Pro portioning valve

[Edemich]

Alright so I have an 85 4x4 with a rear end off a 2001 2500 HD.   The rear has disc brakes.  So my question is, do I need to remove the combination valve that's mounted to the front frame crossmember and replace it with a proportion valve that does disc/disc where it previously had disc/drum. 

Also, where is the best place to purchase brake lines, bending kits, and flaring tools?

[Irish_Alley]

you dont "need" to replace the proportioning valve. but disk use 90 psi and drums use 40psi. so if dont replace it then you will only be getting half the pressure to the rear brakes, they will still work but not well

[Edemich]

Ok so I have the replacement I am pretty sure.  Will there be a problem with my stock master cylinder?

I will plan on rerunning all the front brake lines and the line to the rear as well.  Completely bypassing the stock combination valve on the frame cross member.  Yeah...... Think I knew the answer to my question and wanted someone to confirm it.   

Know a good place to buy a bender, lines and a flaring tool?

[Irish_Alley]

they do have adjustable ones for sale on Summit
benders and flaring tools can be rented from autozone. but i would op for one that cost more than $10
and parts stores sell rolls of brake lines think its 25'
but i will tell you this you dont want too much pressure on the rear or they will lock up real easy. i cant tell you how much to have, maybe someone else on here can

[Captkaos]

I am replacing my master cylinder with a one from a disc/disc car and buying a prop valve for a disc disc setup. Or buying the adjustable one.

Vile told me that a 2000 master will work just need the adapter fitting as later model used the same size lines.

Most people use a 80's Vette MC.

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

[Edemich]

Thanks guys.  The proportioning valve I have is the GM 172-1361 from classic performance. It is for a disc disc setup. I have no idea if it's adjustable.  I have to replumb the front brakes for it anyways so I might as well do them all.  I won't know if my master will work or not until I get the truck running again as there is no wiring or engine in the truck currently.

[Captkaos]

Your current master will work, but I would change it.  CPP had a prop valve that would bolt in I thought.  MP Brakes did.