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Old 05-21-2015, 05:53 PM   #1
drillrod
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72 K5 Hard brake problem

I am having trouble with my brakes being hard to mash. It has decent brakes, but I have to mash really hard to get them to work. Everything to do with the brake system is new (booster,brake lines,calipers, cylinders,shoes,pads,proportioning valve,etc.). The brake light also stays on. I have been told to check the vacuum ,so I did and it appears to be real good. Anybody have any good ideas! Thanks
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Old 05-21-2015, 06:29 PM   #2
sawman
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Re: 72 K5 Hard brake problem

sounds like the power/vacume is not working,first bleed the brakes good you might have air in the lines,
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Old 05-21-2015, 09:09 PM   #3
ClassicStyle
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Re: 72 K5 Hard brake problem

Soundsike you have a booster issue. Check vaccum, if hydro boost check for leaks. Air in the lines would give you a mushy/low pedal
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Old 05-21-2015, 09:27 PM   #4
Onalaska Blazer
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Re: 72 K5 Hard brake problem

First off, it the engine stock ?? If you have a big cam you may not be able to create Vacuum enough to power the New booster.

put a vacuum gauge on the line going to the booster, start truck and see if you generate 14 inches of vacuum. If you have 12 or below the booster will not operate and you will need to stand on the peddle.
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Old 05-21-2015, 09:51 PM   #5
1rippen6
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Re: 72 K5 Hard brake problem

I am guessing since the brake light is on the proportioning valve is tripped one way. Possible it is stuck if bleeding does not fix it and why the brakes are not real good. Bleeding the brakes may equalize the pressure and reset the brake light and start working properly. If that doesn't work and you know the all the air is out of the system I reset a safety switch on the proportions valve but it was about 25 years ago. If I remember correctly I removed the safety switch from the valve and used a pick to recenter it but it has been a long time LOL.
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Old 05-22-2015, 09:21 AM   #6
jaros44sr
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Re: 72 K5 Hard brake problem

Quote:
Originally Posted by 1rippen6 View Post
I am guessing since the brake light is on the proportioning valve is tripped one way. Possible it is stuck if bleeding does not fix it and why the brakes are not real good. Bleeding the brakes may equalize the pressure and reset the brake light and start working properly. If that doesn't work and you know the all the air is out of the system I reset a safety switch on the proportions valve but it was about 25 years ago. If I remember correctly I removed the safety switch from the valve and used a pick to recenter it but it has been a long time LOL.
X2 on stuck or misaligned JMHO
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Old 05-22-2015, 02:48 PM   #7
cleszkie
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Re: 72 K5 Hard brake problem

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Originally Posted by jaros44sr View Post
x2 on stuck or misaligned jmho
x3
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Old 05-23-2015, 03:45 PM   #8
drillrod
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Re: 72 K5 Hard brake problem

Thanks guys for all the info!
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