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Old 10-05-2015, 07:38 AM   #1
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Default Strange Brake Troubleshooting

So after a bunch of troubleshooting, i'm about to lose my mind --

I'm having an intermittent (heavy) brake drag on what seems to be all four corners. When it happens, its enough drag to actually stop the car from casual back/forward rolling on lights. Obviously, I can also tell that the car is slightly slowing in off throttle.

- Willwood F / Sports R
- Willwood Prop valve

When it happens:

- Problem seems totally intermittent
- Pedal gets a strange stiff no travel feeling. With the SS lines and other hardware.. the pedal, as it should is pretty stiff in the first place. However, this "stiff" is different than anything else I've felt. (Intermittent) ill roll up to a red light on the brakes and notice the pedal is "stiff weird" -- then I know its going to happen
- It seems to just go a way after a little bit... like it just randomly gets unstuck and releases
- No smells
- Started to happen recently

What I've checked:

- Hardware seems fine... no loose brackets or anything obliviously wrong
- Seems to happen through full range of adjustment (prop valve)
- No leaks - good fluid


From the beginning I've suspected the problem to have something to do with the prop valve. Also, everything I've known about brakes is telling me that it is a sticky slider or caliper.. However, that does not explain why other corners are simultaneously dragging.


Any help or ideas would be appreciated!
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Old 10-05-2015, 04:41 PM   #2
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I would suggest master cylinder if it seems to be related to all wheels. Put the car up on jack stands and spin them all by hand. If they move freely, crank the car and push the brakes a few times and see if it gets "weird". If it does, see if you can spin any of the wheels by hand. If they are all tight then master cylinder. If one, then caliper, if front or rear only then prop valve.

Alternatively, is is possible the prop valve could be plumbed backwards?
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Old 10-05-2015, 05:28 PM   #3
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when do you feel drag? is the car slowing itself? what do your pads look like? if you lift the car in the air, do you feel the drag when spinning the wheels?
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Old 10-05-2015, 07:24 PM   #4
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Quote:
Originally Posted by sixshooter View Post
I would suggest master cylinder if it seems to be related to all wheels. Put the car up on jack stands and spin them all by hand. If they move freely, crank the car and push the brakes a few times and see if it gets "weird". If it does, see if you can spin any of the wheels by hand. If they are all tight then master cylinder. If one, then caliper, if front or rear only then prop valve.

Alternatively, is is possible the prop valve could be plumbed backwards?
Thanks for the reply guys.


I got lucky and pulled into the driveway with the "weird" feeling.. Jacked up the car to find that all four wheels were dragging pretty significantly. Jabbed the pedal a few times... Handbrake.. Same deal.

Set the car back down (HB off) started chatting with my gf.. Few mins later I literally was watched as a ghost seemed to let off the HB as the car tried to escape my driveway.

I tried to jack up the car and recreate the problem.. Couldn't.


What do you mean master? and what do you mean front and back? If one corner is stuck, will it affect the whole front or rear side?


Ogracing: The car feels like I'm slightly holding the HB. Sorry it's a little difficult to explain. I can totally feel itself not freely rolling.. At stops and can hear a slight hollow whine when driving off (fighting the brakes).

I did laser the disks (as well as spit test) I'm not getting a single of rotor
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Old 10-05-2015, 08:01 PM   #5
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The master cylinder needs to come off and be disassembled and inspected or just replaced.
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Old 10-05-2015, 11:50 PM   #6
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ill try that tomorrow.
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Old 10-06-2015, 12:55 PM   #7
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if it's all 4 tires i'm looking at a faulty master cylinder.
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Old 10-07-2015, 08:04 AM   #8
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Yep, good call guys.

It was a combination of the master and alignment of my custom pedals.
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