Master cylinder....paint or powdercoat?

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MoparMike1974

MoparMike1974

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I need to do something with my master cylinder. Just hung it on last week and its already getting surface rust on it. I know paint generally does not hold up around brake fluid. Will 2K urethane hold up?
Anyone here powdercoat a master cylinder?
 
I've used black ceramic engine paint and it worked ok.
 
You'd have to disassemble it completely, since the powdercoat paint is baked on at 400F...
(Not sure how well it holds up to brake fluid, anyway).
 
I used RPM "Rust Prevention Magic" on a new MC a little over a year ago. Still looks brand new, although car lives in a garage and only comes out on sunny days. Gets washed a lot though, and this is the "Wet coast".
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I need to do something on my 69 Dart with P/B also. I put a new M/C on and it rusted up within a couple months.
 
I used cast iron colored engine paint. It's held up great. Just be careful when filling it up with brake fluid.
 
Here is what mine looks like. It has not left the garage but the weather lately is causing massive condensation when I open the garage door.

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Yes paint It black. And prepare to be scorned and held up for public ridicule. LOL
 
I powder coated one once. Didn’t hold up. It could have been because the lid leaked a bit but once the brake fluid got to it, it bubbled and peeled.
 
I clear coated mine and the brake fluid soaked into the metal and bubbled it off
 
another vote RPM,i used it on all my bare metal and is still like new 4 years later.
 
I ordered some of the RPM "Rust Prevention Magic". Im going to give it a shot.
 
Thanks for the confidence gentlemen but I have only coated a few master cylinder covers thus far. Cast iron does turn out beautifully though and is a favorite substrate to powder coat.

My concern would be centered on the internal seals more than anything. Assuming you have a full rebuild kit and mask the cylinder housing well enough, with proper prep and curing, and keeping any spills cleaned up promptly I see no reason it wouldn't last.

Dot 3 brake fluid is supposed to be caustic. I experimented years ago with a freshly coated bracket submerged and sealed up in old nasty Dot 3 for months with NO adverse effects at all.
Dot 4 or Dot 5 silicone brake fluid will not hurt painted or coated finishes but require a full system drain-and-clean first.

If I was doing one for a customer I'd be inclined to mask not only the interior surfaces and plug the inlets but also about a quarter inch of the exterior too (where the gasket and lid mate to it) just to keep any brake fluid contact to a minimum so the customer wouldn't have to worry.

I hope this helps!
 
MoparMike1974 said:
I need to do something with my master cylinder. Just hung it on last week and its already getting surface rust on it. I know paint generally does not hold up around brake fluid. Will 2K urethane hold up?
Anyone here powdercoat a master cylinder?
Click to expand...


Since I'm redoing my braking system completely lines, master cylinder calipers and all hoses. I went another route . pure synthetic that's not supposed to eat paint if spilled non hygroscopic and higher boiling temp. I does not mix with regular brake fluid though. We'll see, I just clear coated my master cylinder .... and yeah I spilled a bit on the darn casting %#$.
 
My system is all new and completely empty. So I could go with DOT 4 and not have to worry about paint issues.
Can you paint over metal treated with the RPM?
 
MoparMike1974 said:
So I could go with DOT 4 and not have to worry about paint issues.
Click to expand...

No, if you want the non-paint peeling brake fluid, use a silicone base DOT 5.
DOT 4 is usually very similar to DOT 3, being glycol based, just with a slightly higher boiling point.
There may be exceptions to this, but as a rule of thumb, it's safe to follow. Check the label for silicone base.
 
I put DOT 5 silicone in both the brake and clutch masters on my '72 Dart since everything was new and clean anyway. Then I found that the pull-type slave cylinder (from Howe) had seals that didn't like silicone... had to rebuild it. So now there's DOT 4 in the clutch! Would have been nice if their instruction sheet had mentioned that little fact...:realcrazy:
 
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