Packard Forum Index » V-8 (1955-56)

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Just a clarification, the non-power brake master cylinder on the 54 and prior models are actually mounted on the frame rail forward of the firewall. Basically right behind where the steering box is mounted. But it is actuated with a linkage that does go under the floorboard. The pedal arcs under the floor, and then it rotates a cam which pushes master cylinder rod forward. Not sure if the was done as some type of force multiplier or what.

I just ordered new brake hoses for all around..maybe i should've done that first...we will see..

As for getting the knock out of the engine, some were wondering what i used, 4 qt rotella 15w 40 and 1 qt MMO. drives like a dream.

Thanks for the advice..and hopefully i can drive her for more than 30 min..ill let you know how the new hoses work out.

Have u chequed the vents on the vacuum unit and the mc filler plug????? If these are plugged it will cause the problem u describe.

Hm, 30 minutes in traffic and the brakes lock "on", wait 90 minutes and they "unlock" all by themselves.

Could this be a heat problem?

Using the brakes "in traffic" for 30 minutes would mean applying them several times. We know the brake fluid, shoes and drums would heat up some, but could anything in the system expand enough to lock the brakes in the "on" position?

Morgan, are there any peculiar conditions present on that fateful last application of the brakes?

And what about driving it without applying the brakes for 30 minutes. Do they lock up then?

When they lock, have you ever felt the rims for heating, like from a binding shoe?

We reviewed the entire braking system, took most everything apart including the Bendix TV and noted the travel of the hydraulic plunger. On the return after applying the brake it was noted that the tip was a little too long to trip the tip of the compensating valve thus causing the pressure build up. A small non movable spacer was slipped over the shaft at the end and it now properly trips the valve and the brakes are fine. We even tried driving without the vacuum boost and they also worked but naturally with a bit more effort. When the TV was dissembled and rebuilt for the first time last week we noticed that the compensating valve tip was beyond the end of the hydraulic plunger rather than before (if you look at HH56's close-ups he sent). We could never figure out why that was done and it is our guess that this car always had a braking problem since the 1990 frame off restoration. This car has multiple personalities as she was assembled from several 55's, could someone have slipped in a part from a 56 or were the hydraulic plungers the same length? Thanks again for the input.

Am glad the problem appears solved but for clarity in my pea brain, did you mean compensator valve tip or actually did find a problem with residual pressure valve in the outlet. If you did mean tip of compensator valve was beyond the plunger, you are lucky it wasn't bent or broken. Is the spacer firmly attached so it can't move?

HH56 Yes the spacer we used will not move yet has a little rubber to absorb any shock. I really cannot see how the old backward setup could work and it was just by DSL (Dumb Stupid Luck) that it caught our attention. The old tip was not bent as it just could not ever engage. Maybe the old country Doctor who once owned it only drove for 29 minutes and always gave his patients a 90 minute exam. .

HH56 Can see the confusion, yes the compensator valve tip (too much DS) yet this morning and not enough L (luck). I corrected the post.