The Ultimate Brake Caliper Restoration Guide
Brake calipers; they’re something we all need. We could easily say our life literally depends upon them yet so many are left forlorn and neglected behind our immaculate wheels and today’s latest tire technology. Worse yet, they get a shot of spray paint so as not to embarrass the owner when showing off their $2,000 wheel restoration.
These are your brakes we’re talking about gang! You know; the things that stop you when you’re coming to an intersection full of Suburban’s and F350’s? Rocket science? Naaa but, they probably need to be treated with some tender loving care in order to give you another 40 years of faithful service
Over the last 10 years, we’ve built our business around a simple principle of supplying a fully restored caliper to a more discerning and educated buyer/driver. So why on earth would we take the time to write an article that shows you all the tips and tricks of the trade? Pretty simple; there are DIY guys and not DIY guys. If you’re a DIY guy (hey, we know… that’s how this business got started) it would be so much better if you could learn all the tips and tricks ahead of time. You’re going to do it any way, right? Why not do it right, especially when it comes to something as important as your brake calipers?
Read on gang; you’ll learn why you should have your caliper re-plated or re-anodized. We’ll explain why you should never “hone” the bore and why you should never take a pair of pliers to your pistons. Why painting is generally not a great idea and what you should do with your fasteners. We’ll explain the pitfalls with “Big Box” rebuilders and show you all of the steps to bring your calipers back to brand spanking new condition.
If you’ve made it this far, you’re at least a little interested in what lies ahead. We’ve all heard “Any job worth doing is worth doing right”; correct? As with all of jobs, this one starts with good prep. This means having the right tools on hand and finding the right suppliers for every step of the way. Let’s start with the specialty tools. The ones you may not have in the tool box. Thinking ahead, Amazon may be able to deliver these before you’ve even cracked a lug nut:
Ribe (pronounced ree-bie) Bits – If we’re talking about any of the 911 series or early 914’s all but the very first few serial numbers use these Ribe Fasteners (fun fact: some of the first 75 911’s still used the 356 caliper which had standard hex cap screws). While these 5-point star bits look amazingly similar to a common torx bit, they are not the same. A Ribe bit and fastener has a much more pronounced shoulder with sharp edges. Word of caution: Torx bits will fit in Ribe fasteners. My general take on them is, they would be fine for “assembly” work but I would caution anyone from using them to disassemble a caliper that has been stuck together for 40 plus years. The main issue here is, these fasteners are NLA. If you ruin one, you’re going to have to purchase a core caliper in order to get a replacement. Throughout this tutorial we’ll be concentrating on the care required to extract these fasteners without damaging them and, how to treat them so they’ll last another 40 years. Ribe bits are an important part of this. Ribe bit sets can be found on Amazon for around $35.00.
Here’s what you’ll need:
- M-Caliper (911 from 64-75 w/steel front caliper) – R8 bit for an M8 fastener.
- Rear M-Caliper (911 from 69-83) – R6 bit for an M7 fastener.
- A-Caliper and Wide A-Caliper (911SC and Carrera models through 1989) – R6 bit for an M9 fastener.
- Rear Carrera Caliper (911 Carrera through 1989) – R6 bit for an M7 fastener.
- 914 Rear Caliper (70-72) R5 bit for an M7 fastener.
That pretty much covers the “Ribe” usage on Porsche models. I can’t stress this part enough. It’s the beginning of “treat your fasteners like gold”. Many of these odd size (7-9) fasteners are NLA in “any” configuration, let alone Ribe. Numerous calls to Ribe to have fasteners re-manufactured have been met with… “no”. About the only caliper you can readily get 12.9 fasteners for is the M-Caliper with its common M8 fasteners. Then again, they won’t be Ribe and they won’t be original. The rest are priceless.
