View Full Version : Wilwood brakes dragging intermittently
I'm planning to get into troubleshooting tomorrow, but I was curious what the experts thought I should be looking at most closely. I have Wilwoods on my roadster, with about 2000 miles now, and the brakes were great until recently. I replaced the rear MC after a bypass failure, and again, perfect functionality for ~ a hundred miles. Recently I have felt dragging brakes, and a very very stiff pedal. It is intermittent. After the first time this happened, I let the car sit a few days, and when I drove it next I found the pedal was a little squishy as if it needed a re-bleed. Yesterday the pedal felt normal for 20 miles, no squishy-ness, then it crossed over into dragging again with a very firm pedal. Perhaps with heat, as it is worse after the car has been driven a bit. Essentially the pedal won't move more than a tiny bit, the brakes are already engaged; not locked, but definitely dragging. When I parked yesterday all of the rotors were pretty hot, seemed like I could detect a hint of brake pad smell and a bit more heat at the DS front. That's all I know right now. What do you think is happening? I'm not driving it again until I solve this.
I'm thinking: Check brake fluid levels, of course, and check the garage floor and brake line fittings for leaks. Get it up on jack stands, check fronts and rears for dragging. Remove 4 wheels (or just 2 if its obviously fronts versus backs that are dragging or squishy (balance bar deflection should reveal that) and check brake pads, calipers & mounts, rotor alignment, look for anything funny or loose, or tight. Look for a kinked flex line, or any issues/damage with the hard lines. Anything come to mind as a likely culprit? - Alec
Railroad
09-20-2024, 01:06 PM
I do not think any of the things you listed will be the issue.
I would check the length of the master cylinder push rod you recently installed.
I suspect it is too long and with balance rod pivot, it is pressing on the other master cylinder.
I would make sure you have free play in both master cylinder push rods and the pedal is coming back up completely.
I have heard of brakes being so hot, they can boil the fluid in the calipers. I have never encountered it, but it could create a soft pedal.
Good luck,
I do not think any of the things you listed will be the issue.
I would check the length of the master cylinder push rod you recently installed.
I suspect it is too long and with balance rod pivot, it is pressing on the other master cylinder.
I would make sure you have free play in both master cylinder push rods and the pedal is coming back up completely.
I have heard of brakes being so hot, they can boil the fluid in the calipers. I have never encountered it, but it could create a soft pedal.
Good luck,
Ok, I will take a look at the pushrod length of the replacement MC. Makes sense that the new problem would be related to the old one. Was I supposed to trim those pushrods down, I seem to remember something about that during original assembly. So help me understand: if it is a mechanical issue like that, how is the problem intermittent? As the caliper heats up due to friction, how does that exacerbate the dragging versus what you suggested, that heat causes boiling and
brake fade? I'm getting brake fade later after it cools down. The heat is associated with the brake locking. Just curious
Railroad
09-20-2024, 06:14 PM
I did have to trim the push rods on both of my Wilwood MC's.
You had better google it or wait for someone to chime in, with my memory.
Just see what you find on the rods first. Brakes heating up will do many things. Many of them dependent on relevant factors.
good luck,
coyobra
09-20-2024, 06:50 PM
I'm planning to get into troubleshooting tomorrow, but I was curious what the experts thought I should be looking at most closely. I have Wilwoods on my roadster, with about 2000 miles now, and the brakes were great until recently. I replaced the rear MC after a bypass failure, and again, perfect functionality for ~ a hundred miles. Recently I have felt dragging brakes, and a very very stiff pedal. It is intermittent. After the first time this happened, I let the car sit a few days, and when I drove it next I found the pedal was a little squishy as if it needed a re-bleed. Yesterday the pedal felt normal for 20 miles, no squishy-ness, then it crossed over into dragging again with a very firm pedal. Perhaps with heat, as it is worse after the car has been driven a bit. Essentially the pedal won't move more than a tiny bit, the brakes are already engaged; not locked, but definitely dragging. When I parked yesterday all of the rotors were pretty hot, seemed like I could detect a hint of brake pad smell and a bit more heat at the DS front. That's all I know right now. What do you think is happening? I'm not driving it again until I solve this.
I'm thinking: Check brake fluid levels, of course, and check the garage floor and brake line fittings for leaks. Get it up on jack stands, check fronts and rears for dragging. Remove 4 wheels (or just 2 if its obviously fronts versus backs that are dragging or squishy (balance bar deflection should reveal that) and check brake pads, calipers & mounts, rotor alignment, look for anything funny or loose, or tight. Look for a kinked flex line, or any issues/damage with the hard lines. Anything come to mind as a likely culprit? - Alec
Did you bench bleed before bleeding the 4 corners?
michael everson
09-21-2024, 06:16 AM
You need to cut 5/8 off each push rod. The problem may be that the pedal is not returning to rest due to a long push rod. pull the pedal back and make sure its not resting against the 3/4 tube in front of the brake pedal.
Mike
It's not the pushrod. I did trim it. The front brake mc is leaking, so this is failure #2. Rear mc was rebuilt and returned to me, so i can swap it in now to replace the front. But I don't know why either one failed. Hopefully Wilwood can provide some answers.
Mike.Bray
09-21-2024, 01:23 PM
It's not the pushrod. I did trim it. The front brake mc is leaking, so this is failure #2. Rear mc was rebuilt and returned to me, so i can swap it in now to replace the front. But I don't know why either one failed. Hopefully Wilwood can provide some answers.
Time to scrap those crappy Wilwoods and get some Tilton master cylinders. Way too many failures on the Wilwoods.
https://thefactoryfiveforum.com/showthread.php?49560-Swapping-Tilton-MC-for-Wilwood-MC
J R Jones
09-21-2024, 01:43 PM
Alec,
Hard pedal and dragging brakes are not symptoms of leaking master cylinder. Mechanical linkage issues are likely beyond the hydraulics.
jim
CraigS
09-21-2024, 02:21 PM
I am seeing more and more threads about problems w/ Wilwood MCs.
Mike.Bray
09-21-2024, 03:51 PM
I am seeing more and more threads about problems w/ Wilwood MCs.
It's not a coincidence.
Alec,
Hard pedal and dragging brakes are not symptoms of leaking master cylinder. Mechanical linkage issues are likely beyond the hydraulics.
jim
Failure to release pressure (or very slow release) can indeed be a failure of the MC. This is happening on both sides, so it's not a caliper sticking. The leak I found at the boot is likely another symptom of the same failure. we will see when I swap the MC if the problem goes away for good. I agree it's more common to have a soft pedal, but a hard pedal and brake drag can be the MC as well.my guess is that id I didn't fix it soon it would progress to a total failure and a very soft pedal.