Register now to get rid of these ads!

Technical No brake pedal

Discussion in 'The Hokey Ass Message Board' started by 63401nailhead, Apr 18, 2022.

  1. 63401nailhead
    Joined: Apr 4, 2008
    Posts: 164

    63401nailhead
    Member
    from DE

    I just finished doing the rear brakes on my 40 Chevy pickup. New shoes, drums, wheel cylinders, spring kit and rear brake hose. The brakes are gm A body and dual master cylinder with booster. It stopped fine before I started and the pedal felt great, but now the pedal goes all the way to the floor when I go to back out of the garage. Bled the rear at both sides, didn’t touch the fronts. No leaks. Any ideas what could be causing this?
     
  2. alchemy
    Joined: Sep 27, 2002
    Posts: 18,837

    alchemy
    Member

    Did the valve in the proportioner get slid all the way to one end?
     
  3. 63401nailhead
    Joined: Apr 4, 2008
    Posts: 164

    63401nailhead
    Member
    from DE

    I didn’t touch the prop valve. All the did was replace the rears and bleed.
     
  4. alchemy
    Joined: Sep 27, 2002
    Posts: 18,837

    alchemy
    Member

    Sometimes, I've read, if one half of the system goes limp the prop valve will slide the divider to the other side and make sure the other half remains operational. Just wondered if you having the rear half with no pressure made it do that.
     
    2OLD2FAST and Tman like this.

  5. 63401nailhead
    Joined: Apr 4, 2008
    Posts: 164

    63401nailhead
    Member
    from DE

    Maybe I’ll try bleeding again. There seemed to be quite a bit of air in the lines. Bled the rears for a good hour or so. Didn’t bleed the fronts, shouldn’t have to right if it’s a split MC the fronts and tears are totally isolated right? If you get air in the rear circuit that wouldn’t effect the front circuit, right?

    Also, if the rear shoes aren’t adjusted properly, that wouldn’t cause this issue, would it? The backing plates don’t have the adjuster slots, but the new drums had punch outs i guess so you can reach the adjusters from the front of the drum, but they wouldn’t budge no matter how hard I wacked them, and I was too lazy to get the drill out, so I just figured I would adjust them out as much as I could to where I could just barely slide the drum on, and then let the self adjusters do their job the rest of the way. So the rears are kinda adjusted, but not adjusted well or properly. That wouldn’t cause the pedal to go to the floor though, would it? I have discs on the front that I didn’t even mess with.
     
  6. Bleed all 4 wheels .

    re adjust the rears as they may have seated after your test drive .

    I let off the parking brake adjustment when I replace shoes on drum brakes , as sometimes over the years the parking brake gets adjusted out to far and throws off the initial brake adjustment. Not saying this is your issue , but something to look at .
     
    clem, 2OLD2FAST and seb fontana like this.
  7. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,261

    Doublepumper
    Member
    from WA-OR, USA

    If you're using a factory style proportioning block, you need one of these for bleeding. Remove the switch and install this goodie. It keeps the slide in the valve from moving.
    sum-760158_xl.jpg
    Good luck!
     
    bobss396 and Tman like this.
  8. poco
    Joined: Feb 9, 2009
    Posts: 949

    poco
    Member
    from oklahoma

    yes adjust the shoes on rear out
     
    clem and flynbrian48 like this.
  9. manyolcars
    Joined: Mar 30, 2001
    Posts: 8,790

    manyolcars

    Brakes are mentioned so often that we need a sub forum for brakes only
     
    indyjps, bobss396 and Tman like this.
  10. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 4,261

    2OLD2FAST
    Member
    from illinois

    Screenshot_2022-04-18-18-38-30.png here's a you tube to watch , yes , you have go bleed the fronts . sometimes if you stomp the. Brake pedal sharply it will automatically reset the valve .
     
    bobss396 likes this.
  11. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 4,261

    2OLD2FAST
    Member
    from illinois

    But that would stop all the misinformation ,supposition , wives tales ," my buddy saids" , " that reminds me's" , " we gotta know the size of your lug nuts " , "who'd you buy your parts from" , long drawn out engineering theory , & just plain bullshit that makes up every new tech question that's posted :eek: LOL
     
  12. Mr48chev
    Joined: Dec 28, 2007
    Posts: 32,129

    Mr48chev
    ALLIANCE MEMBER

    You did adjust the rear shoes when you replaced the brakes? Back in the early 70's when I was doing several brake jobs a week I often had to straighten out someone's weekend brake job on Monday because they didn't adjust the brakes right.
    I agree with Vandenplas in that you also have to back the park brake adjustment off and then adjust it after you get the brakes adjusted right.
    Tighten the adjuster up until you can't turn the tire with one hand and then back it off 11 clicks. You have to have a certain degree of drag for the brakes to work right.
     
