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#1 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Ok I did a disc brake upgrade to my 68 swb. I already had a power booster and now it feels like it isn't working. I used a 1975 Corvette style master cylinder and the truck stops ok but the pedal is hard. Any ideas?
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#2 |
Registered User
![]() Join Date: Dec 2012
Location: North Carolina
Posts: 4,989
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Re: New master and now no power brakes
How do you Upgrade to newer style Brakes ?
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1971 GMC Sierra 1959 GMC 100 |
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#3 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
Went from drum to disc...
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#4 |
Registered User
![]() Join Date: Dec 2012
Location: North Carolina
Posts: 4,989
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Re: New master and now no power brakes
Oh simple as that then
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1971 GMC Sierra 1959 GMC 100 |
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#5 |
Registered User
Join Date: Aug 2008
Location: Lantana, TX
Posts: 419
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Re: New master and now no power brakes
Just the front disks, upgraded? I'm guessing that you got a CPP master and prop valve combo for disk/drum or disk/disk, which ever you have? Bore size on the master, did you change the pushrod, bleed the brake system correctly?
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#6 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
I used a rebuilt 75 Corvette master with a 1" bore. Stock rebuilt booster that is workiń properly and I believe I bleed the system good. Nice firm pedal. Front disc upgrade only with new CPP disc/drum prop valve
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#7 |
Registered User
Join Date: Dec 2012
Location: Altoona Iowa
Posts: 481
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Re: New master and now no power brakes
Also since you had the booster already, did you look to make sure it didnt have fluid in it? I had to replace mine due to this. And another is poor vacuum pressure. Where are you porting the vacuum for the booster from?
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#8 | |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
Quote:
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#9 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
My concern was maybe I should of used the 1 1/8 inch bore master but I figured the smaller bore would cause higher pressure.
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#10 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
After reading this I'm thinking I may need to switch to the larger 1 1/8 bore
http://67-72chevytrucks.com/vboard/s...d.php?t=561809
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#11 |
Registered User
Join Date: Mar 2013
Location: Peachtree Corners, GA
Posts: 84
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Re: New master and now no power brakes
Did you properly bench bleed the master ? Not sure if that is a brand new (looks brand new from the pic). All the brand new master cylinder I get has a note saying to you have to bench bleed it or at least comes with 2 lines where you can bleed it in the car before installation of the hardlines.
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#12 | |
Registered User
Join Date: Aug 2008
Location: Lantana, TX
Posts: 419
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Re: New master and now no power brakes
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#13 | ||
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
Quote:
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Driving it to work this morning made me realize that I will get used to the firmer pedal and that there is like a half pedal that feels like power and then it hits a point where it feels like manual brakes. I was thinking that with the larger bore that there would be less stroke and maybe that would keep it in the power brake feel realm?
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#14 |
Registered User
![]() Join Date: Dec 2012
Location: Chandler AZ
Posts: 1,149
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Re: New master and now no power brakes
I have done drum to disc on the front of my C20. I have a prop valve that looks like the one on your truck. I am told that the lines have to be reversed to work.... Could this be the issue?
Have you called CPP? I am sure they have run into a question like this before. I have not hooked it up YET. That comes this weekend. I went back to the distribution valve for now and it feels spongy.
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1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9 |
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#15 | |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
|
Re: New master and now no power brakes
Quote:
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#16 |
67-72 parts collector,…
![]() Join Date: Nov 2002
Location: Mid-MO
Posts: 22,698
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Re: New master and now no power brakes
I would try a stock 71-72 M/C.
They have the 1-1/8" bore. http://www.oreillyauto.com/site/c/de...01292&pt=01292
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Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 |
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#17 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
Thanks Keith no actually got one of those yesterday
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#18 |
Proprietor of Dale's Corner
![]() Join Date: Nov 2012
Location: Vacaville , CA
Posts: 16,106
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Re: New master and now no power brakes
Shawn, after reading the link you posted, I think the larger bore is what you need. I think you're heading down the right path.
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"Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man |
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#19 |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
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Re: New master and now no power brakes
Well the silver lining in all of this is I will be able to pre paint the new master
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#20 | |
67-72 parts collector,…
![]() Join Date: Nov 2002
Location: Mid-MO
Posts: 22,698
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Re: New master and now no power brakes
Quote:
No painting that will eventually rust anyway. I painted my '69 M/C with cast look caliper paint,... but now it's starting to look like crap. (with almost no miles on the truck)
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Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 |
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#21 | |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
|
Re: New master and now no power brakes
Quote:
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#22 |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: New master and now no power brakes
I believe the discussion above regarding which line from the mc goes to which port on the prop valve is valid - but only for a 3/4 ton truck (pic of my 3/4 attached). Note rear mc res attaches to the front port of the prop valve and vice versa. You can see the 1/4 (rear) lines and figure out which ports/reservoirs feed the rear brakes and which other ones feed the fronts.
My inline tube purchase matched the old lines between mc and prop valve. BUT, your truck is a 1/2 ton - so my point is dispel the confusion between 1/2 and 3/4 ton. Your mc to prop valve lines are right for a 1/2 ton and the pic below is right for a 3/4 ton. Last edited by jocko; 04-02-2013 at 02:51 PM. |
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#23 |
Junior Member
Join Date: Mar 2007
Location: Hideaway, TX
Posts: 4,950
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Re: New master and now no power brakes
Yep, mine rusted before it was done at the shop. I have a aluminum one for my 72.
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71 Suburban 350/700R4 Project Trixie 72 CHEVY,Highlander,SWB,396,T400 |
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#24 | |
C/10 junkie
Join Date: Nov 2010
Location: Stockton Ca
Posts: 9,093
|
Re: New master and now no power brakes
Quote:
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Shawn 70 LWB C10 current driver/project http://67-72chevytrucks.com/vboard/s...d.php?t=663051 68 SWB C10 Work in progress.....SOLD http://67-72chevytrucks.com/vboard/s...d.php?t=559520 72 LWB C10 Sold 71 LWB C10 Sold 68 LWB C10 CST Sold http://youtu.be/kbB0QrBIs9k My mom always had the best advice. It was just a tad late. After a fall that involved blood, she'd say....."Careful!" ![]() |
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#25 |
Junior Member
Join Date: Mar 2007
Location: Hideaway, TX
Posts: 4,950
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Re: New master and now no power brakes
That is what I used and it still rusted.
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71 Suburban 350/700R4 Project Trixie 72 CHEVY,Highlander,SWB,396,T400 |
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