Michael Russell

Some of you may recall this thread I started RE: my brakes dragging a bit:

https://rennlist.com/forums/997-gt2-...re-a-drag.html

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

P.J.S.

Nicely done... I am sure I am overdue

NorthVan

Me too, the previous owner must have worked the brakes hard

Michael Russell

It's my understanding that if the brakes get hot on a consistent basis, it can affect the durometer level of the inner seal, effectively making it a harder rubber. This in turn reduces that seals flexability, and the pistons may not retract quite as much as they did when new.

Michael

997gt3north

Does the Motorsport Rebuild Kit, that includes the new pistons, also come with the new Yellow ceramic pucks in the picture that you posted? If so, that would be the only way to get new Ceramic Pucks that I know of - I have actually been looking for those.

Do you know, after your research, the rear caliper rebuild kit part numbers / piston sizes?

I have the same model yr - it there a Motorsport Part number to use for the order?


Thanks

Bob Rouleau

Michael, Thanks for the DIY. It is now immortalized in the GT DIY section.

Best,

911rox

Hey Michael, awesome write up, thanx for sharing!

Just when question, I'm not sure I understood, how/when the new dust boots were fitted? Are they fitted after the piston has been slid into place and through the inner seal... Thanx in advance.

Chris

NJ-GT

awesome and thanks!

The DIY helps with Boxster/Cayman/Carrera calipers as well.

Michael Russell

Thanks Bob. Hope all is well in the great white north. I sure do miss running with you guys back there on the east coast. Some of my best car memories are those early October events at Tremblant.

Hey Chris - Great catch! I knew i'd forget a step or two. Anyway, I tried both ways to see if one was easier than the other. In the end I decided to snap the dustboot onto the piston before I slid it back into the caliper. Then, with the piston flush with the caliper, (ie fully compressed back into the caliper) press by hand the dustboot into place. Make sure you have a good seal all around its perimeter. It tends to want to pop out on the opposite side from where you are applying pressure. Not tough at all, just be thorough.

Hi 997GT3North --

Yes, those yellow pucks are delivered on each piston.

As for the rears, there may not be a part number yet, because, get this, supposedly this is the first time anyone has ever ordered a rebuild kit?! I don't know how that can be possible, but I am told that Motorsport had to create the kit when I asked for it. They turned it around in about a day, its not exactly a complex thing. I *Think* the rear pistons are 34mm, but dont quote me on that.

If you are looking for a part number for the front kit, its 997-351-959-91. At least thats whats on my invoice, and on the bag the kit came in, so I am assuming it will work again.

Good point NJ-GT, the only difference of course is the parts themselves would be different.

Michael

997gt3north

People that have been looking for pucks have just scavenged and I think the extent of any rebuilds so far have just been new bust boots - so not what you have done. And, the florida guys have actually led the way for not even using the dust boots as they quickly crumble and instead use the retaining springs - I just put in an entire set of these.

My Toronto dealer is now going to contact Motorsport and order a rebuild kit for all corners - I will see if they can deliver.

JasonAndreas

At one time (and possibly now), Porsche included Klüberfluid 9 R 100 with their rebuild kits for non-ceramics. It makes seal and piston insertion somewhat trivial when compared to using brake fluid as a lubricant. There is also a trick for inserting the seals that might be of some use... You invert the seal into a figure eight with a pair of needle nose pliers. It won't entirely make sense until you see it (the video below shows it starting @ the 1:26 mark).

Michael Russell

Jason --

That's brilliant, wish I had seen that before hand!

M

rubber_ducky

Great info here. Thanks for taking the time to do the write-up

deputydog95

Wow, great timing. My car is an 07 with a ton of track miles. I figured its time. My pucks are constantly falling out so I thought I'd get the retaining clips and have a rebuild done at the same time.

A couple questions.

1) How much was the kit?
2) Can't you reuse the original pucks? Being ceramic, as long as they aren't cracked or lost I would thing they would have an indefinite life span
3) Why do the pistons themselves need to be replaced? Do they wear somehow?
4) Can anyone confirm if the rear calipers are supposed to use ceramic pucks like the fronts? Mine doesn't have them and didn't come with the car. It was purchased used so I don't if it was or wasn't supposed to have them.

seapar

Nicely done Michael.
Me I am happy to be able to check brake pad thickness and look for taper on my Pccbs. Then I bring it to Gerber Mototsport to validate. But that's just me. Gonna have them add some coolant to the water wetter before the coolant fittings get welded this winter....getting colder up here now.