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Old 02-14-2008, 07:21 AM   #1
DANTES JIMMY
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Driving But So So Brakes??

Well It Is On The Road
But I Got Brake Issues How Can One Effectively Bleed The Brakes
New Caliper/new Pads/new Master Cylinder
Bench Bled Master Cylinder/gravity Bled Both Calipers/then Pumped
Up And Bled Both Side And Still Run Out Of Pedal And Cannot Lock Up The Front End (havent Gone Thru The Rears Yet Maybe This Weekend)
What Is A Speed Bleeder And How Does It Work Somebody Else In Another Thread Had Mentioned Them And I Have Never Heard Of Them
Any Input Would Be Sweet.
I M Sure I Still Have Air In The System But Do I Keep Just Bleeding Them Until I Get Good Pedal??
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Old 02-14-2008, 07:48 AM   #2
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Re: Driving But So So Brakes??

My experiance is with speed bleeders is that you just crack it open a little and push on the pedal, ball and spring take care of opening and closing like a valve. Not as messy, if you hook up a hose to it and route it to a can. Usually if you see bubbles in the can, you've got the air out. You still have to work from the farthest to the closest. As soon as you let go of the pedal the spring pushes the ball back against the seat.

Keep an eye on the level of the master cylinder, don't ask me how I know
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Old 02-14-2008, 12:20 PM   #3
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Re: Driving But So So Brakes??

I have a few questions....

1) Did you have the rear drums off?
2) If, so did you check the wheel cylinders for seepage or leaks?
3) Are the rear brakes adjusted properly?
4) Did you bleed all four corners?

Honestly, In my experience blazers don't have that great of a pedal. I can't lock mine up either. but, If the rear brakes aren't adjusted correctly it can cause a bad pedal. So can a seeping or leaking wheel cylinder as it can pull air back in when you let off the brakes. IMHO the best way to bleed a blazer out, is to start with either the right or left side of the truck. Lets say the right, open the right rear and the right front and just let it drip for 20 minutes, close them. Then do the same on the left side for 20 minutes. I've actually gotten a good pedal this way with only myself, but wouldn't recommend it. Then with someone inside pumping the pedal with nice, steady, even, and slow strokes, have them pump till firm, hold it, than open the bleeder screw. Some air might come out or not. Repeat at each corner until a solid solid stream comes out, three or four times in a row with no bubbles. Bleed in the standard RR, LR, RF, LF pattern.

if You have any questions feel free to pm me. I work at a popular west coast tire dealer famous for free beef as a brake and suspension "specialist".

Another thing to think about is a 3/4 ton Master and booster swap. As the M/c has a bigger bore and the booster is a dual diaphragm....
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Old 02-14-2008, 10:44 PM   #4
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Re: Driving But So So Brakes??

Good recomendation on the3/4 ton M/C, that should lock up your wheels. I also thought of another problem you mite have. A rubber hose could be ballooning on you, thing is, you don't see it. When you hit your pedal, the pressure pushes the outside wall of the rubber hose out, then you don't have enuff pressure for the brakes

Something is wrong if your running out of pedal, and it sounds like air
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Old 02-14-2008, 11:26 PM   #5
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Re: Driving But So So Brakes??

In the faq section I put up a post on a power bleeder that I built for very little money - sure makes bleeding brakes quick. Check it out.

I did the 3/4 master swap and my power brakes stop very effectively and have great pedal feel.
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Old 02-15-2008, 01:16 AM   #6
DANTES JIMMY
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Re: Driving But So So Brakes??

Ok Thats Great
Ill Redo The Rears This Weekend And Try All This Stuff
If All Else Fails Ill Switch To A 3/4 Mc
What Model Should I Use For Cross Reference
4x4, Pwr Brake,k20,dana 44
Or Should I Just Make Sure It Is For Proper Year For Fittings
And Booster Mating
Ps I Inspected The Rubber Hoses For Any Sign Of Wear But It Is Still Possible
Would I Be Able To See Or Feel The Swell If They Are Bad??
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Old 02-15-2008, 02:03 AM   #7
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Re: Driving But So So Brakes??

