proportioning valve question for disk conv - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SS68 · 03-14-2009, 06:20 PM

i have a 70 c10 i bought a performance online disk brake conversion kit and a booster and mastercylinder from autozone to save some money. i bought both a proportioning valve made for disk conversions, and a adjustable valve for the rear lines. problem im having is the proportioning valve i bought haves 5 holes for lines to go in. but i only have 4 lines to plug into it. i pulled this picture from the faqs ive been reading to answer my problem and noticed this small piece on top that i dont have. any help on this? thanks

tcb-1 · 03-14-2009, 06:31 PM

on some of the aftermarket prop valves (talking CPP part# PV-1), you will have 2 line connections for the front. you will only use 1 of those. you will need to plug the one you are pointing to in the picture above.

SS68 · 03-14-2009, 06:35 PM

thank you sir, that was my first tought but wanted to make sure, will i be fine if i only run the proportioning valve w/o the adjustable one for the rear brakes?

tcb-1 · 03-14-2009, 06:45 PM

I don't have an adjustable valve on my rears. I never had a problem, but many people will tell you it makes the system much better.

SS68 · 03-14-2009, 06:48 PM

right on ill get these installed tomorrow and get the beast back on the road, thanks

spinning wheels · 03-14-2009, 06:59 PM

This is my set up on my '72 3/4 ton.....

Andy4639 · 03-14-2009, 10:21 PM

This is my 71 1/2 ton. The only time I have ever had a issue with the backs locking up is in a emergancy stop in the rain. On dry pavement they have never been a problem.

A.P. · 03-14-2009, 10:49 PM

Bleeder.

SS68 · 03-15-2009, 09:47 PM

one more question, on the bottom of the proportioning valve the line for the front brakes the fitting that goes in there is 1/8 and i can only fit a 1/8" line all the other lines are 1/4" is this the same on yall?

BLACK AND BLUE 67-72 · 03-15-2009, 10:56 PM

That line is 3/16" and the thing in your first pic is a bleeder screw.

spinning wheels · 03-15-2009, 11:21 PM

Quote:

Originally Posted by SS68

one more question, on the bottom of the proportioning valve the line for the front brakes the fitting that goes in there is 1/8 and i can only fit a 1/8" line all the other lines are 1/4" is this the same on yall?

Not sure what size the brake line has, it is a stock '72 3/4 ton. The proportioning valve is from CCP. They also sell refurbished stock proportioning valves, but they cost more than their inhouse brand.

Jim Osborne · 03-16-2009, 06:54 PM

I also have a question on this subject my truck came with 4 wheel drums . I changed it to 4 wheel disc will the orignal proportioning valve work.

cdowns · 03-16-2009, 07:22 PM

4wheel drums to 4wheel discs you need to change both the master cyl and the prop valve for proper operation

tcb-1 · 03-16-2009, 07:23 PM

Quote:

Originally Posted by Jim Osborne

I also have a question on this subject my truck came with 4 wheel drums . I changed it to 4 wheel disc will the orignal proportioning valve work.

no. you should go with a front disc/rear drum prop valve with an adjustable valve governing the rear. I don't think a specifc disc/disc valve is offered.

**lolife99** · 03-16-2009, 07:42 PM

Quote:

Originally Posted by SS68

one more question, on the bottom of the proportioning valve the line for the front brakes the fitting that goes in there is 1/8 and i can only fit a 1/8" line all the other lines are 1/4" is this the same on yall?

You need to buy a 3/16" male-to-1/4" female adapter to screw into the bottom of the porportioning valve. This will allow you to run a 1/4" line down to the "T" on the backside of the front crossmember.
I got mine at the local ACE Hardware store. They are specialty fittings. (Inverted flare adapters)

cdowns · 03-16-2009, 07:57 PM

all silverados made in the past 6-7years have 4wheel disc master cyl and proportioning valves thats what i'd be looking at to use for 4wheel disc brakes on a chevy truck

csfields · 01-07-2016, 09:11 PM

Quote:

Originally Posted by lolife99

You need to buy a 3/16" male-to-1/4" female adapter to screw into the bottom of the porportioning valve. This will allow you to run a 1/4" line down to the "T" on the backside of the front crossmember.
I got mine at the local ACE Hardware store. They are specialty fittings. (Inverted flare adapters)

Purchasing a POL proportioning valve for disc disc. The new one has 3/8-24 thread 3/16 inv for the front and 9/16-18 for the rear. I am running stock lines. Is the adapter mentioned above what I need to make this work?

Thanks for your help

davepl · 01-07-2016, 10:34 PM

Corvettes of the era offered a disc/disc master, I believe. I don't know what was used in the JL8 Camaros, but I assume the same unit. Parts-store cheap, either way.

Don't forget that on 3/4T the front is the rear line and vice versa, at least as I recall it was backwards from that 1/2 tons.

csfields · 01-07-2016, 10:42 PM

[QUOTE=davepl;7439153]Corvettes of the era offered a disc/disc master, I believe. I don't know what was used in the JL8 Camaros, but I assume the same unit. Parts-store cheap, either way.