Next in our preparation section would be to find a competent metal finisher in your area that deals in yellow zinc. Yes; zinc. While many of the fasteners and bits and pieces on your vintage restoration may be Cad plated, the brake calipers are made by a company called ATE (not a car manufacturer) and they used “Zinc” for superior corrosion protection. Zinc is a sacrificial coating that will begin to corrode protecting the steel around it. This is why your calipers have lasted as long as they have. This is also where I get to interject a pet-peeve on Big Box rebuilders. Congratulations, you just saved $50.00 on a car that could be (or is) worth tens or hundreds of thousands of dollars. You purchased a rebuilt caliper for your vintage ride from RockAuto, AutoZone or PEP Boys. You may even brag to your buddies online about how much money you saved, sneering and taunting those specialty suppliers looking to “rip you off”.
With your brilliant decision you have purchased the following:
- A good core caliper.
- A caliper with absolutely no protective finish on the bodies or the fasteners.
- A caliper with no protective finish in the bore.
- A caliper with cheap aftermarket seal kits.
- A caliper with the pistons, more than likely, installed improperly… (we’ll show you how simple it is to do it right).
- A caliper with aftermarket (wrong) pistons with inferior plating.
- A caliper with an extra bleeder drilled in it to save time and expense of matching left and right units.
- A caliper that will be solid rust in 2-4 months.
- A caliper that will be deemed “unusable” in 5-10 years. They will rust and pit beyond usable condition...
...and the list goes on. We're adamant about getting the proper caliper on your car. There’s a good chance those are the calipers you have on your car, you just have to treat them properly. The way the factory did thirty, forty, fifty years ago. This is why zinc plating is an important pre-step in the process of restoring your calipers. Look for a plater that will not charge a “minimum” batch charge. Look for one that does or has done a lot of automotive restoration work. Large batch platers may not want to touch your greasy, rusty calipers. Start making the calls now. If all else fails, we offer a plating service for just this reason. You may be in a smaller market where a plating service isn’t available or, your plater may charge a minimum batch charge that would make plating some calipers cost prohibitive. Call us: 855-786-7101
A word of caution: taking parts off your car and sending them to a plater can be highly addictive. A final word on plating to sum things up; yes, you will want to have your calipers plated. Remember, zinc is a sacrificial coating that has protected your cast steel calipers for this long. It will do a great job of protecting them for another fifty years. Even if you want to paint your caliper red in honor of the “real” big red caliper Porsche used, plate them first and then rattle can to your hearts delight. We’ll get into this further but you will want to plate the bores as well. We get this question a lot; your bores have wear marks on them and, as we prep the pistons you will see, we will have bare metal on bare metal unless you plate the entire caliper. Here’s a thought, let’s say you’re restoring your 66 911 tub and you just had the shell sand or soda blasted. How long would you leave it outside in the elements before applying the proper protective primer and base coat? You simply wouldn’t. Why would you do something like that with item as important as your brake calipers? You wouldn’t put a rusty crank back in your $25,000 engine rebuild. Want more? You have two caliper shells sitting on the workbench in front of you. One is blasted to bare metal like the big box rebuilders. One has a nice layer of protective zinc plating on it, just like the factory used. Which ones will you use for your vintage Porsche? Great… we’ve established that you’re either too lazy or too cheap to get your calipers plated (or both). Hit Google and find a competent metal finisher in your area.
Now we have the more challenging items ticked off our checklist. The rest will be common tools that every DIY guy or gal should have hanging around the garage. Where we use some specialty tools, we’ll substitute with a more common "workbench work around".
Here’s a list of tools that are very handy for the job:
- Air compressor
- Air wrench
- Set of 6-sided sockets
- 3” 3/8 extension
- 3/8” Ratchet
- Torque wrench
- ½” Breaker bar
- Needle nose pliers
- Dental pick arrangement
- MAPP torch
- Punch Set
- Bench vise
- Grease gun (?)
