Caliper piston material

[Blk00ss]

Had a mishap while doing brake pads on our '05 Tahoe. While compressing the front left caliper I got lazy and was trying to hurry. Ended up pressing my C clamp end right into the center hole of one of the pistons. I got it out, but of course it brought the piston and seal with it (it didn't come out completely, but close). Once I got C clamp removed I attempted to compress the piston and seal back in, it oozed fluid. So, looks like I tore the seal. I can rebuild it, but time is the issue so I may buy a new caliper. My question is this...

Does anyone know what material the factory OE caliper pistons are made of? I ask because many of the calipers both new and reman I'm finding say the pistons on plastic (phenolic)? Maybe the OE ones are as well?

 

[Donal]

Oreilly says pistons are steel for their store brand, front and rear. Their replacement calipers have phenolic pistons.

 

[Joseph Garcia]

Just purchase an OEM caliper and install it, to save you some time.

Regarding the caliper compression, I use a C clamp as well, but I insert one of the old brake pads between the C clamp and the piston, which bridges the piston hole and puts even pressure across the whole piston, just to be sure that I don't do what you did.

 

[MassHoe04]

Mine appeared to be the originals and pistons were steel.
My 05 Rubicon had phenolic from the factory.

There seemed to be nothing wrong with the phenolic pistons, as far as I could see.
They can't corrode or rust...

But if the brake fluid is not water-laced, steel pistons would not rust or corrode either.

So OE-style calipers would be my preference, if it were my truck.
If they were steel, I would just get whatever it came with stock.

 

[asand]

Phenolic pistons insulate the high temps from the brake fluid. Personally I would rather have phenolic.

 

[rockola1971]

Phenolic pistons insulate the high temps from the brake fluid. Personally I would rather have phenolic.

My man taking corners at 70MPH in a Tahoe and got the right wheels off the ground while the left wheels are barking like a dog all the way through the corner. We aint driving race cars. If you got high temp problems in your brakes then you got bigger problems than a phenolic brake piston. You got a very heavy foot OR you riding them brakes like a horse!

 

[Doubeleive]

My man taking corners at 70MPH in a Tahoe and got the right wheels off the ground while the left wheels are barking like a dog all the way through the corner. We aint driving race cars. If you got high temp problems in your brakes then you got bigger problems than a phenolic brake piston. You got a very heavy foot.

*that would be me, heavy foot guy. I don't even know anyone else that has as heavy of a foot as me.

 

[asand]

My man taking corners at 70MPH in a Tahoe and got the right wheels off the ground while the left wheels are barking like a dog all the way through the corner. We aint driving race cars. If you got high temp problems in your brakes then you got bigger problems than a phenolic brake piston. You got a very heavy foot OR you riding them brakes like a horse!

Or you're towing down hill in Colorado. Im just saying, that is the reason brake calipers come with phenolic pistons.

 

[asand]

Not everyone live in Indiana. Come drive highway 101 where we do take corners at 70 and then tell me what you think.

 

[swathdiver]

The pistons are phenolic, 25848320/172-2412. The seal kit is 23276875/179-2262.

While GM does not show it, the same pistons and seals work in the rear calipers on the GMT900s.