wingsfan

I'm going to be rebuilding my brake calipers this weekend, and while I've got everything apart I want to go ahead and powdercoat the calipers.

The holes in the calipers need to be plugged to keep the powder out, and I need something that will withstand the heat for the baking.

I work in a lab where we have several different diameters of silicone plugs that are rated to several hundred degrees, I just need to know what size I need to "borrow". There's a good chance that we don't have the right size and I'll have to order it.

So...Anyone happen to know what the diameter of the hole left after I've removed the pistons?

Thanks

93BlackFD

good luck

powdercoating doesn't hold up to brake fluid or brake cleaner

that's why you buy caliper paint....FYI

wingsfan

It's my understanding that the powdercoat will stand up better to brake fluid than paint will, but I could be wrong. I know of a couple people who have powdercoated calipers with no problems.

Anyhow, I have access to the powdercoating equipment and already have the powder, so it's not costing me anything but the time and effort it takes to get things scrubbed up and ready. If it turns out like hell I can easily take the powder coat off and buy some caliper paint.

And all of this still doesn't answer my question as to what the diameter is. I want to say it's in the neighborhood of 1.5-1.75" but I can't remember off the top of my head. Guess I'll find out when I get it apart.

c00lduke

I'm pretty sure the heat is in the rage of 900F so you might wanna make sure that is still fine, you might also see if you can get freeze plugs at and autoparts store that might match up. But about the size, i'm pretty sure if its in the mack of the server manual.

~Luke

wingsfan

Well, if the heat range is in the range of 900F then the powdercoat is the least of your concerns. Normal DOT3 brake fluid has a boiling point around 500ºF. Exceeding that by 400º would be catastrophic, and by that time you'd probably have set your brakes on fire anyways, not to mention melted all of the rubber in the brake assembly, etc.

Now, I'm not saying that the brakes don't get hot (or damn hot even during spirited driving, just that they don't get to 900 degrees).

Anyhow, the powdercoat goes on at 400-450F and is rated to 600F, so I think it's fine for this purpose. There are also high temp powdercoats that are good all the way up to 1000-1200F, which most people would use for exhausts.

Anyhow, hightemp engine paint is rated to around 500F (I think, just quoting from memory here), so 600F for the powdercoat ought to be good enough. And it's a plastic, so it will provide nice protection from the fluid and brake cleaner. A friend of mine has had his powdercoated for more than a year, and the set that is coated is in noticeably better shape than the set that is not.

As for the sizes being in the service manual, thanks I'll check that out when I get home.

turbohounds

Are you serious? Do you have a clue what powder coating is or why someone would use it?

Essentially, it's a melted plastic coating, cured at 450F (above the boiling point of any new standard use DOT brake fluid) and holds well beyond that when cured. Powder coat is highly resistant to all solvents and abrasives (try stripping it off sometime). I have my exhaust and turbo heat shields powdercoated and it held up fine to everything except the cat.

Back when I was younger but not as stupid as you, I tried the caliper paints on properly prepped calipers. Sadly it didn't last. The powdercoat I have on there now is perfect, and hasn't been phased on track days where I've had my pads smoking from the heat.

93BlackFD

yes turbohondas, i powdercoat as a business

how confident are you in your intelligence on the subject?

go spray some brake cleaner on some powdercoated wheels, plenums, anything...it will turn into goo

caliper paint is made especially for calipers, it resists brake fluid and brake cleaner specfically, acids will still eat the caliper paint

caliper paint is better than powder as far as durability, but overall powder is more univerally useful and cost effective

turbohounds

Owning an Eastwood gun doesn't qualify as a business Thankfully, being literate I'm more confident in my intelligence than yours, as should any one else wasting time reading this garbage. Let's just say, I have very close access to well over 50 years of painting experience, and have painted three of my own vehicles, two restored from the frame up. Lots of research went into deciding which coatings to use.

Powdercoat is far more solvent resistant than most any paint. I have had my Suburban wheels powdercoated for years and they resisted everything I threw at them. I can say the same for oil pans, heat shields, transmission pans, master cylinders, calipers, suspension parts, etc.

Caliper paint is fine for those without access to sandblasting and high quality powder coating facilities. Caliper paint can be used as much as cover up and doesn't require the piston seals to be removed and replaced. Certainly it's more versatile, but lacks the brilliance and color palette obtainable with powder. Possibly the appropriate question would have been, does wingsfan plan on running his FD on track days, where anodizing, plating, or polishing would be a better option, or daily driving/show/autocross, where a more economical coating is appropriate such as powder or specialty caliper paint. To actually answer the original question, a #9 or #10 silicone stopper should work for both front and rear calipers.

