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Posted by: bbrock Dec 9 2018, 09:49 AM

I spent yesterday following @http://www.914world.com/bbs2/index.php?showuser=1110 's how-to instructions on his website and youtube to disassemble my brake calipers to prepare for sending for plating. My car has one early and one late rear caliper that I don't think has anything to do with my problem but just another of many examples of the mismash of early/late parts on my mid-MY 73.

Three and a half of the calipers came apart without a hitch, which is amazing considering this car spent 30 years outside with brake lines opened up. All pistons came out without an unreasonable fight and no fasteners were seized. The problem is with removing the last (inner) piston on that early rear caliper. Spinning the adjuster doesn't move the piston. It feels like the gear is engaged but turn and turn and nothing happens. Cranking the e-brake lever moves the piston out about 3mm and then it goes back when the lever is released. There is no ratcheting of the piston position. I have NOT split the halves of this caliper yet because it is the only one with Ribe fasteners and I'm waiting for my Ribe bit to arrive in the mail. Since the caliper is still together, I tried popping the piston out with compressed air but that does the same as cranking the lever - piston moves out about 3mm and then goes back. I'm not sure what to try next. The only thing I can think is to go ahead and split the caliper and try gently tapping the piston with a wood drift to try to spin it off the adjuster screw. Anyone have a better suggestion?

Posted by: KELTY360 Dec 9 2018, 10:14 AM

Do you have any C4 in your stash?

Posted by: walterolin Dec 9 2018, 10:34 AM

Not everyone will get this.

Posted by: bbrock Dec 9 2018, 10:37 AM

I have plenty but can't use it... they're watching...

Posted by: porschetub Dec 9 2018, 12:48 PM

Compressed air won't move really stuck pistons,attach a grease gun with a flexible hose and fit a spacer between the pistons ,I haven't used this method on 914 calipers but this method has worked well on bus and beetle ones for me in the past,good luck.

Posted by: bbrock Dec 9 2018, 01:20 PM

The problem is that I don't think even grease works on rear calipers because the piston is screwed onto the adjuster which is fastened by clips to the bottom of the bore. Eric's piston removal procedure is simply to crank it out with the adjuster. I could be wrong about the adjuster not allowing the piston to be pushed all the way out with pressure and grease is worth a shot. I'll pick up a zerk adapter and give it a try before splitting the caliper.

I don't think the caliper is really stuck because I can move it back and forth a few mm in the bore and if it was stuck, it seems like the adjuster screw would bind and I shouldn't be able to crank the e-brake lever. I think the problem is something broken or missing in the adjuster mechanism.

Posted by: sixnotfour Dec 9 2018, 02:25 PM

when the adjuster spins , a quick spin from a drill will help it carch

Posted by: injunmort Dec 9 2018, 02:45 PM

if grease doesn't work, a couple of drops of water into the caliper and hit it with the torch. the steam will push the piston out. put a rag on top of and around the piston as it will fly otherwise.

Posted by: bbrock Dec 9 2018, 02:48 PM

So use the drill to spin the adjuster gear?

Posted by: sixnotfour Dec 9 2018, 03:24 PM

yup quick burst ..

Posted by: bbrock Dec 9 2018, 06:03 PM

Well, I tried the drill spin trick without any luck

Posted by: sixnotfour Dec 9 2018, 06:06 PM

Posted by: Eric_Shea Dec 9 2018, 07:34 PM

Teeth are probably broken in the inner adjuster.

The only way to get that inner piston out now is to reassemble the caliper and clamp the outer piston to prevent it from moving. Then, using water or grease, blow the piston shell off the internal mechanism. Then disassemble the caliper and using a pick to hold and spin the mechanism off the adjuster. Once off you can carefully press it back into the piston shell. Then you’ll need to find an inner adjuster. Seeing as how they’re NLA, this all may be moot. Buy a good core for $40-50 and start over. That said, you may find the inner adjuster is fine and everything was just spinning in the shell.

Hope that helps.

Posted by: bbrock Dec 9 2018, 07:49 PM

Thanks Eric. I'll pick up a grease fitting to get that piston out and go from there. I appreciate your help!

Posted by: bbrock Dec 15 2018, 08:43 PM

Just to close this out, I picked up a grease zerk and popped that piston top off the adjuster lickity split. Then the fun REALLY began. The adjuster WAS spinning inside the piston thanks to some rust on the screw that had it seized to the hub. Problem is that those early style adjuster are an over-complicated POS piece of engineering and the hub was just spinning inside the adjuster. Took three hours to figure out how to get that sucker off. I was about ready to follow Marc's recommendation and pull out the C4, but I finally prevailed. I documented the gory details in my build thread but here are finally all the brake bits ready for cleaning, plating, or other forms of restoration. Thanks for all the help folks.

Posted by: sixnotfour Dec 15 2018, 09:12 PM