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Discussion Starter #1 (Edited)
It's been way too long since Brian sent me an extra set of rear calipers to explore and rebuild/restore but I'm happy to say, we finally found the time (and the o-rings) to get the job done right.

What follows will be as detailed a documentary as I can muster to help those dig into their calipers (or decide... maybe not). So, read on and hopefully this will help. Special thanks to Brian for being so patient. Brian, your calipers await you.

Getting started:

Here's what we got about a year ago:





Let's start by removing that spring...


And the bleeders...


We had one bleeder that was really stuck. This usually doesn't happen but when it does I like to use a MAPP torch and ViseGrips. Heat the area around the base of the valve. This valve was also bent in shipping. Time for a new one.


Next it's the fasteners, the M7 (unobtainable fasteners to be precise). I like to power them out fast and easy with a airwrench. These have 11mm heads and seriously gang, they are basically unavailable so treat them with care.


Dental tools are a must here and I like to take a curved pick and get the dust seal clips off. Here's a classic shot of a torn dust seal. When this happens moisture gets in and goes right to the piston cavity. The upper area of the piston (above the bore seal) then gets mixed with brake fluid and rusty water and... they begin to gum up and stick. Yes, from this little hole I've just described the process on how your calipers go bye-bye so... it's important gang.


Yanking the old dust covers. Toss'em:


Next, take a 7mm (the same one you took the bleeders off with) and crank out the inner piston. It's pretty much that simple. Here's some tips; move the handbrake arm full motion before you do this. This breaks the bond any stuck piston may have. Once you've cranked it out as far as it can go use the arm again, this will push the adjuster mechanism against the piston and move it out another 1/8th"


 

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Discussion Starter #2 (Edited)
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? :D 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:
 

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Discussion Starter #3
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.
 

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Discussion Starter #4 (Edited)
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...


...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:
 

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Interesting ...

More please !:eek:
 

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Discussion Starter #6 (Edited)
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.

 

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Excellent write up. One of my calipers is leaking at the 7mm adjuster nut so I'm assuming I am due for a rebuild? Or is there an O ring that can just be replaced for now?
 

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Discussion Starter #9
Thanks.

Outer adjuster? If so, yes. There's a seal on that shaft. See picture 7 in post #3.

I will caution you against a "for now" fix though. I'd say you're probably due for a rebuild. If that seal is leaking that means it's hardened. If it's hardened, that means the other one is as well, etc. etc. You're basically in for a penny in for a pound at this point.

You're going to need to remove the dust seal and piston to get that adjuster out. Once it's out it's a simple task of picking out the old dried seals and walking the new seal down the shaft.

I'd opt for the rebuild.
 

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Thanks Eric

I just found the leak last night and have replacement calipers on order so this will just be a very temporary stop gap until I get to install the replacements when they arrive.

Also, why plate the calipers instead of painting them?
 

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Discussion Starter #11
I wouldn't worry about it then. Just make sure your reservoir is topped off and wait for your replacements.

Paint - Because painted calipers are for ricers? :D OK... on a more serious note:

1. Paint only protects the outside of the caliper... not very well and only temporarily.
2. Paint comes off with odd things like... brake fluid and brake cleaner. ;)
3. Zinc is the factory finish and has superior corrosion protection.
4. Zinc re-plates the bore, which probably needs it by now.

Rebuilders that paint calipers do so because zinc is expensive. They can easily slap on a coat of paint in-house and it speeds up the process. They can even call it cool things like "Ceramic" etc. :D

I think the real benifits of zinc are the bore. While the bore is not a sealing surface, it can get wear from the piston. Wear, lack of fluid changes and rusty caliper shellac will cause a caliper to stick. This usually happens just above the seal where moisture can get in. We use to hone out bores but I recommend against that and I wholeheartedly endorse the zinc bath. The process will clean and replate the bore and make everything good for another 30-40 years.

Brakes are a pretty important part of your car.

Hope that helps.
 

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Excellent information.
What brake fluid would you recommend?
 

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alfetta ATE caliper

Hello,
i've been rebuilding this alfetta rear ATE caliper and confronted a problem. The adjuster of inner piston is not working. I can turn it easily both ways and the piston stays stuck in place. What could cause this problem? :confused:
 

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Discussion Starter #15 (Edited)
The piston is stuck (in basic terms) and the adjuster mechanism inside the piston is turning. Theres a couple things you can try:

1. Move the arm back and forth. This will cause the piston to move in the bore by about 1/16th or 1/8th inch. Breaking that bond (if it hasn't already been broken) should help and allow the piston to move with the adjuster.

2. If you have an air wrench (I like the small butterfly wrenches for this), spin the adjuster clockwise in short bursts. The speed of the adjuster will overcome the inertia of the mechanism inside the piston and move the piston.

When I do these, I do both. I move the arm to break the piston free then use the high speed on the adjuster to overcome the internal mechanism.

Hope that helps.

Eric
 

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Memory isn't too good and it's been a few months so might not be exactly correct but . . .

The tale of two calipers with somewhat similar symptoms.

