Brake rebuild & Powdercoating
06-06-2012, 03:56 PM
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Brake rebuild & Powdercoating
Ive ran into some amazing resources here on brake rebuilding, mostly in the turbo forums.
I have the early caliper style with the dust seals, (reference https://rennlist.com/forums/944-turb...ifference.html), and plan on replacing the seals and hopefully keeping the old pistons. When I drop the brakes off to be powdercoated, should I leave the old pistons/seals in place and just mask over them, or should I pull everything off beforehand? It's going to be baked at 400F for a while. I'm inclined to just leave everything on and just have them coated as-is. Brakes get hot, anyways.
I'm also going to start the painstaking process of pulling off the pad guideplates (reference https://rennlist.com/forums/944-turb...n-caliper.html). It seems that the torx 27 is too large for the bolts, so I'm going to try with heat and a 4mm allen head. This does not look like a fun project...
I have the early caliper style with the dust seals, (reference https://rennlist.com/forums/944-turb...ifference.html), and plan on replacing the seals and hopefully keeping the old pistons. When I drop the brakes off to be powdercoated, should I leave the old pistons/seals in place and just mask over them, or should I pull everything off beforehand? It's going to be baked at 400F for a while. I'm inclined to just leave everything on and just have them coated as-is. Brakes get hot, anyways.
I'm also going to start the painstaking process of pulling off the pad guideplates (reference https://rennlist.com/forums/944-turb...n-caliper.html). It seems that the torx 27 is too large for the bolts, so I'm going to try with heat and a 4mm allen head. This does not look like a fun project...
06-07-2012, 02:46 PM
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I used to rebuild and powdercoat LOTS of calipers. First off, (while this may seem nit picking) the dust seal you're referring to is a "Scraper Ring." They are almost impossible to find replacements for now and when you do they tend to be expensive. My recommendation is to go on eBay and find a set of reasonable condition calipers with the new style "Dust Boot." Much MUCH easier to find the part you need for a reasonable amount of $$.
But if you have to use the calipers you have, then by no means do you want to take them out before powdercoating. It's extremely difficult to tape off where the scrapper ring sits and if you get powder in that groove you will never get the old or new scrapper rings back in. I would always leave everything in the caliper as that is the best way to be certain you don't get any powder where you don't want it. You're going to replace the pressure seals anyway so who cares if they toast a little bit.
That said, if you go this route (leaving things in) then you definitely want to replace the ppressure seals as they are rated for 398 F. Heating them to 400 F will not fry them but it does start to reduce their elasticity and that that is a critical element to the job they do.
As tot he "guideplates." These are called "Spring Plates" and please PLEASE do not use a torx to try to get them out. You will create a BIG problem for yourself. I quickly skimmed the thread you noted on these and there wasn't much good info there. There are loctited in. You need to heat the head of the button head screw til it just starts to glow orange. Then using a 4 mm allen they will come out with relative ease. You still have to be careful in that if you round out the hex/allen head then you will have to weld a nut on to get them out. And that is a ROYAL PITA!!!!.
Once you have the spring plates out you need to take a strong wire brush and get all the crap and crud that has built up over the years off/out. You will powercoat with the spring plates out but screw in a new hex button head screw to protect/cover the threaded holes. The hex button head is a M10 with a thread length of 12 mm. You can find them at McMaster-Carr or Metric and Multistandard.
Typically you do not need to replace the pistons but you will need to replace the pressure seals and the scrapper rings (or duct boots if you follow my earlier recommendation) However as you will not be able to source the scrapper rings individually for all the sies you need you will have to purchase the kit from Porsche. The kit includes a piston, scrapper ring and pressure seal. And by the time you have purchased all of those you need to do a rebuild you will realize you could have bought a new set of Big Black calipers.
Hope this helps. Feel free to ask me questions if you have any. BTW, I also would NOT powdercoat. Powdercoat is suceptible to brake cleaner. So the first time you spray brake cleaner on your claipers to clean them you will screw up your nice new paint job. You can get just as good a finish using rattle can hi temp/caliper paint if you're careful and patient. both VHT and Duplicolor make hi temp/caliper paints in a wide variety of colors.
Michael
But if you have to use the calipers you have, then by no means do you want to take them out before powdercoating. It's extremely difficult to tape off where the scrapper ring sits and if you get powder in that groove you will never get the old or new scrapper rings back in. I would always leave everything in the caliper as that is the best way to be certain you don't get any powder where you don't want it. You're going to replace the pressure seals anyway so who cares if they toast a little bit.
That said, if you go this route (leaving things in) then you definitely want to replace the ppressure seals as they are rated for 398 F. Heating them to 400 F will not fry them but it does start to reduce their elasticity and that that is a critical element to the job they do.
As tot he "guideplates." These are called "Spring Plates" and please PLEASE do not use a torx to try to get them out. You will create a BIG problem for yourself. I quickly skimmed the thread you noted on these and there wasn't much good info there. There are loctited in. You need to heat the head of the button head screw til it just starts to glow orange. Then using a 4 mm allen they will come out with relative ease. You still have to be careful in that if you round out the hex/allen head then you will have to weld a nut on to get them out. And that is a ROYAL PITA!!!!.
Once you have the spring plates out you need to take a strong wire brush and get all the crap and crud that has built up over the years off/out. You will powercoat with the spring plates out but screw in a new hex button head screw to protect/cover the threaded holes. The hex button head is a M10 with a thread length of 12 mm. You can find them at McMaster-Carr or Metric and Multistandard.
Typically you do not need to replace the pistons but you will need to replace the pressure seals and the scrapper rings (or duct boots if you follow my earlier recommendation) However as you will not be able to source the scrapper rings individually for all the sies you need you will have to purchase the kit from Porsche. The kit includes a piston, scrapper ring and pressure seal. And by the time you have purchased all of those you need to do a rebuild you will realize you could have bought a new set of Big Black calipers.
Hope this helps. Feel free to ask me questions if you have any. BTW, I also would NOT powdercoat. Powdercoat is suceptible to brake cleaner. So the first time you spray brake cleaner on your claipers to clean them you will screw up your nice new paint job. You can get just as good a finish using rattle can hi temp/caliper paint if you're careful and patient. both VHT and Duplicolor make hi temp/caliper paints in a wide variety of colors.
Michael
