anth115

Hey all,

I recently rebuilt my calipers and while this isn't a super thorough DIY, I wanted to share some tips to help others out along the way as I didn't find much info specific to these parts or the car/calipers (2006 Z06) in the hope that it'll help someone else who's considering/doing this. Sorry for the lack of pictures during the process, it's a pretty messy one with brake fluid and lots of gunk involved so it is hard to stop/clean/take pics along the way. Last disclaimer, I'm not a pro by any means, so there may be better ways of doing this but this was how I actually did it. Anyways.

Why I did it
I did an HPDE weekend on pretty new Michelin PS4S tires and didn't have much time to put considerable mileage on them beforehand.
Normally I run with all nannies on as I try to follow the mantra of 'if you're driving smoothly they won't be intervening much anyway', especially since Mosport is a very high speed circuit.
This time, while the tires were newer/greasier, I guess the nannies intervened quite a bit - long story short, by the end of the day my front brake pads were spent and the excess heat melted the dust boots on 2 of the pistons. I figured it was a good time to rebuild and upgrade to the DRM SS pistons as a 'while you're in there' mod. I also replaced my Hawk pads (which weren't too great) with Powerstop Trackday pads as they have great reviews from fellow track rats and are priced very reasonably too.

What you need:
- Caliper dust boots & seals. Part numbers: CENTRIC 14362044/14362045 (F/R), or ACDELCO 18G189 {#88875041} Professional/ 18G200 {#88875052} Professional (F/R).
- Caliper Pistons, if not reusing. The DRM ones are stainless steel and prevent heat soaking much better than the OEM aluminum.
- Mechanic's pick (optional but highly recommended)
- M10 nut (to seal the brake system).
- Rubber/latex glove, to cut 2 fingers off & seal the brake system.
- New banjo bolt crush washers. 2 per caliper. Part number: ACDELCO 21012386
- 1/2" x 1/2" x ~12" wood stick. Will be used to help push new pistons in.
- New pads/ rotors as required.
- Brake fluid.
- 2 flathead screwdrivers or plastic pry tools.

How I did it/the process
Okay, so here's the general process to follow. Tips denoted by a ***.
- Raise & support the car, all 4 wheels as you'll eventually be doing a brake bleed on all 4 wheels, if not replacing pads/etc. in the rear too. Goes without saying but please use stands and triple check them - people die needlessly every year from being crushed by poorly supported cars. Loosen the wheel lugnuts while the tires are on the ground.
- Remove the wheels and the caliper bolts from one front caliper. Pull it off the disk and support it on top of a bucket or something to not stress the brake line.
- Leave the old pads in there unless they're brand new/very thick. If so, pull them off and place a thin, approx 1/2"-1" board in there. You'll see why shortly.
- Get back in the car and slowly pump the brakes repeatedly. Every few pumps, go check on the caliper. You want to see the pistons slowly being pushed out from their bores. Stop once they're either touching the board/pads or are loose enough to wiggle within the dust boots. Wipe off any brake fluid and be ready for more to come out soon. If you have compressed air, you can use that instead to do this too, but bag the caliper and watch yourself as pistons/fluids may fly out fast.
- Undo the banjo bolt and detach it from the caliper. The banjo bolt has a copper crush washer on each side of it. Keep these in place.
*** Pull the banjo bolt out from the fitting and slide the 1/2" portion of the rubber glove's finger over the hole that runs horizontally through the body of the bolt to block fluid from entering it. Replace this in the fitting, ensuring that the copper crush washers remain on either side of the fitting. Now secure the bottom with the M10 nut - your brake system is now sealed.
- Take that messy caliper off your bucket and tilt it every way you can think of into a drain pan to get more of the brake fluid out.
*** Move over to your work bench. Now is the time to fully clean the caliper, especially the inside where the pistons are, since the old parts are still in place to prevent gunk from getting in. Use a brush, sponge, etc. and scrub away. Brake cleaner (non chlorinated) is safe on the caliper paint, but once I was done, I cleaned them again with normal soap & water just to be safe. You'll probably have to do more rounds of cleaning as we go, but that's okay. You want to clean them as best you can so that any dirt doesn't get transferred onto/into your new parts later on.
*** For the pistons that are still held in tight by the pressure seals, here is what I used: Take 2 flathead screwdrivers (or ideally a hard plastic variant if you have), and lever them against the top of the caliper guide pins for the middle pistons, or one guide pin and the raised edge of the caliper body for the pistons on either end. By using the flatheads as levels, you should be able to slide the pistons outwards until they're held in only by the dust boots and can be removed by hand.
*** Here's where a mechanic's pick pays dividends. Releasing the internal pressure seals is very easy with the pick. Just gently work it behind one and pull it right out. The dust boots are definitely tougher. I had success by working the pick underneath the base of the dust boot (from within the caliper bore), then backing off by just a mm so I'm not against the caliper wall itself and twisting the pick upwards. It takes a few tries but once you do a few, you'll get the hang of it and the process will speed up. A flathead can work here too but there's a much greater chance of scratching the bores IMO. Plastic interior trim tools may work well too if they're rigid enough.
- Put the new pressure seals in. It may be helpful to soak them in brake fluid for a few hours. If not, just lube them up and place them in. Work your finger around the inner diameter ensuring that they're seated flat and relubing them with fresh brake fluid. I've heard of people recommending assembly lube but I did not use it myself.
- Do the next step in the exact order described, and ensure you work close to the surface of your table so that if you drop a piston, it isn't going to make a hard impact and get badly scratched up. Take your new brake piston (or cleaned old piston if reusing) and your new dust boot. Lube the piston and inner diameter of the dust boot with brake fluid. Ensuring that the dust boot and piston are oriented upwards, slide the piston gently into the dust boot. The inner diameter will catch on the piston groove as it should once installed in the caliper. But now, slide the dust boot further down the piston until the inner diameter comes out of the piston groove and slides further downwards too. Go slowly here or the piston will fly right through. Take a moment to dry the body of the dust boot of any brake fluid - you only want brake fluid on the piston, the inner and outer diameters of the dust boots, and the pressure seals/ inside walls of the caliper bores. Relubricate the outer diameter of the dust boot and the pressure seal. Now gently press the dust boot against the part of the caliper bore where it will sit. Apply pressure evenly and ensure to seat the least accessible area first. If a raised portion of the dust boot remains, now is the time to press it in/flatten it by using a small wood block, wide flathead (gently), etc. Then, gently press the piston downwards until you feel it sit against the pressure seal. Ensure the piston is seated evenly right now.
- Using the 1/2" x 1/2" wood stick, lay it across the piston top and slide it until it is balanced. Now, gently apply pressure with a hand on each end of the stick to help work the piston evenly past the pressure seal. Once it happens, it will slide in smoothly and snugly. The inner diameter of the dust boot will catch on the piston groove, and they'll slide flush into the caliper to accommodate your newer/thicker pads. All is well. Repeat this across the caliper.
- Clean the calipers (again) and reinstall them on the car. Be sure to use new washers on the banjo bolt (after removing the glove bit) and torque to 33lb-ft. Torque the caliper bolts to 129lb-ft.
- Gravity bleed the system in the proper X pattern and be sure to pump the brakes to contact the rotors before moving the car.




Cleaned & seated flush.


Alternate view.

blackbeast99

Thanks for sharing!