Packard Forum Index » V-8 (1955-56)

HH56

Thanks.

Tom

Has anyone brought up removing the vacume unit on the oil pump, and connecting a motor to it.. mount it to the fender, the rt fender,,55-56..

to keep the org, wiper motor. what rpms does the vacume pump work at.?,,600-3000+ rpms?

I don't recall hearing of anyone who has tried to use the original pump. Might be possible with a new support plate and a little machine work. Not sure if they are designed to be run in open air or if they would overheat. The RPM would be same as distributor so if I'm thinking coherently tonight, would guess in the 750-1500 range would be an average range for typical city and highway driving.

One of our Australian friends has converted to an alternator with an attached vacuum pump as was used on some diesel cars. If just the pump portion from that unit was obtained it might be an easier possibility.

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Hi, Howard,

Interesting,, thanks for input. but doesn't oil get real hot?, but then again, machining, a body would be easy ..another project. i have a spare vacume unit think i will give it a try. see what happens. a cordless drill motor might work..and can use the chuck to hook it up... the gearing is all there for torque.

I have read this post and looked at the manual and photos attached. My question is whether the disc at the end of the Bowden cable is affixed or slides on the cable. On one part car, the end does not move, but the unit on my car slides freely.
When the wiper switch is turned on the cable is extended to its maximum length. When inserted into the designated slot it could pull the plastic mechanism but not push anything.
Seems that it should push and pull to have a functional switch but this is on the to figure out lost....after I get the brakes figured out.
Anybody know?

The washer usually slides on the wire but the more important point is that the crimp on end of wire is intact and washer cannot be pulled off cable.

Operation is that the cable wire extends and the wire end is what actually pushes against the plastic slide to turn on the motor. The washer is along for the ride and since it can't come off the wire, the washer does nothing until time to turn off. It does the actual pulling to return the slide.

Without co-ordinator wire would be in the small slot toward the front of the slide and washer and cable end would not be able to separate. Both would be in the small recess acting directly on the slide.

With co-ordinator, its wire and washer occupies the small recess. Vacuum would extend the wire which pushes against the slide and the washer pulls it back via the spring in the co-ordinator cylinder. Identical operation to the manual wire.

Main difference is with co-ordinator the manual wire has moved to the rear mounting position. There is no part of the manual cable fastened or captured by the slide so it is still free to move under control of the co-ordinator. When turning on via manual cable the wire end still pushes against the slide but in a different spot. Because the co-ordinator is attached to the slide it is also pulled along via it's bracket arrangement. To turn off, the washer instead of being in the recess is now pulling against the part of co-ordinator which was moved away from its stop when the slide moved the entire assy. Pulling against that part to return it to the stop also pulls the slide back since the two are fastened together.

One thing I have seen is the plastic on the slide where the cable end pushes against be punctured or cracked. Make sure the slide is intact in the two positions.

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Thanks for the clarification and the photos. I was looking at a possible cable replacement at Hershey because the washer was loose on the cable. Interestingly several vendors offered cables with no washer and another offered one with the same loose washer as the one on my car. Glad I waited to get an answer before spending more money.
I must admit that the service manuals for the 55 Packard are not as clear as someone with no prior exposure could want. The Forum does help fill the information void.
I may get the wipers working before getting back to the Tredlevac . Might be nice to have something work correctly at the end of the day.
I am going to check some old car magazines to see if I can find an article about a power brake conversion done but Troy of Rad Rides by Troy on a 61 Chevy ( " Bisquik"). Pretty sure he used a unit from a Geo metro that was compact and stopped a heavy car with a 600 ci engine. I would like to have a dual master cylinder, but the limited space and the pedal arrangement will require some thinking. I just had total brake failure on a rebuilt Hydrovac unit on my 55 Cadillac- sucked all the fluid into the engine. I was able to secure a modern replacement from Karp brake in California that seems to solve the problem of using old parts to refurbish the units.
The Packard will be more difficult since I do not wish to destroy the appearance.
Thanks again
RJR

The Packard will be more difficult since I do not wish to destroy the appearance.

In a sentence, that is the big problem with adapting modern brake systems to Packard.

The Packard has the BTV at the bottom of the arm so the force to the ram is exactly what you place on the pedal or 1:1. Since it is a ram type displacement unit it can get away with lower force by the relatively long travel of a narrow rod squeezing fluid out of a closed cylinder. A conventional master with a larger piston pushing fluid ahead of it has the piston located higher on the arm. The force on the pedal is multiplied by a ratio depending on the length of the arm vs where the takeoff point is located. With the same amount of force and travel on the pedal end, the cylinder will see a shorter amount of movement but a multiplication of several times the force. Because of the larger surface on the piston, same amount of fluid exits even with shorter travel and because of ratio, fluid still has approximately same force as the ram type.

Most modern power units want a minimum ratio of 3:1 and several want higher. Manual brakes usually have something in the neighborhood of 5 or 6:1. Unfortunately, there is no way to mount a modern unit in the allotted space and get the needed ratio without changing the pedal appearance. Keeping the pedal appearance requires mounting the power unit somewhere else higher up on the arm so the engine compartment appearance is changed.

As far as I know, the only modern unit that can keep the location and pedal appearance is the ElectroBoost system. That is a two part unit. Cylinder operated by pedal and hydraulic accumulator with electric multiplication for the force. The output is adjustable so a nice feature. Downsides to that unit are it is expensive, 12v only, and since the ratio is 1:1, I would still wonder if the thing could stop the car if power failed and reserve in accumulator was used up.

Riki, back to your question about the V8 factory vacuum pump, it runs at 1/2 crankshaft speed, same as the distributor and oil pump.

If you want to replace the factory oil pump-driven vacuum pump with an alternative vacuum booster, rather than start all that engineering to design something new and comples, just go with a dual-action fuel pump as AMC did on the Packard V8 engines.

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O_D, you beat me to the punch recommending a double pump. Or, another way would be to install an electric windshield wiper motor. I prefer the latter as the lesser of two evils.

(o{}o)