Brake line question....

[Moody]

I need to order new brake lines for my blazer and I need to know is there a difference between 1/2 ton and 3/4 line size? I did a four wheel disc swap and have the 3/4 ton m/c vacuum booster. The front should be easier as I will just order the proportioning valve and hard lines to the frame for that application (3/4 ton, 72 ). I would like to order the rest of the lines for the frame and to the rear but am not quite sure which application to order since they never made a 3/4 ton blazer or short bed truck that I am aware of. I called inline tube and told them what I was doing and they seemed totally confused as to what I was doing. I know several people here have done this upgrade using inline tube....any suggestions? I did a search but just found info regarding booster upgrade and m/c, no info for the rear. My rear axle is a HO52 and I saved the hard line on the rear axle I will just need to bend it or add flexible stainless lines to route it to the new brake caliper location.

 

[bp71k5]

I upgraded to 4wheel disc and kept the 1/2 lines. No issues.

If you are getting a new prop valve anyway, just get their 4-wheel disc valve so you don't have to add an adjustable one.

 

[Moody]

Are you still running a 12 bolt rear or a 14 bolt? The reason I ask is because my rear calipers are 3/4 ton and I wasn't sure if the 1/2 ton fittings are the same size.

 

[bp71k5]

I'm running a 14bolt in the rear. I just tested them yesterday. The rear disc brake calipers are the same as the calipers on the 1/2 ton front. Since the front brakes already have enough volume to keep pressure on the smaller front lines so the rear should be fine too.

 

[Moody]

Great! I'll go ahead and order them up!

 

[Burt4x4]

I have been thinking about replacing my P-Valve.

Hyjack On!

What is the reason the P-valve should be changed when you have 4wheel disk brakes?
I am still running the stock P-valve and I have 14FFdisk in the rear. Sometimes when I hold the brakes for a period of time I hear a wine or hydrolic noise?? If I hit the brakes hard they work...

Hyjack Off!
Burt

 

[bp71k5]

The idea with the prop valve is that front discs do much more of the stopping than the rear drums. When you switch to discs in the rear, the rear tends to lockup before the front in hard braking situations. If that happens it can cause a loss of control if your on a turn.

The 4wheel disc valve reduces the hydraulic pressure to the rear to allow the front discs to lockup right before the rears so theoretically all four wheels are sharing the work.

I know lots of people say the results are very different. Some people need the new valve and some people seem to be fine without it. I put one on and things seem to work fine although I haven't locked up the brakes.

 

[bigblock72]

Disc brakes require a lot more hydraulic pressure then drum brake do. To get the most out of your disc brake swap you need to install an adjustable proportioning valve.

I really don't like the nonadjustable direct replacement combination valves because they really aren't optimized, every one of our Blazers is set up differently not only with brakes but tires, weight placement etc. A one size fits all aproach really isn't going to get it done here. I usually order up the adjustable prop valves from Summit for about 40 bucks. I'll then gut the stock combination valve so it's just a distribution block with a warning light. Cut the line to the rear brakes, install fittings, double flare and install.

In most cases the improvement in braking is night and day, especially off road. Just make sure to adjust the rear brake pressure to where the rear brakes aren't going to lock up in a panic situation at 60 mph.