04-18-2012, 07:43 PM | #1 |
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hard brake pedal
ok guys i have a question that i can't seem to figure out. i did the disc brake upgrade to my truck using ece dropped spindles and brakes. i used the original rebuilt power brake booster. and new master.brakes have a hard pedal and don't stop very well. i don't think it is the booster because it worked fine before. any suggestions?? thanks
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04-18-2012, 08:40 PM | #2 |
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Re: hard brake pedal
Did you change the brake hoses? Also did you clean the rotor after installation?
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04-18-2012, 09:09 PM | #3 |
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Re: hard brake pedal
new hoses , brakes bled good. it's not combo valve checked it with light --not on?
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04-19-2012, 11:17 AM | #4 |
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Re: hard brake pedal
It probably wouldn't hurt to tee in a vacuum guage to verify that you have vac at an idle.
Also look at your check valve to make sure that you are capturing the vac. that you develope.
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Les Hunter '59 3803 someday to be 3853 '63 GMC K1000...351E, TH400 Daily '66 GMC 4000...351C, 5&2 |
04-19-2012, 12:10 PM | #5 |
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Re: hard brake pedal
it has a steady 16hg at idle a little low but should be good?
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04-19-2012, 04:39 PM | #6 |
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Re: hard brake pedal
That should be plenty...
You might check the check valve...The plastic 90% thing that pushes into the rubber grommet and has the hose on the other end...If you pull it out of the hydro-vac ....you should be able to blow into it..(toward your intake manifold) and you should not be able to suck through it. I hope it's that simple for ya... By chance, when you bolted yer new master cyl. onto your H-Vac....was the plunger engaging the piston prior to the housing seating against the booster....so that as you tightened the nuts the MC began to stroke befor it was tight...? Just shootin in the dark. Good luck...
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Les Hunter '59 3803 someday to be 3853 '63 GMC K1000...351E, TH400 Daily '66 GMC 4000...351C, 5&2 Last edited by A.T. RockDriller; 04-19-2012 at 04:45 PM. |
04-19-2012, 07:52 PM | #7 |
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Re: hard brake pedal
the check valve works blows but doesn't suck. the pushrod was not engaging the plunger, when installed. i took it apart the other day and adjusted it some so ther is a little play in pedal before it engages plunger. thanks for your thoughts and ideas. i am going to pull wheels and maybe rebleed brakes tommorrow.
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04-19-2012, 08:04 PM | #8 |
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Re: hard brake pedal
Sounds like the master bore diameter might be wrong for the rear wheel cylinder bore diameter.. or the calipers. Too-small slave cylinders can give a hard pedal.
Do you feel the booster kick in if you start the engine with the brake pressed? Last edited by FreakyMalo; 04-19-2012 at 08:12 PM. |
04-19-2012, 08:16 PM | #9 |
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Re: hard brake pedal
yes forgot to add that .. pump brakes let vacume out start engine pedal drops maybe 1/4 in. but you can feel it.
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04-19-2012, 09:04 PM | #10 |
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Re: hard brake pedal
You might check the master cylinder specs and see if the drum side is for 1-inch wheel cylinders.
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