Re: Bendix Treadle Vac, Myths, Fiction and Facts

Posted by HH56 On 2017/2/22 12:05:18

There have been several in this forum who have reported a failure - some permanent and for obvious reasons, and some intermittent. Aside from the obvious and generally permanent failures caused by a leak in a cylinder, or line and even a hard pedal caused by a vacuum section problem, what component other than the compensator valve would allow the pedal to go partially or worst case all the way to the floor at one stop and everything be perfectly fine the next time brakes are applied.

If we can rule out everything but the compensator valve that would allow this to happen, what would keep the valve from closing other than some kind of crud preventing a seal. I think for the most part we have ruled out the spring and the reason for the crud has been proven without doubt -- neglect -- but as I see it a hard crystalized blob of crud is the only thing that would cause an intermittent failure to close. In some cases the cause does not appear to be squeezed or swept away by a rush of fluid going past it.

In some cases I would concede the compensator valve could be one of those poor quality repro valves such as the valve with nothing but a layer of thin flat rubber you or someone else posted a photo of a few years ago but in other cases I see no other explanation other than hard crud. To get that crud out requires at a minimum total disassembly and cleaning of the hydraulic section and not just taking the lid off and cleaning the reservoir.