Treadle Vac rebuild

B

billyj2t

Junior Member
Hi - I am trying to rebuild the treadle vac brake booster from my 59 Edsel Corsair. I have not gotten very far - I cannot get the vacuum piston out of the can. I have scoured the internet and every reference I can find indicates that it should just pull out. I have tried mineral oil bath, excessive pulling and compressed air - it looks like it is held in by a circlip or some other mechanism that I am missing completely.

I would be grateful for any and all advice on this subject.

Bill
 
The piston will pull out, just very hard. Nothing holds it in the can.

Obviously you need to remove the vacuum input tube and the vent screen. Make sure there are no bures on the inside from the screws and the piston is square in the can. Take off the master cover and the big screw in valve under it and you will be able to see the push rod, might be able to pry on the front edge of it to get things started. If it is all goobered up it will help hold the piston in. Blowing air in the master will not help, the push rod is well sealed from the vacuum side of things.

After the piston is out you will see the push rod and a squarish looking plate. Push down on the plate and a "C" clip will come out. Just remove the C clip, plate and large spring. Three bolts hold the master to the can.

When putting the assembly back together the large valve inside the master is the last part to be put in. This is after every other part is back in place. Push the vacuum piston all the way in, screw the valve in place, put the cover back on and re intsall the assembly before you pull the vacuum piston back out. Pull it out just enough to engae the pedal with the pedal down, put the bolt in, and pull it back out with the pedal.
 
Hi Bill, Thanks for the response. I have removed all the vac stuff from the can. I also,at your suggestion, removed the nut and comp valve from the MC, The piston moves freely up and down and can be rotated easily. I can see the MC shaft and it looks OK. The piston still feels like it hits a hard stop at the top of its travel. feel like the MC shaft & the piston center shaft are one piece. Is this a 2 piece shaft & do they just butt on end. I am considering anchoring the can and pulling the center shaft with a come along. Obviously this would be very destructive if there is some mechanical mechanism locking the piston in.

What do you think?

I am envious of your vehicle list.

Bill
 
Bill,

Mine is a 58 and I don't know if any changes were made to the 59. The vacuum piston and the master shaft are two different pieces. The shaft you see in the master will stay with the master when the vacuum piston is pulled. There is an "O" ring on the end of that shaft that seats in the vacuum piston, might be it is stuck hard?

I would try the come along but very carefully. Unless you are wanting to stay 100% stock look at units from one of the many vendors for the 59 Mercury.

Thanks, the Retractable, Ranchero and 60 wagon are project cars. My Pacer is a Louisville first day run car (July 17th), the QER paint code is one of three and it was discontinued in early August. Found the build sheet to confirm options and codes. Working on keeping it stock or non-destructive return to stock. The odometer shows 47+K and I feel it is accurate given door stickers for oil changes. The steering and suspension are tight as can be as well.

Let me know what you find with that unit. Thanks, Bill
 
I attacked the booster with a 5lb slide hammer. I managed to pull the piston shaft completely out - the piston remains rock solid' I am missing something simple. Roy (Merc Cruzer) sent me copies from the merc mm. My unit is some different. I will try to attach a few pics.

Bill
side
top
vac piston 1
vac piston 2
 
Bill what I have found is your car is a "Disc Reaction" TV used in 58 -60 Lincolns and 59 Edsels. Looking at the diagram I can see no reason the vacuum piston should not come out. It is real close to the TV in my 58 which I just finished rebuilding. It's vacuum piston was a two hander to pull out. Can't figure why yours is being a bugger?
 

Attachments

  • 1959%20TV.jpg
    1959%20TV.jpg
    81.9 KB · Views: 13
I agree - the only physical connection holding the piston in is the piston center shaft and the MC shaft. I can see the MC shaft bottom out when the flange hits the MC body. This is where the piston is at the out most position. It must be as suggested, the two shafts have bonded from being idle for more that 20 years. It is hard to conceive of this bond surviving the pounding with the 5 lb slide hammer. I got pretty aggressive with it. I'm going to put some WD-40 into the vac chamber and try to soak the shaft joint a few days.

I appreciate your & Roy's help with this problem. I ordered an new generic booster & MC that I will use if this can't be fixed.

Thanks again.

Bill
 
You must log in or register to reply here.
Back
Top