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How to tell if a caliper piston is still good? by tjoudrey
Started on: 02-10-2020 11:25 PM
Replies: 1 (72 views)
Last post by: theogre on 02-11-2020 10:30 AM
tjoudrey
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I am in the process of rebuilding the rear calipers on my 85. Upon visual inspection the internal nut is extruding farther out than the other, as well the inner mechanisim appears to be slightly crooked.
How do I test if this piston is still any good?

some photos for reference

https://photos.app.goo.gl/gB6vVkKEWhc66b7Z6
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Report this Post02-11-2020 10:30 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
The piston is early version unit w/o 4 notches on front to accept stamped SS clip for the inner pad. (Should have a wire clip doing this.) I think this version is part of brake recall.

Is started to "blown out" the back because can't self adjust.
Front should have vent plug to keep out most crap makes worse rust problems when is missing.

More proof? put piston in the bore w/ park screw and everything on it except the big spring and "o-ring" seals. Very likely you can't "retract" the piston fully by hand even w/o the big spring so new pads and rotor can fit. IOW piston height ≥ 5mm - 3/16in

Get rebuilt caliper from AZ etc w/ a good warranty. AZ uses Phone # to track warranty nation wide.

See my Cave, Rear Piston notes, How to I tell when my piston is retracted enough? and rest of section. Do You Recall? links at bottom but don't bother trying to go to GM for 30+ year old car for a recall if even applies to you.

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(Jurassic Park)


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