Hanging rear caliper

Bernie Benz b.benz at charter.net
Sat Apr 16 23:49:04 EDT 2005

> From: Peter Schulz <pcschulz at comcast.net>
> Bernie:
> Once again other peoples' BTDT overrules your "theory"
> Another case of your "reality" vs others actual BTDT..
Pete, I don't acknowledge to any significant difference, My theory relates
to my BTDT reality, and yours?
> No one said anything about the caliper piston dropping out of the seals.
> Oh, sorry, you did.
Only to make the point that there is absolutely no probalility that pistons
might tend to "jam" in the caliper before such a condition is realized.
> I have personally had to remove worn pads and calipers from 2 cars, and had
> to re "thread" the piston back into the cylinder bore because it was jammed
> - in one case I had to take the caliper completely off the car and mount it
> into a vise to get enough leverage to rotate and drive the piston back into
> the bore.
Big mistake, IMO.  If it won't retract with minimal torque you need to
disassemble and find out why.
> pistons were in fine shape, no torn boots, and had been completely serviced
> within the last two years.
Time makes no diff.
> pads were down to less than 1/8 material remaining.
Just like new, 100K yet to go!  DFI if IAB!

> -Peter
> At 11:17 AM 4/16/2005, Bernie Benz wrote:
>> Come on, get real, Kneale and Peter!
>> Pistons can not extend far enough to drop out of the caliper seals, unless
>> one forgets to install the rotor.  Using the passive pad wear detectors, I
>> routinely wear my pads down to where the backing plates touch the rotor
>> ridges.  Further, there is no piston "cocking force", tendency for the
>> piston to cock or jam within the caliper bore.  They do get sludged up form
>> lack of fluid change though.
>> Bernie
>>> From: Kneale Brownson <kneale at coslink.net>
>>> So, have these gone unserviced for a year and a half?  Did you use new,
>>> OEM, or some rebuilt stuff?  You might have corrosion on guide pins or the
>>> caliper piston, especially if the pads are worn enough the piston is
>>> extended quite a bit.
>>> From: Peter Schulz <pcschulz at comcast.net>
>>> Couple of thoughts...
>>> Ebrake mechanism not fully releasing, or the pads are worn down to less 1/4
>>> depth- and the caliper cylinder is extended to the point where its binding
>>> on the cylinder walls.  If the Ebrake mechanism and cables are releasing
>>> and functioning properly, drive the brake piston completely back into the
>>> caliper.
>>> -Peter
> 1991 200 20v Q Avant Titan Grey
> 1991 200 20v Q Avant Indigo Mica
> 1991 90 20v Q Red
> 1990 CQ silver (awaiting S2 engine transplant)
> Chelmsford Ma, USA

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