MK19
01-12-2004, 08:27 PM
Well, finally, after 15K miles and a ton of autocrosses, cross-country trips and the ever occasional of road jaunt - time to rebuild the front calipers. I am a pretty good mechanic and saw no need to send them off to get done- so I am doing it myself - as we speak . The process is quite simple actually and will work for the 2-pot rear setup as well. Total time, with all items on hand and no issues is approximately 1.25 hours per caliper, less bleeding. Here are the tools that you will need:
(8) Wilwood "D-rings" for piston NOTE: I didn't use new one's
Vise (optional, but highly recommended)
1/4" SAE hex key (calipers are standard, not metric)
Piston removal tool (I didn't have one, so I used vise grips and a rag to get them out)
2000 grit Emory cloth
Medium (blue) Permatex or Loc-tite thread locker (optional, but highly recommended)
Q-tips
Can of compressed air or compressor with air nozzle
Polishing rags
Orbital tool (i.e. dremel) w/ buffing pads (optional)
Seal removal tool or scribe
11mm end wrench
Brake fluid resistant container (plastic or metal bowl works fine)
Brake cleaner
Brake fluid
*** Before you start this project, it is highly recommended that you have as clean a work area as possible- remember, we are cleaning these calipers as well ***
OK, so here is how it starts: First and most obvious is get the front end in the air. Remove the tires and set them out of the way. Ensure you leave the master cylinder cap on to assist you in the retention of brake fluid. Remove the pads and make sure you note their position so that you put them back correctly. Use the 11mm end wrench and remove the brake line at the caliper (at the 90 degree elbow) and immediately take the end and stand it upright next to the strut; this will allow the fluid to stay in the line under its' own gravity. Remove the caliper and take it to the vise. At this time, break out the break cleaner and hose down the caliper all over- use the cleaner liberally. Set the caliper bracket in a rag, place it in the vise and clamp in down snug. Use the 1/4" hex key and break the 4 bolts loose; take care that you do not remove them too quickly. Once loose, remove the bolts by hand, ensuring to hold the loose end so that it does not fall. The caliper housings are separated by 3 plates, of which one side has o-rings to seal for fluids transfer to the opposing side of the caliper. Here you need to note the position of the plates so that reassembly goes smoothly.
Now that the caliper has been separated, time to pull out the pistons. Have a rag nearby, as the calipers are full of fluid. The bracket side of the caliper housing should still be in the vise, so we will start there. If you have a piston removal tool, use it as directed and pop those bad boys outta there. I didn't have access to one at all, nor do I know which one will work (NOTE: The Lisle square piston removal tool WILL NOT WORK! The bore of the pistons is too large). Place a rag over the piston you are removing and place the vise grips and the piston cup lip. Make sure that it is not extremely tight, as this can damage the piston cup. Once attached, rotate the piston left and right to free it up from the housing. You may also opt at this time to reapply more brake cleaner to assist you. As you begin to free the piston cup, begin to pull away from the caliper housing, making sure to continue rotating the piston to aid removal. Once it is free, ease it out and the brake fluid will come out. Repeat the above process for the remaining piston cups.
Once you have all 4 of the piston cups out, time for the fun stuff. Take the seal removal tool or scribe and remove the piston inner seal or "D ring" as referred to by Wilwood. Inspect it for wear/damage. If it is good to go, you can reuse this seal. I did not use any new seals, as mine were in exceptional shape (Dustin at Wilwood tells me they only generally get worn/damaged when they see a lot of off-road exposure). Set the seals aside on a clean surface. Now that the pistons are out, spray down the caliper housings again with brake cleaner- the more the merrier. Take the 4 piston cups, place them in the bowl, and spray them as well with brake cleaner. Allow them to soak for 5-10 minutes.
While everything is soaking, take one of the piston cups, dry it off and grab some of the Emory cloth. Tear off a portion and go to work on the outside of the piston cup. It shouldn't take too much work to get them clean- I was amazed at how well the Emory cloth worked even as grimy as my pistons were. It is at this point, which you may want to use the dremel and buffing pad to assist you. Once they are clean, use a few q-tips and clean the inside of the piston cup as well. Then take the polishing rag and buff the piston clean as possible. Repeat this process for the remaining 3 piston cups.
Now take one of the caliper housings (ensure to drain off any brake cleaner present) and take some brake fluid and a lot of q-tips and begin cleaning the housing and removing the residual brake dust; ensure to get inside the piston cup seal ring grooves. Once the housings are clean and dry, re-insert the new or reused seals. Take a clean q-tip and dip it in some fresh brake fluid and smear it along the inside of the piston bore and ensure it gets all over the piston seal; this will aid in the reinsertion of the piston cups. Once done, take the newly cleaned piston cups and reinsert them into the caliper housings. I recommend that you set them about 90% deep into the piston bore. The pistons should not easily slide in and may require the use of a socket extension or some other tool to assist reinserting the piston cups. Repeat the process for the other 3 remaining piston cups.
Once complete, time to put the calipers back together. MAKE SURE YOU HAVE ALL THE SEALS IN PLACE! Go back to the vise and reinsert the bracket back in the rag and into the vise. Snug it down once again and take the plate separators and ensure they are placed on the correct side of the caliper housing (you’ll find out the hard way if you don’t). Make sure the calipers are as dry (compressed air will help) as possible and apply some thread locker to the bolts and reassemble. I could not find the torque specs for reassembly, so I went snug plus a ¼ (hence the safety measure of thread locker). Now that the calipers are fully assembled once more- simply repeat the above procedures for the other remaining caliper.
