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Old 03-14-2009, 06:20 PM   #1
SS68
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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
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Old 03-14-2009, 06:31 PM   #2
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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.
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Old 03-14-2009, 06:35 PM   #3
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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?
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Old 03-14-2009, 06:45 PM   #4
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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.
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Old 03-14-2009, 06:48 PM   #5
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Re: proportioning valve question for disk conv

right on ill get these installed tomorrow and get the beast back on the road, thanks
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Old 03-14-2009, 06:59 PM   #6
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Re: proportioning valve question for disk conv

This is my set up on my '72 3/4 ton.....
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Old 03-14-2009, 10:21 PM   #7
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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.

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Old 03-14-2009, 10:49 PM   #8
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Re: proportioning valve question for disk conv

Bleeder.
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Old 03-15-2009, 09:47 PM   #9
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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?
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Old 03-15-2009, 10:56 PM   #10
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Wink Re: proportioning valve question for disk conv

That line is 3/16" and the thing in your first pic is a bleeder screw.
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Old 03-15-2009, 11:21 PM   #11
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Re: proportioning valve question for disk conv

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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.
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Old 03-16-2009, 06:54 PM   #12
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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.
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Old 03-16-2009, 07:22 PM   #13
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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
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Old 03-16-2009, 07:23 PM   #14
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Re: proportioning valve question for disk conv

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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.
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Old 03-16-2009, 07:42 PM   #15
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Re: proportioning valve question for disk conv

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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)
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Old 03-16-2009, 07:57 PM   #16
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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
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Old 01-07-2016, 09:11 PM   #17
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Re: proportioning valve question for disk conv

Quote:
Originally Posted by lolife99 View Post
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
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Old 01-07-2016, 10:34 PM   #18
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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.
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Old 01-07-2016, 10:42 PM   #19
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[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.
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