[Rick7520ts]

With these calipers we have adjusters to contend with. These inner adjusters are held in with this clip:

I mentioned the dental tools. Use a straight pick to remove the clip by prying it inward toward the adjuster screw then upward. Tip; hold your thumb over the adjuster end. When the clip lets loose it loves to fly across your shop and hide under something, somewhere where you'll never find it (yes, we have extras but don't do it... you don't want to wait to get these back together.) Once the clip is out, twist the adjuster off the worm gear while pulling it up. There's a seal on this adjuster that needs to be replaced. There's a little "sausage" as I like to call it that sits in the back of the adjuster. It's actually a small push-rod that goes against the arm and pushes the adjuster outward when the handbrake is engaged. Make sure you get it out at this time:

Now on to the outer adjuster. This is fairly straightforward but... there's a little clip on the shaft that prevents this 17mm nut from flying off. You can just make this clip out in this photo, it also likes to fly across the garage:

I thought I mentioned dental tools right? I like to use two to get this clip off. Here's the tip; one pick sits stationary on one end of the clip while you "flick" the other end of the clip with the other pick. Once the clip moves just engough STOP. Put your thumb over it and use the straight pick to get between it and the adjuster. Now finish the job. Best to do this with the projectile path facing your belly ("get in me belly"). If it flies it will bounce off your six-pack abs and hopefully be easier to find.

Here she is...

Next you simply spin off the 17mm nut. Sometimes they stick with that clip galley there. If that happens, use this version of the "Special Factory Tool" better known as ViseGrips and a 5mm hex.

With the nut off you can still turn the adjuster and get the piston out. If the piston is tight, you can use a plastic mallet and tap the adjuster down (do not do this with a regular hammer) and then use the hex to crank the adjuster back up again. Repeat that about 3x and the piston will be out without damaging your adjuster. Once it's out, pull the adjuster and yank the seal:

Here's a shot of the internal adjuster mechanism and a grundgy piston. What you're seeing here is old, old brake fluid that has clumped and turned black like tar:

Next yank all the seals from the caliper bores:

Once all of the caliper 1/2's are torn down and all of the seals are out you're ready to take them to a local plater for a fresh coat of zinc. I've actually had the finish on the calipers tested and ATE used zinc (common misconception is cad).

There's a few questions that will come up here so let me answer them; Eric, shouldn't I take that handbrake arm out? Well... no, not unless you're having a problem with it. A problem woud be a buldging wiper seal (from too much brake cleaner etc.) or if it's currently sticking or hard to move. That would mean there's some rust in the wiper seal area. The arm does not have anything to do with the fluid integrity in your caliper, the seal on the inner adjuster does that job. The seal on the arm is just a wiper seal. If it's working OK the plating process won't harm it. If not, kits are fairly expensive at $39.00 but... we have them. Eric, how do I remove the arm if I deem necessary? I like to cut the welch plug with a Dremel and a carbide blade. ONLY cut the plug and not further as you'll dig into the arm. Once you cut/notch it then stick a large flat blade screwdriver in the plug and mangle it out. There's a clip in there. Remove that and the arm will slide out.

*IMPORTANT* Before you leave your calipers off at your plater, let them know that the cable attachment pieces in the handbrake arm are potmetal. I actually tied warning labels on both of these to let them know. They will then babysit them in the acid path so as not to ruin the potmetal.

Next we'll dig into putting them back together. Here's a teaser:

 

[Rick7520ts]

Back at it today, let's wrap these puppies up.

With the goods back from the plater, we need to start gathering the bits and pieces together. I like to lay everything out on a couple of shop towels and have a nice clean work surface for the assembly.

Outer adjuster.

Bleeders.

Pistons had the tops done but will be polished to a mirror shine on the buffing wheel

Fasteners were treated to a new black oxide coating.

First we start by putting the bore seals in place. This is a fairly simple process that involves walking the seal around the bore and snapping in the last little bit. This is much easier to do "before" you install the adjusters.

Next is re-sealing the adjusters. Dental pick comes in handy here (I know... I sound like a broken record).

Bad picture but, using the dental pick you walk the seal down the shaft, past the clip groove like a hula-hoop as it's falling to your ankles. This is the outer adjuster.

Next you simply press the adjuster back into the hole in the nose section of the caliper.

Install and hand tighten the 17mm nut...

...and re-install the clip.

 

[Rick7520ts]

Next we'll move on to the trickiest part of the job; installing the inner adjuster.

Putting the seal on is fairly straightforward. Drop it down the shaft and use your finger to loop it over the edge to it's galley.

Next fill the cavity on the bottom of the adjuster with brake grease. It's important to use brake caliper grease as it will not swell the seals like standard petroleum greases.

Drop the small push-rod in the "nest" of grease and slather a bit on the top.

Next, press the adjuster into the hole. In some cases you may get resistence from the worm gear. Remember it's there and twist the adjuster shaft as you press. You will feel it as it seats in the bore.

Drop the spring over the shaft...
[imghttp://i60.tinypic.com/rs4myd.jpg[/img]

...then the hat...

...and finally the clip. Make sure your clip is straight and not bent a bit from the removal process. Bend it back by hand of necessary.

We had a special clip tool made for the installation and it's simply a press and snap fit however, here I'll show you the standard garage benchtop method. Take a 12mm deepwell socket and a suitable clamp. Drop the 12mm over the adjuster shaft. Make sure the alignment is all straight and begin to clamp this assembly down tight. The clip will remain loose and workable in the bore.

