Prop valve line routing - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Eagar1 · 09-29-2009, 11:41 PM

Getting ready to mount my brake booster/mastcyl/propvalve, thought I knew how it should be routed then I came across this picture, on a 70's truck that looks like the same mast cylinder I have, and a similar valve. The routing in the picture looks backwards to me. I have a valve off a 75 C10 that was disc/drum. It is just like the diagram shown. Also wondering what the difference is if I plug the top front hole of the prop valve for the front brake(right front) and just T off the lower one(left front) instead of running two seperate lines? Also is there any reason why I couldn't run the rear brake line down the driver's side? Seems odd to run it over the front crossmember for no reason.

markeb01 · 09-30-2009, 12:18 AM

I used a 1975 crossmember, suspension, brakes, etc. in my 1960 GMC. The routing on my proportioning valve is exactly like that shown in the diagram. I think the routing in the photo is actualy similar, other than the valve appears to be mounted backward, with the front side of the master cylinder connecting to the rear port on the valve. There were at least 3 styles of proportioning valves. The original (perhaps 1968?) was a small cylinder style. The 2nd design looked like the photo, and later the solid machined block type. You can certainly run the line down the driver side if you prefer, the braking system doesn't care. You can also mount the valve remotely if you prefer to clean up the booster area. It makes it easier to change spark plugs and looks better. Mine is mounted on the crossmember under the oil pan behind the motor mount, which allows for nice looking lines in the engine compartment:

Eagar1 · 10-01-2009, 09:45 PM

Nice set up Mark, think I will do something similar, I will post pics once I figure it out.

LostMy65 · 01-20-2012, 09:52 PM

I know this is an old thread, and there are numerous duplicate threads asking brake line routing, but this one had a pic a the combination valve identifying what went where.
Thanks.

Here is the pic from LMC that might also help others:

LostMy65 · 01-20-2012, 09:56 PM

related question:
why is there a separate connection for left and right front brakes?

Rich 5150 69 · 01-20-2012, 11:12 PM

I believe there is a metering valve in the end of the block to control the bias between front left/right.

http://www.mpbrakes.com/technical-su...igurations.cfm good info here.

09-29-2009, 11:41 PM	#1
Eagar1 Registered User Join Date: Sep 2006 Location: Las Vegas, NV Posts: 169	Prop valve line routing Getting ready to mount my brake booster/mastcyl/propvalve, thought I knew how it should be routed then I came across this picture, on a 70's truck that looks like the same mast cylinder I have, and a similar valve. The routing in the picture looks backwards to me. I have a valve off a 75 C10 that was disc/drum. It is just like the diagram shown. Also wondering what the difference is if I plug the top front hole of the prop valve for the front brake(right front) and just T off the lower one(left front) instead of running two seperate lines? Also is there any reason why I couldn't run the rear brake line down the driver's side? Seems odd to run it over the front crossmember for no reason. Attached Images

09-30-2009, 12:18 AM	#2
markeb01 Senior Enthusiast Join Date: Feb 2007 Location: Spokane Valley, WA Posts: 8,356	Re: Prop valve line routing I used a 1975 crossmember, suspension, brakes, etc. in my 1960 GMC. The routing on my proportioning valve is exactly like that shown in the diagram. I think the routing in the photo is actualy similar, other than the valve appears to be mounted backward, with the front side of the master cylinder connecting to the rear port on the valve. There were at least 3 styles of proportioning valves. The original (perhaps 1968?) was a small cylinder style. The 2nd design looked like the photo, and later the solid machined block type. You can certainly run the line down the driver side if you prefer, the braking system doesn't care. You can also mount the valve remotely if you prefer to clean up the booster area. It makes it easier to change spark plugs and looks better. Mine is mounted on the crossmember under the oil pan behind the motor mount, which allows for nice looking lines in the engine compartment:

10-01-2009, 09:45 PM	#3
Eagar1 Registered User Join Date: Sep 2006 Location: Las Vegas, NV Posts: 169	Re: Prop valve line routing Nice set up Mark, think I will do something similar, I will post pics once I figure it out.

01-20-2012, 09:52 PM	#4
LostMy65 But Found Her 25yrs Later! Join Date: Oct 2010 Location: Oregon City, Oregon Posts: 10,530	Re: Prop valve line routing I know this is an old thread, and there are numerous duplicate threads asking brake line routing, but this one had a pic a the combination valve identifying what went where. Thanks. Here is the pic from LMC that might also help others: __________________ I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035

01-20-2012, 09:56 PM	#5
LostMy65 But Found Her 25yrs Later! Join Date: Oct 2010 Location: Oregon City, Oregon Posts: 10,530	Re: Prop valve line routing related question: why is there a separate connection for left and right front brakes? __________________ I lost my 65 - Found it 25 years later: http://67-72chevytrucks.com/vboard/s...d.php?t=426650 66 C20 Service Truck: http://67-72chevytrucks.com/vboard/s...d.php?t=428035

01-20-2012, 11:12 PM	#6
Rich 5150 69 Registered User Join Date: Nov 2009 Location: Galt, Calif Posts: 2,437	Re: Prop valve line routing I believe there is a metering valve in the end of the block to control the bias between front left/right. http://www.mpbrakes.com/technical-su...igurations.cfm good info here. __________________ `64 C10 vortec 350/350/373 posi `69 RS/SS 350/350/308 `37 Ford 406/350/324 traclock `68 Dart 370/904/323 suregrip Last edited by Rich 5150 69; 01-20-2012 at 11:22 PM.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.