[200q20v] Soft brakes ... master cylinder?

C1J1Miller at aol.com C1J1Miller at aol.com
Tue Aug 15 17:22:43 EDT 2000

On another note:  do either/both of you bleed your own brakes?  Do you use a pressure bleeder, or do the old "pump and hold the pedal" technique using a helper?  Did you bleed the brakes recently relative to the failure?

Years ago I had a rabbit; bled the brakes using the full travel of the master cylinder.  Shortly thereafter, the master gave out.  Explanation was that the master cylinder typically uses a smaller total travel length in daily use; with bleeding, you force the seals onto an unused area of the piston, which typically is where the cylinder rusts up.  This extended pedal travel damages the seals...

My mechanic at the time recommended:
1) bleed out the fluid every 2 years;
2) if you bleed the brakes using foot pressure, put a block of wood under the pedal to keep from over extending it;
3) pressure bleeders don't have this issue.

Another point;  everyone with these older cars should make a point of checking the flexible brake lines at each caliper on occasion; I've seen them swell and fail (recently on a '92 jetta here at work).  You should also check the hard brake lines in the back; a few "rust belt" cars we've looked at recently have had fairly significant corrosion on these lines; looks like the salt gets splashed up here by the fuel tank/rear bumper, and doesn't get rinsed off.

Replacing the master cylinder is very simple; couple bolts, some brake line connections, and then bleed the entire braking system. BTDT on a co-worker's '86 5k wagon.
chris miller, windham nh, c1j1miller at aol.com
'91 200q20v ==> http://members.aol.com/c1j1miller/

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