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?"
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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.... -
BThayer23 Well-Known Member
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. -
BThayer23 Well-Known Member
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.
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Yeah, I think I've had a very small leak in mine for a lonnnnng time. Need to replace it sometime.
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BThayer23 Well-Known Member
Gasket: part #5
O-ring: part #4
Nuts: part #3