|
Register or Log In To remove these advertisements. |
|
|
|
|||||||
 |
|
|
Thread Tools | Display Modes |
08-07-2013, 05:56 PM
|
#1 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Power Brake Help? New MC and Booster Install
I just asked for some help here last week as I made an upgrade to power brakes from my old worn out manual set up.
My truck is a C20, 1970...for the most part anyway. The Power Brake Booster that I installed is only a 7" Booster, but it clears the steering column, etc. and it was inexpensive. In doing this I stayed with Drum/Drum brakes. I feel my results are about half what I was after. I've been told that I may have the wrong MC for this set up, but it did come as a complete "kit", so I'm not sure how that would be the issue. I've been reading and reading and reading threads here and mostly looking at my pedal travel as it is no where near what it was before. I know to expect some changes, but.... Looking at my photo, it would appear that my pedal linkage is NOT engaging the MC fully as it only travels about 1". ??? This 1" is with the engine running/booster working, as well as with engine off. I just pulled the MC and supported it by rope to the hood and found that my linkage is actually traveling 2" and maybe a tad more. Here's my question... Is my MC blocked somehow? I would think it to move more than 1"? I removed my front wheels and adjusted my shoes out and re-bled everything. My rear wheels are getting new wheel cylinders this weekend and I was wondering if anyone had some advice for me on the MC/Linkage thing while I'm working on the rear brakes. I think that there is something simple going on here that's holding my brakes to only so so power. Something simple that I cannot see...forest for the trees. Thanks again.... Posted via Mobile Device Posted via Mobile Device |
|
|
|
08-07-2013, 06:59 PM
|
#2 |
|
Active Member
 
Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
|
Re: Power Brake Help? New MC and Booster Install
I'm not familiar with the booster that you have so I can't comment on that. Is there a manufacturer name on it?
The boosters that I have seen and taken apart have a direct connection to the master cylinder. In other words, the brake pedal to booster pushrod moves the same as the boost to master cylinder push rod. The baffles inside only assist the braking power. Follow these instructions carefully to see if it helps. (source: http://www.classicperform.com/TechBo...ot.htm#pushrod) Test Power Brake Booster If the pedal feels "hard" while the engine is running, the booster isn't operating correctly. If you suspect the booster is defective, do not attempt to disassemble or repair the power booster. Doing so is unsafe and will void your warranty. Test 1 1.With the engine off, pump the brake pedal to remove any residual vacuum in the booster. 2.Hold pressure on the pedal while you start the engine. When the engine starts, the pedal should drop about a 1/4", this indicates that the booster is working properly. Test 2 1.Run the engine a couple of minutes. 2.Turn the engine off and press the pedal several times slowly. The first pump should be fairly low. The second and third should become slightly firmer. This indicates an airtight booster. Test 3 1.Start the engine and press the brake pedal, then stop the engine with the pedal still pressed. If the pedal does not drop after holding the pressure on the pedal for 30 seconds, the booster is airtight. Inspect the Check Valve 1.Disconnect the vacuum hose where it connects to the intake manifold. Do not disconnect the vacuum line from the booster. Air should not flow when pressure is applied, but should flow when suction is applied. If air flows in both directions or there is no air flow, the valve needs to be replaced. Verify Enough Vacuum 1.Check the operating vacuum pressure when the engine is at normal operating temperature. There should be a minimum of 18 in. of vacuum. Vacuum may be increased by properly tuning the engine, checking for vacuum leaks and blockages in vacuum lines.
__________________
68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
|
|
|
|
08-07-2013, 07:50 PM
|
#3 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Re: Power Brake Help? New MC and Booster Install
Yeah...I did those tests and find things to be correct and working.
I am certain that my booster is working as it really helps to brake with little effort. What I'm baffled by is the fact that my MC Push Rod, with the MC attached only moves about 1". Like it is not going all the way in to the MC. To be certain it is not my pedal or linkage, I took the MC off and I have a full 2" of travel. When the MC is reattached, back to 1" only. I'm going to remove the MC all the way this weekend and inspect it. It seems to me that it moved more than 1" as I bench bled it before install. Would you happen to know the length of throw or bore for a MC? Realizing they are not standardized, 1" seems too short for braking to really work. Posted via Mobile Device Posted via Mobile Device |
|
|
|
|
08-07-2013, 08:49 PM
|
#4 |
|
Registered User
Join Date: Aug 2013
Location: Hiram Ohio
Posts: 619
|
Re: Power Brake Help? New MC and Booster Install
1" master cylinder piston travel is the norm. Get your rear brakes finished, get everything adjusted, bled, etc. Then give em a try. Hard to determine if you have an issue when the entire system is not finished..
Posted via Mobile Device |
|
|
|
|
08-07-2013, 08:54 PM
|
#5 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Re: Power Brake Help? New MC and Booster Install
Gotcha.
