Vintage 911S Caliper Restoration Thread

[MarkS]

Got it Eric, thank you. I will phone the shop.

[ajwans]

99% of all S-Calipers I restore have bad pistons. The factory plated these pistons due to issues with dissimilar metals. When these pistons sit for an extended period of time (and they do), the plating will flake and rust right where it sits against the inner seal.

What's the process for repairing the rusted brake cylinders?

andy

[Neunelfer]

Hi Andy,

I'm not sure what you're talking about. Do you mean the cylinder where the brake piston sits? If so, the rust is cleaned in the plating process. There "generally" isn't much if any rust in these areas. The tight fit of the piston and the brake fluid help keep the rust confined to areas above the sealing ring.

If you mean the master cylinder, I would get "new" where ever and when ever possible. If that is not possible I would suggest finding a shop that could resleeve the M/C or... have them plated and re-honed with a proper hone. 99.9% of the time, it would be best to simply buy a new M/C.

[Neunelfer]

Little bit of an update and word of caution gang:

While the kit posted in this thread is correct (Post #2 Picture 3), the inner seal is tighter than most I've worked with (Post #8, Pictures 7 and 8). There is a fairly delicate and time consuming process in getting the pistons past this seal:

#1 The seal needs to be perfectly centered in the bore.
#2 Use liberal amounts of caliper grease.
#3 Push the piston past the seal "BY HAND", If you can't get it started and past the seal by hand, remove the piston and repeat the steps above.
#4 Once the piston is past the seal you can then press it the rest of the way in (you'll know when this happens).

We used the standard vertical press for the first round on these and it damaged Andy's rear seals. Front M-Calipers are as standard as they get; no problems there. I've sent a message up to ATE about the rear seals but, I'm not sure how long it will take to make it through the supply chain. The rear kits available now "will work" they just require a little more "hands on" love (what early 911 doesn't?).

[boxster03]

yea everyone I have spoken with said "don't take them apart" and I would like to know why? i

[Neunelfer]

I think that's one of those "Urban Myths" that came from Porsche themselves. The stories I heard were; they made it difficult to get the inner caliper 1/2 seals -or- it is not recommended you take them apart. I think the main reson behind this is; they didn't want every Tom, Dick and Harry with a wrench taking apart things like "BRAKE CALIPERS"

While understandable, the process is fairly simple. I would stress NEVER to do this without the proper tools. A torque wrench and proper Ribe bits are a must.

The seals are listed now on their online PET so... I would imagine they are available through a dealer. Years ago, these $0.10 pieces of rubber were $2.50 each. I'd hate to see what they want now.

[boxster03]

You hear the MooreSpeed

[Neunelfer]

You hear the MooreSpeed

Not sure what you mean but, there's a nice Ferarri/Porsche shop in your neck of the woods by that name.

[boxster03]

Oh I called Moorespeed and ask about the Ribe to take the caliper apart and they said "you can't do it"

[Neunelfer]

Ahhh... Best not to tell them about this thread then, it will break their hearts.

Here's a link to a Ribe bit set:

http://www.tooldiscounter.com/ItemDi...gle&kw=OTC5909

If you guys purchase this bit set it is important to note that these are not meant to "turn" the fastener. They will "hold" the head of the fastener while you use an air wrench and a nice 6-sided socket to turn the 11mm or 13mm nuts. If you put one of these Ribe bits in an air wrench and zip away at a fastener... wear saftey glasses because you'll probably shatter the bit with pieces flying across the shop/garage. My method is to take a hammer and tap the Ribe bit into the fastener head, then I attach a simple extension and hold while I use the socket to turn the nut.

We restore the rare Rear 308 GT and GTS (same as the 914-6 and 914-6/GT) calipers as well. Don't tell them that either...