anodizing S calipers

[rick b]

Hi,
Any recommendations on who to send my calipers out to for anodizing? I need the front S units and the rear M units done (1970 911). I am doing the rebuild myself.

Rick

[Flieger]

Eric at PMB Performance!

http://www.pmbperformance.com/calipers.html

[jameshtaylor]

You really can't anodize steel, which is what the M calipers are made of. But you knew that.

[rick b]

thanks for the guidance to Eric. Yes, I knew that but included the M as an afterthought as they need restoring as well.

[merbesfield]

When calipers are Zinc plated, do you have to disassemble the caliper halfs or can you plate them as
a unit? Also, what happens to the insides such as where the piston rides? When you plate them, do you have to re-hone the cylinder?

[Zithlord]

Read the "rebuild calipper" tread by search.

http://www.early911sregistry.org/for...build+calipper

Our expert Neunelfer will explain about honing/zinc plating cylinders etc.

Best
John

[merbesfield]

John, Thanks for pointing me in the right direction. I now remember reading that thread way back when, so much to remember. Today I disassembled all my calipers and unfortunately one cylinder refused to come out. No amount of pressure would pop it out. I ended up having to beat it out with a punch from the back side. Of course it destroyed the piston and marred the cylinder wall. I am hoping Neunelfer will chime in hear and give advice. What I need to know is can the damage be honed level and will it perform ok or do I need to find a replacement. We spent hours trying to get the darn thing out before resorting to the punch. Calipers go to the Platter tomorrow so if I have to find a new one, it will have to be plated separately, which will suck. Also, need to know if my cylinders are usable or not. They look pretty bad. See pics. Thanks for the help.I just realized I forgot to take pics of the pistons, other than the one that was destroyed. I will post them tomorrow. They were corroded along the edges pretty badly and it looked like some of the plating? was flaking off. No where close to looking as nice as they ones you started with.

[Flieger]

Interesting. The Steel/Steel M caliper was the one with the most corroded piston/cylinder? Not the Aluminum/Steel S caliper?

[merbesfield]

I thought I would post a quick update. I took the calipers to be plated, but the Plater did not have success. The plating would not stick to the calipers? He said there must have been some sort of coating or something. He asked me to bead blast them, which I have done, and bring them back. What was strange was the fronts took the plating about 80%, the rears would not take any plating at all. They looked like they had been cooked and were covered in rusty/dirty scale. They blasted clean very easily though. I don't recall reading in Eric's posts where he blasted the calipers prior to plating. The Plater dips all the parts in some sort of cleaner or acid which is suppose to strip the old finish. Not sure of the details but will ask more questions when I take them back.

[smedley]

I ran into the same issue with some early cast iron calipers off of my '67 S a few years back . Excellent plater with prior experience with a lot of my plating, including clear and yellow zinc, black oxide, and some actual cadmium. No rhyme nor reason why the calipers would not take the zinc. On his suggestion we (he) tried yellow cadmium....it took! Slightly duller in lustre, and technically not correct, but it worked. All my stuff is bead blasted before plating, and you just need to knock off the plating in the bores with a small hone before assembly. By the way, in one of your photos there's a pretty signifigant gouge in the caliper bore that looks like it might compromise the seal. I wouldn't use it! That much corrosion with steel on steel is indicative of infrequent bleeding/flushing and funky fluid...MOISTURE! Remember brake fluid is hydrophilic.