- Feb 27, 2015
- 583
OK, i'm at a complete loss, about 8-9 weeks ago I replaced the entire front brake "system" (Pads, Rotors, Calipers, Caliper Mounting Bracket) using one of those Powerstop brand kits, everything was fine and appeared to be working fine, then a week or 2 after that I did the rear rotors and pads (just pressing the pistons in without pinching the line or opening the bleeder screw), this is when my issue started, I noticed my front brakes running much hotter, to the point even the driverside brake would smell of burning pad after hard braking and pulling to a stop.
Last Weekend I bled out the whole system starting at the passenger rear, driver rear, passenger front, driver front. this seams to have gotten the temperature of the passenger front down (I pointed a laser thermometer gun at the rotors shortly after driving and the rear rotors where around 134-140* F and the Passenger front was at 160ish and the Driver Front was at 204*) but as you can tell the driver front is still running hot, so I jacked up the truck and it was MUCH MUCH harder to spin the driver front wheel then the passenger front wheel.
Fast forward to today, First thing I wanted to rule out was a bad brake hose not letting the fluid back to the master cylinder, to that end I perform the test I've seen suggested, Pump the brakes so that you can't spin the rotor by hand, crack the bleeder valve and if you can spin the rotor then your problem is in the rubber hose, well I cracked the bleeder and NOPE, still impossible to turn the rotor by hand (which I kinda doubted it was the rubber hose because I replaced all of those after I had a rear caliper seize up in February of 2021). So next thing I do is start testing different scenarios on the caliper, I remove the slide pin bolts and start pulling off the caliper, at this point I notice the lower piston feels harder to slide off the pads, so that inspires me to test something, so I angle the caliper so that only the upper piston of the caliper is making contact with the pad, at this point with only that piston over the pads I can spin the rotor by hand (not as easily if there was no caliper but it will move), then I angle the caliper so the lower piston is on the pads and not the upper, rotor then won't turn. So I then assume the possibility of a frozen piston on this caliper and decide to try some things, I use my C-Clamp to hold the upper piston from moving then step on the brakes causing the lower piston to extend (as it should), I then press the lower piston back into the caliper using the c-clamp, which it compresses as expected for a good piston that isn't binding up, so the piston appears to be functioning as expected when the pedal is depressed and when pressing in the piston (like you where installing new pads). At this point I assume there is an issue with the caliper and decide to swap back in the caliper I removed when I did the brake upgrade 8-9 weeks ago, only problem is this Caliper is behaving EXACTLY THE SAME, same lower piston making rotor not spin, same upper piston allows rotor to spin, all the same behavior I described of the new caliper is happening with the old caliper, even the cracking the bleeder and still not being able to turn the rotor
I'm at a complete loss of what to try next, the slide pins aren't frozen up, they both move freely, I went ahead and re-greased them just to be safe at the beginning of today's troubleshooting. It doesn't make any sense to me that 2 different calipers would behave exactly the same and releasing the bleeder screw should rule out pressure being held on the brake due to an issue in the brake lines.
Last Weekend I bled out the whole system starting at the passenger rear, driver rear, passenger front, driver front. this seams to have gotten the temperature of the passenger front down (I pointed a laser thermometer gun at the rotors shortly after driving and the rear rotors where around 134-140* F and the Passenger front was at 160ish and the Driver Front was at 204*) but as you can tell the driver front is still running hot, so I jacked up the truck and it was MUCH MUCH harder to spin the driver front wheel then the passenger front wheel.
Fast forward to today, First thing I wanted to rule out was a bad brake hose not letting the fluid back to the master cylinder, to that end I perform the test I've seen suggested, Pump the brakes so that you can't spin the rotor by hand, crack the bleeder valve and if you can spin the rotor then your problem is in the rubber hose, well I cracked the bleeder and NOPE, still impossible to turn the rotor by hand (which I kinda doubted it was the rubber hose because I replaced all of those after I had a rear caliper seize up in February of 2021). So next thing I do is start testing different scenarios on the caliper, I remove the slide pin bolts and start pulling off the caliper, at this point I notice the lower piston feels harder to slide off the pads, so that inspires me to test something, so I angle the caliper so that only the upper piston of the caliper is making contact with the pad, at this point with only that piston over the pads I can spin the rotor by hand (not as easily if there was no caliper but it will move), then I angle the caliper so the lower piston is on the pads and not the upper, rotor then won't turn. So I then assume the possibility of a frozen piston on this caliper and decide to try some things, I use my C-Clamp to hold the upper piston from moving then step on the brakes causing the lower piston to extend (as it should), I then press the lower piston back into the caliper using the c-clamp, which it compresses as expected for a good piston that isn't binding up, so the piston appears to be functioning as expected when the pedal is depressed and when pressing in the piston (like you where installing new pads). At this point I assume there is an issue with the caliper and decide to swap back in the caliper I removed when I did the brake upgrade 8-9 weeks ago, only problem is this Caliper is behaving EXACTLY THE SAME, same lower piston making rotor not spin, same upper piston allows rotor to spin, all the same behavior I described of the new caliper is happening with the old caliper, even the cracking the bleeder and still not being able to turn the rotor
I'm at a complete loss of what to try next, the slide pins aren't frozen up, they both move freely, I went ahead and re-greased them just to be safe at the beginning of today's troubleshooting. It doesn't make any sense to me that 2 different calipers would behave exactly the same and releasing the bleeder screw should rule out pressure being held on the brake due to an issue in the brake lines.