Brake Master Cylinder Paint Question

Hey KZR,

Hope everyone is doing well and having a good spring so far. Like most period bikes my MC on my throttle side of my GPz750 1985 has corroded and paint looks like crap due to brake fluid eating it off. I am getting ready to sand it away and clean it up and repaint it black.

That brings me to my question, based on experience and expertise do y'all have any suggestions on what type of paint to use to help minimize this happening in the future? I know that brake fluid is pretty nasty crap so I doubt there is any paint out there that stops it from being chewed up 100%, but I gotta believe that there is paint that makes it much more resistant at least.

I don't have a paint booth or anything so was planning and masking everything off and using a rattle can of whatever paint y'all recommend to clean her up. Can get a pic posted soon if that helps?

Thanks,
Brett

Clean your whole brake system out both calipers, hose's etc. Use DOT 5 silicone. Problem solved!
And don't ever use K&L rebuild kits. Try and find OEM brake rebuild parts.
Silicone brake fluid does not absorb moisture as does regular DOT 3.
I painted the MC on my stock Harley FLH over 30 years ago with basic Dupont Centari enamel paint. It never changed. I can pull the cap and the fluid is still the purple color as it went in. I have taken it apart a few times over the years.
But those are the facts! And I got fluid for free. My Buddy's Garage had a contract with the local Post Office, to service their vehicles.
They supplied the DOT 5. In a 5 gallon pail. I still have some left after 30 years.
Dot 5 won't eat paint! Plain and Simple!

if you want to use DOT 3,4 you have to live with this fact, it will destroy the paint the only solution I can suggest is, to be really anal about not getting brake fluid on the paint and cleaning it up immediately when you spill it on the caliper's, dont worry too much about the paint something that is high temp will do. Aslong as you clean the fluid off, the paint will be fine, use lots of water, if your calipers survive the initial bleed that being the paint isnt damaged then paint will last along as you dont get fluid on it and are vigilant when fluid is spilled. Also ensure when you install the pistons into the caliper body to use a Cotten bud to apply just enough fluid to slip the piston in the bore, or you could use some grease.

If you take your time and are carful the paint will survive, in my case it didnt because I had to trouble shoot my brakes and that lead to countless spills and me just being plan fed up with it. the less time it takes you to bleed the system the higher chances of your paint surviving.

Also make sure to replace the crush washers and that you bleed nipples have caps this will stop your calipers from peeling from slow long term leaks.

Has anyone tried a powder coat kit on brake parts?

Thanks gang appreciate it! The brake system has already been gone through and just had fluids all replaced (I think, will double check) but next time I will be using DOT 5 if that's the case.

As for the paint sounds like it really doesn't matter just need to b extra OCD about any seepage etc

Thanks,
Brett

DOT 5 is not without drawbacks. It creates a more spongy lever feel for one thing, and it doesn't absorb moisture so any water that gets into the system will settle down into the low spot in the system and cause corrosion there. You also need a spotlessly clean brake system with new lines before using the stuff too. No flushing allowed.

On masters I've painted i used two part urethane. It's not impervious to brake fluid, but it's decent. Another option would be something like Gunkote. Not sure what would happen to the viewing window when subjected to curing heat though.

You generally want DOT 3 or 4 for road use. As mentioned, they absorb the moisture so moisture doesn't collect, but gets dispersed, and this allows you to flush out the moisture by normal bleeding. As Nessism mentioned, if water collects in the low spots, you would have to disassemble the system to get the water out.

Remember; if you mix DOT 5 with DOT 3 or DOT 4 you get bubble gum - not good in your brake system. Ed

The further info and clarification add a lot and makes sense too. Thanks Nessism on the paint tip, will see what I can scrounge up and find there. I'm not trying to make anything bullet proof or concourse lev l but want to make it look nic again and hold up well over time basically.

Much appreciated!

- Brett

Talked to Dupli-Color about painting my front master cylinder. They suggested using their caliper paint. It's designed for use with brake fluid and should ( hopefully ) hold up well. Will be trying it shortly and let you know.

don

gpz1170 wrote: Talked to Dupli-Color about painting my front master cylinder. They suggested using their caliper paint. It's designed for use with brake fluid and should ( hopefully ) hold up well. Will be trying it shortly and let you know.

don

Thanks Don,

That is something I had considered, the only reasons I didn't immediately go there was I know that most caliper paint setups use brushes which I think would likely leave a bristle pattern that I don't want to see, and they are a lot pricier than just a rattle can of high temp gloss black. Will be very curious how your results turn out and would love a pic!

I am heading down to Pops' place tonight to work on my bike since that is where it is stored ATM, since our place is a two bedroom town house with no garage. In around 2-4 weeks though I suspect the bike with be through rebuild/resto-mod Phase I and I will be keeping it in Longmont at our townhouse. Will just build a small ramp for the back gate to get u on the deck and store it under the pop up canopy that lives back there to keep it out of the majority of weather and sun. Plus I can lock the gate as well as lock up the bike.

Anyways, back on topic lol.... Tonight after I show up after work, planning to install my grips and then take some pics of the carbs and bike and a before of the MC. Then sand down the body while keeping the gold Kawi writing/paint on top intact and prep it for paint. Also going to take a peek and see if I can find a place to fab some frame sliders up since I really don't want the old and HTF plastics chewed up.

Will post up pics later tonight or tomorrow.

Thanks,
Brett

I flushed my entire brake system clean of the .3 replaced with .5. I must not have gotten it all out because it melted the rubbers inside the master cylinders and the calipers. The brakes worked for about a month once the calibers started heating up that fluid they needed rebuilt. . A month after that the master cylinders took a shit.
As Ness ism say replace lines..I'd recommend all rubber..