Phenolic or Metal?

[Pen_Two]

I thought this might be an interesting topic to bring up.

What would you consider the "better" caliper piston?

Phenolic Piston so it has less chance of seizing, but increasing the chance brake fade.

Or

Metal Piston to help prevent brake fade, but increasing the the chance of seizing.

 

[Rara]

What makes you think phenolic pistons have a higher chance of fade? They have lower thermal conductivity than a typical steel piston, so less heat reaches the fluid, and therefore, less piston related brake fade.

Phenolic pistons are cheaper to produce, and will not rust (probably where your seizing comment comes from) but are not as durable as steel pistons, especially under very heavy high heat use.

For a typical street car, phenolic pistons are more than adequate, even with some light track use. For a car that sees a significant amount of track use, or long periods of very heavy brake use, I'd look a little harder for a good steel piston at caliper rebuild time.

 

[Dyoel182]

Is seizing even enough of an issue to worry about?

 

[Rara]

Is seizing even enough of an issue to worry about?

No, not really. Siezed caliper pistons typically only happen when a dust boot is torn and/or missing and the piston is allowed to rust, or get otherwise contaminated. Usually a piston seal will start to leak before the piston will actually sieze.

More common is slide pins siezing, and that is completely and totally seperate and unrelated.

 

[Dyoel182]

Yeah I was wondering why someone wouldnt see fluid from a torn seal before they got carried away with the piston seizing.

 

[Pen_Two]

I'm only reiterating what I've read elsewhere. :shrug:

I was more so looking for opinions though. Oh well.:shrug:

 

[Rara]

I'm only reiterating what I've read elsewhere. :shrug:

I was more so looking for opinions though. Oh well.:shrug:

"better" is such an esoteric term unless you qualify with the conditions that you will be judging it by.

A person solely concerned with cost will pick phenolic every time.

A person concerned with high heat in the piston itself for long periods of time (ie, a truck driver, or race car driver) will pick steel every time.

 

[Pen_Two]

In my situation, cost isn't relevant. Both types cost the same for my vehicle. :laugh:

 

[warmonger]

I imagine that a torn dust boot allowing moisture in from the outside is most common in the east/north.
I just want to add that in the south-central to southwest it is almost a non-issue and in fact you find most torn dust boots are ignored. In that area of the country the biggest cause of a piston seizing in the bore is usually from lack of use combined with old brake fluid that has too much moisture. The rust inside the piston becomes significant and locks the piston to the cylinder wall right at the edge where the caliper seal sits.