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Discussion Starter #1
I've been using this forum for the past 3 years since I got my truck and it has been so helpful. Well, finally I have something that I can't figure out from past posts and had to ask myself.

My front driver's side brakes are dragging. Not a lot, but noticeably enough that after a long ride it is much hotter than the other side. I jacked up the truck and that tire is hard to turn by hand. The other spins very easily.

Took off the caliper and one of the pistons was very difficult to compress. I believe this was bad, and I replaced the caliper. Both pistons in the new caliper are easy to compress. I installed all the new hardware that came with the caliper, new pins, boots, and bolts. Put everything back together, bled the brakes, took a ride. Came back, jacked it up, still very hard to turn by hand.

Next I replaced the rubber brake hose to the caliper thinking it collapsed. Put everything back together, bled the brakes, took a ride. Jacked up the truck and its STILL hard to turn the tire.

Did some more diagnosing and it makes zero sense. If I open the bleeder valve, it comes out as I would expect. The caliper does not loosen its grip on the wheel. If I totally disconnect the rubber hose, it does not loosen its grip either, so I don't believe it is a problem with the master cylinder. If I remove the caliper, I can compress both pistons as easily as it should be, they seem normal. And once the caliper is off, or compressed, the tire spins very easily, so I don't believe it could be the wheel bearing.

So what the heck could it be??? For some reason the caliper is keeping a tight grip on the rotor no matter what, unless I remove the caliper and compress it by hand. And disconnecting the brake line does nothing. I've replaced everything on the wheel itself now except the rotor and pads, but I don't see how those could cause this problem. Maybe I am wrong?

Any help is appreciated!!!
 

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Retired and Sleeping Late
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Oops, answered my original question after I posted.

Maybe a bad caliper or you didn't get all the air out of the caliper when you bled it? I haven't been under my truck in a while, is the bleeder at the very top of the caliper? Maybe try taking the caliper off and bleeding it that way, with something like a piece of wood the same thickness as the rotor? That way you could have the bleeder at the very top point and be sure there are no air bubbles hanging out inside either the hose or the caliper.

Also, are you using the old mounting hardware? Maybe the slide pins are worn out on one side?
 

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Discussion Starter #4
Thanks for the replies.

I replaced all the hardware with the new caliper. I bled it as best as I could. The pedal firmness feels right, so I think it is pretty good. Would air in the system cause it to not retract? I would expect the opposite.

I would agree with you Cart. It seems like the pins are the only possible thing. That's what I was thinking before you posted, so I went and took it all apart again. I cleaned out the holes the pins go into and the pins. I then tried it with no lube anywhere so it there was no resistance in the holes. That didn't work. Then I took apart and lubed them and tried, still the same. That caliper is grabbed onto the rotor and it is so hard to spin! But since the pistons can be compressed with normal pressure with a clamp it seems so weird.

The one thing I wish I tried was replacing the new pin with the rubber tip at the end with the old one that has no rubber tip (so it would be two plain steel pins, not a plain and rubber tipped) and see if that changed anything. The pin with the rubber tip is tough to pull, but not that tough. But maybe? I will probably try that in the morning if I don't get any other ideas.

Thanks.
 

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Is there any type of proportioning valve for the front wheels individually? Usually it's front/rear only but who knows.

Is there part of the ABS system that needs bled independently of the calipers/wheel cylinders?

I am not familiar enough with the braking system to know what would disallow fluid not to have relieved pressure. Nor do I own a repair manual that may indicate how the braking system works.
 

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Discussion Starter #7
I was also wondering if there is something with the ABS system that could affect this. I haven't been able to dig anything up, I'd be really interested if anyone knew of something ABS related.
 

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Bleed it at the banjo fitting not the bleeder valve. Sometimes the bleeder valve doesn't work good enough when you have a new caliper.

Do it a few times as well.
 

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I read something on here about having to do something to bleed the ABS but iirc that was only needed when replacing the master cylinder???
 
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Hi mattyd7,

I am sorry to hear that you have a vehicle concern. I understand that you are looking to resolve this issue yourself. I might not be able to provide you with any do-it-yourself advice but if you find that you do have some lingering questions or concerns please contact me via private message.

Jennifer T.
GM Customer Care
 

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Couple more questions.

Are the calipers new or rebuilt? If they're rebuilt maybe the guide holes are out of spec. As for the guide pins, if the OEM one had a rubber tip, there had to be a good reason for it.

Also, are the pads new or used? Sounds like something is causing one of the pistons to not retract. Maybe an unequally worn set of shoes?

Also, air still in the system could keep residual pressure even after the brake pedal is released. Air will act like a spring, compressing when you hit the brakes and attempt to equalize pressure once it's released.
 
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