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Topic Summary

Posted by: Vincent
« on: July 18, 2021, 05:32:49 PM »

Steve,

The tub is not on. So the brake pedal is free, and the 1/2 inch "free play" to the MC piston is not an issue. Once the push rod engages the master cylinder piston, I have about 1/2 inch of movement after bleeding brakes. So when you say, -" To me, a 'properly bled' with 'adjusted to minimum clearance shoes' system, should require not much more than the stated 1/2" MC piston movement. "- that is what I have. I have never had a vehicle without power brakes, so I was concerned when there was very little movement in the Master Cylinder, but apparently, this should be correct.

And I did replace the return springs, and they are indeed quite stiffer than the old ones, which I thought were still serviceable. I will also take Rus' advice and use an assistant to check wheel spin.
Posted by: SteveKfl
« on: July 18, 2021, 10:07:54 AM »

So far the discussion has covered all but the "return spring" and "lubrication of friction points".  As to the "return spring", I replaced my originals, rusted together and crisp, and the new replacements were significantly "stiffer".  Unfortunately a computer glitch lost me my pics of the 'comparison' documented.  The installation was much harder with the new ones.
 
Searche shows different makes have different spring designs for the same models, and no "resistance values" given. 
 https://www.google.com/search?q=willys+upper+9%22+brake+shoe+return+spring&client=ubuntu&hs=e2&ei=8TP0YODYHdLF-gTp_JGwBQ&oq=willys+upper+9%22+brake+shoe+return+spring&gs_lcp=Cgdnd3Mtd2l6EAw6BwgAEEcQsANKBQg6EgEySgQIQRgAUNKhAli0rQJgrNYCaAJwAngAgAHkAYgBngSSAQUxLjIuMZgBAKABAaoBB2d3cy13aXrIAQi4AQLAAQE&sclient=gws-wiz&ved=0ahUKEwigld7s4-zxAhXSop4KHWl-BFYQ4dUDCA4
 
It is my understanding that the less coils the stiffer the spring, and my 'new ones' had 'less' and 'thicker coils'.  The "return spring" is what you are "pushing against" until the shoe is bottomed out.  I like the recommendation of setting the shoes at 'most clearance possible' to see "maximum MC piston 'and' total wheel cylinders combined movement", checking for the 'wheel spin' by an assistant.  From there, tightening the 'shoe clearances' to specs should reduce the distance of 'total travel'.
 
So 'total travel' measurements can be confusing too if not talking about the same measurement.  To make sure we are all talking of the same "travel distance measurement", I just want to clarify that the Manual talks of "initial pedal travel", which as I understand it, is from "pedal at rest with no foot application" until suppressed measured to 'before' the 'MC piston activation', as 1/2". 
 
Now in contrast, the discussed "MC piston travel distance" at 1/2" is NOT measuring the "pedal movement" including the "ratio" of the pedal mount pivot for "leverage", but just "piston movement inside the MC", right?  If so, then the stated 1/2" is what the "hydraulic compression and wheel cylinder pistons movement combined" is requiring.  To me, a 'properly bled' with 'adjusted to minimum clearance shoes' system, should require not much more than the stated 1/2" MC piston movement.  Now that said, the "pedal ratio" result would be "measuring potentially a longer combined distance" of "apparent MC travel movement" at the pedal.  So can we clarify where/how the "MC piston travel" is being measured to get on the same page?     
Posted by: Rus Curtis
« on: July 17, 2021, 08:20:28 PM »

The only thing I'd add is make sure the shoes have been adjusted out to contact and then back off per SM.

Other than that, I'm not seeing anything you've done or are experiencing that could be a problem.  I too redid my brakes (and everything else) with the tub off to have better access.  The brake pedal was hard.  For that matter the clutch was near impossible to depress too.  Without the seat in place and your legs doing the compression, it will feel awful hard.

When you've got the bleed screw open, there's no resistance to the fluid (it just bypasses the wheel cylinder to exit) so you shouldn't feel any pressure at the pedal.  It's important to hold the pedal down until the bleed screw is closed to avoid sucking air back in to the wheel cylinder.  If you have an assistant, lift the wheels off the ground and manually spin them (neutral 2WD), one at a time and then apply the pedal.  I'll bet each one of the wheels lock up.  This would indicate the m/c is passing along the pressure to the wheel cylinders and the wheel cylinders are pushing against the shoes - like you've already observed with the drums off.

To my understanding, that would be a functioning brake.  If I've missed anything hopefully others will chime in.
Posted by: Vincent
« on: July 17, 2021, 05:53:06 PM »

Rus,

So I pumped the brake until I had fluid coming out of the end of each line, then I attached the baggies and pumped about 5 times. I had basically equal amounts of fluid in each bag, which tells me the master cylinder is functioning correctly delivering equal amounts of fluid to each wheel. I also know my lines are clear and clean.

I do have the SM. Been through that.  I have two cams and two eccentrics on each wheel. Since the drums and shoes are new, I set all the adjustments to "loosest" as they can be, and I would work from there.
I understand the 1/2 inch free travel, but the tub is not on. When the bleed screw is open, the master cylinder piston travels easily. When I close the bleed screw, the master cylinder piston barely moves at all.

So I just was wondering if the brakes should be this stiff, or might there be a problem in the wheel cylinders?
Posted by: Rus Curtis
« on: July 17, 2021, 05:18:58 PM »

Vincent,
I'm not sure I've ever heard of anyone attaching baggies to check fluid flow.  Interesting.

Hopefully, you have a Service Manual (SM).  It has a lot of information on the different stages of brake service to include adjustment.  The CJ-3B Page has some good stuff on brakes in the Tech Section.  Here's one about adjusting:
https://cj3b.info/Tech/BrakeAdjust.html

You didn't specify whether you had the 4 cam brakes or the 2 cam brakes.  Those two adjustments are covered in the above link.  I also checked in my SM, SM-1002-R6, and para P-5 (in the link above, it's para P-6). Brake Pedal Adjustment, it specifies you should have at least 1/2" of free pedal travel.  That is best controlled by the push rod attached to the brake pedal arm.  I'd first think that you'd want to ensure the brake shoes are adjusted first.  After that, then worry about the pedal.

If both of those are set to specifications, your brakes will feel pretty hard. 
Posted by: Vincent
« on: July 17, 2021, 04:35:59 PM »

Putting the brakes together on the 53 CJ3A. Everything is stock.  new drums, shoes and master cylinder. Rebuilt the wheel cylinders.  Brake lines installed, but not connected to wheel cylinders. I put a baggie on each of the 4 ends, filled the master cylinder and pumped it 4-5 times.  Got equal amounts of clean fluid in each of the 4 baggies. So the master cylinder works, right? Then I connected the 4 wheel cylinders and tried pumping a few times and I could hardly pump at all.  I went through the bleeding process and got lots of air out, but the pedal, or the master cylinder piston will not move more than about 1/2 inch after closing the bleed screws. I took all the wheel cylinders off and cleaned them out again, reinstalled. pumped the brake pedal without the drums on and I could see the shoes moving. when I put the drums back on, the master cylinder piston still only travels about 1/2 inch. I have never had a vehicle without power brakes before. Is it supposed to be this stiff? If not, any ideas? All that is left is to replace the 4 wheel cylinders, then everything is new, but I don't think they are in bad shape.