With a straight pick, push the backside of the c-clip into the groove area. Then put the pick in the hole on the right and drop it down into the groove. Finish off with the left then press the clip all the way around to make sure it's seated in the clip groove. Do not remove the clamp until you're certain everything has seated otherwise bits and pieces can go flying. Test the handbrake arm. It should snap back into place without any help. A little is OK but, if you have binding you may need to address it before you get much further with a handbrake arm seal kit. It should look like this now:

 

[Rick7520ts]

Remember those pistons? The rings of sludge you saw on them earlier are the beginning of that caked on coating I was talking about when we were looking at the dust seal. It polishes off quite easily on a buffing wheel with a little wax. They should look like this when you're done. I don't like the emory paper method as it can cause too much wear and, the seal and piston are your only fluid barrier.

Pull the new dust cover over the piston and make sure it's in place all around.

It should look like this:

Next, you'll want to coat the cavity bore with the brake caliper grease. This makes assembly a bit easier. The internal mechanisms in the pistons can spin so, it's important to make sure the piston goes into the bore smoothly so the internal mechanism won't spin and leave you stranded.

Installing the pistons is as simple as pressing with your thumb as you crank the adjuster.

Once they are fully seated, install the snap ring lock in place and press it down with either a screwdriver or I like to use the backside of the curved pick.

Once the pistons are in it's time to bolt them back together (almost there). I like to wet the seals with brake fluid and install them into the nose section of the caliper.

On to the back 1/2 of the caliper, make sure your spring mount is centered over the hole directly below the handbrake arm.

Once the mount is in place, leave the caliper 1/2 face down on the bench and drop in your fasteners. Make sure the long ones are in the middle and the short ones are on the outsides. Pick the caliper 1/2 up and the fastener should all slide into place. Now hold the nose section with the seals facing up and drop the back 1/2 down so the fasteners fall into the holes. I like to use a 3" extension and the 11mm socket to hand tighten them. Once everything is hand tight, drop it in the vise. It's starting to look like a caliper again!

Next we torque them down. By numbering the bolts from left to right 1-2-3-4 torque using the following sequence:

7-10 ftlbs.
2-3-1-4

17 ftlbs.
2-3-1-4

Last Step!!! Pull on the springs. The rounded end goes in the holder at the fastener end. The square end goes on the arm. There are left and right springs.

Done! I hope this will add to the bravado and allow some of you to tackle this job. While admittedly, these calipers can be a pain, with a little annual love (adjust the venting clearance) and maintence they should serve you well.

 

[Rick7520ts]

I have a couple questions, as I'm going to do this job on an old pair of calipers I have.

First of all about the orings. All rebuild kits have the piston rings and dust covers, some of them have two orings, which I guess are for the inner and outer adjusters, what should I use for the seal between the two caliper halves? Should I just find an oring of the correct dimension or does contact with brake fluid damage that?

Second question is about the plating, are parts of the adjuster mechanisms in need of plating, just cleaning or else?

 

[Alex]

FYI, I noticed the other day that new calipers are now available from here. Might save some rebuild headaches?

Excellent work, by the way!

 

[mistamun]

Hi Rick,

These are the dimentions of the o-rings you need, inner diameter / cross section diameter / outer diameter, in millimetres, all in EPDM material

7.5 / 1.5 / 10.5
11.5 / 2 / 15.5
6 / 2 / 10 - These are the ones which seal the two halves of the caliper.

If you're in the US, complete rebuild kits are easy to get, Performatek as stated earlier in the thread.
If you're in the UK like me, it's though as most kits don't include any of these orings. I had to source them from 3 different places as neither stocked them all.

Cheers,

 

[mistamun]

Alex,

Do you know if these new calipers are ATE originals or a copy ?

 

[Rick7520ts]

I'm in Italy, if I cannot find a complete kit locally I'm going to look forward to have one shipped.

Big problem for me is finding a good plating company.

New calipers if ATE originals are very interesting for that price!

 

[Rick7520ts]

I disassembled the two pair of calipers I was able to source and I found this difference between the two pairs.

I think all four calipers were rebuilt at least once in their lifetime, so I don't know if this is an upgrade, or downgrade, from ate or from the rebuilders.

Has anyone seen something like this?

 

[kredden]

Is the only difference is the spacer vs. what appears to be a spring?

Kevin

 

[Rick7520ts]

Yes, they were identical in all other parts. I can't see why you would want a spacer instead of the spring in the inner adjuster.

 

[kredden]

Yeah I would agree, can't remember what mine looked like when I took them apart years ago. I don't see either on the other picture above.

Kevin

 

[Rick7520ts]

I think I'll reassemble one pair with the springs, at least for now.

Any idea of how the mechanism inside the pistons works and how to check its functionality?

 

[kredden]

By seeing if the piston moves in and out when you turn it?

Kevin

 

[Rick7520ts]

I managed (by carefully watching PMB video on porsche caliper restoration) to remove the adjuster mechanism from the inside of the pistons. I'll post pics when I'll have time to give a closer look and understand how it works.

 

[PMB_Performance]

That spacer does not belong there in place of the spring.

 

[j.k.QV]

Does anyone have the pics of the first few posts? Very valuable info, but without pictures it is harder to understand

 

[kredden]

Looks like I was smart and saved it off as a pdf years ago, I think this should have what you want.

Kevin

 

[Omega86]

Thanks Kredden, I was just wondering if my computer was failing me. Just what I needed.