Front Brakes Bulkhead - Toyota 4Runner, 3.0L, 1995

When flushing the machine a couple of months ago, the servicemen suggested running diagnostics. Among other things, it turned out that the brake calipers are in poor condition. The anthers of the pistons are torn or completely absent, corrosion on the pistons ... But at that moment the car was braking quite well, the pads were on the way, but still alive.
And now the time has come. Tweeters on the stocks reminded them that it was time to replace them. And at the same time it made sense to shake up the caliper.
Removing the caliper is not a tricky thing (two mounting bolts per side, and a brake pipe fitting). By the way, it may well get used to it, so a special key that completely covers the 6-taper of the fitting will not be superfluous. Previously, it is better to soak the thread and the joint with the VD tube for 5 minutes. When unscrewing, it is worth making sure that the tube does not "roll its head". After twisting the brake pipe fitting, it is better to plug the tube with a suitable plug so that the brake fluid does not leak out - then it will be easier to pump the system. We used a slightly sharpened twig of adequate thickness.
If you, like us, decided to disassemble the caliper in half, then while it is still attached to the fist, it is better to "pull off" 4 tightening bolts. Of course, it is again recommended to pre-soak with a VD-shim both from the side of the heads and from the side of the thread (through holes in the caliper bracket). Well, of course, before "locking" / twisting, you should thoroughly clean the heads of the bolts from dirt, so that the socket head (14) does not jump off and clog the edges of the heads. It is even better to grind off the lead-in chamfer of the end head, so that the contact area of ​​the 6-tones is larger.
So, we removed and disassembled the caliper in half. By the way, do not lose the sealing rings at the joints of the caliper bypass holes - these rings are not included in the repair kit.
And how now to remove the thoroughly soured pistons? To brake them, the course is more or less enough. but corrosion does not allow to be removed freely. Pliers help, perhaps, to disfigure the piston skirt ... What to do?
Reflections were not long.
In the garage, we have an air compressor that produces heat up to 8 atm. We bought it for painting. and in the kit he also has a "gun" for inflating tires and a "gun" for blowing. The last one came in handy.
Realizing that the pressure is pressure, but it misses the target due to the fact that the nozzle of the "gun" is metal and does not provide proper sealing, we decided to put a small piece of rubber hose on the cone of the nozzle. An air reinforced hose 6 mm long 2 centimeters was quite suitable for us.
Pressing the nozzle of the pistol shod in a hose to one of the bypass holes and plugging the second hole in the bracket with our finger, we gave pressure and ... Have you ever watched the launch of a rocket? No? Well, well ... well, at least the moment of launching a pyrotechnic charge of fireworks? Here ... And we saw the same dirt, only without smoke and fire ...: o) The hardboard ceiling of the garage endured the most powerful impulse received from the ejected piston.
From now on we have been smarter.
By the way, if there is not enough strength to maintain the outlet pressure (at the second bypass hole), then you can find a lot of ways to mechanically block this hole. For example, you can put a piece of rubber on the "outlet" hole, pressing it with a strip of metal and clamp this sandwich in a vice.
But normal male hands, in principle, are quite capable of holding this pressure without extraneous mechanical devices.
Let's go further ... There is no piston in the bracket ... and the hollow of the bracket cylinder, of course, the connecting channel gapes. it will not be possible to plug it with a finger (it is not on the plane, but on the edge of the joint between the bottom of the cylinder and the wall ... and even in the groove.
In order to muffle this channel, I used a thin air hose, like the one used in all vacuum control systems on this engine (and others too). Having folded a piece of such a tube in half, I, with the help of tweezers, pushed it with a fold into the sounded hole, but so. so that the brags still remain outside (firstly, we wake them up, for a more dense "jamming" of the hole, and secondly, it will be convenient for them to pull out this "plug" later).
Firmly press the "plug" with your finger, ask your partner (one will not be very comfortable) to take a wad of rags (we used the sleeve of an old work jacket) and put it on top of the piston, holding it, and thereby protecting the piston from ejection.
Channel pressure! second, two ... Bunch-k! There is. The second piston is extruded.
On the inner bracket, in one of the cavities, there is, in fact, a hole from the brake pipe. We also jammed it with our finger ... But, theoretically, it is possible to screw in a corresponding bolt into it, which will clamp the packing in it, for example, made of polyethylene.
In addition, it is more convenient if the bracket is fixed in a vice during these operations.
And as I already wrote (having experienced this from personal experience), BEWARE! The piston catapults very vigorously ... If glass, paintwork of the car body is in the way of its free flight, then problems cannot be avoided ... If it gets into the human body, then a solid bruise, or even an abrasion is guaranteed ... So DON'T FORGET to play it safe by organizing a buffer on the way piston. A lump of rags, which you simply cover the bracket and hold with your hand during the procedure, will do just fine.

So, the pistons were withdrawn, there were no injuries.
Since, as usual, we did not provide (did not order) new pistons in advance, and they seem to be sold only together with a caliper, the only alternative was to clean the surfaces of the piston and cylinder from corrosion deposits and dirt.
For this purpose, 2 types of sandpaper were used (600 and 1500 in our case). The coarser one removed the main coating of rust, and the finer polished the surfaces after "rough" sandpaper.
Of course, corrosion damaged the chrome plating of the pistons ... in some places in the form of "pimples", in some places - to the copper plating layer and even to the base metal ... But there were still no other options, except for cleaning with "sandpaper".
Of course, this is not the best option,

After bringing the working surfaces of the cylinders and pistons to a more or less decent condition (ideally they still cannot be cleaned), the assembly was carried out.

The piston seals were replaced with new ones from the repair kit, the pistons themselves were pressed in, new anthers were put on, on which new retaining rings were installed (everything that sounded like new and is included in the caliper repair kit). By the way, the kit also includes a bag of grease. We understood that this is a "friendly" to the brake fluid lubricant to facilitate the pressing of the pistons into the oil seals (past experience with domestic calipers showed that the oil seals are very easy to break when the piston is pressed in).
Well, actually, that's all. We collected everything, put it in place, installed new brake pads, bleed the brakes.