Bendix Treadle-vac Power Brake Master Cylinder Replacement Option Question - 54 Hudson Hornet

54Hudsonman54Hudsonman Posts: 14Member
edited May 2022 in Vehicles

Hi all,

I'm enjoying our wonderful weather and taking our 54 Hudson Hornet driving around the the Santa Cruz area. I replaced all the brakes, brake cylinders, brake hose lines and also had a rebuilt Bendix Treadle-Vac Power Brake master cylinder but still looses brake fluid. I know the master cylinder can be rebuilt but I also see that is has a possible replacement option with a new part. Has anyone done this replacement with the 1955-57 Chevrolet Treadle-Vac Replacement Booster/Master Cylinder Combo. If you've done it,  is it an easy install?


  • 50C8DAN50C8DAN Posts: 2,729Senior Contributor
    I am guessing that this is a replacement for a Tredle-Vac as it is not a Tredle-Vac itself.  I have replaced my '54 Tredle-Vac with the unit I made from a 7-in dual power booster and a dual MC.  The problem I had is had to modify a 3/4" bore MC to use on this setup as I could not get enough force in the system with a 1" power MC.  However, I am using disk brakes on the front and you may be using the stock drums?  Also note you will need an adjustable rod from the brake pedal bellcrank to the power booster.
  • 54Hudsonman54Hudsonman Posts: 14Member
    Hi Dan,

    I had seen your project outlined in a previous string. What you did is way over my pay grade  :smile: 
    Very impressive
  • RocketRocket Posts: 505Senior Contributor
    You say you are losing brake fluid if you have checked all of your connections for leaks and have not found any the next thing to do is check your carpet under the steering column to see if it is wet because the MC if bad will leak out the back and leak onto your floor it can also leak out the back and into the power brake booster (I have seen these leak into the booster and the vacuum supply would suck up the brake fluid and dump it into the motor) I hope this helps. 
  • BigSkyBigSky Posts: 1,039Senior Contributor
    I have the same problem with my 54’s Treadlevac unit.  I was looking at the same unit from Classic Industries.  I reached out to them for specs on the replacement power brake unit your looking at using. While it took months to get a reply, it finally came a couple months ago, yet it was only the specs on the mounting plate.  I’ve not checked these measurements as of yet since I had shelved repairs to the Hudson to work on the Corvette.  

    Here is what they sent me;

  • 50C8DAN50C8DAN Posts: 2,729Senior Contributor
    Making two adapter flanges from angle aluminum is not that difficult to go from the Tredle Vac mounting flange to a standard 7 in dual vacuum booster.  A 7-inch booster is the largest you can put in the location unless you want to do away with the firewall brace, which I would not recommend.
  • BigSkyBigSky Posts: 1,039Senior Contributor
    Yes, a bracket isn’t to hard but I’m guessing the most important part making sure the rod length is correct & will work with the travel length of the Hudson. 
  • 54Hudsonman54Hudsonman Posts: 14Member
    BigSky said:
    Yes, a bracket isn’t to hard but I’m guessing the most important part making sure the rod length is correct & will work with the travel length of the Hudson. 

    1955-57 Chevrolet Treadle-Vac Replacement Booster/Master Cylinder Combo :

    Says it is easy to install and includes an adjustable rod for correct pedal height. 

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