pb12

Hey guys, finally back around. I decided that I didnt think it was the master cylinder, because cracking the bleader screws on the caliper didnt release any built up pressure. I decided Id rebuild one of the calipers to see if it improved the situation at all. Though the jury is still out as to whether there is actually a problem, I figured, what the hell, seems like a fun project. The first issue was to figure out how to source the parts that were needed. The dust boots are easy, the dealer can order them no problem, and the part numbers are on the parts "fiche". Three different part numbers, for three different sized boots. Note each part number has two boots in the bag. My dealer ordered twice as many as I needed because they thought it was one boot per order. The stickier, (excuse the pun) issue is finding the inner seals. It seems there is no normal part number for them. I asked the dealer to call Porsche Motorsport, and see if they could help out. Turns out they do indeed have a rebuild kit that is made up of the inner seal and the six individual pistons. By the way, there is some confusion on the piston sizes for these calipers, (2007MY PCCB). For the record, they are 28, 30 and 32mm. The kit does not include the dustboots though, so make sure your dealer orders those separately. Ignore those part numbers on the Brembo instruction sheet, those wont help you. The inner seals are color coded: The only mildly tricky part to removing the caliper is removing the brake line from it. Do yourself a favor, and buy a 10mm Flare Nut Wrench. The nut on the end of the brake line is made of brass to be sacrificial, so you don't ruin the caliper if you cross-thread it when re-attaching it. It is very easy to round off the nut using a conventional open ended wrench, so don't. Conveniently, the spring holds the brake line quite nicely! Make sure you put some sort of cap on the ed of the line, or it will weep the whole time. With the caliper off the car I used quick release bar clamps to hold five of the six pistons in place Then gently using compressed air, and a piece of 2x2 to make sure the piston doesn't pop out too far, I eased the piston out. The 2x2 is the perfect size, as its big enough to approximate the width of the rotor, and missing pad, but small enough to move around easily. Plus, that is wood, its soft enough not to mar anything. Once the piston is out, use a (very) small flat head screwdriver to gently pry the boot out of the caliper Next, with a small curved pick, remove the inner seal. It will come out easily, as it just lays in its grove. Now, note which seal you've removed, there are three sizes, as noted above, and they are color coded. (Old on top, new on the bottom) Now comes the fun, getting the new seal back into the caliper. First, thoroughly soak the new inner seal in brake fluid, and then work it back into the inner grove. Its not too bad on the 32mm piston, but the 28mm piston is a pain in the neck to work it back into the grove, and make sure its seated flush. There isnt a ton of room to work with, and of course I was wearing rubber gloves, (because brake fluid is just the most nasty fluid in the car), so it takes a little doing. Its not to tough, just be patient, and it will pop into place. Next, grab the appropriate new piston, and lubricate thoroughly with brake fluid, then gently, but firmly press into the caliper by hand. Be aware that the inner seal you just put into place may be sitting slightly proud of the inner surface, and so the first time you try and press the piston in, it may wedge against the seal. Just pull the piston back out, and feel around inside making sure the seal is as flush as you can get it, then try again with the piston. You will feel a reasonable amount of resistance, but not an excessive amount, and eventually the piston will slide in. Working by moving the clamps around, so you are always working on one piston at a time, it took about an hour to do the whole caliper. Re-mount the caliper with fresh new caliper bolts, torque to 63ft/lbs, bleed the system, and enjoy your fresh new caliper. For this project, it made a meaningful difference in the drag I was experiencing. Though it is still there, as on all cars it seems, it is not as much as it once was. Hope this is useful for somebody. Let me know if I missed anything, or if anyone has a question. Michael

Jermmy -- I ordered all new boots and o-rings, I figured why the heck not, they're not that expensive, might as well, "while im in there". Wont be able to work on it for a week though, as parts wont arrive before thursday, and im out of town untile late friday night, and then leaving sunday, so not even sure ill get to work on it next weekend grrrrr My job is getting in the way of my main objective! :) Thanks for the parts schematic as well, I could sit here and look at that for the rest of the night! I really wish someone around here had the workshop manual.... Michael

These things are really pretty simple as it turns out. the dustboots will pop off with a little persuasion from a very small screwdrive worked around the perimiter. too bad I tore the boot, as assembly is cake once you stop being a knuckle dragging idiot! :) michael

Well, this just turned into a bigger project than it needed to. I was moving each piston in and out, making sure they all moved smoothly, and i made the huge mistake of taking the last piston all the way out....very stupid. In my effort to get it back into the caliper, i tore the **** dust boot. So, i have new dust boots on the way, but i have no idea how to get the old ones out. They seem to be pressed into the caliper, but i really doubt they are. Anyone have a shop manual they could look at and tell me how to R&R the dust boots on PCCB calipers? Thanks Michael

Jermmy Thats exactly right, far more than I should expect in just a short 1 or 2 hour drive. Looking forward to this weekend to try and get it sorted! Michael

Jermmy Thanks again for the input. I was kind of dissapointed by the seeming lack of DIY folks onthe Rennlist GT3 board. Brake systems are not the most complex things out there, and I have no problem pulling the caliper off and messing with it. I wont have a chance to do it before this weekend though as i'm out of town for the next several days. I just need to figure out the best way to do this without pushing the pistons out too far. I really hope you're right with your idea. Just the rebuild kits for each caliper is over $225(!). $225 for 6 little seals and 6 rubber cups?! C'mon.... RE: brake dust, thanks for your input, yours is the first real world input ive seen. Glad to hear its "normal"! ;) Michael

Jermmy -- thanks very much for your reply! I just purchased the car from a gentleman who owned the car for 18 months and drove it less than 2500 miles in that time, so I think it fits your explanation. I have no problem pulling them off and running them in and out. Im thinking compressed air. Do you have a better idea of how to do it without popping the pistons all the way out? thanks again michael

Has anyone seen anythign like this before: http://www.youtube.com/watch?v=2YlXhzZsTV8&feature=plcp It seems that (at all four corners) the pads are not fully retracting, and cause a fair amount of friction. I bled all for corners, but it made no difference. Thoughts? M