- C-Clamps (2 at least)
- Large Rubber stopper (for 42-48mm bore www.mcmaster.com)
- Smaller Rubber stopper (for 35-38mm bore)
- Steel sheet stock the size of the pad cavity or, an old pad backing plate
- Vibratory polisher/Rock polisher or 0000 steel wool
- Proper ATE or FTE seal kits for your calipers
- EPDM caliper ½ seals
- Brake cleaner
- ATE Assembly Lube or Permatex Ceramic Lubricant
Now let’s take a look at those calipers and see what we have. We’ll assume you’ll know how to get them off the car and how to jack up the car and remove the wheels. But, before you take them off the car we’ll want to know a few things about the pistons. Has the car been sitting for a long period of time or is it your daily driver? This will help determine the condition of the calipers and pistons. If it’s been sitting, chances are the pistons are stuck or binding. If this is the case, you will probably not be able to free them up using the simple “compressed air method” (more on that as we progress). If it’s been your daily driver and you’ve changed the fluid every year then chances are compressed air will work. We’ve torn apart thousands of these things and this is almost always the case.
If the car has been sitting, now is the time to get these pistons moving. By leaving the caliper attached to a fluid system (your brake system) you should be able to free up the pistons. Fluid does not compress and air does. This is why the compressed air method won’t work on a stuck piston. Use a buddy and press the pedal until you hear the cracking and creaking of the pistons moving. Remove the pads so they will have some room to travel. Place an old brake pad backing plate or a ¼” of plywood in the bore so the piston won’t come completely out. Bottom line; let’s get those pistons moving using fluid. If they are totally frozen there are a few things we can do on the bench or, you may want to consider professional help at this point.
If the car is a daily or occasional driver and you’re certain the pistons are working, take a few stabs at the pedal to make sure everything is freed up and remove the calipers from the car. These should be good candidates for a compressed air removal.
At this stage all of your pistons have hopefully moved and the calipers are on the bench. Before we get into piston removal let’s get the accessories off. That means pads, pins and springs. Many of these items are hard to find as ATE has not been a very good supplier to the aftermarket community for pad kits. Threat them with care and see if your plater can extend their life a bit. Rear M-Caliper, A-Caliper (911SC) and Wide A-Caliper (911 Carrera 84-89) kits are readily available. Using a pair of needle nose pliers, pull the pin clips up and out. Use the needle nose and the caliper body as leverage. Later calipers (A-Caliper, Wide A and Carrera rear) will have a spring that is integrated into the end of the pin so this step won’t be necessary. Using the appropriate punch, drive out the pin holding the pads and pad springs in place. Keep a finger on the spring as you do this to prevent it from flying across the shop. Remove the spring and then push out the second pin and remove the pads.
Next, remove the piston dust boots. There should be a wire clip running around the perimeter of the seal (pictured above). Take a dental pick and pry this clip up and out. Remove the rubber dust boot and toss everything in the trash.
On to the major step, piston removal; if you were unable to move the pistons in the previous steps and you want to carry on, hang in there. Here’s where we’ll explain some drastic bench top measures to get them free. Again, your calipers will now fall into two categories; 1) pistons that are moving freely and 2) pistons that are going to give you trouble. Let’s get the easy stuff out of the way first.
I like to remove the inside piston first. This is the piston that is in the ½ with the mounting ears. Put a c-clamp on the outboard piston to hold it in place, make sure your bleeder valve is secure and pad the bore with a shop towel. Using compressed air, insert the nozzle in the fluid inlet and gradually squeeze until you see the piston start to move out of the bore. Try to feather it out and by all means KEEP YOUR FINGERS AWAY FROM THE BORE. When these pistons come out using compressed air they can be traveling at bullet velocity. This is why you pad the bore.
Once the inboard piston is out you can put a larger rubber stopper in the bore and cap it off with a steel plate. I like to use a long steel plate that extends into the jaws of the vise so the vise can hold the bottom portion while the top is held in with your c-clamps. An alternative is to use the old brake pad backing plate and strategically place your c-clamps so the plate will hold the stopper in. This is more critical on pistons that are stuck vs. free moving pistons. Using the compressed air and padding the cavity again, pop the other piston out of the bore. Rinse and repeat for your remaining calipers. Count your blessings that you had pistons that were fairly free in their bores. Don’t worry about bore positions and which pistons came out of which caliper, it will all be self-explanatory upon re-assembly.
