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I would almost bet that there was a significant mechanical advantage on the Tbird. Here is a photo of 2 Studebaker applications using the hydrovac (floor pedal is a Hawk). Notice where the pivot is in relation to the mc pushrod on both--a significant advantage on both systems--maybe 5 or 6:1.

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My previous post reply on this seems to have disappeared.

Anyway,

Eric has drivin my 55 Pat with re-located brake pedal. He can compare it to his conversion.

Paul reported to me that his brake pedal position is 1-in higher than stock, but has not been a problem for him.

Keith and others can report if their BTV conversions with brake pedal position has been a problem.

Looking for feedback here.

Craig

The hydrovac was also used on 53-55 and 57 Cadillac and 57 Chevy they both had 1 1/8 and 1 wheel cylinders. My understanding was the use of this system was that it was easy to add to a system that did not have power brakes a "easy" add on.All 57 Cad had the hydrovac as standard equipment
Quite a few trucks also used a version of the hydrovac

In relation to the hydrovac system I have been 'researching' this possibility. As quoted from "studebaker-info.com" The factory used a short pedal with these factory installations. The mechanical advantage of the short brake pedal was such that if you lost the ability of the Hydrovac to boost pedal pressure, you were in trouble and most likely will NOT be able to stop the car with only your leg power."

" Your best insurance against having an accident, is to change out your power brake pedal with a standard length, manual brake pedal. The feel will be the same, but if the Hydro malfunctions, you can stop the car easier."


This does not leave much confidence in using this system.

On every car I have owned if the power brakes do not have a vacuum source such as engine not running or broken hose the brakes action is greatly reduced but I have been always able to stop the car at a greatly increased effort. The same effect as the engine not turning the power steering pump. I do not consider myself a super man but have been always able to stop car as long as hydraulic system is operational system. The manuals usually state that the brake effort will increase when the vacuum reserve is depleted

ok, let me ask this, of all btv owners and former owners. every complaint i have seen about the btv has centered around a failure in the m/c side, not the boost side. correct?

Believe that the case. Only complaints I can remember seeing directly related to the boost section were pedals that failed to return all the way for some reason. Not even sure if that boost related as don't recall seeing a resolution/reason found or posted.

Also note that there have been numerous reports of brake fluid in the vacuum boost canister. I have 2wo such BTV's that have brake fluid in the booster.

My final comment for those who want to keep and use the Bendix Treadle Vac on a driver:

On the question of converting a Treadlevac to a more modern master cylinder:

What about installing the non power brake pedal assembly and using it with a modern master cylinder and booster?

There could be 2 ways to do this. One would be to substitute a modern master cylinder for the original. The other would be to keep the original non power, single cylinder and use it with a remote power booster.

I have seen both setups used on street rods with the master under the floor.