Packard Forum Index » V-8 (1955-56)

Just seen this on the SDC site, a member was asking about the proper oil for the leather seal in the Hydrovac unit. Someone posted this on there as a response, and it got me thinking, how many people keep the leather seal lubricated every 4-6 months? I'm betting no one, and another possible cause for failure. Now, we all know the BTV has a similar leather seal, soo???

Thoughts?

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Keeping the seal lubricated makes sense. However note that hte service manual makes no statement about such a 6 month service procedure to add any oil to the booster.

Of course any brake fluid that mite be drawn into the booster would most likely keep it lubricated???? OR dry out the seal due to the alcohol in the brake fluid??? At this point i don't know.

Thanks for posting the letter Eric. Gives more insite into the BTV and it's potential problems/short maintnenance schedule requirements/headaches.

The BTV unit has a wick, the purpose of which is to lubricate the leather seal. There is a legitimate vacuum cylinder oil and the wick should be soaked in this whenever any maintenance is performed. This could be done as a maintenance item by just removing the vacuum cylinder cover and applying the oil to the wick, but I doubt that is required on a six-month schedule.
I also had ACOlds hone the inside of the vacuum cylinder to provide a very smooth surface for the leather seal to slide on.

All useful information and something to think about. Aside from the leaked fluid and maybe a report or two of pedal not returning-- which may be due to lube-- anyone remember any complaints of a problem with the vacuum side? That part seems to be pretty well designed and even without maintenance, doesn't seem to have had many problems.

The Bendix (B-K) vacuum power brake and clutch boosters used on the Seniors thru 1939 have leather piston seals and I have used Mobil Vacuum Oil to lubricate them without problems. Lubricating them once every 15 or so years (more-or-less every 10,000 miles) seems more than adequate. The Mobil product seems to also do well in vacuum windshield wiper motors as well.

That is the most ridiculous thing I have ever read about BTV. The unit becomes unsafe every 4-6 months.

Now you know why BTV allowed Rolls-Royce to claim its mechanical booster brakes made Rolls-Royce "the safest car in the world."

I recently had a GM BTV car come in which lost its brakes on the way to the shop. All we were going to do was test the unit to compare it to a MM rebuild.

The only thing worse than BTV are these late model ABS cars for which the brake lines rust away and burst and the ABS controllers stop working which causes poor brake pedal feel via an extra inch of travel. Then I catch hell for not replacing more in parts (ABS controller) than the clunker is worth.

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And the solution is... [drum roll] ...replace it with a modern dual master booster unit, preferably new!

That wasn't so hard to figure out, was it?

Craig

Let me clarify my position on this a little better.

This letter is NOT specifically about the BTV, it's about the HydroVac, a similar but different booster.

Even though I'm the #1 advocate of NOT using the BTV, I thought that if I could at least help one person who stubbornly clings to it to make their car safer then I'm doing my job. ANY single-line master cylinder is inherently unsafe, no matter if it's manual or power.

I was thinking that if this brings out a logical discussion on the flaws in the BTV, then that's a good thing. I'm also thinking that the close proximity of the BTV unit to the exhaust could possibly be the reason the leather seal "dries out" quicker in Packards, helping the brake failure that people have reported. As well as causing other issues we have only begun to analyze.

I think the heat and moisture accumulation caused by the location of the unit is the #1 reason for failure in the Packard version of the BTV.

Just bought a '56 Olds Holiday 98 and it has what GM called Pedal-Ease brakes, which I believe to be BTV, so I consider the desirability of ditching it, but at least the proximity to exhaust heat is not as evident as it is in the Packards. Not sure how do-able a conversion to any modern units will be.

Would sure like to see some pictures of the install location and how it mounts. Wonder if that is the real BTV or GM's version of it.