Re: MUSHY brakes!

[Porsray@aol.com]

I have a few ideas you might try:

1) You didn't say what model or if you have ABS.  The ABS cars (and this
might 
extend to other models with hydraulic, not vacuum brake assist) have a bleed
port at the master cylinder location which has to be bled first.

2) how did you bleed the brakes?  My experience (15 years of bleeding Porsche
brakes for track events) is that the only wasy to do it is a pressure bleed -

use an air tank with 20 -25 psi in it hooked to fluid reservoir to force
fluid out
bleed valves.  I have had a lot of trouble with the hand vacuum pumps on the 
bleed screws and the old "assistant pump and hold" method.

3) I assume that you didn't pull the pads out of the rotors; you just bled
the brakes.
 Either you still have air in the lines (bad procedure; have to start at RR,
then LR,
then RF, finally LF; also use pressure bleed) or else the master cylinder is
going.
Are the brakes firm on the second pump (pump the brakes rapidly; stationary
is OK)?  If so, is probably air. If you push down hard on the pedal and it
will very slowly fall, the master cylinider is bad.  By the way, I replaced
the master cylinder
on my 911 TWICE due to using the traditional "assistant" method; what happens
is that you force the piston seals beyond their normal wear point, and damage

them. When I switched to the pressure bleed, I never had another master
cylinder
fail.

4) If you pulled the pads, the pads are probably just hitting on the "high
spots";
you have to bed the pads in.  On a flat, little used road, bring it up to
approx.
40 MPH and hit the brakes hard.  brigh the car rapidly pu to speed and do it
again. Then drive easily and let the brakes cool. Repeat again.

Good Luck!

Ray Calvo (porsray@aol.com)
1990 Coupe Quattro


In a message dated 96-11-19 23:31:14 EST, you write:

<< 
 From: Daniel Hussey <GY3WSX@VM.SC.EDU>
 Date: Tue, 19 Nov 96 22:26:46 EST
 Subject: MUSHY brakes!
 
      Well, I have been having some troubling thoughts recently.  I bought a
set
 of Cool Carbon brake pads and I have the CC's on the rear, and I still have
the
 Repco MM's on the front.  One of the front rotors has some slight scoring,
but
 otherwise, they are perfect.  Plus, the MM's and the (stock) rotors are only
ab
 out 2 years old.  I haven't put the CC's on the front because of lack of
tools
 here at school and I also just got the anti-noise shims for them (I heard
they
 were noisy).  I also just flushed out the brake lines and added new ATE
Super
 Blue brake fluid.  Then I noticed the brakes being a little mushy, so I bled
th
 em again.  Glad I did, I saw a little bit of the old fluid in there?!?!  So,
I
 though all was well, but I have been noticing the brakes feeling very mushy
and
 not as powerfull as they have been in the past.
 
       The car brakes fine, but it just does not feel right!  Anyways, I
would n
 ot normally worry to much, but I am doing a track event this weekend, and
want
 to make sure all is well before leaving on Friday.  Other than putting in
the n
 ew CC brake pads on the front, what can you think of that I need to check?
 Thi
 s really bothers me because I want GOOD brakes on the track, and I also
don't w
 ant my car not to pass the tech inspection because something is wrong?  Do
you
 think I may have to bleed the brakes a third time?
 
       Also, one more thing to add, the brake master cylinder is only about 4
mo
 nths old....I had it replaced this summer.  I can't think of what else I
haven'
 t done.  I know the hydraulic pump is slowly dying, but that shouldn't
affect
 brake performance as long as there's plenty of Pentosin in there, right?  A
fri
 end of mine is comming down on Thursday and he has the tools I will need to
cha
 ge the front pads, but do you think I should just take my car to a mechanic
and
 let them check the brakes, and put on the pads?  Also, remember, I am poor!
 Th
 anks in advance.  Anny suggestions would be greatly apprciated.  Thanks.
 
 
                                                                Later,
                                                                Dan
  >>