You'll only be able to see/feel it as someone else is pushing on the brake pedal. Any 3/4, 1 ton truck M/C will work from our years, don't know on the '73 and up, but possible

Red72blazer is right! I meant to include the booster as well...J.
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Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training
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Old 02-15-2008, 04:52 AM   #8
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Re: Driving But So So Brakes??

you have to use the booster as well.
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Old 02-15-2008, 05:29 AM   #9
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Re: Driving But So So Brakes??

In the 20+ years I've owned my K5 I never had super brakes until I replaced all wheel cylinders, hoses & shoes at the same time. The method I was taught is similiar. I usually gravity drain the old fluid out fully first. Then I have the "assistant" only push the pedal down once and holds it there says "down", then I'd open the bleed valve until the fluid just about stops, shut the bleed valve, then I tell the assistant "up". they reply and tell me when "up" (and off the pedal). The process is repeated until all air is out. Usually 1 full reservor full.
Signs to look for that mean problem components...

If as you bleed if you are getting an excessive amount of air then its possible that the master or wheel cyl are bad (even new can be bad). My experience is that if air bubbles comes back up into the master cyl then the Master cyl is bad. If no bubbles in the master cyl, but air at the wheel cyl=bad wheel cyl.

I like the idea about using the 3/4 ton M/C. Next time mine goes...I'll be plugging one of them in!

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Old 02-15-2008, 06:19 AM   #10
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Re: Driving But So So Brakes??

When I got my 71 blazer almost 30 yrs ago it would lock all wheels up. 16yr old locking up the 44's in the high school parking lot just to hear the sound. Now both my 70 and 71 have good brakes but they won't lock them up. My guess is booster. Since the wife and kids want to ride them I am going 3/4 ton swap
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Old 02-15-2008, 08:40 AM   #11
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Re: Driving But So So Brakes??

Never heard of the gravity idea, but I will keep it in mind next time, Thanks
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All parts offered to help are free, unless otherwise noted

Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training
SAFETY FIRST

AS usual, off topic

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Old 02-16-2008, 04:51 AM   #12
DANTES JIMMY
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Re: Driving But So So Brakes??

Im Going To Borrow A Vaccum Pump From A Buddy
And Give It A Crack And See How That Works
He Swears By It
Will Post Results
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Old 02-16-2008, 05:01 AM   #13
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Re: Driving But So So Brakes??

#/4 ton booster is the only way. It is simply a difference in single diaphram and dual. You will tap the peddle and lock them up. But in order to bleed brakes, especially with a new MC you must bleed the rears!! Start with the tire farthest from the MC and work your way closest (ie RR, LR, RF, then LF) then you'll have as good as you're going to get. The 3/4 booster and MC is about as cheap as just the booster?
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Old 02-16-2008, 10:27 PM   #14
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Re: Driving But So So Brakes??

I have the same deal with my brakes. Can't lock them up. I thought it was becuase I just installed a new motor with a big cam so I got a vacuum booster from summit. It didn't make much of a difference. I like the idea of going to 3/4 ton. Has anyone posted a tech tip on how to do this? Is it essentially replacing the booster and MC, bleeding and that's it? Now with the new engine the truck is fast, but not being able to stop is a little scary. How much do you think a shop would charge to do the swap?
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Old 02-16-2008, 10:54 PM   #15
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Re: Driving But So So Brakes??

I bought mine from Frank Picmup on the left coast for 50 or 60, but haven't installed yet. Looks like a direct bolt up, but there may be issues with the brake lines, I think they have a different orientation. Simple fix would be to bend new line to fit correct location. I could be wrong on the brake lines, I haven't installed mine yet.

Try to buy one complete, including the linkage to the pedal. May be something different there aswell...J.
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All parts offered to help are free, unless otherwise noted

Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training
SAFETY FIRST

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Jim

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Old 02-17-2008, 02:28 AM   #16
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Re: Driving But So So Brakes??

Bolts up if you get one for a 72 3/4 ton, but you have to reroute the brake lines. The front line becomes the rear and visa versa, or buy new lines from in line tube for about $20-30. I did it and I'll never own another 4X4 without that upgrade.
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Old 02-17-2008, 03:24 AM   #17
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Re: Driving But So So Brakes??

