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I"ve been playing around with something under the floor and don't believe a full booster and master is an option without doing some serious relocation of the L side exhaust pipe. The space for the pedal could be worked out but its space allowance in the frame is very limited. The space for a booster and master is not going to easily happen because the torsion bar and exhaust pipe passing right next to it fills what space there is that would be suitable for the booster combination.

The pedal fits in a narrow gap in the frame where the side rail and X join and would take a rework of the brackets that are part of commercially available pedals. I am thinking it would need to be a separate pedal and shaft assy similar to what Packard made or else shorten the shaft and pedal area of the commercial bracket so it would slip in the space. Factory setups seem to be harder to find but I did find several aftermarket pedals which appear similar in shape to the original so buying a pedal assy and reworking to use a different shaft and bracket is a possibility. Doing a photo overlay, one of those aftermarket pedal arms operated by the suspended pedal definitely seems to be doable. The under floor pedal would appear to line up almost identically to a BTV rod. Just need to make an attachment method between the arm and suspended pedal with a bit of pivoting ability -- something like a double ended clevis.

The limitation with the modern Hydrovac available at aftermarket brake places seems to be the dual master capability. Which one did you find for your Cadillac? So far the ones I found available seem to be single circuit but if there is a dual available somewhere I would be most interested. I am thinking that the use of a floor pedal would make a perfect fit for the Electroboost or if there is one, a dual Hydrovac. The ratio concerns of mounting anything modern using only the suspended pedal would be a non issue because that would be handled by the new under floor pedal. The space needed for a dual master cylinder would be not much greater than that for the single manual master.

Here is a crude photo overlay of the stock suspended pedal and an aftermarket floor pedal arrangement laid over an original manual floor pedal drawing. The double clevis would accommodate the geometry change between the suspension pedal and the floor pedal arm and by necessity would raise the suspended pedal slightly more than the original location to allow a bit more travel. Bellows would hide all that.

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Hello Greig,
I would like to know about the BTV solution that you talking about on the forum.
Thank you in advance.

Bumping this great thread...
My GM car offered both the Bendix system or the Moraine (GM) system.
Is one preferable to the other?

I think of the two staying with the Bendix unit would probably be the better choice. Not only is it stock but the Moraine unit has its own issues. As far as operational feel and braking assist ability they are probably comparable.

From what I have read and been told, the Moraine unit was made by GM under license from Bendix and used many of the same operating principles and designs Bendix developed for the Teadlevac but also went off on their own in some areas.

Outwardly, the units look very similar but internally there are some differences. The Moraine hydraulic section is quite different. Some have said the biggest issue with the Moraine is due to how it is laid out, if a hydraulic or vacuum side seal starts leaking the fluid is all but guaranteed to be sucked into the vacuum side because there is no relief passage connecting the seal chamber to atmosphere so there is nowhere else the fluid can go.

In the Treadlevac there is a relief passage with a port opening above the fluid level in the reservoir. Fluid going into the vacuum side is not as likely to happen unless the relief passage or port has been blocked in some fashion. With the port open and functional any leaking fluid can go back to the reservoir and any vacuum leaking thru will only pull air.

Unfortunately when Kanter did teardowns of some failed Treadlevac units it was found that apparently some rebuilders were purposely blocking the relief port with silicone. It would be interesting to know why unless they were imitating the Moraine unit or there was a design change on the more advanced Treadlevac models made after Packard went away. Since the repro castings also do not have that port that could be a reason.

A port issue specific to Packard was the flat reservoir cover when combined with a cover gasket designed for a different "bubble" style cover also blocked the port. If either has happened and a seal leaks then the Treadlevac is also prone to fluid being pulled into the vacuum side. As long as the relief passage is not purposely blocked with silicone the cover issue can be easily corrected by adding a small slot where the gasket and port opening meet.

I continue to wonder how the relief port would work with the remote reservoir that Packard offered as an option.

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I don't know the answer but perhaps Packard did not expect seals to fail in the few years of operation before the car was traded in so never gave it much thought. I also don't know when the remote fill became available but the first brochure I have where it is shown is 56. If it was a 55 or 56 offering it could be that with all the other problems they were fighting and with what was probably a fairly low sale of the option that detail never was totally thought out.

I don't think there is any doubt if the vacuum seal failed all the fluid in the remote reservoir would wind up in the vacuum side of the unit. Doubt much of the fluid in the master reservoir would be affected because the port opening is at or near the top of the working fluid level.

The first generation Treadlevac unit Packard used had the port opening slightly below the lid. There is no way to seal that opening so always the possibility of fluid filling the passage. On the second generation unit the port is flush with the lid and by using the gasket that causes the blocking issue it will keep fluid contained in the reservoir -- but then that defeats the purpose of the port again.

With a remote fill kit one possible solution would be to use the standard flat lid and port blocking gasket but directly over the port opening drill a small hole in the lid so any fluid that seeped thru a seal into the seal chamber could escape or outside air could enter. The gasket would keep the working fluid in the reservoir and remote fill fluid from draining out the hole or entering the port.