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It's me, really
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Discussion Starter · #1 ·
Even though I have all the confidence in the world in my vacuum brakes, they are still softer than the PowerMaster was. I have bled them repeatedly to the point of aggrevation and cannot get the firm pedal I used to have. I am starting to wonder if the proportioning valve is specific to the PowerMaster unit and a N/A proportioning valve would be the better choice to include with a vacuum brake swap. Any gewroos wanna take a stab at this question? dunno
 

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Premium Member
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43,735 Posts
Never had a problem with the regular valve. Make sure you not running one of the original cast iron valves, but, have one of the brass replacements.

Never noticed a soft pedal. I generally either vacuum bleed and/or gravity feed to be sure I got the air out all the way.

Altho' it is not required for our cars, I always found that when using the pedal for bleeding, I got better results by restraining the button on the valve when doing the fronts. BUT, I much prefer vacuum or gravity bleeding as compared to pumping the pedal.
 

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It's me, really
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1,892 Posts
Discussion Starter · #3 ·
I have the stock cast iron valve. I suppose I should find out how much a replacement brass valve is, p/n 25509419. I tried bleeding with a MityVac but it sucked so strongly (LOL) that it created it's own bubbles. I had to work with it gently to get where I am now. I had the plunger pushed in also at the time. I'm stumped.
 

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too many toys
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Did you change the front hoses recently?If they are swelling it will cause a soft pedal.Just a thought.
 

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Fuhgeddaboudit
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Back to brakes 101... Make sure you take all of the adjustment out of the emergency brake (cable hanging) Pull on cable and make sure passenger side rear cable is not frozen or worn through from rubbing on lower control arm (very common) Now adjust rear brakes with star adjuster. Then last you adjust emergency brake cable until emergency brake pedal can only go down half way. This is the major cause for spongy brakes other then air in the lines.
 

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It's me, really
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1,892 Posts
Discussion Starter · #6 ·
Ed, that is good info. I need to try that technique first. Why the heck are you the only one who knows this? The way the star adj are set now is I get about 1/2 turn freespin on the rears (dragging the driveshaft around also). My e-brake is also soft; when fully depressed, I can overpower it if not careful. I definitely need to go through your procedure one time before spending money. Thanks!
 

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Fuhgeddaboudit
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18,613 Posts
When I worked for a very large fleet over 100K vehicles we had a lot of intermediate GM cars.
All the users complained about the brakes. We told GM to find the problems or we won't buy GM's no more. Clout works good :cool: They found what I deccribed and we never had this problem again. Also front pads purchases were cut in half.
 

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I installed a comp cams vacuum resevoir, and it has been the best cheap upgrade on my car to date. Lots of vacuum, great pedal feel, and I can hold 16+ psi on the foot brake.
 

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It's me, really
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1,892 Posts
Discussion Starter · #9 ·
I did the procedure. The GM Service Manual says to engage the e-brake pedal 3 clicks. Then you adjust the cable adjuster until you cannot turn the right rear wheel forward and only turn it backward with two hands. Technical! LOL! Anyhow, I started the car, put it in gear, and the brakes did feel a little better. Too cold for a road test right now but there's some promise. Thanks for the tip.
 

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MASTER GM TECH
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676 Posts
just another thought
am old guy at my dealership showed me this headbang
the adj in the rears usually self adj if you drive in rev(about 5-10 mph) then hit brakes semi hard... do this a few times (keep going backwards) in a empty lot or street(be carefull) youll be amazed on how much
firmer your pedal begins too feel
sloppy rear brakes makes for a sloppy pedal
nothing is better than manually adj them first to free up adjusters but after that if your lazy
(like me) this will work
i do this on my commuter sh!tboxes and works awsome...
in closing they are supposed to auto adjust :rolleyes:
but who in the heck drives like that anyways???
thanks GM silly
 
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