  13. Tow Truck Tom
    Joined: Jul 3, 2018
    Posts: 940

    Tow Truck Tom
    Member
    from Clayton DE

    The pedal height is affected by both proper adjustment and what is in the line.
    What felt like contact may have been from an unseated, off center shoe.
    You may well have gotten the air out. The pedal won't be good 'til the shoes are seated properly.
    Get out the BFH and sharpen that old chisel. Set the drums flat on the ground. After a cup of coffee, Make that chisel sing.
    Now, when the drum is put back on, you can use your brake spoon to run the adjustment tight. Once full contact is made, the adjuster actuator plate needs to be pulled out away from the adj. star wheel. ( You can either find a hook, tool at the store, or fashion a hook from a sturdy coat hanger. ) You can then back the now, centered and seated, shoes off enough to turn the drum by hand, and still hear and feel some drag.
    Time to test. Perhaps bleed, maybe not. Have fun.

    As a young buck I would do this shit all day long. But gimme coffee. They won't let me have it now.
     
  14. Tow Truck Tom
    Joined: Jul 3, 2018
    Posts: 940

    Tow Truck Tom
    Member
    from Clayton DE

    OOPS I FORGOT! what he said....

     
  15. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 4,261

    2OLD2FAST
    Member
    from illinois

    While holding the self adjuster out of the way & turning the star wheel with the adjustment tool , how do you measure / produce " clicks" ?
     
    Budget36 likes this.
  16. Budget36
    Joined: Nov 29, 2014
    Posts: 10,406

    Budget36
    Member

    What’s the plan with a chisel ? I’m not getting it.
     
  17. To punch out the adjustment slot knock-out in the drum.
     
    olscrounger and Budget36 like this.
  18. Tow Truck Tom
    Joined: Jul 3, 2018
    Posts: 940

    Tow Truck Tom
    Member
    from Clayton DE

    In order to open the adjuster hole we need to remove the plug. The drum is stamped with an oval shape, to make the slot. Removing the plug for one thing takes some force. Uncontrolled force can bend the drum face. Should that happen it can be corrected with hammer blows. Better plan though, is to strike the slot plug at its edge line with a sharp chisel to cut into the stamped impression. Once you break the plug from its position you can finish removal with a pliers. Thanks for asking.
     
    Budget36 likes this.
  19. Tow Truck Tom
    Joined: Jul 3, 2018
    Posts: 940

    Tow Truck Tom
    Member
    from Clayton DE

    Good point
    With Mr48chev's permission,, lets say we just loosen the adjuster 'til the drum turns free. Then notch by notch we tighten er up til we feel drag. Once the shoes are making contact then we can hang the tire/wheel and use the reverse gear, back up procedure to finish the job.
     
  20. 63401nailhead
    Joined: Apr 4, 2008
    Posts: 164

    63401nailhead
    Member
    from DE

    Im a little confused on the prop valve. I got one of those things to thread into the top to keep the needle centered, but I can’t figure out how to get it in. When I remove the fitting in the top there is this plastic shaft that’s still stuck in there. I didn’t mess with it too much because I don’t want to break anything, but this doesn’t look like any other prop valve. What am I looking at here?
     

    Attached Files:

  21. I don't think that's a proportioning valve. I think it is simply a brake pressure differential valve, used simply to turn the light on and possibly restrict fluid flow to the side with low pressure. It looks a lot like the valve used on American Motors cars so many years ago, when I worked at the local dealership. You might be able to release the jammed plastic pin by opening up the side that has always had pressure and try and center the valve that has moved because of loss of pressure.
     
    bobss396 likes this.
  22. Mr48chev
    Joined: Dec 28, 2007
    Posts: 32,129

    Mr48chev
    ALLIANCE MEMBER

    The only issue with that is some times the shoes are a tad off kilter and you have to tighten them up so you seat them in the drum and square them up. Doing it right really isn't that hard and it isn't rocket science.
    I've popped probably 300 of those metal plugs out of the front of drums an never had a problem with screwing up a drum.
    If you don't have the spring against the adjuster to feel the click you just go by feel. It isn't that hard to figure out you are moving the wheel about 3/16 of an inch at a time.
     
    Tow Truck Tom likes this.
  23. SS327
    Joined: Sep 11, 2017
    Posts: 1,507

    SS327

    That pin with the plastic may be the switch for the brake warning light. Be careful.
     
  24. Tow Truck Tom
    Joined: Jul 3, 2018
    Posts: 940

    Tow Truck Tom
    Member
    from Clayton DE

    Right you are. So I been thinkin' And thought of a good tip to share. One step I've always taken is before placing the drum on, I'll grab both shoes at the bottom, pull them away from the plate, yank them fore and aft, as much as the holddowns will allow, then center to the plate, set them against the plate. You are correct that they need to be square.
    I guess my issue with hittin the mark on the drum comes from living my life with one eye ( no depth perception ) and 10 years a drunkard. Swinging a hammer for me is a crap shoot.
    Enjoy this day.
     
    bobss396 likes this.
  25. Too complex an item for the application, IMO. I buy distribution blocks from places like Summit for around $70.
    https://www.summitracing.com/parts/clp-apv-db
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.