Now, if Murphy’s Law has struck and you’re in the second category, this section is for you. If you were able to get your pistons to move while they were still on the car, we’re headed in the right direction. At this point, try the compressed air method described in the paragraph above. You “might” get lucky but, I wouldn’t plan on it. The only way to get these stubborn pistons out is with fluid. As mentioned earlier and in your Jr. High physics class… fluids don’t compress so they will blow out just about any stuck piston. The problems will be a) getting the fluids into the caliper and b) maintaining pressure on the caliper once you get one of the pistons out.
Let’s start with getting fluid into the caliper. Water is a fluid and that’s what we use at the shop. Cleanup is a snap but configuring a water pump can be troublesome. If you’ve searched the internet boards, a popular one is an air powered grease gun. It is an attractive option because most of them have a 10x1 fitting hiding underneath the zerk tip or… you can easily get a zerk adapter with a 10x1 male end that will screw right into your caliper fluid inlet. The only problem is… clean up. Let the party begin. As described above. Clamp off the outer pistons and start pumping the fluid of choice into your caliper. The nice thing you’ll notice with this method is the pistons will come out in a very slow controlled fashion. There’s no need to pad the bore. Now… if Grandpa Murphy’s Law has struck and they’re “still” not moving, here are a few tips. Some say heat, I’ve never seen a tremendous return on this investment but, it really can’t hurt at this point. You can get out the MAPP torch and heat up the caliper casting to possibly expand the metals and help break a bond. The “best” method I’ve found is to move the piston inward using a large c-clamp. The point isn’t which direction you move the piston; it’s just that you need to “move” the piston. You need to break the bond. By applying pressure on the piston top and moving the piston in you should be able to break that bond and get it out. Using a large c-clamp, screw it in until you hear the “snap”, at this point you should be good to go.
A final note on stubborn pistons; watch for the pistons “cocking” in the bore as they come out. With these stuck pistons, a lot of times they will want to bind on one side or another causing it to cock in he bore. Take a large screwdriver and correct the angle (you should feel a little snap as it goes back into alignment) and keep pumping.
As mentioned earlier, getting the second piston out can be troublesome. Often, with these stubborn pistons, the pressure needed to get the out will be immense. Your success will be determined by how well you can use the stoppers and the metal plates to keep the pressure in the caliper body.
I hope you’ve had much success up to this point. Next we’re going to move on to the fasteners and splitting the caliper halves. Speaking of which; there’s another Internet myth we need to explode. “You can’t split the caliper halves”. You can and you should. Let’s dig in.
First let’s get those uber valuable and rare fasteners apart and split these calipers. If you have M-Calipers, the Ribe R8 head is quite stout and we rarely have any problems with these. The problem fasteners will be the larger M9 fasteners on the A-Calipers with the smaller Ribe R6 bit heads. These are a very problematic fastener. The first step in all of these fasteners is getting the bit to seat properly so we can begin the disassembly process. Make sure there is no rust or paint in the Ribe head on the fasteners. Insert the bit all the way in for full engagement and, as a good measure tap the bit in with a hammer to fully seat it in the fastener head. This will assure maximum grip on the fastener head. For the M7 fasteners and the M8 fasteners we simply use an air wrench at this time with a suitable six-sided socket. IMPORTANT: For the A-Calipers found on the front of 911SC and Carrera models, I like to do all of those fasteners by hand so you can “feel” what’s going on. In taking them apart by hand we’re going to do the following; 1) Make sure you seat the wimpy Ribe R6 bit in the fastener head with a hammer. Don’t slam it in but tap it and make sure it’s in there. 2) Only use the Ribe bit to “hold” the fastener, NEVER attempt to turn the fastener with this bit (unless you enjoy purchasing Ribe bit sets and core calipers to get more fasteners). 3) Use a long breaker bar and a 14mm deep well socket, the depth of the nut and length of the faster will usually not fully engage a standard socket. Your mileage may vary. 4) Shoot for a “burst” of power on the breaker bar to break the nut free. 5) STOP! If it does not come loose, you’re in trouble. Get out the MAPP torch and crank out your favorite song. The two minutes (average) it takes to complete the tune should have the nut heated sufficiently. Now try it again. If you’re still having trouble, use penetrating oil and more heat and tap the end of the fastener with a smaller hammer to break things free. Be patient or you “will” be purchasing a core caliper to get more fasteners.
