hey pacNW friends.

I posted this on the Under the Hood section, and so far I have one response. I know some of you PacNW people are very mechanically inclined, so I was hoping for some help.

I was changing my rear pads and I noticed the inside pad on the driver side was much thicker than the outside. The rear passenger pads had nearly even wear inside and out.

I tried using a brake piston reset tool to push/twist the piston in and it didn't move. My buddy immediately said the piston had seized. I tried and tried again, and finally got it to move. The weird part is once it got moving there was the regular resistance. Now I have new pads on and the pistons are all reset.

My questions are:

1) how did this happen?

2) how do I prevent this from happening again?

My buddy did say that a new caliper may be in order. But he also mentioned that this shouldn't happen for a 2003 car.

Any input would be appreciated.

oh...and another question... I know my old OEM and racing pads both had this little notch on the back of the brake pad. I was told that notch was to be aligned into the cross of the piston. The new set that I got did not have it. Is that going to be a problem?

 

Yes, missing that little stud is going to be a problem. It is part of the auto-adjust feature of the parking brakes.

Most likely what happened is that the pins that the caliper slide on got stuck.

 

oh crap...that sucks...means i got to get an extra set of pads.

I checked the pins and they were moving fine. it's weird that the piston would get stuck

 

Well it's too hard to diagnose based on just your description. I guess you need to watch it carefully.

 

I've read other brake changing threads and some people have reported stubborn caliber pistons.

When I did my brake job, the caliber pistons just needed a little jump start and then it was easier to rotate.

 

Mike, can you explain that a bit more. How is the pin necessary for the auto-adjust feature?

Thanks.
- Michael

 

..... keeps the piston clocked since the hand brake uses a rotational action to apply it's pressure. Realistically, the missing pin shouldn't be a problem since the threads are at a shallow enough angle (well below the angle of repose) that back driving of the mechanism from the hydraulic system is unlikely. However, if you find your hand brake getting way out of adjustment or the rear caliper binding, you might be inclined to off those POS pads.
BTW, What ghetto a$$ pads did you buy that didn't have the pin?

BTW2, Stuck piston would not wear the pads as described ......... your problem is binding of the slide pins (like Mike said, I think ) that transmit clamping load to the floating side (outside) pad. Yours were is exactly backwards from a binding piston problem. Grease up the pins, yours was not releasing properly

 

I'm not sure exactly how it works. I think that there is aome sort of threaded pawl mechanism in there. The pin keeps the piston from rotating, which means the threaded mechanism does rotate relative to the piston.

When you back it out to change pads, you turn the piston and that backs off the threaded mechanism.

At least, that seems like how it must work. I've never taken it apart to look at it.

Anyway, if the piston is free to rotate then I expect the parking brake will get looser and looser on that side.

 

Thanks Ray, thanks Mike. It all makes sense.

I'm pretty sure my current race pads have the pin (R4, wait, no, got cobalt now). But I had a set in the past that was sans pin. Think it was the ghetto Brakeman pads.

- Michael

 

aaaaahhhh zeeee brakeman #3's .....