Back at it here. I was banned. I mistakenly had my business name as my screen name. Sorry to those I offended. Marks calipers came back from the machine shop. The extra bleeders have been expertly added. We also got to work on the pistons and the internal adjustment mechanisms. I'll dig into all of that here while we wait for the calipers to come back from plating. Here's a shot of the bleeder mod: Image Unavailable, Please Login
Here's a bunch of 38mm pistons for you to oggle over. The ones on the far left are the pistons commonly found in the 914-6. These are basically years 1970-72. I'm guessing that the Dino's have the same internals. Later, ATE moved to an economy of scale model and we have what we see in the 308 pistons. 308 pistons are 38mm and will swap out on the Dino/914-6 caliper but, the internals are those of a 914-4 caliper. They simply used the same part that would go in a 33mm piston by making the walls of the pistons thicker. Image Unavailable, Please Login Image Unavailable, Please Login
As you can tell by all the sludge, we need to get these out and clean everything up! This is where the next little caliper building tip comes in handy. Remember the small pushrod that came out with the inner adjuster? We're going to put that to good use here with a simple trick: Pic 1 - Drop the pushrod down into the adjuster hole in the mechanism. Pic 2 - Mount your "outer" adjuster in your vise. Pic 3 - Screw your piston on to the adjuster. Have a look at that piston... someone's been monkeying with it. See the weird markings on it? Probably 600 grit or the likes. I like to run these through a vibratory polisher but, if you don't have such a device (and most don't) 0000 steel wool works wonders. The stuff that looks like rust on the pistons is basically old brake fluid. It would come off by rubbing your fingernail over it. Either way, vibratory polisher or steel wool and a good dose of high-temp paint for the tops and you should be good as new. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Here you can see the internal mechanism coming out... as the adjuster bumps against the pushrod, the c-ring pulls from its groove and the mechanism comes out. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Why do all this work? A picture is worth 1000 words... This is why people want you to change your brake fluid every year. Kinda like a dentist showing you grotesque pictures of periodontal disease while telling you to brush and floss regularly. I've torn apart thousands of calipers and I can tell the ones that have been maintained regularly (I actually don't see too many of those) and those that haven't. The ones that have regular fluid changes look like brand new inside... dead serious (nothing to gain here) LOL Both types of inner adjusters show here. Both in pretty bad shape. Image Unavailable, Please Login Image Unavailable, Please Login
Here are the early and late adjusters side by side and here are the pistons side by side. Again, you can see that the 308 pistons are much thicker to accomodate the 914-4 internals. This saved ATE some bucks I'm sure. Makes total sense too. Image Unavailable, Please Login Image Unavailable, Please Login
Let's get them back together. The pistons have spent a couple of hours in a vibratory polisher with ceramic media and Simple Green. They come out and get a bath in the parts washer and are ready for reassembly. Internal mechanisms get a parts washer bath and a brass bristle scrub with brake cleaner. A little compressed air and more brake cleaner and they're basically as good as new. You CAN take them totally apart but it is rarely necessary. The spring can be difficult to get back in the holes and wound properly so, this is not something I would recommend herein. For the assembly part we'll want to do a couple of things: 1. I pre-spray the internal mechanism with ProOne lubricant. You can use WD-40 as well. They will bond to the mechanism and whick out any remaining moisture. They will also help the c-ring glide smoothly into the piston. 2. Make sure the internal mechanism is seated squarely in the piston. 3. Use either an Arbor Press (what we're showing here) or a 3" extension in a vise. The later can be tricky but very doable. Press down squarely in the center section and allow the mechanism to slide in "straight". Do not force it and don't let it get cocked to one side or the other. It should slide right in if it's started properly. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
That's it for today... Fasteners are back from plating. The front caliper 1/2's are done as well. The rears will go into plating next week after the holidays and we should get them back... next year! Happy Holiday's everyone. (Jeremy, your holiday goodies are waiting at the local post office)
I received the plated cores back last week and was out of the office this week in LA. I'll get busy snapping pictures and putting the calipers back together tomorrow. Hang tight. The end is near!
