[s-cars] Sticky Big Red

[Abe Berman]

Thanks for the detailed reply Tom.  I should have mentioned in my original
email that the conversion uses the RS2 mounting brackets and the 993TT big
red calipers.  The 10mm allen bolts seemed to be appropriately torqued and
loc-tited when I removed them, although I am not sure what the torque spec
is.  I am not sure about the size or oem application of the rotors, will
measure them tonight.

I was able to figure out the spring clips fairly easily as well as carefully
moving the wires for the pad indicators out of the way.  There was not a
significant lip on the rotor so it was not difficult to remove the caliper.
I have it hung up on the tie rod with some rope for the moment.

I don't know if the pad silencers are in there, I did not see them though.
I will try and get a c-clamp on to retract the pistons using the bleeder
valve trick, I was dismayed when I was not able to use the retractor tool
that I use for the rear brakes.  I tried removing the cap on the master
cylinder and using a quick grip type clamp, but I could not move the fluid
back through the lines with that level of force.

I do have a motive power bleeder that I plan to use.  I guess I just need
use a bit more elbow grease on retracting the pistons...




On Tue, Jun 8, 2010 at 11:54 AM, Tom Green <trgreen at comcast.net> wrote:

> Abe,
>
> The 993tt big reds have a spring clip on top that holds the pad in place.
>  It hinges at one end and the other snaps in place.  Just squeeze the spring
> in to release the end.  If you use wear sensors, they may be clipped to the
> spring.  If you have the pad silencers that stick to the pad backing, they
> protrude into the piston, so you will have to push the pistons out to have
> room to remove the pads out of the piston recesses.  If you are careful you
> won't disturb the adhesive and they can be reused.  I like to loosen the
> bleed valve and put a bleed container on to catch fluid as I push the pad
> out to retract the pistons.  The pistons will move easier and you don't
> force the dirty fluid back up the lines and/or overfill the master cylinder
> reservoir.   If there are no pad silencers installed, the pads should come
> right out the opening.  If they have been there 5 years you may have to use
> lock pliers to grab the ears and pull.  You want to use the pad or a
> replacement block and a c-clamp if you need to push the pistons out so you
> can retract them straight and even.
>
> The monobloc 996tt calipers are similar but use a pin with very small clips
> on the end to retain the pads.  Whichever system you have, just take your
> time and don't force a cocked piston.  They should retract smoothly but
> slowly.  If you use the bleed just open it when you are pushing the pad
> outward and only enough to allow the fluid to slowly flow and this will
> minimize bleeding required when you replace the pads.  The Motive pressure
> bleeders are great for the fluid flush and bleeding.
>
> I don't know how much pad material you have remaining or what rotor you are
> using, but the pad should sweep its total area on the rotor.  The 323 mm A8
> rotor is not centered in the caliper using the RS2 brackets unless the
> bracket is shaved, but the 2 mm shouldn't be a factor until pads are well
> worn.  I have assumed, since you mentioned no problems, that the caliper
> attaching bolts and the adapter were still torqued so that the caliper was
> properly aligned on the rotor and did not move.  You did not mention any
> difficulty removing the caliper, so there must not be much lip on the rotor
> edge.
>
> There are lots of photos of the different brake upgrades on the web that
> should allow you to compare and determine what components you have
> installed.  If the brakes have been on your vehicle 5 years, it's probably
> information you need.
>
>
>   Tom '95 S6
>          '95.5 S6 avant
> Knoxville, TN
>
>
>  On Jun 7, 2010, at 10:58 PM, Abe Berman wrote:
>
>  Removed caliper this evening.  On the inside of LF rotor the pad seems to
> be only contacting the outer edge of the rotor surface, the inner surface is
> rough with some light rust.  The pads seem to be jammed into the caliper
> though and I couldn't easily figure out how to remove them.  I did not do
> the conversion, so I am unfamiliar with this caliper design and the online
> descriptions indicate that the pads should be easily removed.  Is there a
> trick that I am missing?
>
>  On Mon, Jun 7, 2010 at 8:01 PM, Tom Green <trgreen at comcast.net> wrote:
>
>> Abe, I mean clean the brake dust and crud off the caliper so you can see
>> the condition of the dust boots.  You probably are going to have to remove
>> the pads but not the caliper.  If one is torn it is probably best to bite
>> the bullet then and have them rebuilt.  Your inspection of the lines, etc is
>> time well spent.
>>
>> That sounds like a shop you use regularly that checked the balance.
