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Posted by: shane Dec 4 2020, 08:11 PM

I’m rebuild my front calipers and the pistons and cylinders look real nice but the tops of the pistons have a Little bit of rust on them. Has anyone blasted them and coated them with anything? Thanks

Posted by: mepstein Dec 4 2020, 08:16 PM

Eric shows what to do on his PMB site.

Posted by: bbrock Dec 5 2020, 09:01 AM

The process he describes is to clean them in a vibratory tumbler and paint the tops with gray high temperature paint.

Posted by: shane Dec 5 2020, 09:29 AM

Thanks for the reply! Was thinking about a light coat of powder coat just to help protect the surface from future rust but read somewhere you shouldn’t powder coat any surface that touches the brake pads. I’m thinking zinc chromate was the original finish? I could do that but it’s a bit more work and time any thoughts? Thanks

Posted by: mepstein Dec 5 2020, 10:52 AM

Normal powder coat melts at 350 ish so heat might be a factor. Eric has done 10's of thousands so I follow his advise exactly or just have him do it.

Posted by: bbrock Dec 5 2020, 11:10 AM

Read Eric's how-to but this is supposed to replicate the original finish (no plating, high temperature gray paint on the tops). The housings were yellow zinc plated and that helps lubricate the pistons as they slide through the bores.

The how-to is a must read for rebuilding calipers: https://www.pmbperformance.com/brakehowto.html

and also watching Eric's excellent video on rebuilding rear calipers (it helps for understanding the instructions for the fronts too):

https://www.youtube.com/watch?v=dm_DnizKOZM

Posted by: shane Dec 5 2020, 02:39 PM

Sure makes sense with the powder coat being a bit maybe possible not high temp enough. High temp paint is easy and I can still bake it a bit in a powder coat oven at least. Thanks for the advice!