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I went to the url that Eric supplied and read it thoroughly. The two master cylinders he referred to are not part of the BTV system, but are a part of the ATE T50 system that Mercedes contracted for as a replacement for the BTV. These cars were being raced at high speed and admittedly if the vacuum servo fails for any reason it would be difficult to stop the car. They have also determined that the original ATE system has declined significantly and is no longer stopping these cars as well as they did originally. Consequently Mercedes has contracted for a new ATE unit which carries a two-year warranty and is available from Mercedes.
http://www.emercedesbenz.com/Jun06/29_New_T50_Brake_Booster_For_Classic_Mercedes_Released.html

The unit is priced at 2500 Euros plus the VAT tax. 2500 Euros is about $3400.00 dollars. This is not a viable solution for the majority of Packard owners.

As an aside, and because I am familiar with the deterioration of die-cast metal (zinc-pest) I looked into having the master cylinder portion of the BTV copper-plated to seal off any flakes or chips of zinc that could be caught under the compensator valve. My plater said he could not successfully copper plate that casting. It just would not take and to plate the inside of that casting would be even more difficult.
If Bendix still had the die, they might be able to cast new ones. I don't know what the market would be for that and suspect it would not be self-supporting.

Randy:

The models referred to in the article you referenced are all rounded style sedans models 180/190/219/220 plus the big 300 sedan. The unit they originally used was not a Treadle Vac or Treadle Vac style power brake unit with the integral vacuum booster/master cylinder. It operated differently with the car having a convenional master cylinder
whose output goes into this ATE unit. Hydraulic pressure goes in, actuates the vacuum piston, and the piston relays its force to an internal master cylinder which produced high pressure output to operate the brake shoes. In the case of the BTV, mechanical force (foot) goes in, high pressure hydraulic pressure goes out.

The new unit looks nearly identical to the Bendix Hydrovac, used in Studebakers, 57 Cadillacs, manyu trucks and other makes for dealer installed power brakes including Chevrolet.

What is most telling is that Mercedes, one of the most respected engineering houses in the automotive world, did not engineer a dual master cylinder unit. I wonder if they're irresponsible like many of us Packard people??

i have been following and all i can say is i have some tricks to try on the oil pump when it comes time....so i hope to look into this BTV later too. i personally plan on using both in mine.

i have no idea if i will be contributing anything of worth, but eh i'll give it a shot.

Also i want to thank Fred for getting on here and taking the firestorm and still comming back. i have been waiting for the day that someone from one of the major venders was active on the board. i was suprised when i saw Kanter on here, and excited! Thanks Fred. i look forward to purchasing from you soon. i gotta get this motor rebuilt!!

anyways, i didn't have much to say about the subject, so z ya later aligator.

Hank

I rarely take word in topics regarding the BTV issuse, but I feel I have to say what I think of it, although I belive it dose not make a difference:
It took me many a hours to read this topic from the beginning to the end and my own conclusion of this BTV, is that in the end its the car owners free choice to choose weather to use a NOS or rebuild BTV or use a modern two chamber Power brake. If I had a Packard here in Estonia and wanted to use it just for driving on the roads, I might have to convert to a modern Power brake option. But If I would like to get the unice vehicles license plate I must have the BTV or it will not qualify the criteria.

The quality of the reproduction parts from US has been rather good as far as I have seen various parts,some ordered from Kanter.
There is not much that I can say, the 3 working Estonian pre-war Packard have all BTV I know of and they seem to work so far.

All ye take heart, the post from Eric on the Mercedes/Ate unit hold promise for us all. I think it confirms that indeed the sky is not falling. I believe I have analyzed things correctly below, let me know if I have overlooked something.

In the Hydrovac style power brake system, used by millions of cars and trucks in he US and in the Mercedes models here, a conventional single master cylinder without a residual check valve is acted upon by foot pressure. That pressure goes to essentialy what is a hydraulic amplifier.
Hydraulic in, assisted by vacuum acting ona a large pison, high pressure hydraulic out.

Note, if in the Mercedes or any other such equipped vehicle, the single master cylinder should fail there are no brakes at all. If Mercedes is confident to invest several years worth of research and design and then market this to vintage Mercedes owners worldwide they must know something. As a single master based system is good enuough for Mercedes,then it's good enough for me. Obviously Eric wouldn't have posted this link unless it was good enough for him.

Amen.

Fred Kanter
Kanter
Auto Products
Boonton, NL

The BTV has probably been the subject of a dozen or more threads that just go on forever. How about we give it a rest for a while? If some new information comes to light as the result of Fred's analysis, or otherwise, we're all ears, but in the meantime, we just keep recycling the same old stuff.

Newcomers have questions. That is one reason why the "same old stuff" seems to get recycled. They're new folks and don't realize how long the BTV discussions have raged on.

Post #28 above is a partial NOT completed list of topic headings covering the BTV.

I see no point in ending the discussions just because someone shows up recently with a promised future answer.

Post #28 above (of THIS thread) contains some but not all of the discussions for reference for newcommers or anyone to review.

Or to put it another way, i'm sure there are many (but not necessarily all) vendors and service providers of the BTV that would like to see the BTV discussions stop.

I vote to keep them open. NO ONE is forced to participate.

I'd like to think that new-comers would use the "search" function to see if their question has already been posed and discussed, in which case they'd find more than they could read in one sitting on this topic. But that doesn't seem to often be the case, so I reluctantly agree with you.

These scans from a Mercedes Benz Parts Book circa 1960 probably won't help the discussion much but they show the system used in the late 50's-early 60's era. This is an ATE unit.

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@ Clipper 47: Looks very much like the HydroVac on a 1964 GT Hawk I had. My car was disc equipped and had a remote reservoir on the firewall that fed the low mounted master cyl. Basically an updated carryover from the prior frame mounted master cyl system. Worked like a charm and I never heard of a failure among the Stude crowd.