Brakes Wheels 1st Gen Tires Master Cylinder/Brake issues

Discussion in '1st Generation: 2002–06 R50, R53 & 2004–08 R52' started by cct1, May 20, 2010.

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  1. cct1

    cct1 Well-Known Member
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    #1 cct1, May 20, 2010
    My brake pedal is a little off. The brakes engage, but I have to depress the pedal an inch or maybe a little more for them to engage. (They've been bled basically after every track day, don't think that's the issue). They engage fine after that, they aren't mushy, but there is quite a bit of play in the pedal before they kick in, more than I feel comfortable with. With the car on, I can push the pedal down to a little below the gas pedal before it really firms up--makes it tought to heel-toe at times, the pedal sinks a little farther than I'd like--beyond that, it really doesn't sink much further; it's not going all the way down to the floor (at least not yet).

    I have the TSW BDM on the car, OEM's on the rear calipers, ss lines on all four corners; It's the fourth set of brakes (including the OEM one's) I've had on the car--they're the only ones that have really held up on the track, and I don't think the issue is there. So I'm thinking maybe it's time to replace the master cylinder, unless there are any other suggestions.

    Questions:

    1. How hard is it to change the master cylinder? If it's a nasty one, I can take the car to Milwaukee, there are a few good mechanics that work on MINI's there.

    2. Which Master cylinder to replace it with? OEM, or something like this:

    Race Pages - Master Cylinder Mini - Mini

    That one is cheaper--not the overriding issue--but if it's as good or perhaps even better than the OEM Master Cylinder, I'd go that route.
     
  2. Nathan

    Nathan Founder

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    #2 Nathan, May 20, 2010
    I'd start by taking a good hard look at the calipers. Look along the seams for any evidence of minute amounts of brake fluid. I'm using the same basic calipers. When rebuilding them recently there was evidence that a very slight amount of fluid was escaping from one of the seals. With these calipers a rebuild is very easy to do, heck I even did one of them myself and my mantra where ever there is a problem had always been: "Who's name goes on the check?"
     
  3. cct1

    cct1 Well-Known Member
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    #3 cct1, May 20, 2010
    Thanks for the reply Nate.

    I don't think it's from a leak anywhere--I checked the lines and calipers once, didn't see anything. I'll put it up on jacks again this weekend and check again (got some other stuff I need to do anyway). I've only had the BDM on since last spring, got six track days on it--hoping the seals are ok, but I'll double check. Thing is, there has always been a little play in the pedal, since the BDM went on, but it seems its a little worse.

    I'm leaning toward taking it to a brake guru in Cedarburg, but I was thinking about having a master cylinder on hand in case it needs replacing. The Centric one is priced nicely compared to the OEM, just wonder if it's as good.

    Anyway, I'll double check everything again Saturday--I want to get this figured out before I hit the track in July....
     
  4. BThayer23

    BThayer23 Well-Known Member

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    #4 BThayer23, May 20, 2010
    Easiest way to diagnose master cylinder failure is to turn the car on and push hard on the pedal. It should compress and eventually stop. When my master cylinder failed, the pedal never fully stopped and kept slowly heading for the floor.

    It's easy to replace. Work quickly and you won't introduce too much air into the system. Off the top of my head...

    Depending on your airbox, you may or may not still have a small panel in the cowl partition just in front of the master cylinder. If, like me, you wondered why that small piece was removable, it's so you can pull the master cylinder out of the vacuum booster. So remove either the airbox or the cowl partition, then siphon all the extra brake fluid out of the reservoir. If you can't get it all, just put some paper towels under the master cylinder. One torx bolt holds the reservoir to the master; remove that. When you pull the reservoir off, brake fluid will spill, so just be prepared. The reservoir won't go very far 'cause it's still connected to the clutch hydraulics. Unclip the DSC connection and unscrew the two hard brake lines from the master using a flare wrench (forgot what size). Unscrew the 13mm nuts from the vacuum booster, and remove the master. The new OEM master comes with new nuts and gaskets. Installation is similar to removal. Bentley says to be careful to line the master up with the vacuum booster piston; I didn't remember to look but didn't have a problem with that. I went through about 1 and a quarter cans of Super Blue flushing all the air out of the system.
     
  5. BThayer23

    BThayer23 Well-Known Member

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    #5 BThayer23, May 20, 2010
    If you're going to buy the Centric (which might possibly be identical to OEM) just make sure you specify DSC or no DSC. Wish I'd seen that before I replaced mine - it's less than half the price!!! I can't remember if OEM is ATE or Centric, but it's one of those. Also make sure it comes with all the gaskets (2 on top for reservoir, 2 on bottom for hard lines, 1 O-ring for vacuum booster) and two 13mm nylock nuts.
     
  6. cct1

    cct1 Well-Known Member
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    #6 cct1, May 20, 2010
    Thanks for that!

    The DSC one is the top one, it's 20 bucks more, but still, for less than a 150 bucks, it's a pretty darned good price compared to OEM...
     
  7. FUEGO

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    #7 FUEGO, May 20, 2010
    Not sure either but willing to bet it is ATE. If you happen to look at the back side of your OEM calipers you'll find they are ATE. :)
     
  8. BlimeyCabrio

    BlimeyCabrio Oscar Goldman of MINIs
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    #8 BlimeyCabrio, May 20, 2010
    Yeah, I think I've had a very small leak in mine for a lonnnnng time. Need to replace it sometime.
     
  9. cct1

    cct1 Well-Known Member
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    #9 cct1, May 20, 2010

    I checked--OEM is ATE.

    I'll call Centric to check about the gaskets. O-rings are readily available from realoem, as are the nylon nuts, but I'm not sure about the friggin' gaskets...
     
  10. BThayer23

    BThayer23 Well-Known Member

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    #10 BThayer23, May 20, 2010
    Gasket: part #5
    O-ring: part #4
    Nuts: part #3

    [​IMG]
     

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