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Brake Pedal Travel Issue, Soft brakes

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Old 02-21-2008 | 06:39 PM
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Question Brake Pedal Travel Issue, Soft brakes

Well, to keep it short and sweet I have been having issues with the brake pedal travel on this truck since the day I purchased it. All of the brake system is O.E. or O.E. replacement. I have a somewhat soft pedal that depresses 4" total when the engine is running, compared to the maximum travel spec of 2.5" out of a Haynes manual.

I have bled the system 3 times and flushed with new fluid twice since I have owned it, since 78,000 miles. My girlfriend's 2006 RCSB 4x4 5.3 brake pedal is completely solid compared to mine, she has noted on many occasions that while driving my truck my pedal just seems to be soft compared to her truck. For her to notice that is pretty big, as she is not very in-tune to the nuances of vehicles various problems.

I have gone through the vacuum booster check listed in the Haynes manual and have come away believing it is all right. Might this be a master cylinder issue? Any thoughts on this are appreciated. Thanks.
Old 02-21-2008 | 06:48 PM
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I work for GM and the other day I was helping another tech with a Trailblazer. Your problem is very simliar to that trailblazer. The TB problem was a brake modulator valve I believe it was called. I dont know if our trucks have one, but look it up in your hayes book.
Old 02-21-2008 | 08:21 PM
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I wouldn't think the master cylinder, to be suspect.
Old 02-21-2008 | 08:23 PM
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I am having the same problem now.
Old 02-21-2008 | 08:46 PM
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My first guess would be the master cylinder....but that issue with the Trailblazer is very interesting.
Old 02-21-2008 | 08:58 PM
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Originally Posted by Red04Silverado
brake modulator valve .
Is that a part of the ABS module?
Old 02-21-2008 | 11:58 PM
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Originally Posted by joshua022
Is that a part of the ABS module?
Ill find out, but I believe its not part of it.
Old 02-22-2008 | 01:31 AM
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Originally Posted by Red04Silverado
Ill find out, but I believe its not part of it.
Sounds good, let us know what you find out. In the mean time I am still scouring the net looking for possible solutions. Thanks.
Old 02-22-2008 | 08:32 AM
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Just a couple non-hydraulic things to check for are siezed slide pins and a very loose wheel bearing. Either of these will give you a spongy pedal and decreased braking performance.
Old 02-22-2008 | 11:30 AM
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Originally Posted by budhayes3
Just a couple non-hydraulic things to check for are siezed slide pins and a very loose wheel bearing. Either of these will give you a spongy pedal and decreased braking performance.

Thanks for these ideas. I don't believe it is the wheel bearings as my front tires are wearing quite well. I did not notice any slop in the front wheels (side to side and top to bottom) 9 months ago, as that was the last time I bled and flushed the system and applied anti squeal to the pads.

I appreciate this guys, thanks.

Just sick of getting out of my truck and driving the girlfriend's rig and not wanting to get back in mine!



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