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Brake Pistons: Steel or Phenolic?
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Posted On: 6/29/2011 9:13AM
Katakuna

I've put it off long enough: the squealing, the scraping, the clicking and the cringing, it all stops here. And even though I stopped, my Town Car hasn't. So I finally head to AutoZone to get the goods for a brake change only to find out that there is in fact some legwork I need to do before I tear into the damn thing. For instance, is it a limo or is it a sedan? dur, it's a sedan. Let's make it a little harder: Does it have phenolic brake pistons or steel pistons? I never realized I'd have to actually know what sort of brake pistons my car has. It may depend on whether or not it's a cop car, but really.

So, what's the difference? Does it matter? I'd be grateful for any advice, because I'm flat-out lost.

Comments (12)
Avatar By: timpalass
6/29/2011 9:21 AM

The pistons are on the inside. So to me the only difference besides the pistons is the fluid used. Maybe not. It might be a bigger difference than that.

 
Avatar By: DaveyBoyo
6/29/2011 10:38 AM

I'm a counter guy at a jobber parts store and I run into this over and over every day. I still don't know wtf phenolic even means, but I sure know that it matters lol.

 
Avatar By: SouthernGuy8503
6/29/2011 12:30 PM

I can't be 100% sure but I think the pistons are phenolic from the factory. What I would do is take the pads off and take them to the parts store so you can compare them with the pads for both a phenolic and steel piston caliper. Hopefully it would be some difference in the pads, if not maybe it should be a cosmetic difference in the phenolic and steel piston calipers so maybe you could even take a caliper off and take it with you or take a few pics with a digital camera of the caliper. You would think the parts guy would look at part #s between the 2 piston types, if they're the same #s it wouldn't matter since the same pads would work for both. Some parts guys don't seem to know much about cars, they just look them up and go get them (example, I bought a Mass Air Flow sensor for my truck. Just to see what he'd say I asked "that's the big sensor right behind the air filter right?" and the only response I go was "uh ya.. air flows through it" and it wasn't in a smartass tone, it was in a way that he was just agreeing with me. I could have said it went between the throttle body and intake manifold and he might have said the same thing). Also what you could do is call a mechanic and ask them if they look different and if they use the same pads.

 
Avatar By: ink-spot
6/29/2011 5:07 PM

well the phenolic is basically a plastic composite piston, and when i put new calipers on my ranger i changer from phenolic to steel and didnt have any problem. And the pads where the same between either one so i dont think it matters its just another question for the parts guys to ask

 
Avatar By: Nova_Boy454ss
6/29/2011 6:29 PM

Looks like a '94 of that is a real pic of the car. If I look them up for a '94 the phenolic "plastic" piston calipers were pre- 10/31/93 and steel were post 11/1/93. For me I have seen a lot of broken phenolic pistons so they are weaker. The pads are indeed two different part numbers at least for '94. I wouldn't go to Autozone unless you like replacing the same parts over and over again. If you know more than the person behind the counter either find someone else that knows more there or go to a better parts store. Not Advance or O'Reilly's either. If you are just buying pads you will want to check your calipers and rotors before you buy the parts so you don't need parts after you already torn you ride apart. You will also want to consider your driving and how long you plan on owning the car. Just because the parts person says it has a life time warranty doesn't mean they will last long or that it covers ware usually just workmanship and material defects. Consider the price you are paying. I wouldn't spend less than $20 on pads. You will feel and see a difference if you buy a better set of pads. Just remember they are the first thing keeping you from slamming into another car.

 
Avatar By: GTwildfire
6/29/2011 7:09 PM

avoid the hassle dude... buy both variations using cash, keep the receipt. Do the change with the appropriate set and return the other set the same day. By doing this you only have to tear into the car once, change the pads and resolve the matter as quickly as possible.

 
Avatar By: timpalass
6/30/2011 7:50 AM

Phenolic is what Pool balls are made out of. Some shift knobs also.

 
Avatar By: Katakuna
6/30/2011 11:33 AM

@Nova_Boy454ss, you're a major help. If that's the case, then it won't be too hard at all to get what I need. You're also right, that IS my car. :D I'm going to do what GTwildfire suggests and get both sets just in case though, along with some new tie rods (I'm still not brave enough to attempt those on my own yet.).

 
Avatar By: Nova_Boy454ss
6/30/2011 5:30 PM

Your welcome and getting both is always a great way of covering you own A**. I Manage a Parts store and I sell a lot of just in case parts to save us and my customers time.

 
Avatar By: dragorphan
7/1/2011 4:53 AM

If one piston is plastic and the other is steel just touch it with a maganet. If it sticks its not plastic.

 
Avatar By: Katakuna
7/6/2011 9:35 AM

Turns out they were steel pistons. The front-left rotor was also totally fucked. Stops just fine now though. :D

 
Avatar By: Katakuna
7/6/2011 9:36 AM

It was also the easiest brake job I've ever seen done. I didn't want to do it out of laziness, but seeing my dad do it made me want to kick myself...

 

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