When its time to replace my rear calipers on my 2000 GMC Jimmy is it better to go with a Phenolic or Steel piston? What is the consenus! My instinct is to stick with OEM steel piston but I do not have anything really to base it on. Would having Phenolic piston keep it the piston from seizing when it is time to change pads therefore you can replace the rear pads without replacing the calipers each time.

 

Never heard of Phenolic pistons and I've never had the piston seize up on me, either. The slide pin on the caliper, yes, but never the piston.

 

OEM is steel piston but a majority of the rebuilt calipers have phenolic pistons. I did an internet search on this subject and it seems that opinions are split on which one is better but if you are towing or heavy duty the opinion is to stick with steel. Phenolic is not as strong but does not transfer heat as much as steel to the brake fluid. So there is Pros and Cons of both. AC Delco Reman. Calipers are steel.

 

This is an interesting question, as it is time to do my rear brake pads. I have heard through the grape vine that I will probably have to replace my calipers at the same time. Is there any truth to this, is there an issue with these calipers? Just recently bought my 2000 and am working through it bit by bit and this is my next little job. Any info that anyone had on this topic is greatly appreciated.

 

When I replaced rotors and pads all with AC Delco on all 4 corners I ended up with my rear brakes heating up and ruined a fresh set a pads. I found out from this forum that the Calipers are aluminum, Pistons are steel and brake fluid is Hygroscopic. (Absorbs Moisture) and on these vehicles it is recommended to replace the rear calipers at the same time as pads. In fact a co-worker is having the same problem with his 2000 Chevy Silverado replaced the rear pads and he is unable to get the pistons retracted in the rear calipers. He is going to try and bleed the fluid off but I suspect that it is corrosion. Do a search on this forum and you will see other posts. When I replaced my calipers I was not aware of that Phenolic or Steel pistons was a choice. So I just purchased a set of calipers and right now I do not know if I have steel or phenolic pistons in my rear brake calipers but my brakes work perfectly.

https://blazerforum.com/forum/2nd-ge...s-77770/page2/

 

Steel piston, aluminum caliper, cast iron caliper bracket, hygroscopic fluid, negative electrical charge, put 'em all together and you have corrosion big time. That's why calipers, guide pins, brackets, hardware, pads and rotors should all be replaced at the same time. Reman calipers with the brackets, pins & hardware kit, pads & rotors. If you cut corners, you will have problems with these brakes.


Steel & phenolic pistons are a toss up, both have good points & bad.

 

Right on, thanks guys. I will definitely do my homework before I start and have everything on hand to do the job only one time. Great information to have. I have done the front brakes on my 96 s-10 a bunch of times with none of these issues, but it has rear drums so I have not had the joy of replacing rear calipers YET.

 

Rear calipers are a breeze. Bleeding can cause a huge headache if not done correctly though. They must be gravity bled to expel the air. Don't pump the pedal! If the ABS unit, (EBCM) ingests even a little air, you will need to do the automated bleed using a capable scan tool.

 

Thanks Captain, I would just start at the furthest point from the master cylinder (Right Rear) then the left rear while gravity bleeding. Will that do a complete bleed or will I still have to do the old two person pump and bleed routine after to make sure all air is out?

 

If all you open are the rears, there's no reason to do the fronts. Doesn't matter which rear you do first. During the gravity bleed, leave the cover off and DON'T let the master run dry. After they are done gravity bleeding, (usually takes 5 or 10 minutes per wheel) no air bubbles.... close the bleeders, slowly pump and release the pedal until it's firm. Then you can bleed as normal. Usually only takes once, maybe two times at the most.