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Front Calipers. Piston 20 degs alignment???

C

clemmo

New member
Hi All,

my 944 has stood dry and idle since 2005. This year it will return to the road!!

I have currently dismantled all the brakes and the Calipers now lie in parts awaitng re-paint and re assembly.
I notice in my service handbook it states the Caliper Pistons need aligning at 20 degrees??
I also notice that the part of the piston which contacts the brake pad is relieved??

Can any of you explain this 20 degrees?...
Any suggestions for Caliper painting (DIY)..?

Thanks in Advance
 
As regards the painting; shot blast, paint with caliper paint, let dry then cure with heat the hotter the better. I used to work at a factory that had a boilerhouse so i put them under the lagging on the main steam outlet from the boiler.
No ideas on the 20 deg.
I should also mention i had the pistons and seals out to do this, i blocked the cylinders and nipple holes with rags.
 
Thanks for that.

I am about to re-assemble now.
Somebody must know about this 20 dgree alignment!?

Cheers
 
Sorry Clemmo I can't see where they are coming from. If the pistons are cylindrical with no marks or other features you can't align them in rotation neither would there be any need to. IMHO
 
This isn't some claptrap from the Haynes manual is it? [&:]

If it is then burn it, I swear Haynes were probably looking at a Capri when they wrote the 944 book
 
No..! But I understand where you are coming from thou.
This comes from the official Porcshe Technical manual.
I have looked again and think I have an inkling...? The pistons overlap the pads..ie a small portion of the piston diameter push against fresh air. As descibed earlier the end of the pistons has a section relieved. Im starting to think this must be the section that should be in "fresh air".

I am just so suprised that no one else has ever noticed this or questioned it!???

I guess it means it is not too important.

Thanks again....................
 
If you can get a copy of ATE repair instructions for their disc brakes it will tell you how to set up the caliper piston to achieve the correct 20 degree angle. These instructions normally come with the ATE kits.
 
Great!!..recognition that the condition exists!..Thank you..
So now I am searching for ATE instructions..can anyone help?
Thanks..
 
ORIGINAL: clemmo

.....I am just so suprised that no one else has ever noticed this or questioned it!???
Click to expand...

The full refurb is so expensive that most of us have upgraded our callipers in preference to servicing them - that's my excuse. [8|]

Once you get to Big Blacks the pads are soooo mahooosive that I can't imagine there is any overlap at the edges.
 
Try asking your nearest OPC if they can supply repair kits for your specific calipers.
They're not that expensive and the ATE instructions come with the kit.
 
Had my calipers in pieces yesterday but wasn't sure about this 20 degree thing.

I noticed there was also a notch on the rear of the piston but not sure what to line it up to as there was no mention of it in the Haynes manual. Not the end of the world as I need to strip them down again.

Here's a pic (a poor one) of the back of the piston
6-1.jpg

 
I know what you mean. I asked simliar when I refurb'd my calipers.

http://www.porscheclubgbforum.com/tm.asp?m=351882&mpage=1&key=&#352362

It's not obvious, but I think there a bit in the 944 workshop manuals about it. Anti-squeel or something like that.
 
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