Sticky-piston - Can I Fix It?

[CLTGS300]

1999 GS-300

98,000 miles

I'm having a Toyota dealer replace my timing belt and water pump for $600, so my funds for new rotors and pads are limited...ergo, I want to install them myself. I'll get the parts from lexus-parts.com...so no worries there.

My question is that last year when I had my pads replaced for the first time, the mechanic noticed that on my rear brakes, the inner pads were hardly worn down at all, while my exterior pads were really worn down. He said that my piston was sticking, but since I couldn't afford to do anything about it at the time, I just let it stay that way.

Now my rear rotors have warped (propably from uneven heat due to uneven friction with only one pad touching) and I am going to replace the fronts as well. I know how to replace the pads and the rotors, but what can I do about this sticky-piston issue? Can I bleed the brake lines on my own and clean out the hoses and around the piston to fix the problem? Any advice is much appreciated.

[SRK]

It is probably not a sticky caliper piston. More than likely it is one or both of the slider pins the floating caliper "floats" on. If you remove the caliper you'll notice quickly if the pins are stuck - you'll have trouble removing it. Cleaned up with a bit of new high temp grease and it will be as good as new.

If BOTH pads are thin compared to the other side, it's a piston. One means the sliders.

For both caliper's pistons to stick - I doubt it. Check the sliders. It's also quite normal for one pad or the other to wear slightly faster and to see a difference after thousands of miles is no big deal.

[CLTGS300]

Would it be bad if I used new rotors from NAPA (the brand is United)?

[GuyTelefunken]

Rear GS calipers are not the floating variety. There is a piston on each side of this fixed caliper. The best advice would be to replace the caliper with a remanufactured unit. They are readily available. NAPA parts should be fine.

As for rotors, the only caution is to check that the clearance groove on the back side of the rotor does not rub the back pan when the rotor is installed. The pan is the round plate that the parking brake assembly is mounted on. It has a slight edge the fits into the groove on the back of the rotor. The purpose of this pan is to keep road crap out of the parking brake system inside the rotor hat. I have had trouble with several brands of aftermarket rotors not being made correctly. Consequently, when the wheel is mounted, the pan can contact the rotor and create metal to metal rubbing sound. In one case, I the groove was so shallow, I could not turn the mounted wheel at all. If you experience a problem, just return them and try another brand.

Don't forget to bleed the brakes if you replace the caliper. The parking brake shoes also have to be adjusted after replacing the rotor. The service manual shows the procedures in detail.

[Mosh]

Rear GS calipers are not the floating variety. There is a piston on each side of this fixed caliper. The best advice would be to replace the caliper with a remanufactured unit. They are readily available. NAPA parts should be fine.

As for rotors, the only caution is to check that the clearance groove on the back side of the rotor does not rub the back pan when the rotor is installed. The pan is the round plate that the parking brake assembly is mounted on. It has a slight edge the fits into the groove on the back of the rotor. The purpose of this pan is to keep road crap out of the parking brake system inside the rotor hat. I have had trouble with several brands of aftermarket rotors not being made correctly. Consequently, when the wheel is mounted, the pan can contact the rotor and create metal to metal rubbing sound. In one case, I the groove was so shallow, I could not turn the mounted wheel at all. If you experience a problem, just return them and try another brand.

Don't forget to bleed the brakes if you replace the caliper. The parking brake shoes also have to be adjusted after replacing the rotor. The service manual shows the procedures in detail.

RockAutoParts has rear calipers for just under $60 a piece, made by A-1 CARDONE, and rear rotors for under $20 a piece, made by Raybestos. I have bought many parts from them, and they are outstanding. Oh, and rear pads, also by Raybestos, are under $20 as well. Hope this helps you out. www.rockautoparts.com

[GuyTelefunken]

RockAutoParts has rear calipers for just under $60 a piece, made by A-1 CARDONE, and rear rotors for under $20 a piece, made by Raybestos. I have bought many parts from them, and they are outstanding. Oh, and rear pads, also by Raybestos, are under $20 as well. Hope this helps you out. www.rockautoparts.com

I also like Cardone products. A set of their rebuilt front calipers have been working for me for years. The national Carquest chain carries Cardone and cheap rotors. Raybestos is good as well.