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Discussion Starter #1
I have a 2006 g6 gt 3.5l coupe. On occasion, when there is snow I will lift my handbrake and slide my car. One day out of the blue I tried to do this and it wouldnt slide. Figured out that the handbrake was not working on the left rear wheel. I took it to the shop and they replaced my caliper. Still didnt work. Brought it back, they replaced the caliper again. Still doesnt work so I've given up hope for that mechanic. The mechanic did say that when the handbrake is lifted, he can see the cable and the mechanism on the caliper move properly. I cannot confirm this however. Both wheels seem to lock up the first time I lift the handbrake after getting the caliper replaced but then the second time I lift it, only the one wheel locks up. I've seen posts saying that the handbrake probably froze because it wasnt being used but I lifted my handbrake every time I parked the car. I'm stumped, my mechanic is stumped so if anyone could tell me what is going on, that would be great.
 

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I had the same problem when I bought my 9 year old G6. I found that whoever replaced the pads did not orient the caliper piston slot properly to engage the little tit on the backside of the pad on one side. All I had to do was properly line up the piston and everything was fine. I find it hard to believe that a professional mechanic would make such a mistake though.
 

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Discussion Starter #3
I had the same problem when I bought my 9 year old G6. I found that whoever replaced the pads did not orient the caliper piston slot properly to engage the little tit on the backside of the pad on one side. All I had to do was properly line up the piston and everything was fine. I find it hard to believe that a professional mechanic would make such a mistake though.
That would cause it to fail after working perfectly for months? Because it didnt fail until probably 6 months or so after I had my brakes done.
 

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No...if the problem is not properly aligned piston, that wheel would not operate from the get go.
The piston spins up to two full rotations during the course of the life of a set of pads. There is no proper pad alignment to caliper.

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Huh ? There are 2 notches carved into the caliper piston. The notches will line themselves up, vertically, with the piston fully rotated into the caliper. You still need to make sure the notches line up vertically. there is a tit on the pad that fits into the notch. When applying the hand brake, that piston with the notches does NOT spin. The outer piston, the one that operates the hydraulic brakes, is what turns and pushes that inner piston out when you apply the parking brake. There are actually two pistons in the rear caliper. The outer one that is used for the hydraulic foot brakes and the inner piston (the one that you can actually see) that operates the parking brake.
 

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Dan, you are correct and I am not in the piston spinning, my error; but as for lining up the pad?
The brake hardware provides alignment.
The three sets of rear GM pads didn't have alignment nibs and do/did the job perfectly.
The Service Manual makes no mention of alignment nibs.
I don't know the cause of the OP issue, but doubt highly that it is a result of installation error on the pad/caliper interface.

It does make me wonder though if the hardware is clean and lubricated, but more so, if the pins are sliding/floating as intended in the caliper bracket. Those can get sticky and notchy, if not straight out stuck.

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The rear pad....the one with the pad wear sensor flat spring thingy, Has a little tit in the upper center right between the two rivets. Assuming all pad sets use rivets. The rivets lay on the outside of the piston. The tit in the center needs to go into the upper notch of the piston. If the rear pad sets you are getting from GM lack that little tit, they are faulty. I learned how this type of caliper, with the screw style parking brake, work when I buggered up a rear caliper on my 1988 Honda Prelude. Yes...I agree, this would not apply to the OP problem because he would have had the problem immediately after the brake job was performed.
 

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Hmm, this may be one of those things that you just 'do' and don't think about, 'cuz I can't recall those. Fair enough.
Like you said, any alignment would have shown right away.

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When one of mine was misaligned I ended up with a wear pattern that looks a little like the left and right pad edges but from top to bottom. I park on a flat surface at home and at work so unlikely I would have noticed any parking brake issues.
 

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The orientation of the piston is usually not discussed because if you fully screw in the piston the notches will be arranged properly. However, screwing in the piston can be a chore without the fancy tool designed for the purpose. After you feel that you have completely screwed in the piston, you still need to make sure those notches are aligned vertically inside the caliper. Hoping this thread has saved a few problems for those who change their own brake pads.
 

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Discussion Starter #13
I'm wondering now if my original problem was a frozen caliper and then when my mechanic replaced the caliper, it wasnt put in properly. When I get out of work, I'll have to check it out. Thank you all very much for the help. I hope I can fix it.
 
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