OK... back from plating and back at it. As mentioned earlier, yellow zinc is the proper finish for all ATE calipers. The handbrake arms get a coating of clear zinc. Fasteners are all replated in black zinc. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
The first order of business is to get the arms back in the caliper housing. A new wiper seal is put over the shaft and the shaft is slathered with ATE assembly lube. Next the shaft needs to be clipped into place. The c-clip is held with your thumb as you push down the back and around the sides with a small screwdriver until it snaps securely in place. Then the welch plug is added to cap it off and protect that bore from the environment. A quick trip to the arbor press and it's in there for good. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Next we attend to the other side of the arm and attach the spring assembly. The first thing to do is clean up the shaft bushing and drop it in place. Make sure you get the proper spring for the caliper. The arms need to be sprung forward. That lower hook needs to go on the backside of the pin. Don't worry if you get them wrong... it happens to the best of us (quiet Jeremy!) Once we have the proper spring in hand, we grab it with a small pair of Vise-Grips. I like to grab it right at the bend in the top and make sure they're very tight. Next, slide the lower hook around the backside of the pin that is protruding from the caliper. With it hooked on that pin you can use the Vise-Grips to turn the spring onto the arm and into the slot. Once the spring is in the slot and the arm is (hopefully) sprung forward, use a medium screw driver to seat the spring completely. The final step is to install the washer (also replated in clear zinc) and secure it with the c-clip. This c-clip should be easily installed with your thumb. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
We'll finish up today with getting the bore seals in place and the dust boots on the pistons. The bore seals simply need to be walked around in their groove. I like to walk them around until you're left with a little mountain (second picture). Once you're there, simply put your finger on the top of the mountain and press it into place. Make sure your seal is now lying flat and there are no twists or kinks. If you have a slight twist, take a dental pick and run it along side the seal... all will be good. Next, pull the dust boots on to the piston tops and you should be ready to go. Tomorrow we'll install the adjuster mechanisms back into the calipers, pull in the pistons and bolt them back together. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Starting with the inner adjuster mechanism, everything gets cleaned up and the seals slide down the adjuster shaft. Slide the seal into the groove and position it with your thumb. After the seal is in, the end gets filled with ATE assembly lube and the small pushrod gets seated in the cup. Done... drop the assembly into the caliper bore and press it into place until you feel it almost "snap" solidly into place. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Next you'll want to drop the spring over the shaft... Then the hat... And finally, the c-clip. Once everything is in place, drop a 12mm deep well over the top of the assembly and clamp it down with a large c-clamp. Make sure everything is seated but do not press too hard, you can damage the hat. With everything tightly in place, take a straight dental pick and start by pressing the backside into the groove area and work your way out to the ends. Once the back 1/2 of the clip is seated, use the pick to grab a hole in one of the ends and pull it into the bore. Do the same with the other side. Then, press the c-clip all around and make sure it snaps into it's groove all the way around. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Now we're ready to pull in our first piston. Before we do that, I like to lube the bore with ATE assembly lube. In the first picture you can see how much I like to use in the bore. Take a small brush and paint the sides of the bore with the assembly lube. Next, position the piston over the shaft and give it a slight clockwise twist to seat it onto the adjuster. Put the adjuster gear in the back of the caliper and begin to pull the piston in with a 4mm hex. Make sure you use a good amount of thumb pressure to push the piston in while you turn the gear "counter clockwise" Finish everything off with a new inner adjuster cover. These are new 5mm covers with a much deeper hex slot. You will never strip a 4mm cover again (very common problem BTW). Piston in and dust cover clips in place. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
On to the outer adjusters. The first thing I do with these is run a dye over them and chase the threads. The 13mm lock nut always seems to get hung up on the clip groove if you don't do this. Next, the adjuster is cleaned and a new seal is pulled onto the shaft with a dental pick. Basically "Hula-Hoop" it down the shaft until it falls into it's groove. The dental pick helps you manage this process past the clip journal. Then you simply press the adjuster into the outer section of the caliper. You should feel it again, almost snap into place. Top it off with a new 13mm thin nut and install the small c-clip. Use some small needle nose pliers to get the clip into it's groove. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Time to pull in the outer pistons. Use the ATE assembly lube on this bore as well. A little dab and paint it around the bore. Again, using thumb pressure, push the piston while turning clockwise with the 4mm hex adjuster. Image Unavailable, Please Login
Now comes the fun part... putting the caliper 1/2's together. I like to insert the outer fastener and use it as an assembly post. Put the caliper 1/2 seals in their small bores and stack on the spacers. Install more caliper 1/2 seals and carefully (balancing act) drop the back 1/2 onto the front. Install an 11mm nut over the fastener and install another fastener on the opposite end. Follow up with the remaining fasteners and nuts. I have a 3" extension with an 11mm socket handy at this time to use as a tool to hand tighten the nuts. Position your index finger over the fastener head and tighten with the socket and extension. You should be able to tighten everything up enough to mount it in a vise for the final torquing of the fasteners. When you torque the fasteners I like to use the following sequence, numbering the fasteners from left to right 1-2-3-4 7 ftlbs. 2-3-1-4 17 ftlbs. 2-3-1-4 Guess what, you're done... Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
