Packard Forum Index » Post-War (1946-54)

I had the BTV rebuilt by a competent rebuilder Used the kit from Kanter. Problem is that there is too much pressure, Nose to windshield pressure. any ideas on what to do with this?


John

I'm not sure I understand the problem??
Do you mean the brakes are too touchy?
These Bendix systems were very touchy when new and required very slight toe pressure to stop the car. Perhaps you also have a dragging shoe or shoes?? Double-check the shoe adjustment on all the wheels. What year Packard do you have??

Did u drive the car RECENTLY (within the last year) before rebuilding the BTV ???? How did the brakes act THEN????

I have to ask the above question because quite frankly i don't know u personally but i do know of severl people localy and abroad, that are not accustomed to driving anything but modern power brakes.

LEt me state it another way in plain english:

In 2011 there are many people that do not know a good brake if they stepped on one or not because they are so used to driving MODERN power brakes over the last 25 years or so.

Quote:Randy,

It's probably this one.

I'm perhaps confused. Didn't we try to answer all this for you about a week ago when you posed the same question? I don't have anything new to add.

From what I know aobut the design of the BTV it is impossible to get "too much pressure".

On a related subject, I am again asking for owners who have catastrophic BTV failure to contact me so I can analyze the unit and determine the reason for failure, or has teh "epidemic" subsided?

I've been following this with interest since it first popped up and I'd like to chime in with my own experience. Now that I'm deep into the middle of "middle age" I would like to relate my experience. Back in the early 70's when the "old man" would let me learn how to drive using his car the first thing he told me was not to push too hard on the brakes. Most of my dad's cars were Buicks, Olds and Pontiacs and my grandmother even let me drive her Caddy. What each one of these cars had in common was a set of fantastic power breaks! I learned very quickly not to push too hard as it would be face to the windshield time. The heal and toe method that Ross spoke of is exactly how I learned how to drive these cars. I think the issue may be generational. If you grew up in the 60's and early 70's cars and their safety systems were so much different than they are today. For me, the BTV system is completely normal.

All of us who have been around power steering and power brakes from cars of the 50 and 60's remeber that power meant they were soft or really easy. One finger operation. power steering and and resting the heal to insure just the light touch needed to activate brakes. I remember a Buick Rivera we had it seemed if you looked at the brake pedal the car would slow down. Low effort power brakes and steering were selling points for luxury cars back then road feel was a 80's and later selling point

Quote:

On a related subject, I am again asking for owners who have catastrophic BTV failure to contact me so I can analyze the unit and determine the reason for failure, or has teh "epidemic" subsided?



I don't know if there ever was an "epidemic" just the occasional failure. It would be nice to know the reason, but I think the vast majority here happened years ago and those units are no longer available for study. Of the two or three recent ones here that I remember, I believe you looked at one and found silicone. The other, don't remember hearing about. A third failure turned out to be a tube or hose instead of BTV. Maybe expanding the inquiry to other forums would get some results.

Doing a search for Treadle Vac failure brings up several forums with a mention. We seem to be in the majority and several of them reference us but there are reports on the Chevy forum, Olds forum, Cad forum and even a Mercury using a different model BTV than we do. Interestingly, the failures are all the same--brakes one stop, none the next and then maybe works again. The Mercury had a split membrane in the hydraulic reaction piston (which we don't use) so a second point of failure apparently. That one allowed all the fluid to be sucked out. Just doing a quick read, they don't seem to be recent failures though.

The comments other posters made on their forums are the same arguments we have here. BTV was used in lots of cars and failures are isolated incidents, poor rebuilds, etc etc. One factor might be cars that sat for a long time never had any work done on the units. Fill with fluid, car stopped, and away we go. IMHO, one disturbing thing that has surfaced seems to be that some vendors or "experts" may not be doing a good or thorough job rebuilding them. I don't see why a properly rebuilt unit should need to be returned or exchanged once, let alone more than that or ever have silicone in it. I am still of the opinion a proper rebuild should be gutted and anything original yet replaceable in the hydraulic section is changed including moving hard parts. Even to the point of sleeving the casting's seal area if one pit is found. Obviously, I'm in the minority as a kit and paint job must be considered a rebuild to some.

BTV's will probably forever be one of those areas where everyone just agrees to disagree. For those comfortable with the BTV, use it, for those not, options are available.

first of all let me aplopgize. I never saw the comments on the first BTV post i did, I didnt think it registered.

IM used to BTV have driven them when new and did some driving on this 54 when they were working just fine. I am having a problem with too much pressure. I remember the 53, 55 and 56'sd being especially touchy after an adjustment, but this is beyond that. Thank you for the suggestions about readjusting the brakes. and checking for grease on the linings. I will do that.


John