Bendix Treadle Vac problem

54Hollywood
54Hollywood Senior Contributor
in HUDSON

Hi everyone. I am flummoxed with an issue regarding the Treadle-Vac power brake unit in my '54 Hornet that I hope someone can help me with or otherwise, point me in the right direction of another chapter member who has this unit.

The other day I was doing some routine maintenance and noticed that the vacuum hoses on the system were actually transmission oil cooler hoses. The car would stop fine when driving around town but just didn't really want to slow down from highway speeds. I was told that the reason could be with the incorrect hoses. So I replaced them with Gates vacuum hoses but now the brake pedal is rock hard. Cannot get it to depress at all and I'm at a loss as to why. All I did was changes the hoses. Any idea about what's going on and what I can check? I'm really frustrated and don't want to try to drive the car in this condition.

Thanks for your help.

Hudsonly,

Tim Perko

Comments

  • KenU_Tx
    KenU_Tx Member

    First of all, if the pedal is rock hard, that means there is little to no vacuum reaching the Treadle Vac. Since this occurred after changing the hoses, check that the nipples the hoses attach to have not cracked or come loose from the vacuum reservoir on the right inner fender and the Treadle Vac vacuum chamber itself. Also make sure the check valve at intake manifold to vacuum reservoir is good. You mentioned the brakes worked ok before changing the hoses at lower speeds but not so well at higher speeds. This is often due to problems in the brake drum itself....leaky wheel cylinders soaking the shoe linings, glazed linings, or drums turned too far oversize and expanding from heat (fade).

    Have you done a complete brake job on this car with new wheel cylinders, new shoes, hoses, and rebuilt Treadle Vac?

  • 54Hollywood
    54Hollywood Senior Contributor

    Hi Ken. Thanks for your reply. In 2015 a lot of restoration work was done on the car including new brake shoes, hoses, turned drums and I was told, a rebuilt Treadle Vac unit. So I dunno. Regarding the check valve, I was told to spray some carb cleaner into it, wait until it dries and try to blow air into it. Well I can't get any air into it which I was told was a good thing. So again, I dunno. The car probably doesn't have over 3500 miles on it since the restoration work was done. Other than reconnecting the vacuum hoses and making sure the connections are tight, what the heck else can I check? Is it really just kind of a simple thing that there's a vacuum leak somewhere or what and how could I find it? Thanks very much for your help.

    Tim in WI.

  • onerare39
    onerare39 Expert Adviser, Member

    Take a look at the rubber brake hose that goes from the Treadle-Vac unit to the distribution block on the frame. If it is the original one from 72 years ago it has probably deteriorated and swollen on the inside keeping the brake fluid from flowing to the brake lines. I had a hard brake pedal on my 54, absolutely no brakes, then all of a sudden they would lock up! I found a company that makes new brake hoses that are DOT approved, Tompkins Industries. They have locations around the country and can make the hose up and mail it to you. Here's the invoice from the one that I purchased with the specifications listed, that's all you need for them to make you a new hose.

    BQ101 - is the type of hose

    HF 16, HF16 - are the style of ends

    16.75" - is the length

    Image 11-19-25 at 9.26 PM.jpg


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