caliper/piston question -
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Unread 07-30-2013, 10:20 AM   #1
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1999 XJ Cherokee 
Join Date: Apr 2008
Location: CA
Posts: 19
caliper/piston question

Replacing the front calipers on my 99 XJ. Went in to Napa and the guy asked me if I needed a metal or phenolic piston. I have no idea. Calipers on there now are stock, but I don't know the difference between the two pistons. Here are the links at napa:

Any ideas which one I need?

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Unread 07-30-2013, 12:22 PM   #2
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2006 TJ Wrangler 
Join Date: Feb 2013
Location: Baton Rouge, Louisiana
Posts: 721
Phenolic pistons are plastic. They dont expand as much as metal when they get hot. Arguably they are weaker. the metal pistons are steel. They will expand and contract with the heat. They may sust if you get moisture in your system. They are structurally stronger. The reality is, either will work. I prefer to run the same on both sides although it probably doesnt matter.
Newtons3 is offline   Reply With Quote Quick reply to this message

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