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Thread: brake help

  1. Default brake help

    hi guys n girls

    can some please enlighten me as to why my pedal starts sinking to the floor when driving hard?? when it sinks, drive slow for a bit and pedal travel is normal again. drive hard and then same stuff happens over again! very annoying.

    now, here is what i have done to my car.
    rotors : replaced with cross drilled and slotted
    pads : remsa - sold to me by gsl rallysport
    brake fluid : penrite sin600 / penrite brake fluid racing - sold by gsl rallysport
    master cylinder : replaced with brand new oem
    brake bleed : done to all 4 wheels; not done to abs or clutch

    note: i had this issue before replacing the master clyinder too

    oops this post is in the wrong section; can someone pelase move it thanks.
    Last edited by dar_vedar; 04-10-2012 at 08:46 AM.

  2. #2

    Default brake help

    If your fluid is topped up I'd say you need to bleed it again.

    Does it increase pressure if you 'pump up' the pedal with the engine on? If so - air in the brake system. Re-bleed.



    Or vacc leak to master cylinder but unlikely.....

    Other thing - which I have been told is not the case with MPS - but on a previous car because the abs distribution block was quite high up and has no bleed valve, if you drain the system you can't get the air out of that block no matter how many times you bleed at the caliper. Has to be 'pressure bled' professionally.

    That gives you a bit to work with! Good luck!

    @Redjinn had this problem - try find his thread.
    Last edited by SMOKEY; 04-10-2012 at 09:06 AM.

  3. Default

    if i pump the pedal while its spongy, it doesnt firm up - this is while driving.
    but once it cools, its back to normal

  4. #4
    Join Date
    Apr 2010
    Location
    Canberra
    Posts
    9,459

    Default Re: brake help

    Possibly Get better brake fluid...
    Happens to anyone who uses brakes hard...

    @Reedy and myself on the track
    @LittleredMPS on a cruise
    Only way around it is a full brake system upgrade

    Sent from my Galaxy Nexus using Tapatalk 2

  5. Default

    what fluid do you guys use??
    and yes you are correct. this does happen to me when i am on a cruise which is normally every week! @Reedy @LittleredMPS what do you guys use??

  6. #6

    Default brake help

    He's got good fluid.

    Shouldn't be heating it enough to boil on the street anyway unless you drive like an absolute maniac :-p

    I'd just duck in and have a chat to a brake specialist.

    Brakes are not something you want to take chances with.

  7. Default

    exactly. @SMOKEY you know any decent brake specialists??

  8. #8

    Default brake help

    No sorry mate - not sure where you're located either: just go to a brakes plus or something.

  9. #9
    Join Date
    May 2010
    Location
    Sydney
    Posts
    2,600

    Default

    I use Penrite Sin brake fluid. Same boiling point of other race fluids (310C) but costs half the price of AP racing and equivalent fluids.

    Possible causes in order of likelihood as I see it:
    Air in the brake line
    Shitty brake fluid
    Pads not bedded in yet properly
    Pads unevenly worn/caliper flex issue like I had
    A Split/Bluge somewhere in your brake line.

    I have Remsa pads on my car and they give quite a firm pedal feel. My Project Mu race pads can give some very funny mushy pedal feel when they are cold and the cat is stationary but they changed dramatically once they started warming up. My Remsa ones are always firm tho. Pad compounds react and soften when they get hot, it depends on how hard your driving because I never really push my Remsa pads very far but I can't imagine it becoming a problem anywhere outside of a racetrack.

  10. #10
    Join Date
    Aug 2009
    Location
    hunter valley
    Posts
    6,403

    Default

    Rebleed, start with left back- right back-left front-right front. If it till does it check for fluid leaks, If you start the car put your foot on the pedal hard it shouldnt go down. If it does you have a air in system or a leak, If it holds try braided brake lines.

  11. Default

    does the abs system ned to be bled?

  12. #12

    Default

    No, and because the ABS module is on the passenger left hand front, you bleed slightly different to normal.

    Start at right rear and finish at passenger front side.

    And for gods sake, keep an eye on your fluid levels, because the clutch takes fluid from the brake reservoir, and bleeding the clutch is a bastard if you go too low lol.

  13. Default

    booked the car in with mazda next week. hope they do a better job.

  14. #14
    Join Date
    Mar 2010
    Location
    Sydney, NSW
    Posts
    1,233

    Default Re: brake help

    It's Mazda, I wouldn't bother. Take it to someone who knows what they are doing.

    Sent from my Nexus S using Tapatalk 2

  15. Default

    i was told the abs system needs to be bled becasue the brake system was run dry when replacing the master cylinder.
    and to bleed the abs unit you need the mazda computer hooked up to the car so it activated the abs on demand.
    and the forman (or whoever, the guy who sepervises) will be wokring on my car becasue i explained how importnant it is,.

  16. #16

    Default brake help

    So I WAS right about the ABS. All you guys in the last thread said I was wrong.....nay sayers!

    Good to meet you last night, Dar. Hope it's back to good soon.

  17. Default

    @SMOKEY if your systenm is run dry, there is no way you can puump fluid into the abs system unless you force it to open - either drive and bleed at the same time which is not possible or hook it up to a mazda dealer only computer diagnostics system which simulates the ABS system working (by opening the abs valves).
    anyway, ill update this thread next week

  18. #18
    Join Date
    Aug 2009
    Location
    hunter valley
    Posts
    6,403

    Default

    @SMOKEY I have done 4 3MPS's and have not had any issues with a normal bleed.

  19. #19
    Join Date
    Aug 2009
    Location
    hunter valley
    Posts
    6,403

    Default

    Quote Originally Posted by dar_vedar View Post
    @SMOKEY if your systenm is run dry, there is no way you can puump fluid into the abs system unless you force it to open - either drive and bleed at the same time which is not possible or hook it up to a mazda dealer only computer diagnostics system which simulates the ABS system working (by opening the abs valves).
    anyway, ill update this thread next week
    @dar_vedar If you live near the Hunter Valley and want me to have a look at it im free saturday morning.
    Many want Power not many hold it long.........

  20. #20

    Default

    Let us know if that fixes it. That makes sense if you're braking hard enough to activate the ABS system. I'd like to hear the outcome to this!

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