14 replies to this topic

[Joe 91]

Hi everyone,

I have recently removed and stripped the rear subframe from my 91 mini.  The subframe itself is solid with no signs of rust.  I am certain I would like to sandblast it to remove all dirt from over the years.  But I now face a dilemma whether just to paint it or powder coat it.  I would like to hear your thoughts and advice on what you would do. 

Many thanks, 

Joe  

[THE ANORAK]

i also have a 91 mini in rugby and have stripped my subframe

[Simont]

I sandblasted mine and powdercoated, then gave it a liberal coating of stone chip underseal and waxoyl the crevices,

[Mervyn]

I had mine dipped then blasted, zinc'd, powdercoated and then I internally coated then with bilt hamber dynax s50

Cost £240 for front and rear @ STP coatings in Telford but they should last for a long long time

Merv

[cal844]

All I do is clean it with petrol or thinners

 

Then wire brush it 

 

Stonechip then  brush paint it

[Spider]

I have mine blasted then paint with POR15.

 

POR15 if you are not familiar with it, is a paint like no other, If the surface is prepared properly, it won;t chip or crack - even if hit and bent at a later point.

 

Powder Coating, while I've heard some good stories in recent times, it can be quite hit and miss. It's generally used an an industrial finish. As far as I am aware, it's applied electrostatically, where they electrically charge the subframe and then spray on dry powder. Because it uses electricity to attract the powder, it will always take the path of leave resistance and fall to the places closest to the gun. That's fine for flat panels and simple shapes but with things like subframes there's just so many nooks and crannies that it won't go to (say around the drive shaft holes on the front frame for example).

 

Also, I've seen it hundreds of times with powder coat where on an edge, the powder coat will crack then, it lifts a little from the parent metal underneath and lets water in. The powder coating is basically like a plastic sheet, so it holds said water. It all looks good for a while until you see the huge rust bubble under it some time later.

 

I've always found too that Powder coat doesn't always adhere to steel too well, but is the bee's knee's on alloy parts, much better than any paint here.

[1984mini25]

The last new one i bought and fitted. I rubbed/sanded off the crappy black primer, gave it 2 coats of red oxide followed by 2 coats of black metal paint (probably from lidi or aldi). I then mixed up some wax oil/engine oil and poured it into all the box section, nooks and crannies.

 

As rear subframes tend to rot from the inside (the radius arms mounts are the first to go) and no amount of powder coating is going to ever reach those places.

Edited by 1984mini25, 20 May 2017 - 08:53 PM.

[Joe 91]

I sandblasted mine and powdercoated, then gave it a liberal coating of stone chip underseal and waxoyl the crevices,

After it was powder coated, did it leave any nooks and crannies uncovered?

Edited by Joe 91, 21 May 2017 - 11:12 AM.

[tiger99]

I think that between Moke Spider and 1984mini25, the consensus is that it does leave nooks and crannies uncovered.

 

But the other problem is that if there is the slightest damage or failure to get full coverage, water will creep under the coating and cause unseen corrosion. Certain French vehicles used to (hopefully no longer!) use powder coat, or similar, on the brake lines, and the same happened, with disastrous results from pinholing. People were killed. (Cupro-nickel often called Cunifer or Kunifer, is the only correct  and safe material for brake lines, and does not need protection.)

 

The subframe needs to be comprehensively protected against the effects of minor defects in the outer coating, and that is best achieved by galvanising, which will achieve full coverage, arc spraying of zinc/aluminium, which with care will do a good job, or painting with Zinga. Then it can be overcoated with as many layers of good stuff as you like, such as epoxy primer followed by a gloss coat (my preference), or just a powder coat. Then if you like, and I certainly would, a wax preservative in all the nooks and crannies.

 

The zinc works by the principle of sacrificial corrosion, and although the zinc lasts longest if coverage is perfect, it still gives full protection for about 60 years if scratched.

[sonikk4]

Powder coating is only as good as the operative cleaning the subframe then applying the powdercoat.

 

There has been numerous debates about it on here some positive some negative but again like any coating its down to the person applying it. That includes paint, galvanising etc etc etc.

 

Once you have your coating applied then give things a coat of a wax based product of your choice. My subframes are powdercoated as are the frames on my sons car. He liberally applied Waxoyl in all of the nooks and crannies. I will use Dinotrol on mine, my choice. If its good enough for Civil Airliners and the abuse they get then its good enough for a mini.

[Spider]

Actually, just on reading tiger's post ^ why are they not hot dip galvanised in the UK?

[tiger99]

Cost? It is known that they do not distort if processed correctly, so there would seem to be no other valid technical reason.

[Spider]

Cost? It is known that they do not distort if processed correctly, so there would seem to be no other valid technical reason.

 

A few people in our part of the world have had them done. I think the trick is finding a galvanizing yard that doesn't do bridge girders and other heavy industrial parts.

[Dusky]

What I have done on cars before is mix an anti rust paint ( bit like Hammerite DOR) with elastifier. It gives the subframe a tough but slightly rubbery finish. Makes it a lot harder for stones to chip it

[richmondclassicsnorthwales]

Caldo Oils sell Anchor Wax.

 

I used it on all frames I built. i would place a good quantity in the lower and upper cross members then turn the frame several times and run it through the frames entirety.Basically the frame would drip with the stuff, then once fitted, give all the mounting points a good lashing too, I used to 2k paint all frames primarily. Still all good 30 years on.