[net.auto] CURIOUS BRAKE PROBLEM: '78 VW RABBIT

lacasse@randvax.UUCP (Mark LaCasse) (03/16/85)

If I press my brake petal hard, then let up, then press hard again, the
petal sinks down about 1/2 inch.  This is observabable whether or not the
car is moving.  The sequence of brake pressure must be:
    hard,   let up ~ 1/2 sec.,   hard again.
There is no "sinking" if the presure is monotonically increasing.  If I
keep doing this over and over about 10 times, I can get the petal all the
way to the floorboard.  If I take my foot of the petal, it will restore
normally, so I can start this sequence all over again.  If I drive the car
normally, I don't notice the flaw: the brakes work fine.

Do I have air in the lines, need a new master cylinder, or what?

Also, I first noticed this problem after picking up my car from a "major
maintenance special" at the local VW dealer.  One of the items they did was
"check brake fluid", and check a brake line under the right passenger
floor-area-rug due to a recall (for possible corrosion of this line).  They
say they only looked at the line.  Could the dealer have caused the
problem?  Or is my noticing the problem the day after getting the car back
just a coincidence or more careful scruitiny of the dealer's work?

Thanks.

      Mark LaCasse                  qantel!hplabs!sdcrdcf!randvax!lacasse
      c/o The Rand Corporation       cbosgd!ihnp4!sdcrdcf!randvax!lacasse
      1700 Main Street              lacasse@Rand-Unix
      Santa Monica, CA 90406
	213/393-0411  ext. 7420