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ersatzS2
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Soft pedal after bleeding brakes?
01/16/12 at 10:54:51
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Finally got around to bleeding brakes.  discovered huge amounts of air in the rear lines, along with ugly looking fluid.  So I started from scratch, and adjusted all four brakes, then bled systematically from right rear to front left.  Entire system has new fluid, and no air.  Furthermore, pads are all close to drum now, unlike previously.
So why do I now have a soft pedal?  Travel is 2/3s way to floor on first application.  Then with two pumps, it is up high and very firm.  In fact it is firm on the first application, just has lots of travel.  I'm mystified, it doesn't seem logical. 

Now that shoes are adusted, presumably the brake cylinders have a bit further to travel than before?  But that's the only thing I can imagine would cause pedal to travel more than before, especially since there was so much air in line previously.

Thoughts?  Thanks! 
  

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Re: Soft pedal after bleeding brakes?
Reply #1 - 01/16/12 at 11:13:48
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The brake cylinders wont have anymore travel than before, the pistons will be further out but they stay out.  Sounds like your MC may be leaking back.
  

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Re: Soft pedal after bleeding brakes?
Reply #2 - 01/16/12 at 16:25:42
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No, your brake shoes are not adjusted as close as you think they are. If the pedal is firm when you push it down the first time then there is little or no air. Now, go back and readjust the shoes and pay particular attention to them slightly dragging when you lock the adjuster down. When you adjust them you want a very slight drag on the drum as it turns and after the first few stops they will not drag.

There is a slot in the drum into which your supposed to slide a feeler gauge to check the clearance of the shoe to the drum. Did you do that? I doubt you did. However, if you use the slight drag trick it will work. Setting the gap from top to bottom is tricky and most people can't do it right.
« Last Edit: 01/16/12 at 16:29:19 by Carls_jeep »  
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Re: Soft pedal after bleeding brakes?
Reply #3 - 01/16/12 at 23:16:57
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It's critical that brakes be adjusted using the factory method. If the top and bottom are not carefully adjusted together here's what can happen:

If the bottom is too close then when the brakes are applied the bottom of the shoe will contact the drum long before the top and in some instances the top will never make contact -> spongy brakes (you're flexing the shoes).

If the top is too close then the top makes contact and the bottom never does -> hard brake pedal but insufficient stopping power (not enough shoe contacting the drum).

You can't adjust one all the way and then the other. You must use a feeler gauge. You'll find that you'll actually have to back one end off in order to get the other where it touches the feeler gauge. It will take several top then bottom then top etc before you achieve the correct balance.

http://www.vernco.com/Brakes/id348.htm




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Re: Soft pedal after bleeding brakes?
Reply #4 - 01/17/12 at 09:53:29
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Yep, using the feeler gauge is the best way and it does take several adjustments top and bottom on each shoe to get them right.

You can't skip through adjusting the brakes correctly. It takes a lot of time to do it right.

There's something else that is seldom if ever done now, grinding the shoe to fit the drum. When the drums are turned and new shoes are installed the shoes have to be ground to have the same arc the drum has so they fit flush all the way from the top to the bottom of the shoe. If that is done the brakes will stop better.

The common way now is to let the shoes wear in to fit the drum rather than grind the shoe to fit the drum.
« Last Edit: 01/17/12 at 09:57:05 by Carls_jeep »  
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Re: Soft pedal after bleeding brakes?
Reply #5 - 01/17/12 at 11:18:28
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Carls_jeep wrote on 01/17/12 at 09:53:29:
There's something else that is seldom if ever done now, grinding the shoe to fit the drum. When the drums are turned and new shoes are installed the shoes have to be ground to have the same arc the drum has so they fit flush all the way from the top to the bottom of the shoe. If that is done the brakes will stop better.

The common way now is to let the shoes wear in to fit the drum rather than grind the shoe to fit the drum.

You can thank Osha for that... they outlawed grinding the brake shoes due to asbestos issues. About the only way to do it now is put some heavy sandpaper inside your drum and sand against it with the shoe. Modern brake material is not supposed to contain asbestos but all the drum arcing machines are tossed in the scrap barrel by now. I just let mine wear in...We were taught in college in 1980 to arc them.. the next year they took the arcing machines away.
  

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Re: Soft pedal after bleeding brakes?
Reply #6 - 01/17/12 at 11:24:09
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What size feeler gauge?
  

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Re: Soft pedal after bleeding brakes?
Reply #7 - 01/17/12 at 13:15:05
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.008

Larry
  
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Re: Soft pedal after bleeding brakes?
Reply #8 - 01/17/12 at 13:55:06
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They no longer use asbestos in brake shoes as I understand it. Find a shop that has a drum lathe with a brake shoe grinder and have him do them. My brake lathe still has the grinder with it and when I replace my shoes they WILL get ground to fit.

Tom, all this is brake stuff is in the Willys shop manual. You have one don't you?
« Last Edit: 01/17/12 at 13:56:26 by Carls_jeep »  
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Re: Soft pedal after bleeding brakes?
Reply #9 - 01/18/12 at 09:13:44
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Great stuff, thanks.  My drums do have the slots and I read about the correct procedure but I inferred from Vern's description that the fact that they eliminated the slots later meant they weren't critical.  Your explanation(s) help me understand why.  I will go back and do it correctly!
« Last Edit: 01/18/12 at 09:15:57 by ersatzS2 »  

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Re: Soft pedal after bleeding brakes?
Reply #10 - 01/18/12 at 10:04:54
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this begs the question...Whay did they eliminate the slots?  I noticed that last night while cleaning the drums for the 3B.
  

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Re: Soft pedal after bleeding brakes?
Reply #11 - 01/18/12 at 12:57:30
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I don't know why they eliminated the slots but I can tell you how I adjust mine and that may be why they removed the slots.

I adjust the top adjuster until the shoe rubs and back it off until it is just touching lightly. Then I do the bottom the same and then check the top and if it only takes a slight movement to make it tight I back it off and go to the other shoe.

I do all four wheels the same and in my mind that is as good as it gets without getting anal about it.

When adjusting brakes with a star wheel as on newer self adjusting systems you snug the adjuster until the wheel stops turning then back the wheel off about 10 clicks and that is about what your doing with the feeler gauge.
  
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Re: Soft pedal after bleeding brakes?
Reply #12 - 01/18/12 at 18:45:24
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Johnny, I just replaced a front drum on my 3B with a Rugged Ridge (china) drum. The old drum had the slot and the new one does not. I suspect it was cheaper to skip the slot. I adjust the same as Carl does although the 3B brakes are a little easier with only 1 cam per shoe.
  

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Re: Soft pedal after bleeding brakes?
Reply #13 - 01/22/12 at 20:38:19
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OK I started over today.  Realized that I must not have adjusted the front lower eccentrics at all since I don't have a gooseneck wrench that is thin enough to get onto the locking nut.  So I'll have to go out and buy a cheapo and grind it down.  But I see what everyone means.  The eccentrics aren't very accurate and you have to make tiny movements to the adjusting pin to get it right.  Also manual says .008 up top and .005 at bottom. 

Job is only halfway done since I can't do fronts without making a tool. 

  

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