Intermittent soft pedal - JeepForum.com
 
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post #1 of 13 Old 01-28-2014, 11:55 AM Thread Starter
row684
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My brake pedal randomly goes soft on the first press, firm the second. It has done this the last couple of days and last night my brake light (in the speedo) came on when it was soft. I've checked for leaks and found none. Brake fluid looks awful but is only about 2 years old when I did new lines calipers rotors and pads. Front reservoir was a little low too but hardly enough to bother adding more.

It's all stock manual brakes on an 84.

Master cylinder??? If so can I get a power booster and power master cylinder and will they bolt up to an originally manual Jeep?

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post #2 of 13 Old 01-28-2014, 02:29 PM
LumpyGrits
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Bleed the breaks-Sounds like air in the line.
Did you just do some brake work maybe......
LG

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post #3 of 13 Old 01-28-2014, 03:13 PM
jcalhoon84
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Sounds like a leak, possibly the master cylinder against the firewall...that's what caused that issue on mine.
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post #4 of 13 Old 01-28-2014, 10:48 PM Thread Starter
row684
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Quote:
Originally Posted by LumpyGrits
Bleed the breaks-Sounds like air in the line. Did you just do some brake work maybe...... LG
It's been 2 years since I've had to do the brakes and they have worked fine until now, 2-3000 miles.
I will search for leaks more thoroughly tomorrow but the one reservoir is only down 1/4" over 2 years. the fluid does have a metallic look to it and is very contaminated however (symptom of something?) in the reservoirs would just like to isolate the problem before I flush it all...
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post #5 of 13 Old 01-28-2014, 10:53 PM
LumpyGrits
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As the brakes wear-The reservoir goes down.
Flush and refill with FRESH/NEW, DOT 3 fluid. Never mix brake fluid types.
See if that changes anything.
LG

Have'n you along, is like loose'n 2 good men
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post #6 of 13 Old 01-29-2014, 02:13 AM
RWise
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You might want to look at the rear (drum) brakes, if the auto adjusters stopped funtioning the pedal would slowly go down to the point it needs to be pumped to get enuf fluid to the rear slaves to move the shoes far enuf to hit the drum.

Brake fluid is the most over looked fluid on any vehicle, it seems we expect it to last forever in its sealed system, even though moisture (condesate) can go through metal and contaminate the fluid. Not to mention the particals of metal and ruber floating(or suspended) around in it,,,, which is kinda like grinding compound.
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post #7 of 13 Old 01-29-2014, 10:04 AM Thread Starter
row684
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Quote:
Originally Posted by RWise
You might want to look at the rear (drum) brakes, if the auto adjusters stopped funtioning the pedal would slowly go down to the point it needs to be pumped to get enuf fluid to the rear slaves to move the shoes far enuf to hit the drum. Brake fluid is the most over looked fluid on any vehicle, it seems we expect it to last forever in its sealed system, even though moisture (condesate) can go through metal and contaminate the fluid. Not to mention the particals of metal and ruber floating(or suspended) around in it,,,, which is kinda like grinding compound.
The parking brake still works correctly, would this rule out the adjusters?

Any idea where the metal flakes and other crap floating around in it could have come from? The fluid was clean this last summer.
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post #8 of 13 Old 01-29-2014, 10:09 AM Thread Starter
row684
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Quote:
Originally Posted by LumpyGrits
As the brakes wear-The reservoir goes down. Flush and refill with FRESH/NEW, DOT 3 fluid. Never mix brake fluid types. See if that changes anything. LG
I will work on that today.
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post #9 of 13 Old 01-29-2014, 01:03 PM
RWise
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Quote:
Originally Posted by row684 View Post
The parking brake still works correctly, would this rule out the adjusters?
No but you may be able to set the parking brake and have more pedal.

Quote:
Originally Posted by row684 View Post
Any idea where the metal flakes and other crap floating around in it could have come from? The fluid was clean this last summer.
Normal wear! The ruber parts rubing against metal parts, also crap that was already in the system. When I worked with hydrolics, the formula they used to predict the next down was 50% of the previous run time, no mater how clean the job was done.
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post #10 of 13 Old 01-29-2014, 08:07 PM
jeepmor
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Second on checking rear drum adjusters. Sounds like they are not spinning anymore and your brakes have worn, making the wheel cylinders have to move farther to get the brakes to bite. Does not sound like air in lines, although, this is the same symptom typically. Engage E-brake and see if it becomes consistent. If it does, that's it. If not, could be air in there somehow, but doesn't sound likely from your description.
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post #11 of 13 Old 01-30-2014, 03:34 AM
RWise
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The adjusters activate when braking in reverse, IF the pedal comes up with the parking brake set, you might try driving in reverse and pumping the brakes, fairly hard stops may jar them loose and let them adust out.
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post #12 of 13 Old 01-30-2014, 02:49 PM
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Quote:
Originally Posted by RWise View Post
The adjusters activate when braking in reverse, IF the pedal comes up with the parking brake set, you might try driving in reverse and pumping the brakes, fairly hard stops may jar them loose and let them adust out.
I used to do this in my culdesac, always wondered if the neighbors thought I was crazy.
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post #13 of 13 Old 01-31-2014, 10:07 AM
Balvar24
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I recently had the cable for the adjusters break in my rear brakes. Check that too.

"Work hard, rock hard, eat hard, sleep hard, grow big, wear glasses if you need 'em."
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