[Shop-talk] Disc brake piston explosion

[John Miller]

On 1/26/2015 2:41 AM, eric at megageek.com wrote:
>
> I don't know what they were made of.  Here is a photo of one of the
> calipers with the failed pistons in it.

Yeah, those are the phenolic pistons.

What year was this truck?  Are those the original calipers?

Automakers will claim they use them to reduce heat transfer from the pad 
to the fluid, and this may be one consideration, but they are also much 
cheaper than steel.

The biggest downside, of course, is what you've just seen, whether due 
to heat or to physical damage.

If this quote:

90% of all Ford cars and light trucks now
come with phenolic brake pistons, and 100%
of Chrysler production is equipped with
phenolics. GM is starting to use phenolics
also.

from this document:

https://my.cardone.com/English/Club/Products/Brakes/Protech/Training/brake2.pdf

is true, I think we're all gonna see a lot more of this.

John.