Quote:
Originally Posted by 70rs/ss View Post
Bolts up if you get one for a 72 3/4 ton, but you have to reroute the brake lines. The front line becomes the rear and visa versa, or buy new lines from in line tube for about $20-30. I did it and I'll never own another 4X4 without that upgrade.
The one on my K-20 is a manual and it's lines are set up the same as my 70 blazer. Guess they changed the routing a bit from 70-72?

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Old 02-18-2008, 10:45 AM   #18
DANTES JIMMY
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Re: Driving But So So Brakes??

Well I Just Vaccum Pumped All Of Em Just Like Everybody Says And Then We Got A Pile Of Ice And Snow Salt Monster Is Lurking Every Where
Cant Test Drive Yet
But If They Arent Better I Will Swap To 3/4 Ton Immediatly
Not Being Able To Lock Em Up Just Sucks
My Little Guy Will Not Be Able To Ride In It Until I Have The Most Braking I Can
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Old 02-20-2008, 08:06 AM   #19
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Re: Driving But So So Brakes??

I agree 100%. Tell me when your sitting, does the pedal "feel" rock hard? Because my 70 K5 with the current drums (25+ years old) and new cylinders, hoses & shoes is like a rock sitting, and will lock all 4 up if I hit it hard at about 45mph. Thats my test speed.



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Old 02-21-2008, 02:06 AM   #20
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Re: Driving But So So Brakes??

Dante, any update on the brakes? I'm in the same boat so I ordered the 3/4 ton booster and mc from NAPA. I thought I might replace the proportioning valve and calipers too. does any one know if this proportioning valve would work too? http://cgi.ebay.com/GM-Proportioning...QQcmdZViewItem
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Old 02-21-2008, 02:50 AM   #21
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Re: Driving But So So Brakes??

Nope Still Bleeding
I Did Again Last Night And They Are Much Better But First Pump Can Go To Floor
Second Pump Actually Feels Pretty Good
If I Could Duplicate It On The First Pump I Would Be Tickled
Please Please Let Me Know How Well The 3/4 Ton Stuff Works
How Much Was The Booster And M/c From Napa??
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Old 02-21-2008, 03:17 AM   #22
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Re: Driving But So So Brakes??

booster and mc from napa was $173. core is $33. It will take a week or so to get them though. I'll let you know how they work out.
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Old 02-21-2008, 03:45 AM   #23
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Re: Driving But So So Brakes??

Quote:
Originally Posted by Big Chief View Post
Dante, any update on the brakes? I'm in the same boat so I ordered the 3/4 ton booster and mc from NAPA. I thought I might replace the proportioning valve and calipers too. does any one know if this proportioning valve would work too? http://cgi.ebay.com/GM-Proportioning...QQcmdZViewItem
Seems like you have some of it covered on the prop. valve, discs and drums, but it has a application listed for cars. I would do a little more digging to find out if it would work, my guess is, no. I could be wrong
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Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training
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Old 02-21-2008, 05:05 AM   #24
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Re: Driving But So So Brakes??

Quote:
Originally Posted by DANTES JIMMY View Post
Nope Still Bleeding
I Did Again Last Night And They Are Much Better But First Pump Can Go To Floor
Second Pump Actually Feels Pretty Good
If I Could Duplicate It On The First Pump I Would Be Tickled
Please Please Let Me Know How Well The 3/4 Ton Stuff Works
How Much Was The Booster And M/c From Napa??
Sounds to me like the shoes arent adjusted properly. Assuming your drums are new, when you slip the drum on and rotate it, is there any drag at all? With new shoes you should have a little, and I mean little drag, not enough to create alot of heat, but close enough to prevent excessive pedal travel.

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Old 04-06-2008, 07:16 PM   #25
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Re: Driving But So So Brakes??

I'm doing the 3/4 ton swap booster and master cylinder. I am having a tough time finding the short brake lines from the proportioning valve to the mc. Any advice? Do I just get stock 3/4 lines from inline tube? My understanding is that the lines are reversed from the half ton? Help! this is all I have left to get my Blazer on the road.
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