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Important Saftey Question

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Old 08-14-2009, 09:12 AM
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Hello Everybody!

I have a question regarding the safety of my braking system.
first of all i want to tell you how it all began.
abut two months ago the "brake / warning" light on my dash lit but the brakes were fine.
about a month ago my front brakes got locked while i was driving and got released after i let the truck cool down and they never got locked again.
now, about two weeks ago i noticed that the brake paddle is low and very soft. i tested the brakes in a deserted road near my house and i discovered that i got no brakes. the truck came to stop only when i stepped on the paddle really hard.
i discovered that the second exit of the master brake cylinder produce lower pressure than the first exit. (the second one is for the rear brakes).
so i removed the master cylinder brake and got it refurbished, mean while i opened the entire brakes lines system and got it cleaned with a compressor.
when i installed the refurbished master cylinder both exits produced the same pressure but the rear brakes lines were still empty and no oil came out of them (ever after i drained all the air out of the system of course).
now i came to a conclusion that the "standard rear wheel anti-lock breaking system" is jammed or something. i removed it, cleaned it and installed it back on and now when i tried to drain air out of the rear brakes, oil did came out and the brakes paddle returned to it's normal position - so i took the truck to a spin in order to test the brakes and i realized that when i stop an emergency stop the rear brakes still won't work.
I've lifted one rear wheel in the air and put it into "D" in order to examine the problem and i discovered that when i apply normal power to the brakes paddle the wheel stops, but when i apply stronger power to the paddle like in an emergency brake situation the wheel continues to rotate like i never pushed the paddle at all.

now that I'm through drilling an hole in your heads - my question is:
does this test gives my any indication that the "standard rear wheel anti-lock breaking system" works, or the wheel should stop no matter how hard i push the paddle?
the big picture is that I'm trying to find out rather my "early abs" system works fine or not, and more importantly - does my rear brakes works properly?

thanks in advance, Yarin
 
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Old 08-15-2009, 11:19 AM
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anyone please?!
 
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Old 08-16-2009, 12:07 PM
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hello everybody!

I could really use your professional attention on this one. i grounded my truck because I'm concerned for it's safety.
All i really need to know is how this "Early ABS System" works under emergency brakes situation.
By the way my truck is 1990 k5.

Thanks in advance, Yarin.
 
  #4  
Old 08-16-2009, 01:00 PM
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Something doesn't sound right. So if you apply the brakes "mildly" they slow you down but if you apply them forcefully they don't work at all? And only on the rear brakes? The front brakes work properly or no?
 
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Old 08-16-2009, 01:52 PM
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well the front brakes works in both situations.
the rear brakes don't work at all when i push the paddle with great force.
this "early ABS System" that i'm talking about is connected to the rear brakes lines with valves and with a solonoid if i'm not mistaken.
i'll get you guys some pictures of the system as soon as possible.
any more ideas?
 
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Old 08-16-2009, 05:28 PM
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Check this out. LINK. Sounds eerily familiar.
 
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Old 08-18-2009, 12:03 PM
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well.. i gotta say that this article convinced me. I'll bypass the system.
I can live without a system that decides for me when I'm in an emergency and how much force i should apply to my brakes.
Isn't that so?
 
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Old 08-25-2009, 04:02 AM
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also note the rubber lines should be replaced because the rubber gets old and collaspes and restricks the proper fluid flow and there is a switching valve that can go bad you can see one on e bay used for around 100 bucks.
 
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Old 08-25-2009, 09:20 AM
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well eventually i ended up replacing most of the VERY rusty brake lines system.
and by the way, where is that switching valve you were talking about?
 

Last edited by yarinzim; 08-25-2009 at 09:24 AM.
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