Brakes Sticking...Then Not

askiles

Goblin Guru
So I drove around quite a bit today. It was pretty hot. Too hot for normal driving. LOL Everything was going great, then I noticed at a light on a slight slope, the car wasn't rolling backwards. I get home, and I can't push the car back and forth freely. One of the calipers had hung up somehow. I went about my business, going to get back to it later today, the car has cooled down, and now it rolls just fine. Do you think I may just have some more air in the system that needs bled more?? I bled the crap out of the brakes, and they work wonderful. Could this be a fluke?? Any and all guesses are accepted... LOL Thanks!!
 

Ross

Goblin Guru
Your guess (air in the brake system) sounds reasonable to me. Any softness in pedal feel?
I vacuum bled all 4 calipers, and still had a soft pedal. Then I re-bled the system using the brake pedal to push the brake fluid, and got some air out that way. Now it has a good solid pedal feel.
 

askiles

Goblin Guru
Your guess (air in the brake system) sounds reasonable to me. Any softness in pedal feel?
I vacuum bled all 4 calipers, and still had a soft pedal. Then I re-bled the system using the brake pedal to push the brake fluid, and got some air out that way. Now it has a good solid pedal feel.
I first did the brakes with a pressure bleeder. Then I did it semi the old fashioned way, pressing the brakes, but I have speed bleeders in all 4 corners so it’s quick and easy to do that way. I went around the car like 4 times doing that until each time there was no air. I wouldn’t say the pedal feels soft at all. It feels great. Nice and easy when the power is on, nice and firm when it is off.
 

askiles

Goblin Guru
I also went and drove it around again this afternoon, no issues with the brakes at all. I hate intermittent problems.
 

ctuinstra

Goblin Guru
Okay, I bet I know what this one is! We had this same issue with both builds but the second time I already knew the fix.

Ours started with the brakes were hard to bleed because I just couldn't get fluid to want to flow through the system. Then we noticed the brakes not completely letting go but if you let the car sit they would be fine again. Sometimes it would be days between issues but every now and then they would stick again and all the brakes rotor would start to get hot.

It ends up being the pedal is not allowed to release the brake all the way. The distance between the pedal box and the MC is too close and when the pedal is out, it's still holding a slight pressure on the MC and not opening up the internal ports in the MC. This is why we were having problems pushing fluid through the system to bleed it. It also keeps the pressure from releasing.

The easy fix is to bend the pedal stop to allow it to release more. The pedal stop is basically the push switches for the brake lights. Bend the mounting tab on the switches to open the gap and allow more space for the pedal to release.

I believe I posted about this in our build, I'll have see if I can find it. I don't know if I had pictures or not.
 

ctuinstra

Goblin Guru
If it does it again, just use your foot to pull up and back on the brake pedal to see if it releases the brakes. If so, then adjust the switch brackets.
 

askiles

Goblin Guru
So it did it pretty consistently when I drove it. Last night I pulled the wheel and caliper, and it seems the piston was kind of stuck. I am wondering if I have a slightly defective caliper where the piston doesn’t move as freely as it needs to. I pushed the caliper in with a caliper piston tool, and now it won’t really brake. I have to deal with it later this afternoon but as of right now I am not getting any fluid out of the bleeder screw when I try and bleed it. That wasn’t happening until I pressed the piston back in. Ohhhhhh the problems. Lmao. What is a car build without them??
 

George

Goblin Guru
Yes, some times the inner wall get damaged, it will swell up internally and block the fluid return. after a while it will bleed off. Is it a rubber hose or a stainless steel?

Brad
 

ctuinstra

Goblin Guru
I didn't realize that you were having an issue with only one wheel.

It could be something (debris) caught in the line either in the hose, connections, or caliper itself. That could be fun to get out. You will have to open it up and flush it out.
 

ctuinstra

Goblin Guru
Brad is correct, especially if the hoses are kinked or allowed to carry the weight of the caliper, or just plain getting old.

We opted for the SS lines. Not only do they look better, they don't balloon as much under pressure and give a more solid pedal feel.
 

askiles

Goblin Guru
I have brand new SS lines from DF.

Yes, it turns out it is just the driver's side rear caliper giving me issues. I jacked up the car and it was the only one not turning freely. I then pulled that caliper off, and pressed the piston in a bit so that it would go back on the caliper bracket and over the brake pads easily. Then I went to bleed it, and no fluid is coming out of the bleeder screw. I will pull the bleeder screw this afternoon and see if fluid comes out.

I have a feeling something is catching the piston up, where it still works, but not 100% properly. It would work for a bit, and then start catching. If I let the car sit for a bit, it eventually rolls freely. I bled it before I pressed the piston back in, and it was bleeding fine, with no air coming out. But of course the piston was stuck out.
 

askiles

Goblin Guru
I removed the caliper and tore into it s bit, the piston is froze. I can’t get it to move either way. I am going to replace it, and that should fix the issue.
 

Briann1177

Goblin Guru
It could also be that the seal is wonky. But yeah, I'd replace the caliper too just to make sure. Sucks if you already have them powder coated.
 

Desert Sasqwatch

Goblin Guru
Andy, air pressure can help you remove the piston, just be careful as you can make a cannon out of the piston. Then you can check the seal and piston.
 

askiles

Goblin Guru
I replaced the caliper, bled the system again, all is well. I’ll contact DF and hopefully they can replace the caliper for me...
 
Top