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Starting on a '55 Plymouth Plaza Suburban

Discussion in 'Other classic cars' started by 71Charger_fan, Nov 26, 2016.

  1. pt006

    pt006 Active Member

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    71; I was expecting to see an adjustable proportioning valve like Summit sells. Similar to a regulator on an air compressor.

    Don't 'fiddle' with the brake adjustments. Learn and understand how the adjustments work. You'll be happier later.
    First the shoes have to be square to the drums. There may be an adjustment for this. A straight piece of wood laid across [over] the brake shoes and a small carpenters square should be good enough.
    The large cam bolts act as the pivot point of the shoes. The goal is to adjust the bolt so that the brake lining makes contact at the top AND the bottom of the shoe when the brakes are applied. Because you're starting from scratch, I'd recommend making a special tool for the initial set-up. Take a 1 x 3 by 8" long, draw a center line lengthwise along the entire length. Put a cross line 1 1/2" from one end. Measure the brake drum and divide by two, then add 1/8". So if the drum ID is 10", then it's 5" plus 1/8". Put another cross line 5 1/8" from the first line. Drill a 1/8" hole thru both locations. Drill a hole the size of the axle on the first cross line. Adjust the hole size so the wood ends up being square when the wood touches the brake shoe. Then drive an eight penny nail in from the other side so the nail head is in the middle of the shoe width. The nail can be bent slightly to fine tune the shoe diameter. By rotating the tool you should come pretty close to the adjustment for each shoe. An old brake drum with holes machined out at the outer rim area and a feeler gauge would also work. Might even be better.

    Happy motoring.
     
  2. 71Charger_fan

    71Charger_fan Active Member

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    As much as I hate pulling the drums with the tapered axles, I'm going to take my best shot at making that setting jig/gauge. These rear brakes have me at my wits end.

    I measured the rear today in case I decide to just get rid of these old brakes entirely. It was 60 1/16" from wheel mounting surface to wheel mounting surface on the drums. It seems every list of rear ends I find lists a different measurement point. Since I have to pull the drums again, I'll be able to get a flange-to-flange measurement.
     
  3. 68RT

    68RT Well-Known Member

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    problemishes with that is the backing Plate does not necessarily match up with the same depth.
     
  4. 71Charger_fan

    71Charger_fan Active Member

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    I made a wooden jig, but it didn't work well. So, I took some flat aluminum stock I had and a 1/4-20 screw and made one from that. It worked out pretty well. At least now I have the shoes properly set and concentric to the axle shaft. Almost 8 quarts of bleeding and I still see some air bubbles. I swear there's a leak, but I can't find one.
    Plaza brake gauge.jpg Plaza brake gauge (2).jpg Plaza brake rear.jpg
     
  5. Bearhawke

    Bearhawke Things happen for a reason

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    Apparently: a 1966-70 Mopar B 8 3/4" body rear end is the correct drum to drum dimensions as the 1955-56 Plymouth diff; but, the leaf spring pads will need to be swapped over. I suspect a 1965 B body diff would work as well despite being a tad narrower. Another choice may be an F-M-J body 8 1/4" unit since it's very close to the others.
     
  6. 71Charger_fan

    71Charger_fan Active Member

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    The 3.90 gears (or something close) that I'd need to match the factory set up would make the 8.25 rear somewhat problematic. I figure on having to relocate the leaf spring pads on any rear I might pick up. With a flathead six, even a 741 housing 8.75 would be more than strong enough.
     
  7. pt006

    pt006 Active Member

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    71; nice job on the tool. The shoes look nice an square. Now that the shoes [linings] are concentric they have to be adjusted outward to achieve ~.006 clearance. !!!! Not easy. See post # 198 from 68RT. 'Aligning and Relining'. page 6 shows .006 at the heel [bottom of the shoe]. Page 22 shows the upper cam as 5-22-1. This adjustment is done from the differential side of the backing plate. This should be done first. Get the drum to drag, then back off slightly. Then remove the drum and adjust the bottom cam bolts [and the other upper cam] so that the shoes are concentric again. I'd do this whole procedure twice to be sure. Once this has been done correctly, any future adjustments can be done by using the upper cams only. That is, without removing the brake drums.

