Okay, I'm trying to figure this out: what are the brake calipers (rear 'vert and front 4-pot 'vert) made of, aluminum or steel?

There are a few reasons I'm asking. #1: I'm going to paint them and want to sand the mazda name so it looks all shiny and stuff. If they are steel I'll need to clearcoat the name so it doesn't rust. #2: I'm rebuilding my rear calipers and mazda happily sent me the WRONG seal kit... the piston seals fit fine but the outer dust boots are too small (how odd is that, btw?)... and so is the outer dust boot clamp ring. If I let the caliper sit with only a surface coating of brake fluid (and the assembly grease) inside the chamber, will it rust while I wait for the proper seals to come in?

Also, the brake piping. Will the piping rust if I leave it open to air while my brakes are off the car for cleaning, painting, and this rebuild?

And last but not least: if I'm going to paint the calipers and bake them like I'm supposed to, should I do this with the calipers and seal kits all assembled or should I disassemble them before I turn it up to 250degF or so? I mean, the brakes get hotter than that on a nice driving day, so I would assume it wouldn't hurt, especially if they are steel (and would then rust if disassmbled and heated), as I would assume they are.

 

cast steel??

 

^^ Bump ^^ Any info guys??

 

Ok I found out: the REARs are steel, the FRONT is aluminum. WTF??? Why can't they use aluminum for the rear too? Ugh... now I have to worry about rusting.

 

I would bake them before you put the seals and all on.

 

bake them for 30 min at 350 degrees and VOILA, baked brake calipers, low in carbs high in protein. no really, why would you bake them?

 

Cast steel?
Are you sure about that?
I thought all brake calipers were cast aluminum?


-Ted

 

not a Stupid Q at all. i dotn know and all this sounds very interesting. why do you bake them, and why is one aluminum and the other steel. where are the smart people???

 

I'm assuming he's going to paint them Or for this clear coat he's talkin bout.

 

 

Grab a magnet, if it sticks = steel. if it don't = aluminium

 

Bakeing makes the paint adhere better.

 

Brake caliper paint requires "curing" at 250-350degF for about 30 min. before its solvent resistant. That's why. And no I'm not sure anymore but somebody who sounded pretty authoritative told me the rears were steel plus they weigh like steel, not aluminum. And I'm still a bit unsure about how to pull all the guts out and bake it and not run the risk of rust inside the cylinder bores.... :-/

 

My fronts are aluminum, rears are cast iron.

I bet a few 0-60-0-60-0 runs would cure the paint..

 

was just about to say that as I read your post

 

Yeah if I had one convenient I would.

 

You do! In your alternator!

 

Okay yo. Regardless of what the rears are made out of (I'm 95% sure its steel, magnet or not), I went ahead, sprayed the inside of the caliper bores with WD40 to protect them while I painted, etc. Then I taped the piston faces up with aluminum duct tape (the kind that is actual metal, and sticks to metal best) and taped up the rest of the important fasteners on the calipers. I sandblasted the entire outside of each one, and then hit them with about 20 light coats of PlastiKote 900degF caliper paint. Interestingly enough, after comparing the back of that can with a can of VHT, PlastiKote says nil about heating to increase solvent resistance, although it says on the can as a selling point that it is solvent resistant. So perhaps it doesn't require the same process the VHT does. Regardless, we'll see how it holds up to basic cleaning and brake fluid as I put the new seal kit in tomorrow.

Front calipers are waiting till I get more sand to blast them clean with (I ran out), hopefully Monday I can finish cleaning up all the parts that remain rusty, crusty, and dirty, and finally start putting both subframes back on!