Tedd Thompson

While on my last trip in the 55 I lost the power brake assisted(treadle-vac) part of my braking system, no power brakes only manual. This only happened first thing in the morning and lasted for about 5 scary miles in heavy morning commute traffic other than that no problems for many miles after. It was freezing cold outside and the car was parked with no cover.The Treadle- Vac was a new rebuilt unit about 30 thousand miles ago and is bolted to a Bindex master cylinder. Any ideas on what part would fail to cause this, any tips on how to trouble shoot this intermittent occurrence?

I had noticed this problem on startup a couple times this winter but was gone by the time I backed the car out of the driveway, maybe 30 seconds and not everytimeI started it.I need to find the fix soon as I'm getting afraid to drive the car out fo sight of the house ......Tedd

59-59-59

So this happened on initial startup? And only on extremely cold mornings? If so I remember a story about how the check ball in the vacuum line somehow iced up and froze in position and wouldn't supply the booster with vacuum until the car really warmed up. Sounds strange

Tedd Thompson

Ya, but the times at home that this happened the car was in the garage, cold but not freezing.I also thought that the vacuum valve may just be stuck open maybe from oil or sludge but this valve is isolated and away from most of what would cause that to happen. I thought I would just replace it anyway but I can't find a source for that valve either, I wonder if a PVC valve would work?....... Tedd

55miketn

I think you have a vacuum leak and the power doesn't work until the vac. is built back up in the res..

Tedd Thompson

No doubt that there is a vacuum leak but trying to isolate a interment occurrence is where I am having trouble . Why the vac will hold a vacuum sometimes for a week then overnight lose it's vacuum and not regain it for some miles while I drive it down the road, Interment brakes suck.

I hate to pull the whole unit off and replace it with a new one (they are expensive) if I could find the problem and just replace a valve or gasket.

The season is almost on us and I don't want to lose the first of it with the car sitting in the garage just like last year....Tedd

55miketn

Yeah, didn't know it would hold a while and release. I am thinking like you that there is a problem with the check valve!? I would think any kind of positive seal check valve would work for a test. Then maybe find a valve somewhere? Wish I had a better solution.

Rocketowner

Rocketowner

Hey Ted,Ecklers Chev.parts Has A Treadle Vac. check Valve For 1957 Chev.For $10.99. it Looks Different(90 Degree Angle) But It Could Probably Be Made To Fit. Good Luck, Larry

Rocketowner

Ted,I Was Also Told That These Brake Systems Need 16-18 Inches Of Vacuum At End Of Vacuum Hose That Attaches To Reserve Canister, And You Might To Pull A Vacuum. on The Canister To Be Sure It Is Not Leaking. lLarry

Tedd Thompson

Thanks for the suggestions the car is in a shop as of Friday and I will pull a vacuum test. If this problem wasn't so interment it would be easy to diagnose. If something suspicious doesn't show up soon I'm going to replace the whole Tredle-Vac and get on with the season....Tedd

Olds Dad

Tedd - This was what my Treadle was doing before I did the brake conversion. Everything I read - including on some Packard boards (they used the same setup as us) indicated that this intermittant 'failure' is very common to these units. The cost of the new unit vs the cost of my experiment was the reason I tried the under floor brakes.

Unfortunately, I think you have a new TreadleVac in your future...but at least you live in California and have a '55 convertible...

Tedd Thompson

We pulled the Treadle Vac down and found the Morane ( not the Bindex as I thought I remembered I had) was leaking a very small amount of fluid past the seals, Just enough to gum up the vacs works or thats what we ( my mechanic friend) think. Every thing else looks fine.

Gordon if this happened earlier in the winter I would have given your experiment a go. I think it is the best way to go to keep the car looking original plus the use of cheaper newer and less difficult to get parts is attractive also.

Right now I am pretty limited to what I can do physically,I'm getting ready for a double knee replacements, so some of my repairs will be farmed out or I will assist where I can, hard to get a mechanic to venture into seldom traveled waters unless they are adventures.I will let you all know how this all turns out when done....Tedd

Olds Dad

Tedd - sounds like a good plan at this point. Been such a kick-you-in-the-a$$ winter here in New England, that I haven't done much on any of mine...still working a few kinks out of my brake experiment anyway...pressure check valves are hanging up it seems - wouldn't want to see you having any more down time on that princess than necessary!

Fitti Six

Thanks again Tedd and good luck. I'll be tuned in right here, with the popcorn

Roy

Tedd Thompson

After disassembly of the master cylinder we found leakage around the seals that keep the Tredal vac dry and devoice the two units as described in my previous post. were talking less than a 1/4 teaspoon of brake fluid that we found. I have noticed having to add fluid once or twice a year, never more than one or two ounces and didn't think much about it, now I know where it was going.After checking out the Tredal vac we could find nothing leaking vacuum wise or out of place the unit was cleaned and reinstalled with new parts on the master cylinder side only so the conclusion is that the weak point is that joint (conection)....Car stops wonderfully...so far

PS. that master cylinder is the strangest, most different piece of equipment I have ever worked with that stops cars but it seems to work ....Tedd