Saturday, June 19, 2021

Brakes II

It's a good time to get the calipers done now that the master cylinder's sorted.  So that's what I did.

The calipers are a two piston design and very effective.  Rebuilding isn't all that hard as long as you start with good cores.  All the parts needed for a rebuild are readily available and of good quality.

Disassembling the calipers is easy enough.  First, take them off the car.

Ugh.  But this car has sat for a long, long time, so accumulation of crud is a given.

After a little cleaning, the next step is to remove the pads, and then the pistons.  These should pop out under a little air pressure.  Fortunately, mine did; that good-luck train keeps on rolling for me.

Once the pistons are free, the calipers get split apart by removing the two bolts holding them together.  Many people say you should never do this - but I have done this when rebuilding Gidget's brakes, and it's no big deal.  There is a seal that fits between the two halves, and that seal is readily available.  Here, I have done this for both calipers and cleaned the bores, which thankfully look good.

That's it for disassembly.  Now, it's time to meet Master Blaster for a good cleaning (protecting the bores, of course).  Here's a before-and-after shot.

Once both are clean and washed, a coat of caliper paint makes them pretty and will keep them from rusting.  Be careful not to get paint in the bores...

The rebuild kits include all the seals and the pistons, which unless the originals are prefect are definitely to be replaced.  The kits do NOT include the little seal between the caliper halves, so don't forget to order them!

Assembly is straightforward, but requires care.  Here's where I started.

There are two seals per piston; an inner and an outer seal. The inner seal is the solid one, and the outer is the grooved (it is a wiper seal).  The inner seal does all the heavy lifting.  The wiper seal is held in place with a retaining ring, and the two halves are joined by that little seal in the bottom of the image.

Each half gets a piston.  Lubricate the seals with a little brake fluid and insert the inner seal.  The wiper seal is tricky to install and takes serious care to keep the retaining ring from being distorted, which is way too easy to do.  My trick is to chamfer the bottom of the ring a bit to help it locate in the opening, and to gently tap into place with a block of wood just wide enough to span the ring.  If the ring does not want to seat with gentle taps on the block with a light hammer, STOP AND RESET.  With a little care, a good result is obtained.  If the ring is distorted but not badly, it can be gently massaged back into shape with a small hammer (not pliers!).

Once the seals are fitted, the pistons can be inserted.  Lubricate the pistons and seals with a little brake fluid and gently press the pistons into place.  This should not require too much pressure, so if the piston does not feel like it will go in, STOP AND RESET.  It is easy to pinch the wiper seal.

Also note that the pistons have an orientation.  The indented part faces in towards the hub, which is towards the mounting holes.  In the image below, you'll see that the indented parts face each other when oriented correctly.

Once the pistons are in place, install the caliper seal and fit them together, then bolt them up.  I used a little Loctite (blue) on the bolts since they do not have lock washers.

And there you have it.

All I need are the rest of the parts for Alice's whoa-ers (rotors, pads, drums, shoes and wheel cylinders).  These are all easy to obtain and low cost, so there's no real reason not to replace everything else in the name of safety.  I was hoping to save the wheel cylinders, but they're trash, so that's where they went.  I did manage to save the adjusters, which just needed a good cleaning.

I'll do some cleanup on the car before installation, and then it's time to bleed the system.  Stay tuned!

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