Technical Need help with Treadle-Vac Fix

I was successful in taking off enough stuff to get the Treadle-Vac unit out of my Stude pickup. So this afternoon I made couple calls to see about having it rebuilt. $450-$700 plus shipping each way. Ouch. I’m not afraid to tackle it myself, and kits are available but to order the correct kit I need to identify it. I did some internet searching but didn’t find any that looked like mine. I read that there are ID numbers stamped in the end of the M/C but I don’t have it with me to check it.
This was obviously not standard Studebaker equipment, so I need a little help figuring out what the donor car was so I can order a rebuild kit. I’m hoping someone here may recognize it and can point me in the right direction. It has a steel booster can, aluminum M/C, long dipstick tube. The push rod has a ball on the end that snaps into the back of the pedal. (Not shown) Here’s what I’ve got, what did it come out of?

 

I don't know how you would positively ID it without the stamped info. How far away is it?



Even if someone ID's it by sight (similar), the overhaul kit may not be for that particular unit.

 

Bob...a quick tour on Google images and it looks like the kind a 1953 to 57 Olds would use. I didn't spend forever looking, but those are the only ones with that kind of dipstick I saw..

 

Bob, good read here for education purposes
Bendix Treadle Vac, Myths, Fiction and Facts [General] - Packard Motor Car Information (packardinfo.com)

 

Call Harmon Classic Brakes, He will tell you how to identify it and will have the correct, quality kit for you. Have used them many times and parts have always been correct. They are pretty easy to rebuild.

 

Thanks for the responses. The link to the Packard forum was interesting with the Kanter fellows chiming in.
Once again, the old “single circuit M/C” argument comes into play. My first thought when I bought the truck and saw the Treadle-Vac was, “that’s gotta go”. But once I crawled underneath and looked at the real estate available for an under the floor pedal assembly I had to reconsider rebuilding the T-V.
With the Mopar front clip (it splices in right under the center of the cab), torsion bars, steering box and the wide Jet-a-Way transmission, there’s no room for a street rod type pedal assembly.

I could probably make a pedal/pivot assembly to fit and mount the M/C farther back but the torsion bar anchor is still a problem I’d have to get around.
If you’re familiar with the quirky Studebaker truck firewall/dash design, it doesn’t lend itself to a hanging/swinging pedal arrangement well either. Although I will be taking another look at that possibility.
So that’s why I’m looking into rebuilding the T-V unit. I’ve got to admit, it’s definitely not my first choice, just the quickest way to get the old truck back on the road.

 

I cleaned up the old Treadle-Vac a little so I could read the ID numbers. I can’t say I was surprised, but it had a reservoir full of powdered brake fluid. I’m guessing it would be at the $700 end of the rebuild scale were I to send it out. I’ll take it apart and check the bore next.

After a marathon cleaning session….


And the ID numbers….

I’ll go forward with the disassembly but in the back of my mind I’m working on a Plan B.

 

I have rebuilt one of those, I have no idea how they work. There isn't even a seal on the piston.

 

I’m guessing Plan B does not involve the TV?

 

First of all, I thought I had left the Treadle-Vac unit on the workbench down in LA. My better half said, “No, you put three big greasy things in the van when we left, I’m pretty sure one was the brake thing” LOL, she was right. The “brake thing” was under my lathe, behind the roadster radiator, right where I left it. I also brought along the starter and the exhaust manifold so I could spiff ‘em up a little.
I’m curious how those things work too. Gonna take my coupe to a little car show at a local lake tomorrow am, when I get back I’ll put on NHRA qualifying and dive into it.
Yeeeah, there’s got to be a way to weasel a pedal up under there or hang one under the dash somehow, even if it means adding a bell crank or something. If the TV master cylinder needs to be sleeved, I’ll probably have to let a rebuilder do it and I’m not too happy about spending that much money on that old system. But if I can fix it myself, I’ll give it a chance.

 

treadle vac is the same as what is in my 57 Olds "88"

 

Thanks. I did as Black Panther suggested and looked through google images. Like you say, it seems to be a ‘57-‘58 Olds. Just trying to educate myself before calling about kits and stuff.
After reading some on the Packard forum, it sounds like it makes a difference who you pick to rebuild it or who supplies the rebuild kit. Something to do with the compensator valve. I need to do some more investigating.

 

I looked at Kanter’s website and it seems like most of the kits for that style of Treadle-Vac are $184. I haven’t checked other sources but Kanter’s takes these things seriously, even testing them for the types of failures some have reported anecdotally. Their kits include a stainless steel piston and the unit works as it was designed to work. But enough of that, on to the dirty work.
I slowly disassembled the vacuum side by un-bending the tangs and removing the cover plate. Here’s what I found.

More hose. There’s 3 screws that project into the cylinder, take them out and the big vacuum piston comes out, (with some cleaning and cussing). It’s the brains of the unit.

The vacuum piston assembly (yellow circle) has quite a few parts inside. It works like the directional valves in Ford’s old slave cylinder power steering. The rod on the right moves with pedal pressure, the internal valve senses the movement and opens the main chamber to vacuum assist and vents it when the pedal is released. That big spring pushes it back. The big leather seal is in the red circle. The pad in the center of the fins is the seat for the long M/C piston. Down deep in the big can are the screws that mount the M/C to the can. So off comes the M/C….

