next winter when it will take twice as long.
First job is to sharpen the worst wood chisel you have (but sharpen it as well as you can)
I find a 3/4 inch one is a good size, then get scraping.
And you end up with this
Which shows that you need to start making more patches
But eventually that bits ok but
There always seems to be another bit.
At least it better than getting the seam sealer off
I should have replaced all the steel tags that are used to secure the brake and fuel lines (and start the rust) with proper plastic clips but I couldn't do it and instead went for like for like.
I know I will regret this but I've spent too much trying to keep it original.
While I was at it I discovered a spot where something had fallen off.
A few hours on the internet later and I learn it a guide for the handbrake cable to stop it getting caught up in the drive shaft.
10 min to make and fit the clip 4 or 5 hours to find out what it was.
I went for a good prod, poke and pull when my integrale was upside down - stripped the dodgy bits, left the rest. Blasted the rusty bits (still removing the glass beads from horizontal surfaces in the garage several years later).
Figured it had done 25 yrs and was still stuck - it's do some more I have a fear of damaging original zinc coating etc and whatever I put on not being as good in the undamaged areas.
Cracking job there Dcal....well done indeed....I went through exactly the same thought process too.
It's amazing what you find when you poke around though....I use a dewalt battery grinder (5AH batteries) and a twist wire wheel + full face shield. It does hammer the batteries but for me I was on a creeper and wires are really annoying because they get caught up in the creeper wheels!!
@bricol That was what I was going to do but some gobshite covered the bottom with tar and it was smearing everywhere and left me with either putting on more tar or taking it all off. I wasn't doing it with tar so all off is the only real option.
The factory underseal is still soft and moves about when you attack it with the wire brush but it does come off. I haven't really uncovered many places that I didn't know about, just a couple of tiny spots.
@Pigeon_Droppings2 can't believe you managed that crawling under the car with a cordless grinder! Ive a 4 1/2 inch 5 inch and 6 inch grinders and a couple of die grinders, all with various wire brushes in them and I'm still struggling.
I'm at the stage where I'm really sorry I started this and might have to leave it for a while before I really sicken myself.
Continuing on with the patches that were always needed but I was putting off.
DS rear chassis leg at the jacking point was getting a bit frilly and decided to replace the bottom section, probably would have blasted up but in for a penny and all that.
With the rear suspension out, the only real place for the 2 poster legs is on the jacking points which was in the way of the repair.
First job was to move the 2 post leg out of the way.
Had a bit of 3/4 and 4inch flat bar so welded it up to extend the jacking point on to the main arm to let me get access.
If I hadn't replace the jacking points I would have tried something else but worked fine and a good test of the new jacking point. (and my stick welding)
With the section cut out I had to make the tools to punch the dimples out.
Luckily I had already made the oval one for a repair on the other side so just the circular one to make.
I had a hole saw that provided male and female dies that were pretty much a perfect size.
Just had to grind it down a bit, round the edges, weld the male slug to another bit of flat bar and job done.
Next job was to mark out and drill a bit of 1.2mm steel with a smaller hole saw.
Then clean it up with a file and punch the dimples out on the hydraulic press.
I made the dies a loose fit as I was just going to eye ball it (not worth a proper set up) and didn't want to shear the steel if I didn't line everything up precisely (knowing my luck it would be the last one.)
I then just used the female die as a dolly to sharpened the edges with a ball peen hammer and ground the dishes to the right depth.
Then fold the edges in the vise and shape to suit. For one horrible moment I thought I had folded the edges the wrong way, but all good.
There is a drain channel formed in one side so decided to have a go at replicating that too.
I had to cut the lip to let it bend, so hammered the drain channel into it after it was cut before welding a wedge back in to fill the gap ad dressing it up.
Turned out well but an awful faff to make a 3 by 8 inch patch.
I try in my MGB thread here to show how I arrived at the decision I have and how I rectify what I need to based upon that decision .
I could do it on the Q T ... not post a thread but ‘leech’ information, that’s not my style neither is it dcals , information that gives not an idiots guide but a good rough guide is excellent , we will all face different challanges ... with reference to someone has faced it before with a rough guide that’s gold !
Nothing worse than seeing a ‘I bought this’ thread (not on here ) and a few yrs later it’s .... ready for paint .
Just ticking off the last few bits to let me finish the underside.
Small patch where the petrol pipes come through the rear floor
Another small patch in the same area, it seems to be a drain from underneath the rear seat as the other side is the same (only in better shape)
While I was in the area I had another look at the top of the rear chassis leg.
It had been patched by someone before and would have passed the MOT but I but decided to rip it out and start again. Bottom left of the picture is the small drain /patch from above.
Worst of the old patch removed.
I had welded the rear jacking point in (I was going to let it go) so had the pleasure of grinding all the old weld out. Serves me right for not doing it properly when I had the chance.
It then was just the tiny matter of getting all (or most) of the previous repair ground out.
and painting the inside of the chassis leg with Jotun 87A
Finally, this bit (at least) is finished.
I decided to beef up a couple of areas that had cracked / deformed in use.
First was the rear anti roll bar mounting points.
These already have a "small" stiffening plates spot welded to the inside of the car, but the spot welds had let go or were about to.
Made up a couple of doubler plates out of 1.2mm. This is another way of saying putting a patch over a patch but whats the alternative?
Before I installed the plates I painted the back of the patches and the area where they were to be installed with galvafroid. Don't know if it will do any good but my thinking is as it's over 90% zinc, the zinc might remain after the binders are burnt off during the welding and do some good. Who knows? but what harm can it do and yes I do wear a mask when welding zinc.
For good measure I stitch welded the inside plates as well
Next up was the floor behind the front seats, where a couple of strengthening bars bolt on
I'll drill the mounting holes when I reinstall the bars.
The repairs from the inside after tidying up the welds, stripe coating and seam-sealing
The big sockets are to stop the temporary bungs (these holes have grommets) from blowing out when I'm painting the underside.
I have finally all the welding to the underside, well from the engine bay back (more of that later) so for a change I decided to finish this bit and get it in paint before tackling any more repairs.
After removing all the under-seal I was going to get it outside to blast the rusty bits, but the weathers not playing ball so decided to do it on the lift.
I set up a bit of a tent to try and contain some of the mess.
The worst bit was around the rear spring mountings, it was pretty solid but very rusty.
It would have been a good place to try out some of the converts etc but thought it better to just do it as best I can
I blasted all the rusty bits and just gave the rest a sweep blast to key it for the epoxy
Ready for paint (or as near as I'm going to get it)
After strip coating all the bits that were rusted and any welds or anywhere that would be hard to spray etc.
A brush for painting behind radiators, after a hair cut, was perfect for getting into all the awkward corners.
First spray coat.
I used a cheap gravity gun with a 2.5mm fluid tip and it was a total pain trying to paint the horizontal panels above your head. When you try to paint overhead all the paint runs away from the inlet and it stops spraying.
I had to keep the cup full to the neck and it took far longer than it should have.
This is the spray gun I used if anyone is interested, but a suction gun would have been a better option for once.
Having said that I did get a good finish with the gun of I was spraying the way it should be used
This is a couple of rusty arms from the rear suspension that I painted at the same time. They were really pitted and I'm using the Jotan to fill out the rust pits. They have already been painted and sanded this is after the next coat. One got more sanding that the other which is why the pits are more viable on the top arm. But this is the finish straight from the gun.
I think the Jotan sands fine as well.