Re: HELP: 93 Toyota Corolla vibration problem! PROBLEM SOLVED!

On May 12, 11:32=A0pm, jonb55...@[EMAIL PROTECTED]
 wrote:
> On Apr 8, 12:21 pm, jonb55...@[EMAIL PROTECTED]
 wrote:> I have a
1993ToyotaCorolla=
with 265k miles on it. =A0There is a
> > vibration that has the following symptoms...
>
> <snip>
>
> The solution to the problem was that one of the cups in the master
> cylinder was disintegrating. =A0This debris made its way down the line
> and clogged the pro****tioning valve. =A0Thus, when the brake pedal was
> released, fluid could not flow unimpeded back to the master cylinder
> and brake pressure built up. =A0Replacing both the master cylinder and
> the pro****tioning valve fixed the problem. =A0Thank you to all who
> contributed to helping me diagnose this problem.

Glad to hear the problem is fixed; however, can someone explain to me
how this fix is possible?  I have never seen a pro****tioning valve
that in any way affected the operation of the *front* brakes, is there
something I haven't seen before on the prop valve of the OP's car?

As an aside, if there's rubber debris in any brake component, it's
50/50 whether it came from the master cylinder or not.  when I hear of
something like this, my initial reaction is that it's likely rubber
debris from the calipers/wheel cylinders or brake hoses forced
backwards through the system by a technician who did not open the
bleeder screws while pu****ng the pistons back when replacing the pads/
shoes.  However, since as I recall you've already replaced both the
calipers and the hoses, you ought to be good to go.

Also, this whole exercise gives me an excuse to mention that I like to
change the brake fluid in my vehicles every couple years, whether or
not the FSM recommends it.  This not only reduces corrosion but
flushes all debris like this "downstream" and out, and most of the
corrosion/rubber failures tend to happen closer to the wheels.

nate