Next let’s get the bleeders out. Now that the fasteners are out of the way, it will be easier to get a grip on that bleeder. With M-Calipers and Rear M-Calipers you will have M7x1 bleeders. These are very delicate and they can easily round off and/or break. There are two ways to deal with these bleeders. First off is to use a deep well 7mm socket. The only problem is, most deep well 7mm sockets are not really deep well and they can strip the bleeder because they don’t fully engage with the hex. If yours slides all the way on, go for it, crank that bleeder out.
If you don’t have a deep well 7mm, use a pair of small Vise-Grips and get a “very” tight grip on the bleeder. Apply even and increasing pressure on the bleeder until you feel it give way. Once the bleeder has loosened, you can use an open end 7mm wrench to finish the job and, you should still have a usable bleeder when you’re done.
We’re almost done with the entire disassembly process. The only thing left to do is remove the bore seals and get these bits plated. Again, the dental pick is the way to go here. Reach under the bore seal and yank them out. Throw everything away and prep the calipers for plating. If you used grease to get the pistons out, now would be a great time to make sure all of the grease is out of the fluid bores and journals in the caliper. Blow compressed air down the caliper forcing the grease into the piston bore where you can scrape it out. Next using brake cleaner, clean the journals and the bores and have everything as clean as possible for the plater.
You should have your caliper bodies plated in “yellow” zinc and the fasteners re-plated in “black” zinc. If your plater does not do black zinc, see if they have a more common black oxide treatment and then oil the fasteners. Your springs and pins should be yellow zinc. The plater should prep the caliper bodies properly before plating. A body that has not been prepped properly will have spots shortly after the plating as the zinc goes to work trying to protect the caliper from the contaminants. A good solid sand media blast is in order to cut the rust. Do not worry too much about the bores. They will only need light media blasting and they should be fine. You will want them plated as well.
A word about yellow zinc; your calipers were finished in yellow zinc which is a zinc finish with a yellow dichromate bath. This is a question we get often as well; weren’t my caliper clear zinc? No. After you split the caliper ½’s you should be able to clearly see the yellow zinc on the mating surfaces. Over the years, the yellow dichromate can wash off the caliper making them appear to be clear (silver). The actual factory finish is a light yellow with a dip of about 20-25 seconds in the yellow dichromate. Imagine a factory assembly line process with an automatic dip tank. It’s your call on the finish but, the more dichromate dip the slightly better the protection is. Let’s send them off for plating and get to work on your pistons.
While the calipers are being plated, it’s a great time to turn our attention to the pistons. With vintage ATE pistons, you will rarely need to replace the pistons. That said; early 911 and some later SC pistons are staring to enter into the rust belt with a decent number of them needing to be replaced. My guess is your pistons look awful right about now. The best method we’ve found for a nice factory finish is to vibratory polish the pistons. This is one of those areas where the average DIY mechanic may not have a vibratory polisher so we will recommend some substitutes that should work just as well. Regardless, the vibratory polisher at about 30 minutes with a mild solvent should net you perfect results for cleaning up your pistons. If not, the next best thing would be a tumble polisher. Nothing more than the rock polisher you had in your youth. With the proper media (we like ceramic) and a mild solvent your pistons should look great in about 1 hour. Finally, 0000 steel wool can clean up the sides of your pistons while a wire brush can handle the task of prepping the tops. I don’t like using fine grit sand paper as it can cause an out of round situation on the piston.