93BlackFD

so go spray some brake cleaner on your wheels and take pics for us ;-)

BMike

You've gotta be freakin kidding me right, have you ever USED brake cleaner? It doesnt stay on anything, its made to evaporate, and ive sprayed it all over on stuff like powder coated frame pieces etc and never seen anything turn into goo with it. Do you mean brake fluid? cuz ive gotten that on wheels and the finish stayed on fine with it too, though i didnt leave it for hours. I really dont see how a plastic based product like powder coating is going to be affected easily by chemicals. Hell if brake cleaner is so bad for it why do they use a plastic spray nozzle on the stuff?

93BlackFD

no, and i'm not trying to argue with anyone....

i powdercoated a plenum for someone, they brought it back with some kind of residue on it from a bookbag sitting on it in heat

so i tried mineral spirits, no luck, i tried degreaser, no luck, and then tried brake cleaner...and the powder rubbed off all gooey

perhaps it's just the eastwood powders that are like that, what brand powders are you guys using?

93BlackFD

no, and i'm not trying to argue with anyone....

i powdercoated a plenum for someone, they brought it back with some kind of residue on it from a bookbag sitting on it in heat

so i tried mineral spirits, no luck, i tried degreaser, no luck, and then tried brake cleaner...and the powder rubbed off all gooey

perhaps it's just the eastwood powders that are like that, what brand powders are you guys using?

wingsfan

Well, I forgot to post the piston sizes after I looked them up, but according to my shop manual the fronts are 1.42" and the back is 1.37" I could plug the fronts with a number 7 stopper for the sandblasting, and I'll use a number 8 for the powdercoating. The rears will be interesting because of the piston design. There's a threaded center pin in the rear caliper that will make pluugging it interesting. I used a wadded up paper towel and masking tape for the sandblasting, but I'll ahve to rig something for the powdercoat.

Anyhow, I'm in the process of cleaning the calipers up and getting them ready for the powdercoat. I just got done sandblasting the fronts, and I thought I'd share a before and after pic. They were pretty nasty and the difference is astonishing.

The brakes had 91K miles on them, and the only love they'd received were new pads from the previous owner. While I had everything apart I went ahead and installed Goodridge stainless lines and Porterfield R4S pads. It should be like night and day difference.

BC-FD3S

iTrader: (2)

FYI: Most OEM Aluminum Wheels are finished by Powder Coating.

BC-FD3S

iTrader: (2)

FYI: Most OEM Aluminum Wheels are finished by Powder Coating.

wingsfan

well, here's how they turned out. I'm pleased. I may take some of the wife's silver sparkle nail polish and outline the "mazda", but otherwise they are ready to go

FRtengoku

I am sorry for asking stupid questions!
But what exactly is powered coating??? From reading the post, I think its melting some form of plastic on the the calipers? but how can you DIY that???

wingsfan

It's not a stupid question. Powdercoating is essentially excatly as you described. You melt a plastic covering on to the caliper. To do it yourself you need access to a powdercoating kit (gun + air compressor + powder) and an oven.

I basically snadblasted the hell out of the old calipers to get a clean surface, and then you al=pply the powder to the piece by running an electrical charge through the piece and spraying it with the powder of your choice. The powder is cheraged, and sticks to the piece because of the current running through it. THe powders are available in a variety of colors, so just choose the one you want. Afer applying the powder you bake it a 425º for 10 minutes and then drop the temp to 400º for another 20 minutes. Then you just let it cool down and you have a nice durable finish.

FRtengoku

WOO!!
Thats somework!! Thanks for the great Info!
BTW the Cliper Looks Great!!

tekno62

looks sweet man.. now let us know if it gets all F'e up from the brake fluid..

not being an *** ( like some ) but would like to know.. if it works you'll see alot of guys doing it

Tek

wingsfan

I got brake fluid on it when I was rebuilding the caliper after the powdercoating (you use it to lube up the pistons). Anyhow, it was in contact with the caliper for around 5-10 minutes, and it didn't eat off the coating. Whe I wiped it up with a paper towel it was a little pink, so if you let it sit for days it might be an issue. Brake cleaner did nothing to it.

I have some installed pictures after the silver nail polish, but the forum is being bitchy about letting me post them. Maybe later.

full-cruise

iTrader: (5)

lets see the finished pics???

wingsfan

The forum is still being a little bitch about attachments. Here it is on another forum.

rotarynemesis

Just would like to say wow that is damn nice.

I just have a quick question.

How did you sandblast them? Do you have a kit for that?

wingsfan

Air compressor and a sandblaster.

Basically I cranked the compressor to 125psi and blasted away. I used a fine(ish) grade industrial quartz (#30 I believe, I also bought some #20 at the same time, so it could have been that). Anyhow, the sell them in 50 pound sacks at your hardware store (not Home Depot though, they've never had it when I went to look).

You basically fill a 5-10 gallon and submerge the "siphon" portion of the tool in the "sand" And then blast away. Sand gets everywhere, and you'll be washing it out of your ears and your *** crack for a few days.