Re: Brake Noise & Fading

Posted by HH56 On 2022/10/22 12:36:14
There is no adjustment because the operating rod is attached directly to the pedal. All you can do externally is ensure the pedal is not binding or mechanically cannot move full distance.

Return is done by a heavy internal spring that pushes the hydraulic and vacuum power piston back. It needs to be in good condition and properly seated behind the retainer and clip. Lube on the vacuum cylinder side walls and leather piston cup can not have become so gummy or thick that the piston will not move freely.

If fluid is leaking past the hydraulic seal and the relief port is blocked it can accumulate in the vacuum side and become very sticky. Anything with the spring, lube, or fluid accumulation requires disassembly to check because they are behind the power piston and cannot be seen.

Assuming items behind the power piston are all OK the only other things inside the unit that would prevent full travel and need checking is to make sure the internal vacuum hose has not twisted out of place or the felt cushion pad at the upper side of the power piston is not dislodged or so thick that the piston cannot travel the full distance to rest against the lid. Those items can be checked by only removing the lid.

The residual check valve is a unit assembly and calibrated to a specific psi. Don't remember the number offhand but it is conceivable a contaminated fluid could have swelled the rubber inside the valve unit and knocked the calibration out of whack.

This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=249508