Brake line question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Frozen1010 · 11-20-2010, 10:38 PM

I am working on redoing my brake lines, and I want to make sure I hook them up correctly at the master cylinder. The PO stated that the brakes were "soft" the last time he used them, and thought they needed to be bled because he recently has work done on them. When I tried them before I purchased the 'burb, the lines blew out about the middle of the truck. Looking underneath they were rusted bad, but it has looked as if portions were replaced at some point. So any way I decided to just replace them all. I got a replacement kit form LMC truck, supposedly pre bent, well the are mostly correct, but I have to do some adjusting. I have started with the front, and I am now wondering if they were correctly hooked up at the master cylinder. In the photos below the line still connected goes to the rear brakes. Is this correct? The fronts were connected to the bottom right port on what I believe is the proportioning valve.

babyJay · 11-21-2010, 02:22 AM

I've never seen a setup like that. Usually the prop valve is mounted on the front crossmember below the radiator, and there are usually 2 lines leaving it.

babyJay · 11-21-2010, 02:35 AM

I'll try to get some pics to help you out tomorrow, unless someone else can chime in. IIRC the larger of the two lines goes to the front brakes leaving the prop valve.

Frozen1010 · 11-21-2010, 07:46 AM

It has RWAL. The black box is the control module. the AL block may not be the proportioning valve just guessing. My service manual does not show any pictures of the setup, only a simple block diagram.

Frozen1010 · 11-21-2010, 08:52 AM

Found this doing some more searching on the web.

The further out view shows the front lines to be connected to the tube coming off the bottom of the AL block (Combination Valve). The close up view (View B) it looks opposite. All I need to know is which one goes to the T fitting down by the radiator.

Big Port Jimmy 6 · 11-21-2010, 09:51 AM

Quote:

Originally Posted by babyJay

I'll try to get some pics to help you out tomorrow, unless someone else can chime in. IIRC the larger of the two lines goes to the front brakes leaving the prop valve.

Nope the rear line is larger. They are 1/4 inch, as they go to drum brakes, and need more volume. The fronts are 3/16 as disc need more pressure versus volume. Jay

Frozen1010 · 11-21-2010, 10:26 AM

Thanks. The last thing I want to do is have them flipped. The current set up has the larger on the rear breaks, and goes to the AL block closer to the Break Booster/Master cylinder. Seems like they were hooked up correctly.

11-20-2010, 10:38 PM	#1
Frozen1010 Registered User Join Date: Nov 2010 Location: Rome,NY Posts: 32	Brake line question I am working on redoing my brake lines, and I want to make sure I hook them up correctly at the master cylinder. The PO stated that the brakes were "soft" the last time he used them, and thought they needed to be bled because he recently has work done on them. When I tried them before I purchased the 'burb, the lines blew out about the middle of the truck. Looking underneath they were rusted bad, but it has looked as if portions were replaced at some point. So any way I decided to just replace them all. I got a replacement kit form LMC truck, supposedly pre bent, well the are mostly correct, but I have to do some adjusting. I have started with the front, and I am now wondering if they were correctly hooked up at the master cylinder. In the photos below the line still connected goes to the rear brakes. Is this correct? The fronts were connected to the bottom right port on what I believe is the proportioning valve.

11-21-2010, 02:22 AM	#2
babyJay Arrived on a Pale Horse Join Date: Mar 2007 Location: SnagTown Indiana Posts: 2,524	Re: Brake line question I've never seen a setup like that. Usually the prop valve is mounted on the front crossmember below the radiator, and there are usually 2 lines leaving it. __________________ Jason 87 V30 350TBI/400 White w/Boss V-plow 89 R3500 CC SRW Last edited by babyJay; 11-21-2010 at 02:22 AM.

11-21-2010, 02:35 AM	#3
babyJay Arrived on a Pale Horse Join Date: Mar 2007 Location: SnagTown Indiana Posts: 2,524	Re: Brake line question I'll try to get some pics to help you out tomorrow, unless someone else can chime in. IIRC the larger of the two lines goes to the front brakes leaving the prop valve. __________________ Jason 87 V30 350TBI/400 White w/Boss V-plow 89 R3500 CC SRW

11-21-2010, 07:46 AM	#4
Frozen1010 Registered User Join Date: Nov 2010 Location: Rome,NY Posts: 32	Re: Brake line question It has RWAL. The black box is the control module. the AL block may not be the proportioning valve just guessing. My service manual does not show any pictures of the setup, only a simple block diagram.

11-21-2010, 08:52 AM	#5
Frozen1010 Registered User Join Date: Nov 2010 Location: Rome,NY Posts: 32	Re: Brake line question Found this doing some more searching on the web. The further out view shows the front lines to be connected to the tube coming off the bottom of the AL block (Combination Valve). The close up view (View B) it looks opposite. All I need to know is which one goes to the T fitting down by the radiator. Last edited by Frozen1010; 11-21-2010 at 09:07 AM.

11-21-2010, 10:26 AM	#7
Frozen1010 Registered User Join Date: Nov 2010 Location: Rome,NY Posts: 32	Re: Brake line question Thanks. The last thing I want to do is have them flipped. The current set up has the larger on the rear breaks, and goes to the AL block closer to the Break Booster/Master cylinder. Seems like they were hooked up correctly.



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