Packard Forum Index » V-8 (1955-56)

Not bad. You could trim that Chevy pedal down a tad or weld on a plate sized to accept the Packard rubber pad. Except for the different side of steering column for a 55 which not many would catch, a casual view of the inside would be hard pressed to tell it was changed.

Thank you for the extra pics of your setup Craig, gives me a better idea of what it looks like, and if you have any of the Malibu setup I'd be interested in checking that out as well.

Brandon Quote:

I guess you misunderstood my post. The pics above ARE of the 1979 Chevy Malibu adaption, NOT my Panther project.

Craig

Haha yes in fact I did, took another look at that after I posted and had a "wait a minute" moment.

But again thank you for the post Craig.

Does the Malibu power unit fit the fresh air vent without drilling or modifying the oem Packard firewall???

Has anyone in the past tried to mount a modern dual master to the original vacuum can of the original Treadle?

IIRC, It was discussed some time back but there were some issues and as far as I know it has never been tried.

Vacuum sealing and power piston guide are a couple of problems since the master bolts directly to the vacuum canister and covers openings and provides the mount area for sealing components. Something to take care of that would need to be machined. The hydraulic piston shaft also provides the guide for the power piston which would be essentially unsupported otherwise. Not sure a regular rod on a modern master will be smooth enough for sealing or large enough to support the power piston and keep it from twisting inside the canister.

The bigger issue is the type of hydraulics. The BTV uses displacement where a relatively narrow ram moves a large distance into a closed chamber to squeeze the fluid out. It can get by with the low 1:1 ratio Packard has. A modern master has to push the fluid a short distance ahead of a fairly large piston area and requires more ratio or boost.

It is thought using a narrow piston master might alleviate some of the additional ratio needs and might be able to work with the Packard geometry. It would be interesting to know if that idea works but don't believe anyone has tried one.

Thanx HH, this is one project I am playing with. I just picked up 5 treadle vacs to experiment with.

Obviously the smaller dia master will deliver more psi to the wheel cyl however, if gone too small, pressure can build too quickly giving a jerky peddle.

I am playing with 5/8 to 1.039 bore, any bigger may give a harder peddle.

I have the master mounting and vacuum sealing all down. I need to turn a new plunger shaft to accommodate function in the vacuum can as well as the MC plunger.

Any other thoughts as I play with this is appreciated.

The big issue is what happens if the boost is gone. Even the displacement BTV gets a bit hairy trying to stop the car with no power. With a conventional master and 1:1 ratio, 100 lbs of foot pressure will not give much more than that out. That is the main reason all the modern boosters using 1" cylinders recommend a minimum ratio of 3 or 4:1 and most prefer 6:1. At least with a higher ratio that same 100 lbs will provide a few hundred psi to the wheels. The smaller diameter master might alleviate some of the issue but how much is the question.

Assuming a 1:1 oem pedal ratio then any mc bore > 13/16" will make for a hard pedal. Again, i tried a 86'ish honda civic power unit and MC on my 56 Exec with OEM pedal and oem pedal arraangement. Mounted it to the toe board in the same location as the oem BTV. IT worked but was the pedal effort was more like a manual brake than a power brake.
On a 4500 pound car with speeds capaable of 110 mph ALL DAY LONG the power brake is most needed. For trailer queens then maybe not.

BTW the 86 Civic was a MASTERS brand unit.

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