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

theyammieguy · 01-16-2009, 05:33 PM

I did a quick search and found this thread on the correct proportioning valve so Im assuming I have the wrong one.

I have a 68 with front disc and rear drums and my question is, is this the right proportioning valve? If not which years will work? Im headed to the junk yard tomorrow.

Here's the thread I found with I think is the right valve.
http://67-72chevytrucks.com/vboard/s...d.php?t=241722

Here's the one I have.

**john** · 01-16-2009, 05:47 PM

What you have is a distribution block used on drum brake trucks. Pre 1971. The prop valves shown in your link are the right ones.

theyammieguy · 01-16-2009, 05:48 PM

Quote:

Originally Posted by john

What you have is a distribution block used on drum brake trucks. Pre 1971.

Right on, thanks man. Can I use any year prop valve or does it have to be a specific year?

airdale94 · 01-16-2009, 09:08 PM

The link is corect for front disc with power assist. Since you don't have power the one you have may be the corect one. Notice how your front lines are as big as your rears. Do you know if they are factory disc no power? This was just covered on thread not long ago. And I don't know for sure.

theyammieguy · 01-17-2009, 03:29 PM

Quote:

Originally Posted by airdale94

The link is corect for front disc with power assist. Since you don't have power the one you have may be the corect one. Notice how your front lines are as big as your rears. Do you know if they are factory disc no power? This was just covered on thread not long ago. And I don't know for sure.

Mine is a 68 so it didnt come with disc.

texanidiot25 · 01-17-2009, 02:12 AM

If your truck originally had manual brakes, and you didn't swap the MC and p-valve, then technically no, it's not setup right. Yes it will work, but not to it's full potential. Disk brake MC's have a bigger front brake reservoir and flow more fluid to the front disk, since of course their cylinder takes more volume to push the brakes than the rear drums.

theyammieguy · 01-17-2009, 03:31 PM

Quote:

Originally Posted by texanidiot25

If your truck originally had manual brakes, and you didn't swap the MC and p-valve, then technically no, it's not setup right. Yes it will work, but not to it's full potential. Disk brake MC's have a bigger front brake reservoir and flow more fluid to the front disk, since of course their cylinder takes more volume to push the brakes than the rear drums.

I didnt do the disc conversion and Im willing to bet that is the original mc.

cdowns · 01-17-2009, 04:12 PM

easiest is probally go with a 71 or 72 master cylinder combination valve and prebent brake lines//having the 2different sizes of brake lines is very important for proper operation

theyammieguy · 01-17-2009, 05:06 PM

Quote:

Originally Posted by cdowns

easiest is probally go with a 71 or 72 master cylinder combination valve and prebent brake lines//having the 2different sizes of brake lines is very important for proper operation

Thats what I was thinking.
Guess I need to try and locate one.

01-16-2009, 05:33 PM	#1
theyammieguy accepting donations Join Date: Oct 2008 Location: houston tx Posts: 521	proportioning valve question I did a quick search and found this thread on the correct proportioning valve so Im assuming I have the wrong one. I have a 68 with front disc and rear drums and my question is, is this the right proportioning valve? If not which years will work? Im headed to the junk yard tomorrow. Here's the thread I found with I think is the right valve. http://67-72chevytrucks.com/vboard/s...d.php?t=241722 Here's the one I have. __________________ 1999 Yamaha roadstar 1600 chop. (in progress.) See my builds here>http://s113.photobucket.com/albums/n238/nickrp_2006/ "Ya'll can go to hell, I'm going to Texas." David Crockett

01-16-2009, 05:47 PM	#2
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	Re: proportioning valve question What you have is a distribution block used on drum brake trucks. Pre 1971. The prop valves shown in your link are the right ones. __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/ Last edited by john; 01-16-2009 at 05:49 PM.

01-16-2009, 09:08 PM	#4
airdale94 Registered User Join Date: Jan 2007 Location: Topeka,KS Posts: 778	Re: proportioning valve question The link is corect for front disc with power assist. Since you don't have power the one you have may be the corect one. Notice how your front lines are as big as your rears. Do you know if they are factory disc no power? This was just covered on thread not long ago. And I don't know for sure. Last edited by airdale94; 01-16-2009 at 09:09 PM. Reason: add

01-17-2009, 02:12 AM	#6
texanidiot25 Eat My Rust Join Date: Jan 2007 Location: Cypress, Texas Posts: 3,362	Re: proportioning valve question If your truck originally had manual brakes, and you didn't swap the MC and p-valve, then technically no, it's not setup right. Yes it will work, but not to it's full potential. Disk brake MC's have a bigger front brake reservoir and flow more fluid to the front disk, since of course their cylinder takes more volume to push the brakes than the rear drums.

01-17-2009, 04:12 PM	#8
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: proportioning valve question easiest is probally go with a 71 or 72 master cylinder combination valve and prebent brake lines//having the 2different sizes of brake lines is very important 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

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