After all is said and done, replace the calipers back on the vehicle and properly bleed the brakes. Now you are good to go! Go, Drive, Stop, Enjoy!
(8) Wilwood "D-rings" for piston NOTE: I didn't use new one's
Vise (optional, but highly recommended)
1/4" SAE hex key (calipers are standard, not metric)
Piston removal tool (I didn't have one, so I used vise grips and a rag to get them out)
2000 grit Emory cloth
Medium (blue) Permatex or Loc-tite thread locker (optional, but highly recommended)
Q-tips
Can of compressed air or compressor with air nozzle
Polishing rags
Orbital tool (i.e. dremel) w/ buffing pads (optional)
Seal removal tool or scribe
11mm end wrench
Brake fluid resistant container (plastic or metal bowl works fine)
Brake cleaner
Brake fluid
*** Before you start this project, it is highly recommended that you have as clean a work area as possible- remember, we are cleaning these calipers as well ***
OK, so here is how it starts: First and most obvious is get the front end in the air. Remove the tires and set them out of the way. Ensure you leave the master cylinder cap on to assist you in the retention of brake fluid. Remove the pads and make sure you note their position so that you put them back correctly. Use the 11mm end wrench and remove the brake line at the caliper (at the 90 degree elbow) and immediately take the end and stand it upright next to the strut; this will allow the fluid to stay in the line under its' own gravity. Remove the caliper and take it to the vise. At this time, break out the break cleaner and hose down the caliper all over- use the cleaner liberally. Set the caliper bracket in a rag, place it in the vise and clamp in down snug. Use the 1/4" hex key and break the 4 bolts loose; take care that you do not remove them too quickly. Once loose, remove the bolts by hand, ensuring to hold the loose end so that it does not fall. The caliper housings are separated by 3 plates, of which one side has o-rings to seal for fluids transfer to the opposing side of the caliper. Here you need to note the position of the plates so that reassembly goes smoothly.
Now that the caliper has been separated, time to pull out the pistons. Have a rag nearby, as the calipers are full of fluid. The bracket side of the caliper housing should still be in the vise, so we will start there. If you have a piston removal tool, use it as directed and pop those bad boys outta there. I didn't have access to one at all, nor do I know which one will work (NOTE: The Lisle square piston removal tool WILL NOT WORK! The bore of the pistons is too large). Place a rag over the piston you are removing and place the vise grips and the piston cup lip. Make sure that it is not extremely tight, as this can damage the piston cup. Once attached, rotate the piston left and right to free it up from the housing. You may also opt at this time to reapply more brake cleaner to assist you. As you begin to free the piston cup, begin to pull away from the caliper housing, making sure to continue rotating the piston to aid removal. Once it is free, ease it out and the brake fluid will come out. Repeat the above process for the remaining piston cups.
Once you have all 4 of the piston cups out, time for the fun stuff. Take the seal removal tool or scribe and remove the piston inner seal or "D ring" as referred to by Wilwood. Inspect it for wear/damage. If it is good to go, you can reuse this seal. I did not use any new seals, as mine were in exceptional shape (Dustin at Wilwood tells me they only generally get worn/damaged when they see a lot of off-road exposure). Set the seals aside on a clean surface. Now that the pistons are out, spray down the caliper housings again with brake cleaner- the more the merrier. Take the 4 piston cups, place them in the bowl, and spray them as well with brake cleaner. Allow them to soak for 5-10 minutes.
While everything is soaking, take one of the piston cups, dry it off and grab some of the Emory cloth. Tear off a portion and go to work on the outside of the piston cup. It shouldn't take too much work to get them clean- I was amazed at how well the Emory cloth worked even as grimy as my pistons were. It is at this point, which you may want to use the dremel and buffing pad to assist you. Once they are clean, use a few q-tips and clean the inside of the piston cup as well. Then take the polishing rag and buff the piston clean as possible. Repeat this process for the remaining 3 piston cups.
Now take one of the caliper housings (ensure to drain off any brake cleaner present) and take some brake fluid and a lot of q-tips and begin cleaning the housing and removing the residual brake dust; ensure to get inside the piston cup seal ring grooves. Once the housings are clean and dry, re-insert the new or reused seals. Take a clean q-tip and dip it in some fresh brake fluid and smear it along the inside of the piston bore and ensure it gets all over the piston seal; this will aid in the reinsertion of the piston cups. Once done, take the newly cleaned piston cups and reinsert them into the caliper housings. I recommend that you set them about 90% deep into the piston bore. The pistons should not easily slide in and may require the use of a socket extension or some other tool to assist reinserting the piston cups. Repeat the process for the other 3 remaining piston cups.
Once complete, time to put the calipers back together. MAKE SURE YOU HAVE ALL THE SEALS IN PLACE! Go back to the vise and reinsert the bracket back in the rag and into the vise. Snug it down once again and take the plate separators and ensure they are placed on the correct side of the caliper housing (you’ll find out the hard way if you don’t). Make sure the calipers are as dry (compressed air will help) as possible and apply some thread locker to the bolts and reassemble. I could not find the torque specs for reassembly, so I went snug plus a ¼ (hence the safety measure of thread locker). Now that the calipers are fully assembled once more- simply repeat the above procedures for the other remaining caliper.
After all is said and done, replace the calipers back on the vehicle and properly bleed the brakes. Now you are good to go! Go, Drive, Stop, Enjoy!