There’s a dust seal, a fluid seal, a snap-ring, a steel washer, and a Bakelite washer. Then the piston/shaft comes out. I had high hopes when I found that the trapped fluid had turned to a paste, the consistency of chassis grease. Almost the entire cylinder wall is perfect except for one little spot. I need to take measurements to see if the spot is in the path of seal or behind it. Tomorrow I’ll clean everything and do a careful evaluation.
The suspect pits…. They may not be in the working area of the piston, if they are it will have to be sleeved.

 

Here’s an “exploded view”….

 

any reason you couldn't adapt a dual circuit MC to it?

 

Good question. I’ll take a look at that possibility.

 

I bought a 54 Lincoln, had the original Treadle Vac with a Mustang fruit jar adapted, worked great, I never fooled with it.

 

The treadle vac master cylinder is pretty long and I don’t know how much room there is for a longer one. I have an extra Mustang m/c on the shelf, I’ll take some measurements. The T-V master has a roughly 1.400” bore, that moves a lot of fluid. The Mustang m/c that I have has a 1” bore. If I do try a swap, I’m wondering what sizes are available and if I should start with the one with the ID closest to the T-V m/c, or just go with a common 1” bore. The truck has ‘58 Mopar front brakes with the two wheel cylinders on each wheel, size unknown, and ‘57 Chevy rear brakes.

 

Just a dumb question, have you thought about just eliminating the power brake assist and just go with a manual brake setup? Could convert to dual master cylinder at the same time, although I believe a maintained single master is fine. That would solve your space/room issues I think? May need to work on pedal ratio.

 

Not a dumb question at all. The idea is to get this old Pontiac powered, hot rod Stude pickup drivable the quickest and easiest way without throwing away too much money. The truck is 400 miles away in LA in a garage with nothing more than a toolbox, floor jack and jack stands. The Treadle-Vac pedal assembly was operating fine in daily service during the 1964-late ‘60s when it parked with fuel injection problems. After over forty years in a warehouse, the engine now runs, the transmission seems to work and I’m now getting the brakes operable. They transplanted a complete ’55-‘58 Olds power brake pedal assembly, booster and master cylinder. It’s an awkward, ugly transplant to say the least, but it worked.
The Treadle - Vac pedal has no pedal ratio, the push rod snaps right into the back of the pedal pad. I most certainly could (and probably will) build a better pedal assembly but for now I just want to get the brakes working and get the truck home where my shop is. Someone mentioned swapping to a different m/c and I thought, that just may be a viable option. I can’t see spend $500-700 on a rebuilt unit only to replace it with more modern stuff in the near future.
Mostly, I’m just documenting this oddball adventure as I tinker with it, so folks here who haven’t messed with one get to see what that strange brake system is about.

 

Ok, now here’s a place where this unit starts to get really quirky. Instead of a conventional piston moving back and forth in the m/c bore like a hypodermic syringe, it has a piston that looks for all the world like a small Ford king pin and a stationary double acting seal. The “piston” moves into the bore displacing and pressurizing the fluid which acts against the cup side of the seal make it seal tighter, while pushing fluid to the brakes. The piston itself never touches the main bore.
As the piston moves in and out, apparently the washer on the inside end actuates the compensator valve that lets fluid into and out of the reservoir. The washer also acts as a hard stop to keep the piston from coming out.
The king pin. (piston)

With the compensator valve and the main seal

 

They are kind of strange aren't they, but they work.

 

Yep. I haven’t even opened up the big piston that moves back and forth in the big vacuum can yet.
Unfortunately, the piston shaft has serious corrosion damage where the seal sat on it for 40+ years. That means that I’ll have to buy the expensive kit or seriously consider adapting another m/c.

 

I'd imagine that kingpin/piston setup reduces the effective bore of the master cylinder substantially, what's the stroke length of the TV/master?

 

That’s a good question, there were no obvious witness marks on the shaft. I’ll put it under magnification and look again.
It doesn’t look like the Mustang m/c will be a candidate, it’s 2.25” longer than the original one. Also, I hadn’t considered that my T-V unit is mounted to the floor boards at a typical foot board angle. Most conventional master cylinders are meant to be mounted level or just slightly tilted.

 

Just did one this year for a MK II. Came out perfect except there was some inner rot in the M/C part and the bleed only lasted 1 or 2 brake pumps. The master cylinders are getting hard to find if not unobtainium. The canister is almost self explanatory, my kit had silicone grease for the leather edge piston. Soda blast the aluminum or cast parts if you can, if not use well worn glass bead. No sand. Not a bad job and those units were used in a shit ton of cars.

 

How about a single pot Master Cylinder?

 

Harmon has brand new master cylinders or they can sleeve your original.

 

I think my master cylinder is ok, just a small spot of corrosion in an area that doesn’t affect the seal.
I thought about the fruit jar but I don’t see any advantage and there’s still the big angle mine sits at.

Where was the rot? Did you end up sleeving it?

 

The rot was within the casting in a place not fixable. Somewhere in the chamber and not the cylinder. They build hydraulic pressure by displacement vs compression like we're used to. And there's a return vent in the top that's critical to function. Many plug that, can't be plugged, yet not all have it. Wait til you do a Hydra-vac. They suck...