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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#41
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HH56
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Out of curiosity, anyone versed enough in fluid dynamics to explain why the BTV can use a 1:1 ratio with their setup. The diameter is virtually same 1", difference being piston displacement forces fluid out vs conventional cylinder with piston pushing fluid. Is the vacuum portion that much stronger or is it the displacement vs push that makes the difference. Has anyone tried adapting a conventional PB cylinder on the BTV vacuum?

Posted on: 2009/5/18 21:47
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#42
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55PackardGuy
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I need to sign off here, too. I apologize if I leaned on this too hard, but it is as everyone here knows, an important subject and worth some serious thought.

I think Chuckltd made some excellent points.

Quote:

Chuckltd wrote:
On a lot of dual system cars with power brakes, people tend to not notice when the rear brakes have failed or started to.

...lots of vehicles I've worked on appeared to have not had functioning rear brakes for years. If you have a front system failure and your rear system is not up to par, then you're in for trouble. If you maintain both sides of the system as you would a single system car, then you're ok. That includes the proportioning valve and warning light system.

Maybe I've been lucky. I'll take a properly maintained single system any day over a neglected dual.

Bottom line: Dual system is no safer than a single unless properly maintained, in fact it may be worse.


Chuck,

Maintenance and driver alertness are essential, and without a functioning warning light, the dual systems lose almost all of their value, particularly if a failure of rear brakes is ignored... and a "false sense of security" is produced.

Dual systems do provide a decent margin of safety, but as you say, they aren't "foolproof" by any means.

As for your "bottom line," it could be true in some cases, depending on how you define "well maintained" vs "neglected," but given two equally maintained systems--good or bad--which would you rather be on the road with? (Purely rhetorical question.)

Posted on: 2009/5/18 21:55
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#43
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Eric Boyle
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Quote:
Has anyone tried adapting a conventional PB cylinder on the BTV vacuum?


You can't because there's no room for one.

Posted on: 2009/5/18 21:58
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#44
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PackardV8
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"why the BTV can use a 1:1 ratio with their setup. The diameter is virtually same 1", difference being piston"....

It is NOT a 1 inch piston!!!. YES, i know that the manual says 1". IT IS NOT ONE INCH!!! The piston is 0.655 inch diameter. THAT IS slightly more than 5/8 inch diameter.

Take one apart and measure it.

THe BTV is NOT a CUP TYPE cylinder. It is just 5/8 plunger that penetrates a 1" bore. They could have used a bore that is 1 mile in diameter or as small as 0.655 and would make NO difference because there is NO SEAL on the pluger EXCEDPT at he very rear of the housing.

IF u do not believe that it is NOT 1 inch i will take a picture of one and post it here. I have one apart on the bench right now.

Posted on: 2009/5/18 22:31
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7245
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#45
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PackardV8
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" In my case, it wouldn't work because of the factory AC blower "...."

Ah yes!!! good point!!!! i forgot about that.

Posted on: 2009/5/18 22:42
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7245
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#46
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PackardV8
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Also. The BTV has a LONG travel compared to other cylinders. The piston in the cylinder moves very deep into the cylinder compared to other conventional cup type MC's.

Posted on: 2009/5/18 22:45
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7245
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#47
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HH56
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Quote:
THe BTV is NOT a CUP TYPE cylinder. It is just 5/8 plunger that penetrates a 1" bore. They could have used a bore that is 1 mile in diameter or as small as 0.655 and would make NO difference because there is NO SEAL on the pluger EXCEDPT at he very rear of the housing.


Yes, I know-very familiar with them. Bad choice of words in calling it a cylinder. But still doesn't explain why they can get away with the 1:1 when all others want at least 3:1. Only reason I can see is the length vs diameter. Like a hydraulic jack principle--A little displacement in a longer distance would squeeze the fluid out & need less pressure than a larger piston would. Would be interesting to connect a pressure gauge and see what is developed. The PB stores say a conventional drum setup needs around 1500psi on large cars.

Posted on: 2009/5/19 8:23
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#48
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PackardV8
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The smaller the piston then the less effort required by the foot. BUT the foot must travel a longer distance to displace a fixxed amount of fluid at a fixed pressure. So that is why the 1:1 RATIO works.

Put a larger piston in the bore and it becomes more difficult to push the pedal so the pedal ratio must afford more leverage to displace the fixxed amount of fluid at the SAME pressure.

Posted on: 2009/5/19 9:05
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7245
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#49
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PackardV8
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The "1 inch" specification in the manual is completely erroneous. If not i wish someone would explain to me otherwise. The BORE of the BTV cylinder is about 1-3/16 inch. THe piston is 0.655. I can not find ANYTHING on the BTV that is 1 inch +or- 1/16 inch.

Posted on: 2009/5/19 9:08
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7245
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Re: BRAKES: Easamatic Power Brakes aka Bendix Treadle-Vac--Change or Not??
#50
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PackardV8
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"Has anyone tried adapting a conventional PB cylinder on the BTV vacuum?"

The problem is finding such a master cylinder. It would have to be about .655 inch diameter +or- say an 1/8 inch maximum. ALSO such a cylinder would have to have a piston with enuf travel. Also it has to fit into a very tite place. The original factory set up places the end of the MC about 1/4 inch from the frame which is JUST ENUF clearance to allow for body sag and belgium block compliance.

Posted on: 2009/5/19 9:18
VAPOR LOCK demystified: See paragraph SEVEN of PMCC documentaion as listed in post #11 of the following thread:f
packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=7245
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