97 Lesabre low pedal after rear drum replacement

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  #1  
Old 05-17-19, 10:14 AM
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97 Lesabre low pedal after rear drum replacement

Hey guys, hoping maybe someone can lead me in the right direction here.

1997 Buick Lesabre- just replaced the rear brakes. Did both wheel cylinders, brake shoes, drums, adjusters hardware. Even after bleeding both rear brakes repeatedly, when stopping the brake pedal goes pretty far down. It was fine before touching the rear brakes. I did not bleed the fronts, only the rears.

I have read that since the front and rear brake systems are separate, bleeding just the rears should be ok. Is this wrong? Is there something else I should try? Any help appreciated!
 
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Old 05-17-19, 10:28 AM
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Did you adjust the brakes? The self adjusters will tighten up the rear brakes but it can take awhile. Generally the rear brakes are separate from the front but on my jeep it's diagonal [1front and 1 rear]
 
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Old 05-17-19, 10:34 AM
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Yes I did tighten the adjusters so that there is a slight drag.
 
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Old 05-17-19, 10:37 AM
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Disregard, Posted after your last post
 

Last edited by Tumble; 05-17-19 at 10:38 AM. Reason: Answered question
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Old 05-17-19, 11:41 AM
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It sounds like you were pretty thorough, so sorry if this is too basic, but did you check your fluid level when you were done?
 
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Old 05-17-19, 05:30 PM
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I would bleed the front also. Did the MC go empty when you were working on the rear. If it did you most likely have air in front.
 
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Old 05-17-19, 06:43 PM
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Bleed back passenger side driver rear passenger front and driver front.
 
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Old 05-17-19, 08:10 PM
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The Master cylinder did not go dry when bleeding the brakes, but I will try to bleed the fronts this weekend and see if it helps!
 
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Old 05-18-19, 01:01 AM
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If the master cylinder reservoir has separate zones for the front and rear, then you should be alright by just bleeding the rear. If it's just one pool of brake fluid for the whole car, then you need to bleed the front and rear. Start from the furthest bleeder away from the master cylinder (usually passenger rear > driver rear > passenger front > driver front)

This is what came up when I searched for a 97 LeSabre master cylinder:




Looks like it's a shared reservoir for both the front and back. In theory, if you kept fluid in the reservoir the entire time and didn't let it go dry, no air should have made it's way back into the reservoir. However, If perhaps your timing was off with pressing down the pedal/your helper opening and closing the valve (or if you used a bleeder bottle and missed it sucking in air) then it would introduce air into the entire system. I recommend bleeding the entire system and seeing what you get. Make sure you or your helper watches the line until there are no more bubbles, and keep the reservoir full.

If your pedal is still soft afterwards, I would pull the rear drums and take a look at the wheel cylinders. Are they wet? Is the line wet? Did either of the seals on each end of the cylinder come out? Did the pins become unseated?

Good luck!
 
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Old 05-18-19, 06:27 AM
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Normally, lines are crossed front front to rear. So it's passenger front and driver rear and driver front and passenger rear. reason being if one line is damaged, you still have even braking force applied to BOTH vehicle sides. It does not make any sense to have rear and front separate.
So normally, when you bleed, you want to do all 4, starting with the farthermost one from the master, which is passenger rear>driver rear>passenger front>driver front.
 
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Old 05-18-19, 07:43 AM
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Normally, lines are crossed front front to rear.
The norm it diagonal but it varies by vehicle!
 
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Old 05-18-19, 09:07 AM
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Back when drum brakes were on all 4, the brakes weren't separated. When they started putting disks on the front they separated the front and the back. No expert but I think the diagonal thing came about when they went to all 4 disk brakes.
 
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Old 05-18-19, 09:51 AM
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Just bled the fronts.. same deal with the low pedal.
 
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Old 05-18-19, 10:53 AM
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After bleeding the brakes again, I took a look at the rear brakes. Way too loose. The right rear adjuster some how adjusted it self back in keeping everything loose. I readjusted both rear brakes out a bit and the pedal feels great! Not sure why the adjuster on the right side had went all the way back in by itself? Dont they normally adjust out?
 
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Old 05-18-19, 04:38 PM
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Normally - my favorite word - you manually adjust adjuster. It should stay there thereafter. If it "self adjusted" you messed something up during the job. Those are VERY simple mechanical things that don't get mind of their own.
 
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Old 05-19-19, 04:05 AM
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The way I did rear brakes is to adjust until wheel would lock up. That way I know adjuster is tight. I then loosened adjuster till the wheel would turn. Was a brake mechanic foe many years and this always worked for me.
 
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