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Author Topic: stiff brake pedal when going above 45 mph  (Read 4620 times)

Offline tj wand

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stiff brake pedal when going above 45 mph
« on: August 14, 2013, 07:42:17 am »
hello, i have an 82 c10 scottsdale with a newly rebuilt 305. when the vehicle is going about 45 mph or faster the brake pedal gets really hard. as if the power brakes has quit working. if anyone has a way to fix this for the cheapest amount please let me know
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Offline bd

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Re: stiff brake pedal when going above 45 mph
« Reply #1 on: August 14, 2013, 09:56:21 am »
Do you have one or two strokes of power brake assist before the pedal starts feeling hard after you shut the motor off?  If not, you may need to replace the brake booster vacuum check valve.  You should also check the vacuum hose to the booster and confirm that it's not restricted or collapsing under vacuum.
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Rich
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Offline tj wand

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Re: stiff brake pedal when going above 45 mph
« Reply #2 on: August 14, 2013, 12:01:45 pm »
idk ill have to check the strokes i believe its 2 but if the vacuum hose is restricted or collapsing wouldn't I get a stiff brake no matter what?
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Offline Irish_Alley

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Re: stiff brake pedal when going above 45 mph
« Reply #3 on: August 15, 2013, 12:05:52 am »
what im thinking is below 45 your pulling sufficient vacuum to operate the booster but due to a leak when your cruising 45+ you engine vacuum drops and isnt sufficient enough to operate the booster. wouldnt know how to test but if you have one just laying around it might help. if you have a vacuum gauge it could show you. never really payed attention to the vacuum of our trucks but this is what im thinking, someone will correct me if im wrong.
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Offline flips87c30

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Re: stiff brake pedal when going above 45 mph
« Reply #4 on: August 15, 2013, 04:18:49 pm »
Im with Irish. My first thought was insuficient vacuum. But im definetly no expert. (my truck has hydro boost :-\)
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Offline Irish_Alley

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Re: stiff brake pedal when going above 45 mph
« Reply #5 on: August 15, 2013, 10:38:24 pm »
at idle can you hear the booster hiss when you press the brakes?
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If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline tj wand

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Re: stiff brake pedal when going above 45 mph
« Reply #6 on: August 21, 2013, 04:52:00 pm »
no sorry for the late response had no internet for a while but when the trucks idling theres a sucking noise coming from the driver side headers
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