Give me a brake

[Fat_Nate]

Hey all,

Changed pads and fluid on the front brakes of the SV before this weekend.  Fluid came out black.  On Saturday, the front brakes were spongy.  The lever would come back almost to the bar, even with the lever set full out.  The brakes were re-bled, and after that had good feel and power at first, but would fade significantly after 3-4 laps.

Questions:  why was the brake fluid black?  Does this make me a bad person?  Is it time for a new master cylinder?  If I need a new master cylinder, do I go with a generic master cylinder or brembo, and what would I expect to pay?

Thanks,
Nate

[Protein Filled]

The fluid turns black when you do not change it for a while and it contaminates. Brake fluid absorbs water easily. Did you use a brand new unopened container of fluid when you bled them? It shouldn't have damaged your master cylinder though. Sounds like it wasn't bled 100%. You may want to bleed it again. FYI, I tend to swap brake fluid every 2 weekends.

[Jeff]

Fluid came out black.   Does this make me a bad person?

Only if you're a hater...

Don't be hatin Malibu!  REPRESENT!

[Fat_Nate]

It shouldn't have damaged your master cylinder though.

What are the symptoms of master cylinder failure (aside from flying off the track at the end of the straight)?

[cardzilla]

The things that you're experiencing are signs.  You may just need to rebuild it, maybe a bad seal or something.  You most likely have a tiny leak somewhere that's allowing air and water in.  It could be the banjos or the cylinder itself, even the bleeder valves.  If you recently changed lines or something, check the crush washers... you should have replaced them anyway.  The usual cause of this is a loose banjo or bad washer... I've never had to rebuild a master cylinder.

[Fat_Nate]

I see.  Could these "symptoms" nonetheless be a legitimate excuse to buy a brembo master cylinder?  (I should probably get tire warmers instead . . ..)

[Gixxerblade]

N8,
 I just got off the phone with FastLap and I bought a brand new stock MC with a set of pads for about $200. I am also having terrible fading problems and I think it has to do with pad warpage. I also ordered some new piston seal (dust & piston). I am going to try all new seals and MC with all new fluid and pads. We'll see what happens. I am thinking after half a season of racing this thing that I may be having stiction problems in the pistons from brake dust build up.

[tug296]

Nate,
 After my last race of the day at Homestead in Feb.
pulled in to the garage and lever came to the bar.
Had to just sit there for a moment and be greatful.
 A friend and I rebuilt the Master Cylinder, there were visable wear marks on the plunger.
Never a problem until that moment, no indication or fade, always kept fresh clean fluid in it etc.
4500 race pace miles before it went.
 Good as new since the rebuild.

[cardzilla]

I see.  Could these "symptoms" nonetheless be a legitimate excuse to buy a brembo master cylinder?  (I should probably get tire warmers instead . . ..)

*LOL* absolutely!  Not that you need an excuse, mind you.