Don't forget that on 3/4T the front is the rear line and vice versa, at least as I recall it was backwards from that 1/2 tons.[/QUOTE

It is a corvette style master cylinder with a pol proportion valve. Just want to make sure I have everything I need when I go to hook it up. Thanks.
Posted via Mobile Device

03-14-2009, 06:20 PM	#1
SS68 Registered User Join Date: Apr 2008 Location: Dallas, TX Posts: 126	proportioning valve question for disk conv i have a 70 c10 i bought a performance online disk brake conversion kit and a booster and mastercylinder from autozone to save some money. i bought both a proportioning valve made for disk conversions, and a adjustable valve for the rear lines. problem im having is the proportioning valve i bought haves 5 holes for lines to go in. but i only have 4 lines to plug into it. i pulled this picture from the faqs ive been reading to answer my problem and noticed this small piece on top that i dont have. any help on this? thanks Attached Images

03-14-2009, 06:31 PM	#2
tcb-1 Nothing to see here..... Join Date: Jun 2007 Location: Shawnee, KS Posts: 4,625	Re: proportioning valve question for disk conv on some of the aftermarket prop valves (talking CPP part# PV-1), you will have 2 line connections for the front. you will only use 1 of those. you will need to plug the one you are pointing to in the picture above. __________________ Doug THANK YOU to our American Soldiers & Veterans - POW MIA "You will NEVER be forgotten". The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. Thomas Jefferson

03-14-2009, 06:35 PM	#3
SS68 Registered User Join Date: Apr 2008 Location: Dallas, TX Posts: 126	Re: proportioning valve question for disk conv thank you sir, that was my first tought but wanted to make sure, will i be fine if i only run the proportioning valve w/o the adjustable one for the rear brakes?

03-14-2009, 06:45 PM	#4
tcb-1 Nothing to see here..... Join Date: Jun 2007 Location: Shawnee, KS Posts: 4,625	Re: proportioning valve question for disk conv I don't have an adjustable valve on my rears. I never had a problem, but many people will tell you it makes the system much better. __________________ Doug THANK YOU to our American Soldiers & Veterans - POW MIA "You will NEVER be forgotten". The democracy will cease to exist when you take away from those who are willing to work and give to those who would not. Thomas Jefferson

03-14-2009, 06:48 PM	#5
SS68 Registered User Join Date: Apr 2008 Location: Dallas, TX Posts: 126	Re: proportioning valve question for disk conv right on ill get these installed tomorrow and get the beast back on the road, thanks

03-14-2009, 06:59 PM	#6
spinning wheels Registered User Join Date: Sep 2001 Location: Hacienda Heights, California USA Posts: 474	Re: proportioning valve question for disk conv This is my set up on my '72 3/4 ton..... Attached Images __________________ '72 GMC custom camper 350/350

03-14-2009, 10:21 PM	#7
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: proportioning valve question for disk conv This is my 71 1/2 ton. The only time I have ever had a issue with the backs locking up is in a emergancy stop in the rain. On dry pavement they have never been a problem. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. Last edited by Andy4639; 03-14-2009 at 10:22 PM.

03-14-2009, 10:49 PM	#8
A.P. Black 72 Chevy Join Date: May 2002 Location: Los Angeles, California Posts: 662	Re: proportioning valve question for disk conv Bleeder. __________________ 72 Chevy, SWB, 350engine, TH400

03-15-2009, 09:47 PM	#9
SS68 Registered User Join Date: Apr 2008 Location: Dallas, TX Posts: 126	Re: proportioning valve question for disk conv one more question, on the bottom of the proportioning valve the line for the front brakes the fitting that goes in there is 1/8 and i can only fit a 1/8" line all the other lines are 1/4" is this the same on yall? Attached Images

03-15-2009, 10:56 PM	#10
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: proportioning valve question for disk conv That line is 3/16" and the thing in your first pic is a bleeder screw. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

03-16-2009, 06:54 PM	#12
Jim Osborne Registered User Join Date: Feb 2009 Location: Crumpler, North Carolina Posts: 93	Re: proportioning valve question for disk conv I also have a question on this subject my truck came with 4 wheel drums . I changed it to 4 wheel disc will the orignal proportioning valve work.

03-16-2009, 07:22 PM	#13
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: proportioning valve question for disk conv 4wheel drums to 4wheel discs you need to change both the master cyl and the prop valve for proper operation __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

03-16-2009, 07:57 PM	#16
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: proportioning valve question for disk conv all silverados made in the past 6-7years have 4wheel disc master cyl and proportioning valves thats what i'd be looking at to use for 4wheel disc brakes on a chevy truck __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

01-07-2016, 10:34 PM	#18
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: proportioning valve question for disk conv Corvettes of the era offered a disc/disc master, I believe. I don't know what was used in the JL8 Camaros, but I assume the same unit. Parts-store cheap, either way. Don't forget that on 3/4T the front is the rear line and vice versa, at least as I recall it was backwards from that 1/2 tons. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

01-07-2016, 10:42 PM	#19
csfields Registered User Join Date: Mar 2011 Location: Elizabethtown, Kentucky Posts: 322	[QUOTE=davepl;7439153]Corvettes of the era offered a disc/disc master, I believe. I don't know what was used in the JL8 Camaros, but I assume the same unit. Parts-store cheap, either way. Don't forget that on 3/4T the front is the rear line and vice versa, at least as I recall it was backwards from that 1/2 tons.[/QUOTE It is a corvette style master cylinder with a pol proportion valve. Just want to make sure I have everything I need when I go to hook it up. Thanks. Posted via Mobile Device



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