heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Brackets are back and, unfortunately, I think I made the wrong call by going with paint.



This specific paint is too glossy and I feel like it just screams "look at me!". Not a fan of flashy stuff. But whatever, it's a part hidden in the engine bay, who cares.

The real problem is with the mechanical properties of the paint. It didn't seem to adhere properly and most of what was under the fasteners ripped off when torquing. It also feels extremely squishy and I do not trust that these parts will stay torqued like they should over time. I don't know if this was caused by poor prep, by the "high temp" paint, by the paint having been laid on too thick or by all of the above.

I would love to powder coat these parts and get it over with, but I'm afraid of accidentally annealing the strut tower brackets during the cure step. I think cerakote makes some low temp stuff, so will probably end up looking into that.

Sigh...

[karter16]

Brackets are back and, unfortunately, I think I made the wrong call by going with paint.



This specific paint is too glossy and I feel like it just screams "look at me!". Not a fan of flashy stuff. But whatever, it's a part hidden in the engine bay, who cares.

The real problem is with the mechanical properties of the paint. It didn't seem to adhere properly and most of what was under the fasteners ripped off when torquing. It also feels extremely squishy and I do not trust that these parts will stay torqued like they should over time. I don't know if this was caused by poor prep, by the "high temp" paint, by the paint having been laid on too thick or by all of the above.

I would love to powder coat these parts and get it over with, but I'm afraid of accidentally annealing the strut tower brackets during the cure step. I think cerakote makes some low temp stuff, so will probably end up looking into that.

Sigh...

I was really surprised when I got my rear RACP bar powder coated. The guy asked what I wanted and I said gloss black, and he looked at me and said “are you sure?” And showed me gloss black, and I thought it looked good. Then he showed me “satin semi gloss” and it was better, then he showed me matte and that was the best of the lot. Very similar to the OE stock strut bar finish so that's what I went with.

I thought the temp for annealing was quite a bit higher than powder coating temps?


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[bigjae46]

Brackets are back and, unfortunately, I think I made the wrong call by going with paint.



This specific paint is too glossy and I feel like it just screams "look at me!". Not a fan of flashy stuff. But whatever, it's a part hidden in the engine bay, who cares.

The real problem is with the mechanical properties of the paint. It didn't seem to adhere properly and most of what was under the fasteners ripped off when torquing. It also feels extremely squishy and I do not trust that these parts will stay torqued like they should over time. I don't know if this was caused by poor prep, by the "high temp" paint, by the paint having been laid on too thick or by all of the above.

I would love to powder coat these parts and get it over with, but I'm afraid of accidentally annealing the strut tower brackets during the cure step. I think cerakote makes some low temp stuff, so will probably end up looking into that.

Sigh...

Blast and then anodize? Powder coat will also chip off under and around the bolt heads.

Carbon fiber would look better :P

[maupineda]

Heinz, all these needed was a can spray. You should have taped the bearing surfaces.

I’d leave as is. Painting is fucking annoying, and sanding 1k times more.

Since they are fresh get paint removal and see it comes off if you want to redo them

the aircraft paint remover works good

[heinzboehmer]

I thought the temp for annealing was quite a bit higher than powder coating temps?

Maybe annealing is not the most precise word to be using here. What I mean to say is that I don't want to significantly affect the yield strength of the material by exposing it to higher temps than it will see in the engine bay. Thermocouple data says that the parts will likely never see above 90C, so anything past that requires scrutinization, to keep the brain happy.

Was looking into this last night and found a bunch of literature on AlSi10Mg (e.g. 1, 2, 3, 4, 5, 6).

With a bit of biochemical neural networking (i.e. lots of switching tabs to compare results ), I've arrived at 150C being the max "safe" temp I'd like to expose the alloy to. A bit conservative, based on some of the results in the papers, but I don't have a way to test the parts to failure, so would rather stay on the safe side.

Seems like powder coating cure temps are closer to 200C and I really don't trust some random shop to not crank the oven up arbitrarily, so that's why that process is ruled out. Other more common alloys (e.g. 6061) seem a little less susceptible to those temps, but strength still drops fast as the temp starts climbing.

Blast and then anodize? Powder coat will also chip off under and around the bolt heads.

This was gonna be my next approach, buuut then I reached out to the guy who cerakoted my brake calipers and was informed that there are some formulations that can fully cure and bond to aluminum at just 82C.

I have not treated my calipers with any care at all and the finish still looks brand new. I've smacked wrenches/wheels/rocks into them and have hosed them down with brake cleaner plenty of times, but have yet to affect the coating.

Here's a pic I took a few minutes ago:



Calipers are disgusting and have been bathing in track pad dust for a while, but the cerakote is showing no signs of wear.

Agreed that coatings will likely still chip under bolt heads given enough time, but as long as they don't do this during the first torque cycle, I'll be happy:



I'm essentially trying to replicate the durability of the BMW paint/coating. It does chip away with time under bolts heads, but it doesn't fail catastrophically.

Heinz, all these needed was a can spray

I do agree, buuut:

Painting is fucking annoying, and sanding 1k times more.

I absolutely hate painting stuff. It never comes out how I want it to and prep is so boring to me. I thought if I outsourced this, I would get a better finish and also have to do zero work. Not sure I was in the right here, though.

I did think of taping the bearing surfaces, but figured that if BMW got away with painting them, I could too. Also, I thought the parts would look a little weird with unpainted surfaces, since some of them are rather large.

I'm pretty confident the cerakote will work out well. My brake calipers have taken a beating with essentially no wear.

[heinzboehmer]

Yikes:



I'm glad I didn't drive with these installed. Not sure my alignment would have held.

Going for cerakote soon.

[0-60motorsports]

Cerekote will be really nice

[heinzboehmer]

Agreed! I'm excited to get the parts back. They should look very similar to how they came from factory.

I might have snuck in another engine bay component to get cerakoted as well