The first would only move in one direction (inward unfortunately) with the adjuster. The piston was worked out with a similar technique to PMB's last post #1 suggestion. Using the emergency brake arm, which applies force to the piston directly through a small push rod, the piston was moved outward slightly. Then the adjustment screw adjusted outward a couple of turns. The piston did not move here but it seemed to change the position of the internal mechanism such that subsequent movement of the brake arm allowed for additional outward piston movement. Repeated these two techniques a few times eventual allowed the piston to be removed. Further inspection revealed that the C-clip that holds the 'hat' in place had come out (see picture #6 and #7 in post #4). How, why, or when is unknown. The caliper came with an extra transaxle so no known history. The hat and clip were reinstalled and all is well. The caliper adjusted fine and is working fine. Am I worried about it happening again? Not really but maybe I should be? All looks in order.

The second caliper was very crusty. Didn't try PMB's #2 suggestion and although it sounds clever, not sure if it would of mattered here. Really, really crusty. With technique #1, the piston was freed but the technique used on the first caliper did not work and the piston would not move outward any further. Instead, a C-clamp was used to gently coax the piston back in slightly while the adjustment screw was turned in the proper direction. The brake arm was again used to move the piston back out followed with the C-clamp technique. After a few tries back and forth, no further progress was noted. Maybe PMB's #2 would have worked at this point, dunno. Then decided to try to C-clamp the piston back in a bit farther to work a different position and extend the piston range. Unfortunately, this plan backfired as the piston became frozen at the nearly full inward postion and no brake arm movement or adjustment would unfreezed the piston. Increasingly risky and futile efforts were made to unfreeze culminating with piston breakage in a failed attempt to pry the piston with leverage applied to the piston groove for the dust cover. Not a good idea. Was very gentle and tried to lever at two opposing postions but the thin ridge (casting:eek:) is very fragile. In retrospec, the problem with the second caliper was probably not the same as the first. Probably just excessive crud, rust, etc. (yes, the entire effort was begun with copious PB Blaster).
Never did remove that piston.

Good luck
 

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Discussion Starter #17 (Edited)
For extremely crusty pistons you want to use a combination of each. Using the arm "only" to move the piston. Here's how:

Remove the spring. Tap the arm back using a plastic mallet or carefully with a hammer. BE VERY CAREFUL TO ONLY TAP IT FAR ENOUGH SO IT RESTS AGAINST THE ARM STOP. If you tap it too hard you can break off the arm stop in the body.



Once the arm is tapped back, rotate the adjuster clockwise with high speed bursts. While doing so, you will see the arm move forward again. When the arm comes fully forward, stop and tap it back (moving the crusty piston out) to the full back stop. Rinse and repeat until the piston is out. :D

Hopefully this is making sense, you use the leverage of the arm to push the crusty piston out and handle the load (the gears are not good at handling that much load). Then the gear can move the arm back into position with no load and you're ready to push the piston once again with the arm.

The piston may hang on the last 1/8th inch of bore (it will be off the adjuster now and just past the bore seal). For this I've modified my vise to grab the piston without hurting the fragile edges that hold the dust cap:





There is another full restoration thread on our Facebook page that may help. It's a set of Ferrari calipers but, they are very, very similar. You can probably get some ideas and, you can see how to get the piston internals out which I didn't show in this thread:

http://www.facebook.com/album.php?id=72240238192&aid=245424

I've never found C-Clamps to be useful in any aspect of the restoration of these calipers.
 

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The piston is stuck (in basic terms) and the adjuster mechanism inside the piston is turning. Theres a couple things you can try:

1. Move the arm back and forth. This will cause the piston to move in the bore by about 1/16th or 1/8th inch. Breaking that bond (if it hasn't already been broken) should help and allow the piston to move with the adjuster.

2. If you have an air wrench (I like the small butterfly wrenches for this), spin the adjuster clockwise in short bursts. The speed of the adjuster will overcome the inertia of the mechanism inside the piston and move the piston.

When I do these, I do both. I move the arm to break the piston free then use the high speed on the adjuster to overcome the internal mechanism.

Hope that helps.

Eric
Thanks for the advice, I don't have an air wrench but I could go to the nearest garage to use it. I think it's important to add that handbrake arm moves easily back and forth, but the piston does not move a bit. Do you still think air wrench would help or the problem is much bigger? :(
 

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Once the arm is tapped back, rotate the adjuster clockwise with high speed bursts. While doing so, you will see the arm move forward again. When the arm comes fully forward, stop and tap it back (moving the crusty piston out) to the full back stop. Rinse and repeat until the piston is out. :D.
This 'high speed burst' is the component of your technique I had not tried, as even unloaded as you described, the arm would not reset its position with hand ratcheting of the adjustor.

So you have had %100 sucess with this technique?

I've never found C-Clamps to be useful in any aspect of the restoration of these calipers.
Well with regard to piston removal, neither did I. Counter productive to move the piston back in when the goal is its removal but then, I was out of options at the time.

As you have outlined in post #4, the (C-)clamp is useful for the 'hat' and C-clip installation.

Thanks for the tip Eric.
 

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. . . I think it's important to add that handbrake arm moves easily back and forth, but the piston does not move a bit. Do you still think air wrench would help . . . :(
I'm sure Eric will chime in here but my take from what he has already stated is that, yes it will. You should position the arm as it is normally held by the spring, short burst of the adjuster, cycle the arm positon outward (piston should move slightly) and back to the sprung inward position, short burst, and repeat.
 
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