This problem has been happening g for a year since I got the Jeep. The front driver brake caliper wont release once it gets hot but will release when it cools down. I have replaced the pads, rotors, flex lines with stainless lines, calipers , freshly lu fixated everything that needs it, and there is a new used axle in the front , with all those changes the problem still is happening and it happens every time the brake heats up now , where it used to only happen every so often. Proportioning valve maybe? I have no clue, I’ve replaced everything that would cause the problem except for the valve, maybe the actual metal line running to the flex tube from the proportioning valve? Anyone with ideas please help, I need my car back because it’s my daily
Driver side front brake caliper won't release when hot
- Thread starter domfonts
- Start date
what do the ears on the knuckle look like, are they worn causing grooves and the surface the brake pads slide on?
I wire brushed them smooth and all clean again when I put the new pads on, they look aren’t unusually worn that would cause a problem I don’t think. I have the shims on the brake pads as well and those are lubricated with silicon grease, maybe the pads are expanding as they get hot and then staying stuck? I just thought it unusual because this happened with the old pads on the old axle and is happening with the new pads on the side axle
It only locks up when the brakes get hot ie: being used for 5-10 min and then once I let it sit and cool down it releases ...only the front left
That's a good question. If the brake releases at that time the fluid pressure was being held by something. Proportioning valve maybe?
If it doesn't release, it's just plain STUCK.
It can't be the proportioning valve for two reasons. The first is the proportioning is only done to the rear fluid circuit and the front circuit is just a T connection inside the combo block.That's a good question. If the brake releases at that time the fluid pressure was being held by something. Proportioning valve maybe?
If it doesn't release, it's just plain STUCK.
Normally if he hadn't replaced the lines, if you open the bleeder when it is stuck and it releases, that points to something upstream of the caliper piston. If it doesn't release, that points to the caliper piston.
I'd take a hard look at how tight the pads are shimmed on the sliders by pulling the shims as a test.
I never really realized how the proportioning valve achieved what it does. Thanks for that info.
It is simple and complex at the same time. There is a valve in the rear fluid circuit. The proportioning is controlled by the stiffness of the spring and the diameter of the plunger. There is a very odd little cup seal in the mix on the plunger. The cup seal has dimples around the base of it that rest on a flange on the plunger. It doesn't seal very well until the dimples are compressed by a sudden high pressure surge. The pic below shows the interior. What is missing that helps a bunch more is how the fluid path routes through and around the end of the plunger and seal at G since an end mill was used to do the cut away and expose the innards.
I will remove the shins to test, and thank you for confirming my beliefs with the proportion valve
Also, could the sensor where the plug coming off the wiring harness that plugs into the prop block have anything to do with this problem ?
It isn't a sensor, it is a simple plunger switch. It holds the shuttle valve in position until differential pressure is high enough to move the valve and limit flow to the other end.
Where is that located and how can I test that? And after the car sits a couple minutes that plunger switch would release allowing the caliper to then also release?
Try switch, which is what I explained it was. A simple plunger switch, not a sensor. It is not your problem.
Okay the caliper woidlnt release again and I cracked the bleeder valve and no fluid came out at all
The timing of this thread is convenient as I recently started to have this same issue. Driver side rotor was getting extremely hot, however it was pulling passenger when I would brake. Just this past weekend. I was supposed to go up about a two hour drive from where I live and about 30 minutes in I started smelling brake pads burning. I'd tap the brakes and it would pull passenger. Pulled over the I could feel the heat coming off the driver side caliper. I drove it home and decided I would have a shop take a look at it. It sat for a day since it was the weekend and when I drove it to the garage the issue was gone. They spent a couple hours taking everything apart and road testing it multiple times to try and replicate it with no luck. They couldn't find anything wrong with the calipers and everything went in smoothly. I got them to flush the brake fluid since it needed to be done and will see if the issue returns. They said if the issue returns to come straight back and they would dig deeper.
Edit: I was also driving the Jeep earlier that day for work and didn't have the issue on the shorter commute.
Edit: I was also driving the Jeep earlier that day for work and didn't have the issue on the shorter commute.