That's the truth too. Trying to fix half a system is foolish, but my wallet said to do it this way. This is a one day a week driver for deliveries, so as it earns money, I try to put a few back into it. Every week...a little better of a truck for it. This weekend will be fun too. It'll be my first time playing around with Full Floating Axles! Posted via Mobile Device |
|
|
|
|
08-07-2013, 08:59 PM
|
#6 |
|
Moderator
 Join Date: Dec 2012
Location: ON, Canada
Posts: 2,169
|
Re: Power Brake Help? New MC and Booster Install
Did you purchase a Drum/Drum master, or is there a chance it is a disc/drum master?
|
|
|
|
|
08-07-2013, 09:02 PM
|
#7 |
|
I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,993
|
Re: Power Brake Help? New MC and Booster Install
Once you have it all back together,try locking up the brakes.They should lock with your completely rebuilt brakes.
__________________
The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil" |
|
|
|
|
08-07-2013, 09:18 PM
|
#8 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Re: Power Brake Help? New MC and Booster Install
The MC was sold to me as Drum/Drum, but I wouldn't know if it were the flux capacitor itself??
What would a Disc Drum MC do different? The guy said that I would not need a Proportioning valve, so I figure the two parts of the piston to be the same. The bowls are the same size, I can say that. BTW...I think that I may have the "bug" here with the trucks. It's been fun making this one go again. Posted via Mobile Device |
|
|
|
|
08-07-2013, 10:00 PM
|
#9 |
|
Active Member
Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
|
Re: Power Brake Help? New MC and Booster Install
The drum/drum master cylinder has the residual valves on both ports to keep the pressure at about 10psi (google for location). The disc/drum m.c. usually has a larger front reservoir than the rear and doesn't have a residual valve for the front disc brakes.
One thing to remember, good brakes are a necessity for these heavy trucks so don't take shortcuts. If in doubt as to the type you have call the people you bought it from or buy one made for you drum brakes. If you have the old drum/drum m.c. you could probably use it as a test.
__________________
68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
|
|
|
|
08-09-2013, 01:59 PM
|
#10 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Re: Power Brake Help? New MC and Booster Install
Ouch! Lifted the rear end onto stands, applied the brakes, and the back wheel spun freely!
No wonder my braking is lousy! Thought I just had a leaking wheel cylinder. Turns out that I'm looking at 20+ years of total neglect! I'll have to clean this mess up, add some new shoes and wheel cylinders, and see what I have then. No matter what...guaranteed to be double what I had! Posted via Mobile Device |
|
|
|
|
08-09-2013, 05:56 PM
|
#11 | |
|
Registered User
Join Date: Aug 2013
Location: Hiram Ohio
Posts: 619
|
Re: Power Brake Help? New MC and Booster Install
Quote:
|
|
|
|
|
|
08-09-2013, 06:57 PM
|
#12 |
|
Registered User
Join Date: Jan 2011
Location: Redmond, OR
Posts: 760
|
Re: Power Brake Help? New MC and Booster Install
Unfortunately, with an older C20, you had to pull the axles and bearings to do the rear brakes, so they were often neglected. Mine were beyond metal to metal when I got it.
__________________
68 Chev C20- son has it now 83 K20 - bought from son 70 C20 - in progress |
|
|
|
|
08-09-2013, 07:15 PM
|
#13 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Re: Power Brake Help? New MC and Booster Install
I guess that I'm "lucky" there.
My pads are so gone that the drums were not being engaged, so the look fine? That is the reason that I did all the Booster, MC, Front, then the rear. (guess i'm guilty too) I will say though, that I was dreading it from past experience with rear drums. Jeep. VW. Buick. etc. My truck is a 14 Bolt and I cannot believe what a total breeze it is to pull those babies! With the help of this forum...no trouble at all. Never even reached for a hammer. That is until.... I cannot get the Wheel Cylinder out? Bolts are FROZEN! So, pulling the backing plate to get it off and onto the workbench where I can really break stuff! Those Four Mounting Bolts are TOUGH! Got my Dad's air ratchet and some PB and a torch...back at it in the morning. I've put down the tools...It's Time For Cocktails!! Posted via Mobile Device |
|
|
|
|
08-09-2013, 10:42 PM
|
#14 | |
|
Registered User
Join Date: Jun 2010
Location: San Diego Co.
Posts: 1,176
|
Re: Power Brake Help? New MC and Booster Install
Quote:
__________________
1972 Chevy C-10, SWB, Fleet, 350/350, PS, PB, HEI, mostly stock, Survivor. 
|
|
|
|
|
|
08-10-2013, 08:14 PM
|
#15 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Re: Power Brake Help? New MC and Booster Install
Boom! Bang! Boom! Bang!
