Packard Forum Index » Post-War (1946-54)

There are ONLY 3hree things that can fail in the master cylinder:
1. rear seal.
2. compensator valve.
3. residual pressure valve (maybe).

Did i miss anything???

I'll have to admit that my post #15 above about the Residual pressure valve failure may be reaching a bit. Especialy in view of many cars that had the standard brake master cylinder mounted to the frame rail. But those had no vacuum booster thus no possibility of a vacuum draw into the mc reservoir.

Let us consider a TV unit that is leaking vacuum between the mc and the vacuum can. Parked on a hill headed UP. The fluid in reservoir is covering the verticle seal lubrication hole in the back wall of the mc. Engine starts and runs and vacuum sucks fluid from mc.

That's plausible although I don't think it has to be parked any special way--believe the fluid is always higher. There is only the single rubber lip around piston shaft that is the liquid seal. If any kind of pitting occurs anywhere the lip normally sits, it's over. Several parts cars we had were in that condition after sitting for years, and if those TV's were returned to service without a go thru, there would have been an issue.

I don't believe any leaking fluid would account for the issues of intermittent no pedal though--believe that is strictly compensator valve. It would, in my opinion, be hard for the residual valve to fail in any way that would lose brakes unless somehow it totally blocked the outlet. In that case, would think the pedal could hardly move at all--even if the vacuum were sucking fluid it would be a fairly slow move to floor.

See post #12 above by Trog:
"My brother has both an Edsel and a '56 Lincoln Premiere with Treadlevacs and we've not experienced the problems we've known on the Packards. Also he rarely needs to top off the reservoir. On all four of my '53-56s, I need to top the reservoit off several times a year. And on the Premiere and Edsel, access to the unit is right there up high rather than on the ground and in the floorboard.."

I know Trog. He is most meticulous with all of his many vintage cars and stores them under superb conditions.

we need to know the difference, if any, between TV's on Packard vs other makes. Maybe there is a an extra seal on the other makes between the vac can and the MC that packard chose to delete for cost reasons. How much higher did other mfg's set the TV than Packard.

Maybe some of the Country Club service suppliers need to chime in here like the Egge rep did for the pistons. THis is the problem. Service providers say NOTHING. "Just send us your junk and some money" is their attitude. When that doesn't work anymore they will probably just stop rebuilding the Packard units.

Service providers say NOTHING. "Just send us your junk and some money" is their attitude.

That's certainly not a true statement as far as Ed Strain goes. I've spoken with him at length on the phone even when not making or considering a purchase and he's willing to spend all the time needed. Why don't you take it on yourself to give Ed a call with your questions, and let us know what he says. I think we'd all be interested in the results.

Just did a search for treadle vac and came up with several forum hits for other makes. Lots seem to be having issues with the sticking pedal for various reasons. Their respective gurus all pretty much say wrong lubrication, binding linkage or corrosion inside can.

Did not see anything that jumped out re outright failures other than a chevy guy mentioning the spring on comp valve and links to Craig's site and a few to Pinfo. Lots of people are wanting to update or change mostly due to cost & parts availability & looking for alternatives. PV8's conversion to a Honda unit from a post on AACA, and Craigs Panther site is mentioned. Didn't see anything re Erics Ford unit conversion.

One of the rebuilders stated that a good rebuild could not be accomplished without "extensive machining" of the MC which his shop did but others didn't do & just changed the seals. That was a guaranteed failure in short order was his feeling.

There was an article from a Hemmings magazine about the gradual demise of the unit by early 60's and their conclusion seemed that it just couldn't compete. There were similar units made by others, mfg's wanted larger vacuum portions for more power, and firewall mounting requiring thinner & more flexible units were coming in vogue.

Thanks HH56, good info and thanks for taking the time. I'd still like to see someone call Ed Strain or another reputable rebuilder and gather some good information for us. As I've said I've not had any TV problems over decades and I don't know how many miles, thus I'm not familiar enough with them to understand the intracacies as you and PackardV8 seem to.

One of the knock-off units I recall was the Delco-Morraine, they looked so similar to Bendix at first glance that you had to take a second look to see what it was.

A bit off the topic, but Bendix had a long history of making power brake boosters for Packard and many others, including many heavy trucks of the era. I believe the got into this when they acquired Bragg-Kliesrath (in the early 30s?) who made the power brake and clutch boosters for mechanical brake Packards thru the 14th series. Of course they also had a long history of making hydraulic systems for aircraft, the company name wasn't Bendix Aviation Corp for nothing. I've got a great little 150 page booklet Servicing B-K Vacuum Power Brakes published by Bendix, year unknown, which covers repair of many of these units.

Magazine mentioned the Delco-Moraine and another as well. Also a couple mfgs made knock offs of the Hydro-Vac one I believe said (as of 2005) was still available. There was also apparently a similar to TV unit Bendix made for truck air brakes used till late 60s but it didn't go into much detail.

HH56 writes:
" Lots of people are wanting to update or change mostly due to cost & parts availability & looking for alternatives. PV8's conversion to a Honda unit from a post on AACA, and Craigs Panther site is mentioned. Didn't see anything re Erics Ford unit conversion"

The Honda unit should be second choice.

Those wanting to convert should use Erics Ford conversion. It's GREAT!!! NO BUTCHERING of OEM platfom necessary except to elongate holes about 1/16 inch in the mount for the parking brake mechanism and relo the PB relay. I would prefer a single stage cylinder but have not found one yet. PRobably a late 60's F single cylinder will work.

The Honda unit was a first conversion attempt by Craig and then me. It works ok but creates a bit of a hard pedal due to the 13/16 piston in the mc. Also has very short stroke. It's ok, it works, but leaves a bit to be desierd and believe Craig will agree also.