Treadle-Vac Issues

[Russ Thurber]

I am finishing a # 3 resto on a 1958 Bird. I am a desperado in search of a solution to my brake problem. ALL components are new with the exception of the treadle-vac booster. I have adjusted and bled the brakes thoroughly and still have pedal going to the floor when running, but have a nice firm pedal with an inch or so of play when not running. There does not appear to be any vacuum leaks anywhere. I have just enough braking ability to slowly get the car stopped at 15-20 miles an hour with about a half inch of remaining pedal at the floor. SCARY stuff. Also my research (via Thunderbird Headquarters) tells me that the correct master cylinder bore size (now on the car) is i ", but the original unit that came off the car has a bore size of 1 & 1/8". So what's up with this discrepancy? No big deal? Please HELP this very frustrated almost nut case. THANKS !!! Russ

[Frango100]

It looks that you will have to adjust the rod in between the pedal and the master cylinder. I had the same happening to me when i used a repair kit on the master cylinder and didnīt see that the new master cylinder piston had a deeper hole where the brake rod enters. Ended up with almost no brakes and the brake pedal almost on the floor. After adjusting the rod, the brakes work great.
Donīt you have the Kelsey-Hayes under dash booster in your bird?

[simplyconnected]

Did you bench bleed your new M/C?
BTW, a one-inch bore should work just fine. Actually, it's easier to push but the pedal stroke is a little longer. - Dave

[Russ Thurber]

Readle-Vac Issues

Hi Frank
Yes, the booster is under the dash, the bellows type. If I have to go under the dash to adjust the eccentric for lengthening the rod, I will have to remove the dash panel just to access the adjustment lever on the rod eccentric. Really ??? Not even enough room for my hand to begin getting up in there How much longer do you think the push rod needs to be to make a correction and could it be done with a tapered "button" type shim in front of the master cylinder piston to give me a longer reach?
Thanks for helping....much appreciated !!
Russ

[Frango100]

For some reason my bird doesnīt have the adjustable rod anymore, so I also had to put a "filler" shim inside the piston to make an adjustment. When I remember well I had put a 3 mm filler to make it work well.

[Russ Thurber]

Treadle-Vac Issue

Hi Dave
Yes, I bled the master....air is out. Short of pulling out the dash panel, I don't know how I'm going to reach the rod eccentric to adjust the length, if that's my only option at this point. I might try installing a shim in the bore in front of the MC piston if it's necessary to get the right length.
Thanks for your help
Russ

[simplyconnected]

Russ, is the new M/C piston depth that much different from your original M/C? I would think you can simply adjust with the brake pedal bolt (which IS the eccentric). Simply loosen it and turn. You will see the rod change lengths.

I asked if you bench bled. It takes me about 20 pumps to get all the air out of a dry M/C. Doing this on a level bench is much easier. I use plastic tubes to return the fluid to the reservoirs. That way I don't waste brake fluid, I can see the air and I know when it's running clear. With some 'dry' M/Cs, I shade the output with my finger just to get things going while I pump the piston. YouTube has many videos regarding, 'bench bleeding'.

What brake fluid are you using?

If you get all the air out and properly adjust your wheel cylinders and your brake pedal rod, a one-inch bore M/C will work nicely. I am not a big fan of Treadle Vac boosters because they don't offer much assistance (even when new) and they are expensive to rebuild. I don't think there is much 'bang for your buck' after all is working again.

Part of the reason is, I believe every Squarebird that drives on our highways is in competition with modern cars that have disk brakes. Squarebirds do very well with power front disk brakes. It's one of the very best moves I made on our '59 Galaxie. Many of our Squarebird members have retrofit their cars. I haven't heard one complaint yet nor has anyone gone back to drum brakes (that I'm aware of). We use a two-stage 8" booster with a 1" dual-piston M/C. The difference in stopping is amazing. - Dave

[OX1]

I would think you can simply adjust with the brake pedal bolt (which IS the eccentric).
Simply loosen it and turn. You will see the rod change lengths.

Wouldn't that just change the brake pedal height?

Anyone have experience driving one of these new. My mom got her 60 new, but I didn't think to ask how the brakes
were from ages -4 to 13 (and doubt she would have said horrible, not having driven any modern car with disks yet).

My first car, 63 dodge Polara had 4 wheel drum, manual, and they "stopped", but not very well,
especially since it had a 383 in it, so it wasn't slow.

When I got my 59 recently, all the parts looked re-furbed or new, but the brake pedal was still very low and the
brakes were barely adequate, just keeping up with traffic. I also had the underdash booster, which still worked, but
made almost no difference, even when I disconnected vac line to it (just to see).

[Dan Leavens]

Henry

My first car, 63 dodge Polara had 4 wheel drum, manual, and they "stopped", but not very well,
especially since it had a 383 in it, so it wasn't slow.

You brought back memories as my Father had a 63 Dodge Polara 383 with the push button / Park bar transmission. When I was a young 14 and my parents were out at a function, I took the Polara out with a buddy and literally smoked the brakes which the peddle went just about to the floor driving all over the neighbourhood. Placing the car exactly where my Father had it in the driveay I heard him say the next day to my Mother, that he needed to check the brakes as the peddle was soft Can't imagine why??

