Packard Forum Index » V-8 (1955-56)

Looks like a first class rebuild Kev. Sleeving the vacuum cylinder is a good idea if yours was pitted.

Now to conclude: we pulled out the BTV there was still fluid in the lines. If I ever get a chance i'll set the unit up on a test bench, so at the moment no reason on why the failure pccured, though not long before the total failure, I experienced a very spongey brake pedal. Which appeared fine again before the accident. Though asides from that I would like to report that I contacted ABS Power Brakes in California.

abspowerbrake.com/electrichppage.html

They recommended using the 10-59-6 unit. This is what they installed in a 56. I am in the process of installing this. My vehicle is about to be re-painted and then the engine re-installed, so once this is all done i'll get some pics to post.

This is just another option for those looking for an alternative.

Is there fluid in the vacuum power unit and about how much????

Another poster was going to try the electrobrake but don't remember seeing any info as to whether he did or not. Wonder if or how that worked.

When you post the pictures, any chance of some "as you go or in progress" shots or a description of any problems the mechanic runs into & reasons why he chose to do something a particular way. The more details the better for the next person.

I'd still bet money the compensator valve failed to seat for some reason--and think a likely suspect would be some debris floating in the cylinder portion that landed under it.

I would also be interested in the details of this installation as I want to ultimately replace my BTV with something more modern.
I'm still having problems trying to source parts for the vacuum piston.
Has anyone checked out the bolt in replacement advertised for the BTV by abspowerbrakes it's in the 55-57 Chevy section of their catalogue part PB-377974...? I'm dubious if it would fit in a 55-56 Packard as it's a 7'' booster and suspect it also might be tight under the steering column...? and if it did fit maybe unable to remove the filler top.
I emailed them for a suggested replacement but so far no reply.

Dave.

IIRC, the 55-57 Chevy BTV mounts on the firewall, NOT below the steering column on the toe plate, so it's an apples and oranges comparison.

Craig

I had also thought the BTV replacement might work as it is a dual 7" booster but another poster called for info and the company said no. The problem you are going to run into with any modern vacuum unit in the original location aside from fit under the column and clearing the frame is the pedal ratio.

Since the piston is larger for adequate volume with a short stroke and actually pushes fluid ahead of it, most modern units require a 3 or 4:1 lever advantage. Packard located the unit at end of pedal & utilized the Treadle-Vac which does it's fluid displacement by a narrow rod and long travel. The rod by just being inserted into a closed space squeezes or forces fluid to go somewhere instead of using piston push power but, by location, is 1:1. The Chevy replacement is dash/firewall mounted so has the lever advantage. Craig has detailed this problem using a 7" booster in the original location and his fix on his Panther site writeup.

The Electro-Boost is adjustable on the pressure output so if a bit less is there initially in the original location, it can be compensated for up to a point. It's also fairly small, being in two pieces with boost pump somewhere else but is 12v and expensive.

There appeared to be quite a substantial amount of fluid in the unit as when everything was disconnected I depressed the rod and fluid came out from the unit. Most likely my problem was due to the compensator valve this sounds like the most likely suspect as this wasn't replaced

I will be down at the car on friday, i think from memory wer begun mounting the unit. This unit can either be mounted on the firewall or on the chassis. The unit itself is a nice looking unit so one wouldn't be ashamed of having it in their engine bay. i have however opted for the chassis mount. They also have a brake disc conversion kit for the 55 & 56 models for (from memory $950) i have also decided to install this aswell and this was a reasonably easy bolt in operation done in less than a day

On Friday I will take some pictures and post them

Cheers,
Mathew

Finally we got there With the engine still out of the car we dummy fitted the brake system. Enjoy the images. As you can see she fits quite nicely where the BTV once did.

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Fitment looks great! Can you supply manuf part numbers?