    Even a 7 1/4" rear would be strong enough. They took a lot of abuse from 273's and 318's over the years.
     
  8. Bearhawke

    Bearhawke Things happen for a reason

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    Please refresh my memory here: does your longroof have an OD tranny? If not; I'm pretty sure your Six would have enough torque to safely pull your wagon down the road, even with ca. 3:23 gears. :)
     
  9. dana44

    Ad-Free Member

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    3.23 would be good on the highway, that's for sure, and second to pull long hills would be a lot faster than running her at redline to do 40mph.
     
  10. 71Charger_fan

    71Charger_fan Active Member

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    I don't have OD, but I do have a 489 case 3.23 sure grip center section that came out of my '71 Charger when I swapped in a new Dr. Diff 3.55 sure grip unit.

    I ordered new brake line tubing and plan to (again) re-plumb the brake lines from the proportioning valve back. I'll also replace the Centric wheel cylinder on the right side with a NAPA one and replace the brake hose. I think I'll also relocate the frame mounting point for the brake hose to put it closer to the axle as it shouldn't be stretched tight when the car is jacked up.
     
  11. pt006

    pt006 Active Member

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    71; The 8 3/4" has a larger center section, so check for clearances. 3.23's might be too much for your engine. I drove a 225 with a 3 speed standard and 3.55 gears in a pick-up. It was ok with a light load.
     
  12. Bearhawke

    Bearhawke Things happen for a reason

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    Any updates on your brake saga?
     
  13. Fast Eddie

    Fast Eddie Valued Member
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    After following your resto on this car from the beginning I will be so happy for you when it drives and especially when the brakes work normally!!!!!!!!!!!!!!!
    :)
     
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  14. 71Charger_fan

    71Charger_fan Active Member

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    Carlisle weekend. It's been a few days since I've touched it. My new coil of brake line came on Friday. But, getting home from Carlisle Friday evening I found not only a new coil of brake tubing, but also that a severe storm had come through while I was at the show and I had a tree come down. So, I've got that to deal with.
     
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  15. Bearhawke

    Bearhawke Things happen for a reason

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    Eish!
     
  16. 71Charger_fan

    71Charger_fan Active Member

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    Until today, it's been too hot in the garage since Carlisle to work on the Plymouth. I finally got around to replacing the right rear wheel cylinder with another new one from NAPA and making up new rear axle brake lines. I looked, but couldn't find a rear axle brake tee listed for a '55. I saw one at Inline Tube listed for '59 to '76 8.75 rear. I ordered one and it was an exact duplicate of the '55 brake tee. I also picked up another new rear rubber line, but it's no longer than the existing one. I'm trying to make a bracket to move the brake hose mounting bracket inboard a few inches to hopefully put some slack in the line when the car is on a lift.
    php9tug4WPM.jpg php4TnR6NPM.jpg phpRLf23KPM.jpg phpYibaudPM.jpg phpOSj3rFPM.jpg
     
  17. 71Charger_fan

    71Charger_fan Active Member

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    The new NAPA hose I picked up was the exact same length as the one I had on the car that was stretched overly tight when the car was jacked up. I used some scrap I had in the garage to make a bracket and spaced the bracket where the hose and hard line join off of the frame rail. It was just enough to allow the line to rest without being stretched.
    phpsy3cEIPM.jpg
     
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  18. saltydog

    saltydog Well-Known Member

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  19. 71Charger_fan

    71Charger_fan Active Member

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    I'm at the point of buying and installing a 3rd new master cylinder. A friend of mine came by yesterday and we spent the afternoon bleeding the brakes. I can pump the pedal and make it feel okay, but just getting in and pushing the pedal, it goes to the floor. I used my Mityvac bleeder that works with the compressor and pulled fluid until I saw no more bubbles. My buddy came by and we used his Mityvac hand pump and pulled a few more reservoirs full through the lines. Then we bled all four corners by me pushing the pedal and him working the bleeder screws. We pushed almost another quart through the system. We went over the system, component by component, and found no leaks. I have new calipers, new front hoses, all new hard lines, new proportioning valve, new wheel cylinders (again), new master cylinder (again), new rear hose (again), and new brake tee. This is driving me nuts.
     

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