Protecting new parts from rust

[Blink]

I'm putting new parts on the underside of my car and I'm looking for advice/ideas on how to protect & rustproof them before they're bolted back on.

New parts include rear subframe, trailing arms, upper & lower arms, brake backplates, discs, hubs, rollbar, etc.

The factory paint on these items isn't the best so I don't know whether to just put more paint on top of the existing paint (after keying it) and then apply wax over the top of that.

Or ...

Strip all the existing paint off (sandblast?) and repaint with primer and top coats, then apply wax on top. This is obviously a very expensive route to take.

Any suggestions?

[JerseySteve]

Have you seen this thread?

https://the75andztclub.co.uk/forum/s...d.php?t=297932

[Blink]

Only after typing mine.

[T16]

Firstly I would take all the new parts and get them blasted, zinc primed, and wet finished in proper paint.

Secondly, use some 3M cavity wax on the insides of the subframe and suspension arms.

Thirdly, use Dynax-UB for under the car and spray anything you dont want to corrode.

I even got my new made in India fuel tank strap re-welded (strengthened) and blasted and painted properly.

Will probably outlast me.

[Dawn]

I wouldnt have a clue where to get things blasted but I did strip mine back then 2-3 coats of red oxide then 2 Hammerite. If I ever need to fit them a rustproofing agent inside and out over the top. Best I could do lol!

[Blink]

Thanks for the advice everyone.

I'm read so many options & opinions on this forum and in others that my brain hurts - so I still can't decide what to do.

Logic says sandblast, then galvanise, then paint (primer & top coats) and finally wax. But my wallet says "" about the sandblasting stage - it's likely to be several hundred quid to do this little lot (line 2 post 1). So decision number 1 is whether to sandblast or not.

Decision number 2 is which products to use. The list is endless but Bilt Hamber and POR-15 seem to get a lot of recommendations. I contacted POR Support and they said don't galvanise*- go straight from sandblasting to the priming stage. So that confuses things even more. https://porproducts.com/our-brand.


Edit Just to add to the above: i.e. sandblast or don't sandblast. POR Support said either way will work. Using POR-15 over factory painted new parts will extend the life of the paint, but POR-15 on sandblasted parts is a permanent solution.

Edit *The reason being (say POR) that there's no advantage over using the POR 3-step system.

[The Mighty Quinn]

Originally Posted by Blink

I'm putting new parts on the underside of my car and I'm looking for advice/ideas on how to protect & rustproof them before they're bolted back on.

New parts include rear subframe, trailing arms, upper & lower arms, brake backplates, discs, hubs, rollbar, etc.

The factory paint on these items isn't the best so I don't know whether to just put more paint on top of the existing paint (after keying it) and then apply wax over the top of that.

Or ...

Strip all the existing paint off (sandblast?) and repaint with primer and top coats, then apply wax on top. This is obviously a very expensive route to take.

Any suggestions?

Rear Subframe: Cavity wax inside / UB wax outside (epoxy mastic might be beneficial on the exterior, but the subframe is very exposed to debris and will always take a beating, so not sure if there's any paint/coatings that will stand up to too much in this regard - regular maintenance is key).

Trailing arms: Corrosion isn't going to be much of an issue with these - they're of very heavy-duty steel construction. Paint up and wax all around the trailing arm to body brackets though, as these seem to be the weak point. Bushes will be replaced in the trailing arms many times before corrosion becomes a problem.

Upper and lower arms: Get cavity wax products injected inside and UB outside. These are consumable items and if we get 10 years out of these before they need to be renewed, that's probably not bad.

Brake backplates: Again, I'd call these consumables - just buy a spare set or two, if you're planning on keeping the car for over 10 years (my originals lasted 15 years).

Discs/hubs: You can get pre-painted discs that will delay the corrosion process, but these too, are consumables - and would be difficult to rust-proof to any meaningful extent.

Rollbar: This will always take a beating, so whatever you apply, just check on it regularly and touch-up as required.

If your car is a daily driver, I think the above approach is reasonably practical and cost-effective.


Cheers,
Karl.

[Blink]

Originally Posted by The Mighty Quinn

Rear Subframe: Cavity wax inside / UB wax outside (epoxy mastic might be beneficial on the exterior, but the subframe is very exposed to debris and will always take a beating, so not sure if there's any paint/coatings that will stand up to too much in this regard - regular maintenance is key).

This is the main one I'm worried about. It's a new part but the factory finish is so poor that it's already been touched it up even before it was sold to me - the areas you can see with matt finish have all been overpainted. Other parts of it look like the factory painted over loose swarf! (You probably can't see them in this pic 'cos the website won't allow high res pics to be uploaded - they're there though).



There's no way I'm going to fit it like this. Once it's on the car, it'll be staying there for good - I'm not going to do all this work twice . So it definitely needs a proper job doing. I was really impressed by Jim's sandblasted and repainted one here (4th & 5th pics) and I want mine to have a similar job before it goes on the car. It's doubly important because the upper surface can't be reached once the frame is bolted into place.

Originally Posted by The Mighty Quinn

Trailing arms: Corrosion isn't going to be much of an issue with these - they're of very heavy-duty steel construction. Paint up and wax all around the trailing arm to body brackets though, as these seem to be the weak point. Bushes will be replaced in the trailing arms many times before corrosion becomes a problem.

I agree - the toe-in adjustment brackets are the weakest point here. I bought a brand new pair on eBay for £39.95. plus 6 new bolts to go with them from Spalding Fasteners.

Originally Posted by The Mighty Quinn

Upper and lower arms: Get cavity wax products injected inside and UB outside. These are consumable items and if we get 10 years out of these before they need to be renewed, that's probably not bad.

These are the second-worst parts to have to change on the rear end so I don't want to have to re-do them in a hurry. I think they need the same treatment as the subframe above.

Originally Posted by The Mighty Quinn

Brake backplates: Again, I'd call these consumables - just buy a spare set or two, if you're planning on keeping the car for over 10 years (my originals lasted 15 years).

Discs/hubs: You can get pre-painted discs that will delay the corrosion process, but these too, are consumables - and would be difficult to rust-proof to any meaningful extent.

Rollbar: This will always take a beating, so whatever you apply, just check on it regularly and touch-up as required.

Yes, all of these parts are so easy to change that they're not worth worrying about too much. Just a really good coating of wax on the new ones (not the discs, obviously ) and put them on the car.

Good idea to get some spare backplates btw.

Originally Posted by The Mighty Quinn

.....assuming you have new parts, not yet on the car?

Yes, absolutely everything is new (including all nuts, bolts, washers, brake hoses) - and no, I haven't put any of them on the car yet.*

* I'm still trying to sort out a new trolley jack - at least that's my excuse and I'm sticking to it.

[T16]

Factory finish is so poor I get them blasted primed and sprayed on all new parts now.

Had a new rear rollbar, stripped, primed, re-powder coated. Same with all the xenon brackets, suspension arms, the lot.

Powder coat is essential for roll bars, but the rest should be wet finish, powder coat is no good if it gets chipped.

[Blink]

Originally Posted by T16

Factory finish is so poor I get them blasted primed and sprayed on all new parts now.

Had a new rear rollbar, stripped, primed, re-powder coated. Same with all the xenon brackets, suspension arms, the lot.

Powder coat is essential for roll bars, but the rest should be wet finish, powder coat is no good if it gets chipped.

What sort of blasting did they use on yours? I've just read this and now I'm more confused than I was 10 minutes ago!

Doesn't the roll bar get chipped by stones? I can't tell with mine because all the factory paint has peeled off - it came off in curved/cylindrical lengths, like a snake shedding its skin!