[jopizz]

Anyone have experience driving one of these new. My mom got her 60 new, but I didn't think to ask how the brakes
were from ages -4 to 13 (and doubt she would have said horrible, not having driven any modern car with disks yet).

My first car, 63 dodge Polara had 4 wheel drum, manual, and they "stopped", but not very well,
especially since it had a 383 in it, so it wasn't slow.

When I got my 59 recently, all the parts looked re-furbed or new, but the brake pedal was still very low and the
brakes were barely adequate, just keeping up with traffic. I also had the underdash booster, which still worked, but
made almost no difference, even when I disconnected vac line to it (just to see).

Although drum brakes are a far cry from today's discs you should have sufficient pedal where it's not going to the floor. Most of the low pedal problems with drum brakes come from not bleeding them properly or not having the shoes adjusted properly. It certainly takes a different mindset to drive with drum brakes, especially in high speed traffic.

John

[Russ Thurber]

Treadle Vac Issue

Russ, is the new M/C piston depth that much different from your original M/C? I would think you can simply adjust with the brake pedal bolt (which IS the eccentric). Simply loosen it and turn. You will see the rod change lengths.

I asked if you bench bled. It takes me about 20 pumps to get all the air out of a dry M/C. Doing this on a level bench is much easier. I use plastic tubes to return the fluid to the reservoirs. That way I don't waste brake fluid, I can see the air and I know when it's running clear. With some 'dry' M/Cs, I shade the output with my finger just to get things going while I pump the piston. YouTube has many videos regarding, 'bench bleeding'.

What brake fluid are you using?

If you get all the air out and properly adjust your wheel cylinders and your brake pedal rod, a one-inch bore M/C will work nicely. I am not a big fan of Treadle Vac boosters because they don't offer much assistance (even when new) and they are expensive to rebuild. I don't think there is much 'bang for your buck' after all is working again.

Part of the reason is, I believe every Squarebird that drives on our highways is in competition with modern cars that have disk brakes. Squarebirds do very well with power front disk brakes. It's one of the very best moves I made on our '59 Galaxie. Many of our Squarebird members have retrofit their cars. I haven't heard one complaint yet nor has anyone gone back to drum brakes (that I'm aware of). We use a two-stage 8" booster with a 1" dual-piston M/C. The difference in stopping is amazing. - Dave

Hi Dave
To adjust the M/C rod length, I would have to remove the dash panel to get at the rod eccentric bolt & nut which is way above the booster. Now the eccentric for the booster valve IS accessible right in front of the booster but I don't think that adjustment can effect the pedal travel. Can a shim "button" inserted in the M/C bore in front of the piston be a possible solution to get the rod length I need? M/C has been bled, wheel cylinders bled, shoes are well adjusted. Everything is new except for the booster.
Thanks for your help. I need to do something soon !!
Russ

[Frango100]

No, the eccentric on the booster doesnīt change the pedal rod length. With that eccentric you can adjust the point the booster starts to work. If its not set well, you will feel a vibration in the pedal while braking.
I donīt have the adjustable rod on my bird anymore and used a shim inside the MC piston hole, but I think if you have the adjustable rod, that you better use that adjustment, even if it would give more work now.

[simplyconnected]

Hi Dave
To adjust the M/C rod length, I would have to remove the dash panel to get at the rod eccentric bolt & nut which is way above the booster...

You may need to remove just a bottom panel, not the dash. The eccentric shoulder bolt is #2462:

[partsetal]

Some facts-The Bendix Treadle-Vac was never used on the Squarebird. What was used is the Kelsey-Hayes bellows type under the dash unit and the Bendix Master-Vac under the hood. The Kelsey Hayes units were found exclusively on the 58, some early '59's and all Air Conditioned cars. The Master-Vac was installed in late 59 and 60 non-Air Conditioned cars. All power brake equipped Squarebirds left the factory with the 1-1/8" Master cylinder, the 1" for non-power. The 1-1/8" provides a harder pedal but a shorter stroke. This M/C is no longer produced and many catalogs of today and many counter people affirm that the 1" is correct since it is still available.
The rod on the Kelsey Hayes unit is adjustable using the push rod adjusting eccentric lever. It is hard to reach with the lower dash installed. My method is to use a 9/16" open end wrench and loosen the nut at the eccentric just a bit and rotate the eccentric upward to shorten the rod and downward to lengthen the rod. You should be able to feel resistance when lengthening the rod, this means the pushrod is seated in the M/C bore. You should be able to go a little more but then check to see that you have not blocked the compensator port in the M/C. Another key to getting better pedal is to adjust the brakes after they have been run a little. This gives the lining a better chance to seat in and may allow you to shorten pedal travel. My method is to tighten the adjuster while rotating the wheel, stop when you just hear a whisper of contact. What has worked for me with the Kelsey Hayes setup is: Use the 1 1/8" master cylinder; re-bleed the system; adjust the pushrod length; re-adjust the brakes after a short drive.

[NC Tbird]

Is there any adjustment possible on the Bendix Master-Vac brake pedal?
My '60 square bird also has a low pedal when braking with maybe 3/4" clearance when fully depressed - makes sudden stops a religious event.