For early model calipers (pre-1975) you will probably have pins and knock-back mechanisms in your pistons. All but the very early cars will have these stamped in the piston so they will be impossible to remove without damaging the pistons. The rears should all be removable with a small c-clip inside the back of the piston. Regardless, clean these up with brake cleaner and compressed air. If you can remove them, do so and make sure that are as clean as possible. Later calipers did not have these mechanisms and they will have a simple “cup” type piston design that allows for more surface area for better cooling with less mass. The “Knock-Back Mechanism” is simply a ratecheting design to help keep the pistons and pads out closer to the rotor giving the car a higher pedal feel. Many people mistake caliper flex for what is happening inside these knock-back mechanisms. This is why many have opt’d for A-Calipers over S-Calipers. If you want to remove them you can simply snap off the pins or remove the mechanism from the piston and… move on with life. No big deal either way. The only word of caution here would be, do on to others. If you do this to the front, do it to the rear as well. Do not have a mismatch of early and late style pistons in your calipers.
Once the sides and insides are done, tape them off with some 3M Blue tape and spray the tops with high temp paint (muffler paint or BBQ paint). Gray is the factory finish.
Once you get your bits and pieces back from the plater there is really not too much to do other than to re-seal everything and bolt it all back together. Ready for the next Internet myth? “You must hone the bore”. You must “not” and you “should not” hone the bore. I know they make brake hones and I’ve even been on record honing bores on calipers in the past. Here’s the real story:
You just did everything right. You’ve plated your caliper bodies and they look fantastic. The last thing you want to do is to remove the protective plating from the caliper bore. Remember our earlier analogy with the bare metal tub? Rust never sleeps gang (which is why you should have plated your calipers in the first place). You do not want a fresh steel surface inside of a system that is open with hydroscopic fluid. Rust will form and it will be fairly quickly. I recently had a friend weigh in on a thread online questioning the whole plating process in his words; “I rebuild my calipers every couple of years. It’s not that tough and I’ve never had to have them re-plated…” This is not a job I would want to do every couple of years and, the fact that the bores were not re-plated is why they keep coming back with issues every couple of years. A nice factory caliper with the proper zinc plating should last for hundreds of thousands of stopping miles if the fluid is changed on an annual basis. So… please do not hone the bores. You’ll find they should be smooth and perfect when you get them back from your plater. The seal is the real sealing surface anyway.
So now we’re going to take our freshly plated caliper bodies and we’re going to install the bore seals. Pretty simple; walk the seal around until it comes to a head and push it into place. Do that on all of your caliper bores and we’re ready for the pistons.
Remove the fancy blue tape front your freshly reconditioned pistons and you’re now ready to apply the dust seal. Put the dust seal around the top of the piston before you push the piston back into the caliper. Set these pistons aside and let’s talk about the next internet myth.
There’s nothing I like more than exploding Internet myths. This one is the “You have to make a 20 degree angle tool to set the piston position.” You absolutely do not have to make a 20 degree angle tool. I’m not saying you don’t need to set the proper angle, you just don’t need a tool to do it. The piston is already notched for this 20 degree angle you just need to know the trick on how to set the piston prior to pressing them in. It’s so much easier than you would have ever thought. Play along at home:
- Bleeders up. Air has to escape which is why we have bleeders on our calipers and air bubbles travel… “up” so, your bleeders go up.
- Your rotors need to travel into the face of this groove or, your groove needs to be placed “up” at a 20 degree angle facing the oncoming rotor. This notch allows your pads to angle into the oncoming rotor making for a much quieter operation. Bleeders will give you the hint on which way to place the notch.
- That said; simple draw an imaginary line down the center of the pad cavity and place the bottom notch on this center line. As stated previously, your pistons are already cut for the 20 degree angle so, if your bottom notch is in the center of the pad cavity, your top notch is set perfectly at 20 degrees.
