Which parts to get powder coated?

[peteracs]

Hi

About to start amassing parts from the HPE for blasting/powder coating. The question is which parts such as subframe etc should I get powder coated and which painted with an alternative?

Thanks

Peter

[Neil-yaj396]

Personally, I'd paint the subframe. With that complex shape isn't there a risk of a bit of powder coat not properly adhering then letting in moisture? The bits of the frame that might get chipped can be touched in if you paint.

What did you do last time?

[SanRemo78]

I don't think I'd powder coat the subframe either. If it gets damaged then moisture gets retained underneath the coating promoting the unspoken word. Is it possible to get it galvanised and then etch primed and painted and wax injected? That should see us all out!

Anything that has a moving component I'd consider plate and paint. Something like the engine brace and the strut braces would be suitable provided any bushings can be removed/replaced but there's always going to be surface damage when tightening fasteners with lock washers down.

Guy

[mangocrazy]

I absolutely wouldn't get the subframe powder coated. It's inevitable that there will be points where the powder coat fails, due to stone chips etc., and when that happens moisture gets underneath the powder coat layer and is trapped, forming a corrosion cell. For me it would be galvanising every time. That's what I intend to do with the subframe on my Beta, after I've had some judicious strengthening gussets welded in. By all means powder coat, underseal or paint on top of the galv, but make sure it has a nice thick coating of sacrificial zinc before you do anything else.

[peteracs]

Hi All

Thanks, that has sorted the subframes, what else would benefit from similar process on the suspension parts?

In answer what did I do on the Spider. The answer is the front and rear subframes were never removed and I cleaned with wire wheels etc and then hammerited them the best I could and then an unseal type of covering. So not ideal, but I did not remove the engine or rear suspension arms. The rest of the suspension was removed, cleaned and Hammerited.

Peter

[mangocrazy]

You could get the anti roll bars galvanised, I guess, but I'm not sure if they suffer that much from corrosion. You could possibly also do the wishbones, but the galv might interfere with the mounting bushes, as it will add noticeable depth to the metal and reduce effective diameters/hole sizes.

I've been advised by people who know about this kind of thing that, aside from galv, the most effective form of anti-rust finish is obtained by using two coats of epoxy 2-pack primer followed by 2K top coat paint. But 2K must be applied by an operator using full air-fed mask and appropriate PPE, as the stuff is hazardous to health. Certainly not DIY territory. The epoxy primer can be rollered, brushed or sprayed on and is essentially benign, but 2K paint contains isocyanates.

[SanRemo78]

I'd be wary of hot dip galvanising a sprung part as it may affect the spring rate? I could be wrong - I'm no engineer! But ask before going down that route.

[mangocrazy]

I'd be wary of hot dip galvanising a sprung part as it may affect the spring rate? I could be wrong - I'm no engineer! But ask before going down that route.

Yes, there is a side effect known as hydrogen embrittlement that should be fully researched before employing a metal treatment that involves heat (which galv obviously does). I was given a severe telling off by the late Guy Croft for having high tensile (10.9 and 12.9) bolts plated. Guy just threw them in the bin. 8.8 grade can happily be plated, but the higher grades should not. Which is why nearly all high tensile fasteners come in black self-colour finish.

[Nigel]

Hi Peter,

I'm not a fan of powder coating for all the reasons already mentioned.
An effective clean, primer and top coat of paint is more manageable for
touch up long term.

Regards
Nigel

[WestonE]

Hi Peter

Be aware there is a superior form of Powder Coating called Epoxy Powder Coating that is way tougher than paint. It will out last any paint system you can access. We sometimes forget when we see flaking powder coat it is 40 years old and was the cheap version!

Enjoy

Eric   

[peteracs]

Hi Eric

My bodywork/painter guy suggested that there is a modern take which is much improved over old system.

I am thinking of trying a few parts out in it to see how they turn out.

Thanks

Peter