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#1 |
Registered User
Join Date: Mar 2009
Location: NW, Colorado
Posts: 285
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Brake help please....
So I have a 1972 Chevy Blazer. It has been lifted running 36" tires. The brakes have always seemed a little weak. So this spring I decided it was time for new rotors, pads, drums etc. So I got all of it switched over. Got the system bled and had decent (not awesome) brakes in my inital test drive for about 4-5 good hard brakes. After the 4-5 test, the brakes were gone... Nothing. the pedal sits all the way to the floor, the lights stay on etc. There is no fluid leaking, the master is full and I even bled it before the line bleeding. I did it all in the right order etc.
Does the fact that there is no pedal mean my master cylinder went bad? It is not leaking, but I can't really even pump the brakes. If it is a master cylinder, what up grades can I do that will makes the system better with out costing tons of money and forcing all sorts mods. Can I swap in a larger cylinder? Aftermarket upgrades? Or will a new master make all the difference. I have had the blazer for a little over 3 years, not sure how old the cylinder maybe.... I don't mind reading if you find a link.... I searched did not my situation per say.
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Confidence is the feeling we have before we fully comprehend the situation |
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#2 | |
Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
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Re: Brake help please....
Quote:
A poor working brake booster could be causing you issues too. A vacuum leak in the booster diaphragm or just not enough vacuum coming from the engine due to a large cam will make your power brakes work worse than manual brakes and take a bunch more effort to stop the truck. How much vacuum does your engine make at idle?
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miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars |
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#3 | |
Registered User
Join Date: Mar 2009
Location: NW, Colorado
Posts: 285
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Re: Brake help please....
Quote:
Thanks for the pointers. I have looked and found a thread on the 1 ton master cylinder and boaster swap. I have the right bracket so I will probably go that route. I do have a pretty aggressive cam and at idle the engine is loping a bit to idel. Not like a race car, but definitely more than a stock/rv cam. I will have to dig out my vacuum gauge and see what I get for vacuum pressure. Will that be an issue if I do the 1 ton swap? I could run slightly higher rpms which should create more vacuum. Not sure what else I could do if that is an issue... Manual brakes over power? Thanks for the pointers. I do not want to do a disc brake swap as someday I am hoping to built another 14 bolt for it and then go to disc brakes at that point. THanks...
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Confidence is the feeling we have before we fully comprehend the situation |
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#4 | |
Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
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Re: Brake help please....
Quote:
http://www.summitracing.com/parts/MRG-3701/ The 1-ton brakes will still have the same problem if you don't have enough vacuum to run the booster properly. Another option is convert to hydra-boost. Power assist by hydraulic pressure off the power steering pump. Used in lots of diesel GM trucks and some Astro vans as well as a few others. This would be your best option with a big cam.
__________________
miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars |
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#5 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,218
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Re: Brake help please....
You need a new master cyl. These are dual master cyls. No upgrade is needed. You should always replace the MC when you do extensive brake work. Like C-10 says, a reman. is not expensive.
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