Re: Treadle vac rebuilds?

Posted by Packard Don On 2019/5/5 14:21:59

At the front, they connect from the chassis to the cylinder in each wheel. At the rear there is a single one that connects from the chassis to the rear axle. Nearly every car ever built with hydraulic brakes has this, or a similar, configuration.

When these hoses get old, especially when the system hasn't been maintained by annual flushing and new fluid, they start to collapse internally. In their early stages of deterioration the master provides enough pressure to actuate the brakes but the brake shoe return springs might not be able to push the fluid back out into the master reservoir, causing the brakes to drag. The more the hoses collapse (and it's completely invisible from the outside), the worse the problem. This happened on our 1972 Mercedes and with one removed I couldn't even get 120lbs of air through it! It was totally collapsed shut while on storage.