Master cylinder and brake pedal set up

[348tripower]

I have a universal 8 inch booster, master cylinder and swing pedal in the wagon. Yesterday I bled all the bakes again because it has the Eldorado rear calipers and they say they are a bugger to bleed. I didn't see any air on any caliper. I didn't have any pedal until I was at the bottom of the travel.

I got under the dash and adjusted the push rod on the unit. I had to pre load the booster/master cylinder about one half an inch to get pedal. I had just replaced a booster on a ford F150 and no preload is built into that system. I do understand that it is factory designed too.

I had help over so they pushed the car back and forth while I pushed the pedal to make sure there is no pad contact. We adjusted until I had a good pedal and no drag. I am wondering now if this set up is for disc drum and not disc disc as I thought I ordered. I do know all of the brakes are working.
I also wonder if this is just a characteristic of this type of brake combos.

This is the set up with a proportioning valve and set up for disc/disc I believe. I don't know how to tell the difference.

PBU6001 - Under-Dash Brake Pedal Assembly- 8" Dual Pirate Jacks website.
If you guys have any ideas I am listening!

[kb426]

Don, my 1st thought is if it was disc-drum and had the 10lb residual valve on it, you would have dragging brakes on the rear. My next thought is because the master is higher than the calipers, you will have continual gravity flow to the calipers unless there is a restriction somewhere. Is it possible that the mounting position of the calipers is allowing air to still be in after bleeding?

[UGLY OLDS]

I remember reading someplace that the Eldorado calipers have "adjustable" pistons or some type of adjustment for the parking brakes that has to be "adjusted" / set / turned /  and that adjustment part moves / works / does "something" on every brake application..... :?:  :?:

Supposedly it has to be done at every pad replacement ....

Maybe Wayne can comment ...      He's more up to date on that "new" high zoot stuff..  :?

Bob...

[UGLY OLDS]

Hey Don ...I just found this after a quick search .....

Bob....

The rear calipers adjust off the parking brake. The parking brake is incorporated into the caliper. You must set the parking brake every time you park the car.The rear caliper pitons utilize a one way clutch inside the caliper piston. When the parking brake is applied the clutch senses when there is .030" or more clearance between the friction material and the rotor on the inboard side. When there is more than .030" the clutch turns inside the piston adjusting it out keeping the rear brakes adjusted. If you do not set your parking brake every time you will start to lose brake pedal (low and spongy) and the adjuster mechanism will not work any longer.

[wayne petty]

 a video of a REALLY LOOSE ADJUSTMENT.  

you should watch some of the other eldorado caliper videos you will find there also.

one can with the spring and cable disconnected. you can work the lever..

if you still run into issues.. with the spring and cable removed. you can loosen the nut.. move the lever to the applied position.. carefully remove the nut and the lever holding on to the shaft.. twist the shaft outward and then reinstall the lever as close to the fully retracted position as you can..  put the nut back on and you should be good..

PLEASE don't allow the stud to retract into the cylinder.. you may need to use a 14MM or 9/16 thin wrench to twist it out.. there is a very easily damaged square cut seal that rides in a groove on the stud just below the surface and a thrust washer inside.. both can be damaged if it pops in..   brake fluid will come out also.. there is a thin teflon flat washer then a rubber face seal that go on below the lever..  if these get damaged.. you will want to purchase a caliper rebuilding kit to get replacements.

the lever should not come more than 7/16 off the stop..


work the cable end bead out of its groove , i normally bent the lever tip back just slightly to do this  ..   to free up the spring with Long nose pliers,   20 degree offset long nose pliers or duck bill pliers are great at pushing the return spring in slightly and getting it over the retaining tab..  this way the spring can be removed easily and reinstalled easily.

[Crosley.In.AZ]

Yuuup.  If the rear calipers have adjuster - parking levers on them.. you will not get a high pedal till the levers are cycled to move the pads out.

A friend just went thru this on a new  car build . He replaced the rear calipers with units that had 'no' parking brake setup.  Brakes work well now.

[UGLY OLDS]

Don ...  These two U-Tube videos show the caliper & adjustments at its best .......
Proof positive that Rube Goldberg is alive & well ... We now know that he works for GM .....

 Im SURE happy that I use "Rub stick on tire & drag feet" brakes.....    

 Get prepared for some work.....

Bob...

 

 

[wayne petty]

that guy has it close..  i added this to the youtube comments.

a few things.. as i have dealt with these brakes since 1980.. i have scrounged a spare parking brake arm and cut it down to a hex.. i should have marked it to the stop angle before i cut it down but i had not. i install the now hex section of the parking brake lever and with the nylon and rubber seal installed.. and the nut holding the hex plate i turn the hex to retract the piston.. this allows me to spin the inner piston to attempt to get it to the proper spot.. sorry i don't have any of these for photos.. i also used at one point a A/C service wrench.. it is a ratcheting box end wrench with 1/2" and 9/16 hex on one end.. and 1/4" and 5/16 square on the other.. i ground the faces of the 1/2-9/16 end so i could get it on the stub shaft and the nut on a few threads.. i could work the actuator shaft and spin the inner piston to a new position. this worked great. till it grew legs.. the last tool i had was either a 9/16 or 14MM crow foot tubing wrench.. HF and other people sell them in kits.. that i ground thinner so it would go on the actuator shaft and the nut would go on to hold it. then i could just spin the heck out of it with a ratchet.. i did have to grind the end near the drive square.


what i forgot to add is that the grooves in the face of the piston are NOT deep enough for the guide pin on the back of the pad.. only ONE is deep enough. the other 4 are for rivet head clearance on the back of the pad.  so clocking the piston is not a fix..

[348tripower]

Yuuup.  If the rear calipers have adjuster - parking levers on them.. you will not get a high pedal till the levers are cycled to move the pads out.

A friend just went thru this on a new  car build . He replaced the rear calipers with units that had 'no' parking brake setup.  Brakes work well now.

Crosley,
I tried searching for those calipers and I couldn't find any info.
I found the push rod in the booster was adjustable and way to short for contact with the master cylinder piston. So I adjusted it out and now I have a pedal. I am still working on the ebrake. The levers come of the stops but I don't have a lock up as of yet. I will adjust the cables some more later today after the daily driver repairs are done. I can pull the lever to the max so it should adjust.
Bob, thanks for those Utube links. Some good info there.

[348tripower]

what i forgot to add is that the grooves in the face of the piston are NOT deep enough for the guide pin on the back of the pad.. only ONE is deep enough. the other 4 are for rivet head clearance on the back of the pad. so clocking the piston is not a fix..

Wayne,
I will investigate this too.

[WZ JUNK]

I had to work through this problem a couple of months ago.  The self adjusters would not take up the slack and I had to much travel in the brake pedal, although the brakes were working.  I used my air hammer to vibrate the caliper while I worked the brake lever on the caliper with the other hand.  After a rather long time the first one started self adjusting.  The second one took even longer but now they are working great.  The Lincoln Versailles uses a very similar design. I think the guys who came up with the design were distant relatives of the guy who designed Lucas wiring.

John

[kb426]

This makes those Ford rotors with brake shoes inside look a lot better. For a guy with an automatic that doesn't use the parking brake, you'd be back to periodic brake adjustments. ?