brake piston retraction tool

Bernie Benz b.m.benz at
Sun Jun 9 19:37:51 EDT 2002


The piston will move inward about 0.1" per rev if you can apply the "right
force" in assistance.  What is the right force?  With a newly overhauled,
sweet and clean caliper it is almost zero, just enough to hold your turning
tool engaged.  This required force increases as the internal condition of
the caliper deteriorates.  Too much force, in any stage of caliper
condition, will cause the retracting nut to turn with the piston, thus no

My rule of thumb:  If the piston won't easily retract it is telling you it
is not in prime condition internally and needs overhaul.  Easily done at
zero cost (DIY), and the right time is when changing pads.  If one
religiously flushes brake fluid at least biannually, this period can be 10+
years.  I overhaul calipers only once, when the used car is new to me.


> From: Bryan Foster <bfoster at>
> Date: Sun, 9 Jun 2002 20:49:04 -0400 (EDT)
> To: 200q20v at
> Subject: brake piston retraction tool
> Listers,
> What tool do you use to retract the rear caliper piston when changing
> pads?  Where do you buy such a tool?
> Does turning it clockwise alone retract it or do you have to apply
> pressure?  How many revolutions does it take to get it in?  I tried to
> spin it about 10 revolutions with a pair of needle nose but it didn't seem
> to be moving much.
> Thanks for any advice.
> -Bryan Foster
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