Now that you have this “notch” mystery solved, it’s time to place the pistons into the caliper bores. I like to liberally lubricate the bore with Permatex Ceramic Lube. This is a brake caliper lubricant that will not damage and swell the factory rubber seals. Once you’ve lubricated the bores and positioned the pistons in place you simple press them into place. At the shop we use a bench top arbor press to apply even pressure and press the piston into place. In the garage, a padded bench top vise and some various sized sockets should do the trick. The trick here is “even” pressure putting the piston in the bore. If the pistons is not sliding down into the bore, you’re pressure is cocked to one side or the other. Reposition the caliper body slightly until the piston slides right in with little effort. If you are working on a later model caliper with the “cup” style pistons, you should be able to simply press the pistons in with the pressure of your thumbs.
Once the pistons are in, finish everything off with the dust boot clips. Do this now as it’s much easier than trying to do it once the caliper has been assembled.
Speaking of caliper assembly… we’re there!!! Hopefully your plater was able to do the black zinc or black oxide and your fasteners are now ready for another 50 years of faithful service. Let’s bolt these puppies back together. If you have solid rotors you’ll simply need to lay in your EPDM caliper ½ seals and get ready to put the halves back together. If you have vented rotors you will have spacers to contend with. Regardless, here’s the process for getting them back together.
Starting with the nose section (this is what we call the outer section that hangs over your rotor), I like to place the outer, shorter on some models, fastener into the nose section and turn it over in the palm of my hand. I’m holding the solo fastener in place with my index finger as I lay in the EPDM o-rings into their special grooves. If you have spacers, balance them on top and lay the second set of o-ring on top of the spacers. Now bring the caliper back half down over the fastener and align it with the nose section. The weight of the offset back half should keep the fastener in place and allow you to install the nut finger tight on the fastener. Next install the other outer fastener and nut and cinch them up finger tight. Follow this up with the middle two fasteners and nuts. Using a 3” 3/8” drive extension and the appropriate sized socket, hand tighten the nuts and get the caliper ready for the torque sequence. At this time you should be able to manually adjust the caliper halves and spacers to make everything line up as best as possible. Note: These have never been and never will be a precision fit. Do your best and tighten them up as best as possible.
You should now be able to handle the caliper without worrying about the o-rings moving out of position in the caliper halves. Mount the caliper in the bench top vise and have the proper Ribe bit on a breaker ready to secure the fastener from the back as you torque to spec. This is worth repeating from our tear down procedure; use the Ribe bit to only "hold" the fastener. Do not attempt to torque using the Ribe bit.
Torque in the following sequence to the following specs:
M7 Fastener Specs:
Torque One: Set to 7lbft. and number the fasteners from left to right 1-2-3-4
Torque as follows: 2-3-1-4
Torque Two: Set to 17lbft.
Torque as follows: 2-3-1-4
M8 Fastener Specs:
Torque One: Set to 14lbft and number the fasteners from left to right 1-2-3-4
Torque as follows: 2-3-1-4
Torque Two: Set to 25lbft.
Torque as follows: 2-3-1-4
M9 Fastener Specs:
Torque One: Set to 17lbft and number the fasteners from left to right 1-2-3-4
Torque as follows: 2-3-1-4
Torque Two: Set to 29lbft.
Torque as follows: 2-3-1-4
With very little fanfare and pomp and circumstance… you’re done. Double check all of your piston angles and make sure the open notch is facing up where the bleeders are on your calipers. If not, don’t worry, this isn’t your day job. Take your time. Pop them back out (it will be much easier this time) and get them right (do not try to turn them with a screwdriver or pliers). Once your done you can sit back and admire your handy work while basking in the glory of knowing you did it right. You did it much better than (just about) any caliper rebuilder or local P-Car genius should could or would ever do. Your calipers are ready for many-many years of service.
One final note; just like the dentist after the cleaning exam… CHANGE YOUR FLUID ANNUALLY. If you do, I will dare say you will never need to rebuild your caliper again for as long as you live. We’ve seen the insides of thousands of calipers and the best advice I can give is to change your fluid annually. Take care of them and they will continue to take care of you.