>>  Knowing the problem, I am sure they would also look for a leaky piston or
>> other possible causes.  The shop I use will tolerate my inspection while
>> they have the wheels off.
>>
>> I use Mintex red box and Hawk HPS for street pads.
>>
>>  Tom '95 S6
>>           '95.5 S6 avant
>> Knoxville, TN
>>
>>    On Jun 7, 2010, at 3:27 PM, Abe Berman wrote:
>>
>>  Tom,
>>
>> Thanks for the tips.  I did not closely inspect them, no, my mechanic
>> actually did the balancing as I do not have access to a balancer.
>>
>> What constitutes an "exterior cleanup"?  I usually wipe down the caliper
>> exteriors and the surrounding with a rag and simple green when I change
>> winter and summer wheels.  I clean the rotors with brake cleaner should any
>> simple green get on them.  I do not however remove the caliper or rotor.  I
>> do inspect the lines and suspension components whilst down there.
>>
>> Any recommendations on pads and fluid from the group?  As far as
>> performance needs, this is a spirited daily driver only, no track use.
>>
>> Thanks,
>>
>> a
>>
>>
>> On Mon, Jun 7, 2010 at 2:31 PM, Tom Green <trgreen at comcast.net> wrote:
>>
>>>
>>>
>>>
>>> Did you have a chance to inspect the brakes while the wheels were being
>>> checked for
>>> balance?  You don't mention any intervening maintenance since the brakes
>>> were
>>> installed 5 yrs/30K miles ago.  It's certainly time for a fluid flush,
>>> exterior cleanup and
>>> inspection, and perhaps a pad change.  If they are one piece rotors,
>>> turning them to
>>> provide a new and true bedding surface for new pads is a good idea.  If
>>> the pads are
>>> worn 1/2 or more, the reposition of the piston may be all that is needed
>>> along with the
>>> new fluid, but if the pistons are out that far you might be advised to
>>> check behind the
>>> dust boot to make sure the pistons are clean and add a little plasti-lube
>>> to insure they
>>> retract smoothly when resetting for new pads.
>>>
>>> Then clean and inspect the brakes at least yearly and flush the fluid at
>>> least every two
>>> years.
>>>
>>>  Tom '95 S6
>>>          '95.5 S6 avant
>>> Knoxville, TN
>>>
>>>  -----Original Message-----
>>> Date: Mon, 7 Jun 2010 10:16:42 -0700
>>> From: Martin Kozaczek <mkozaczek at gmail.com>
>>> Subject: Re: [s-cars] Sticky Big Red
>>> To: Abe Berman <yellowcuda at gmail.com>
>>> Cc: s-car list <s-car-list at audifans.com>
>>>  Message-ID:
>>> <AANLkTilHqJpT3apSTxEfyJ0goZq8B9FwRMlw0kiQ_1Dp at mail.gmail.com>
>>> Content-Type: text/plain; charset=ISO-8859-1
>>>
>>> I've read that some have had luck with taking the caliper off (easier to
>>> work this way) removing the seal or boot whatever it's called, then
>>> cleaning
>>> out the piston bore with liberal amounts o WD40 or equivalent, clearing
>>> out
>>> with compressed air and reassembling.
>>>
>>> My calipers were new so I didn't bother, just sent them back.
>>>
>>> On Mon, Jun 7, 2010 at 10:01 AM, Abe Berman <yellowcuda at gmail.com>
>>> wrote:
>>>
>>> Thanks for sharing Martin.
>>>
>>>
>>> Hmm, guess I should check the archives.  I am hoping (read: praying) that
>>> I
>>>
>>> don't need to replace the caliper(s).
>>>
>>>
>>> On Mon, Jun 7, 2010 at 12:40 PM, Martin Kozaczek <mkozaczek at gmail.com
>>> >wrote:
>>>
>>>
>>>  This seems to be a common problem with the older style two piece
>>>
>>>  928GTS/993 big reds or blacks.  I had a brand new set that did it right
>>> from
>>>
>>>  day 1.
>>>
>>>
>>>  I tried everything and could not get it to go away, so I returned them
>>> and
>>>
>>>  temporarily replaced them with 996 C4 calipers while I wait for my
>>> 996TT big
>>>
>>>  reds.  Problem went away immediately when I put the 996 calipers on.
>>>
>>>
>>>   On Mon, Jun 7, 2010 at 9:27 AM, Abe Berman <yellowcuda at gmail.com
>>> >wrote:
>>>
>>>
>>>  Patient - 95.5 Avant mit Porsche "Big Red" front calipers
>>>
>>>
>>>  Has anyone had problems with sticky Porsche calipers?
>>>
>>>
>>>  I have been experiencing incidences of shuddering on the highway and
>>> feel
>>>
>>>  it
>>>
>>>  slightly (but intermittently) around town at lower speeds.  Checked
>>>
>>>  balance
>>>
>>>  on all 4 wheels and its fine.  Tires are new and have no external
>>>
>>>  defects.
>>>
>>>
>>>  I experienced this to a HEAVY degree whilst on the highway on Friday
>>> and
>>>
>>>  immediately pulled off at an exit.  Front Left wheel had serious heat
>>>
>>>  radiating off of it and a strong brake smell, all others were normal.
>>>
>>>
>>>  I did some reading and it seems like the correct procedure would be to
>>>
>>>  clean
>>>
>>>  and lubricate slide pins and flush brake fluid/bleed brakes to
>>> eliminate
>>>
>>>  possible gunk/moisture in lines.
>>>
>>>
>>>  The Big Reds were installed approximately 5 years/30k miles ago.
>>>
>>>
>>>  Thanks in advance for any thoughts.
>>>
>>>
>>>  Abe
>>>
>>>  Burlington, VT
>>>
>>>
>>>
>>
>>
>>
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