More uses for Plastic - this is a new one to me!

[macabethiel]

Having sought some advice on a Jeep website I am slightly horrified to be told that Jeep WJ's often suffer from sticking front brakes when the pads are replaced.

Apparently they have Plastic Brake Caliper Pistons !!

Sounds horrible I have been told they tend to distort at the end of the piston as the pads wear down and when you push them back in they stick !!

 

[panelbeater]

new to me

 

[rustic]

new to me

Car manufacturers don't normally make these parts but buy in from brake specialists, Lockheed, Girling etc that being the case, this will not be a first either, so look out for other models world wide.
Rustic

 

[Banshee]

Jesus!!!!!

 

[terranosaurusdoug]

Just doesn't seem right does it.

 

[macabethiel]

The Benefits of Phenolic Caliper Pistons ?

The claimed benefits of Phenolic Based "Plastic" caliper pistons.

1. They will not rust and thus become stuck in the caliper.
2. They keep the brake fluid cooler as they do not transfer the heat like metal ones and thus reduce the chance of fluid boiling.

Downside is they are not suitable for high performance and very heavy braking due to deformation in the exposed part of the piston over time. As the pads wear down the leverage on the exposed part of the piston becomes greater incresing the risk of deforming. Hence why they can stick when you push them back into the caliper as they loose the perfect cylindrical shape.
Good news is overhaul kits that include slider components & new pistons & seal are not that expensive. Circa £69.95 for Jeep full set or £39.98 for aftermarket ones.