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Thread: anybody out there has problems with Wilwood master cylinder?

  1. #1

    anybody out there has problems with Wilwood master cylinder?

    Hello, ppl out there, this is Shawn Baek studying automotive engineering at Kookmin University in South Korea.

    I'm in charge of pedal box and brake system for 2014 F-SAE Michigan. but currently i have some problems with master cylinder.

    I set up master cylinders which i bought from Wilwood to our car and finished bleeding the brake system.

    after test driving, i checked if there was any oil leak from the master cylinders and i noticed the brake oil was leaking along the push rod!!!!

    it shouldn't happen but it actually did..............

    so i switched it to the new one and it ended up happening again.

    I'm kinda frustrated now and there is no one around me knowing the answer.

    that's why i'm posting this now.

    does anybody here know what the problem is and why it happened?

    BTW, the push rod is being actuated at no angle.

    Thank you for reading this and I wish all the best for your team!

  2. #2
    Senior Member
    Join Date
    Jun 2007
    Perth Western Australia
    What type of fluid are you using?

  3. #3
    Brake fluid should not leak at all out the back of the master cylinder. However if this is a new system, it could just be a bit of oil from assembly and bleeding. Wipe it off and check again.
    University of Tasmania (UTAS)

  4. #4
    Pete Marsh, Bosch brake fluid DOT4

  5. #5
    Jonny Rochester, I did, and it happened again. it didn't come out as much as it did at first. but the oil slightly leaks.

  6. #6
    Senior Member
    Join Date
    Nov 2010
    NSW, Australia
    Are you stamping ridiculously hard on the pedal and going beyond the maximum recommended load on the M/C? I imagine other components in the system would fail before this but I guess it's something to consider. Your pedal ratio might be incorrect, so perhaps try a lower ratio and see if it happens again?

    Have you actually had a close look and seen the fluid leak out along the pushrod under use? If not make sure you wear safety glasses when checking

    UoW FSAE '07-'09

  7. #7
    Put up a photobucket pic if you can.
    As above, is your pedal ratio similar to a bought Wilwood brake pedal or passenger car?
    Is your pushrod to the master on a crazy angle?
    University of Tasmania (UTAS)

  8. #8
    You should be able to pull the rubber dust boot off the front of the master cylinder so you can see where the brake piston rod goes into the seals. Then have a team member push hard on the brake pedal and hold it, and you watch and see if you can see fluid weeping out from the seals, or from the pressure outlet fittings, or something like that.

    Are these used cylinders, or new ones?

    Northwestern Formula Racing Alum
    Head Engineer, Frame/Suspension 2006-2009

    My '73 Saab 99 Road Race Build

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