Packard Forum Index » Modification Discussion

Good recomendateion for those using FACTORY air-con. Altho it sounds to me like there would be a terrific amount of linkage and bracket fabrication to make it work.

For those withOUT FACTORY air-con then Erics conversion is about the cheapest, fastest and nearly foll-proof bolt-on conversion available altho it does eleminate the left fresh air duct.

Unless there is a parts car involved, would almost require the use of a bolt or weld in street rod under floor setup for the pedal assy. My 2 bits thinks it would be a viable option doing it that way with a remote power unit but as Craig pointed out, there is not enough frame depth to put a power unit under the car without making some kind of room. Also still think that despite the different arcs, there would be a way to do it with the original pedal in place for looks.

actualy the idea i have is this. if the booster side is fine and dandy with everyone but the m/c is not, why not keep the booster side and adapt a different master? that way the issues of mounting location,pedal position, propper boosting ability and such are nil. just adapt a better m/c!

as for the ignorance thing eric,just ask any die-hard brand-x guy. every one of them will tell you we're all ignorant for owning something other than a "x". so i might as well just be "ignorant" and help out the guys who want to keep the btv. even if it's in modified form!

The MC change would be a good idea if one can be found & adapted. Problem is the stroke and pedal ratio.

Stroke ideally would have to be around 4 inches but the bigger problem is the 1:1 pedal ratio. Unless there is something incredibly more efficient in the Bendix power unit, a 1:1 conventional cylinder won't work. Craig found this out in his use of the MPB modern unit where he had to go back and rework the pedal leverage to keep his unit in original location and feel comfortable with it.

No one versed in fluid theories has spoken up as to the exact reason why TV works at that low ratio. Best guess is because of the narrow piston and longer stroke, it's essentially displacing fluid by inserting mass & squeezing it out rather than "pushing" it out the opening in front of a piston.

At any rate, that plus the extremely limited room for any other cylinder is the problem. There are some fairly small bore cylinders which might be able to fit but think most conventional cylinders only have about a 2 - 2 1/2" stroke. There's also the question of with a small bore & short stroke is that enough fluid volume available for the wheels and does the ratio still need to be higher. Haven't looked but it might be possible to move the unit toward engine an inch or so which might help the fit problem--but not the mechanical advantage.

Quote:

I have found evidence of a small amount of brake fluid on the very bottom of the vacuum cylinder - a level far too low to be sucked up through the vacuum piston. In those cases, the seal(s) had been compromised by either by dry rot or a pitted plunger rod.

However, note that there is a passage that runs from the top rear of the reservoir down to the counterbore for the seals - between the leather seal and the rubber cup seal. Was the intent to permit a small amount of excess fluid to enter the bore and keep the seals from drying out?

Yet, a failure of the compensator port valve would, upon application of the pedal, cause fluid to be pushed back into the reservoir and down that same passage. As such, I'm wondering if that could be another source of fluid found in the bottom of the vacuum cylinder.

Now as regards your latest sig line:

Quote:
I'm not sure a diaphragm-type seal could be rerofitted to the BTV reservoir cover as a replacement for the compensator port valve. Seems to me that M/Cs using such diaphragm have a heavier, formed cover that is held in place by a wire bail; I question whether all that could be easily adapted to the BTV.

Seems easier to come up with a proper replacement spring to use in conjunction with the new replacement compensator port that is provided in repro rebuild kits.

BH writes: "I'm not sure a diaphragm-type seal could be rerofitted to the BTV reservoir cover as a replacement for the compensator port valve. "

NO. NOT as a replacement for the compensator port. The idea is to develope a seal to keep atmosphere from entering into the reservoir. That is to keep the system SEALED like the modern brake systems.

"Yet, a failure of the compensator port valve would, upon application of the pedal, cause fluid to be pushed back into the reservoir and down that same passage..."

1. if the compensator port fails (even just slightly) there will be NO brakes as in absolutely NO BRAKEING effect WHATSOEVER.. So pushing fluid down the lubricator gallery is a moot point. My BTV never failed. NOT ONCE! But i had to continualy fill the cylinder about every 200 miles.

2. THe vacuum unit should be SEALED from the MC AND the atmoshere at the mateing point of the cyl/vacuum unit.
That is to say, that it should not matter if the MC leaks or does not leak or even if the MC is assembled to the vacuum unit at all. THE VACUUM unit SHOULD NOT LEAK VACUUM AT THAT POINT! PERIOD.

"No one versed in fluid theories has spoken up as to the exact reason why TV works at that low ratio. Best guess is because of the narrow piston and longer stroke, it's essentially displacing fluid by inserting mass & squeezing it out rather than "pushing" it out the opening in front of a piston. "

I don't think it requires a PhD. in fluid dynamics.
A SAMLL piston requires less effort than a larger piston.
A 1:1 pedal ratio requires more foot effort than say a 3:1.

THe BTV 5/8 piston is a SMALL piston compared to nearly every other automobile MC i've ever seen. Most MC's are at least 7/8 inch to 1-1/8 inch diameter. But such cylinders have a lot of pedal leverage.

The fact that the BTV "squeezes" out the fluid rather han "pushing" out the fluid is irrelevant.

Samll piston = 1:1. Big piston = more pedal leverage needed.

The smaller the piston the further it has to travel to displace the same amount of fluid that a larger piston would displace at less travel.

Keith:

The reason you are beating this dead horse is?

Maybe Bendix could have hired you to figure out the reason for the Treadle-Vac problems back in the day. But now?

I thought you were "moving on".

Craig

No excuse SIR !!!