After lots of crawling around on my knees, banging on stuff, and a fair share of swearing... Got the old off and the new on! Broke the old brake lines in the process, of course, but that gave me a chance to use my new line benders. All back together with the lines bled and the wheels still off. Gonna leave it sit and bleed a bit more in the AM. Couple more questions..... I found that I have 11" Drums, but my springs are from a 13" set. So that's the parts I replaced it with, Shoes for 11", Adjuster kit for 11", and new spring kit for 13". Anyone ever to that? Also, what's your method for tightening the axles up? Mine's a 14 Bolt, so it goes...Hub with seal and bearings, then Spacer with single tab, Spanner, Lock Washer with multi tab, another Spanner then Axle with Shim. (hope that makes sense) Anyway... I tightened first Spanner until the Hub wouldn't spin, then backed off about 1/8 Turn. Then added Lock Washer and other Spanner till it was tight, then backed off to the very next tab and sank it in. Is this about right? I've read it many ways here and would be curious as to any other take on it. Thanks again...should be rolling again tomorrow! Cheers! Posted via Mobile Device |
|
|
|
|
08-10-2013, 11:36 PM
|
#16 |
|
Account Suspended
Join Date: Oct 2012
Location: Salt Lake City, Utah
Posts: 3,331
|
Re: Power Brake Help? New MC and Booster Install
Nice job. You're getting closer, but I still can't seem to get past thinking that the MC might be wrong for your application. That looks like the ones that disc brake trucks use. Drum/drum boosted trucks tend to look like this
 If all else fails, you can get the booster with MC from Oreillys for about $150, and then they'll give you $30 back for a core return off that for your current booster/MC. Keep the bracket and push rod to the pedal to use. Posted via Mobile Device |
|
|
|
|
08-11-2013, 12:43 AM
|
#17 | |
|
Registered User
Join Date: Jun 2013
Location: Somewhere
Posts: 3,101
|
Re: Power Brake Help? New MC and Booster Install
Quote:
A good beginning would be to define the problem. |
|
|
|
|
|
08-11-2013, 11:58 AM
|
#18 | |
|
Senior Member
Join Date: Jul 2010
Location: South Dakota
Posts: 4,093
|
Re: Power Brake Help? New MC and Booster Install
Quote:
 .Posted via Mobile Device
__________________
1969 Chevy c20(Miss Hackjob) |
|
|
|
|
|
08-12-2013, 10:02 AM
|
#19 |
|
Registered User
Join Date: May 2013
Location: Catawba Island, OH
Posts: 203
|
Re: Power Brake Help? New MC and Booster Install
Sorry...hard to describe the problem as it was pretty much everything.
Also, I had to tackle my brakes as time on the weekends and funds were available. And I've learned a LOT in the process with everyone here's guidance. Thanks again. My front brakes were okay and I had the Wheel Cylinders replaced when I had some front end work done that was beyond my tools and capability. (new power steering box, linkage, and some other from suspension stuff) After that, I had the funds and time to swap out my (leaking) original Manual MC for a new one with a Booster. Here's where I get stewpid as I thought that would get my wheels gripping the road like never before. Or was it a combination of stwepid and lazy...or more so fear... I had never pulled hubs off a FF Axle before and was a bit intimidated by it. Turns out, so was everyone else that ever owned this truck as the brake pads were GONE! Down to the metal, as in NO PAD AT ALL! Geesh! Guess I should'a went there first. With 20+? years of no maintenance on the rear brakes, I conscripted my Dad in on it and we basically rebuilt the back brakes with new Pads, Adjusters, and Springs throughout. And Wow! What a difference I have now! The MC and Booster that I have are for front Disc, but I was told it would run Drum/Drum also. I thought about that for a while and went with that as I may convert to Disc/Drum if I decide to keep the truck around for a long time or not. Would this be a bad set up with Drum/Drum? I wouldn't know, but I am happy with my braking now. And my booster makes it no effort at all to push on the pedal. I was concerned that the MC only had about 1" of travel on the Piston, but have been told that to be about right. I also learned about the valve in the distribution block that kept me from bleeding the rear brakes until I had sufficient pressure in it to "re-center" it? Didn't even know that thing existed? So this whole thing has been a learning curve, but with everyone's help and a few weekends, I think I have a Grasp (pun intended) on my Braking! Cheers! And thanks for the input/help/advice/nudge in the right direction. Posted via Mobile Device |
|
|
|
|
08-12-2013, 11:22 AM
|
#20 |
|
Registered User
Join Date: May 2013
Location: WEST PALM FLORIDA
Posts: 1,174
|
Re: Power Brake Help? New MC and Booster Install
I had a very dificult time with brakes recently also , replaced almost everything , almost , dont forget that rubber hose in the back the goes from the hard line on the pasengers side frame to the y block on the rear end , its about 12 bucks , and they brake down with age . It was a problem for me , replaced it,,,, and bingo killer brakes
|
|
|
|
|
| Bookmarks |
|
|
Linear Mode
