72 4x4 disc Brake help.

[donelan07]

I only had a front right brake catching and it pulled badly to the right. So I put new calipers on my disc and new brake pads. I bled the line and no luck. So I put a new master cylinder in and still no luck. Does the proportioning valve have to be hooked up correctly even if the rear brakes aren't working and there is a hole in the line?



Hole in the line.

My pickup

[glock35ipsc]

Are you driving and trying to diagnose a brake problem with a broken rear hard line? I think I would fix the obvious problem first, the broken line, then worry about it pulling to the right.

[donelan07]

No the truck isn't being driven. When I drove it home I noticed the brake pulling so I thought I would fix it before driving anymore but I can't seem to get the calipers to close down. Is there any way to see if the brake booster is bad?

[glock35ipsc]

I'm a little confused by the pics your prop valve. Both the front and rear brake lines should be coming out of the prop valve, and both ports of the MC should go to the prop valve.

Edit - I just went and looked at my 72. There is only one line coming out of the prop valve for the front. It runs to the frame, then tee's off to each front caliper. So if one side of grabbing and not the other, and you have already replaced both calipers, then you probably have a blocked/plugged hard line after the tee.

Since the prop valve's job is to divvy up fluid to the front and rear appropriately, the rears should to be hooked up correctly to the prop valve and the broken line repaired to properly diagnose everything.

[glock35ipsc]

Here is a pic of the MC/PV on my 72. It's missing the short line from the front port of the MC to the prop valve, but the rest is correct.

[sandking]

First of all, you need to have the rear brake line connected, you will lose all pressure there.
You prop valve should have two lines coming in and two lines coming out. The fron leaves the prop then to a tee on by the steering box then to each side from there. Then the rear runs along the inside of the passenger side frame rail to a tee before the rear axle then to each drum from there.

[Blazer1970]

I would bet that your problem with the front brakes is that one of the hoses is swollen shut inside.

[donelan07]

Would inline tubes 10pc kit for disc brake lines for my 1972 short box be the way to go since I have a broken line and everything is so rusty I cant brake it loose?

[GruntMoanCough]

I would suggest replacing all of your brake lines and connecting them correctly, then carry on from there.

[sandking]

Originally Posted by GruntMoanCough

I would suggest replacing all of your brake lines and connecting them correctly, then carry on from there.

Without a doubt, this is much needed on this truck.

[Classic Heartbeat]

I know exactly what your problem is. Someone has plummed one side of the front brakes through the proportioning valve and the other from the rear brake side of the master cylinder. This is all wrong!!!! They probably did that because it may have bad brakes on the rear, or mabe bad brake lines. I would hasard a guess that you will need all new brake lines and the proportioning valve to solve the problem. (Maybe new shoes and drums on the rear also) WES

[americanmusc1e]

Originally Posted by Classic Heartbeat

I know exactly what your problem is. Someone has plummed one side of the front brakes through the proportioning valve and the other from the rear brake side of the master cylinder. This is all wrong!!!! They probably did that because it may have bad brakes on the rear, or mabe bad brake lines. I would hasard a guess that you will need all new brake lines and the proportioning valve to solve the problem. (Maybe new shoes and drums on the rear also) WES

ya, I agree something dosen't look right there, both lines coming off the master cylinder should go into the prop valve. and one line should come out and go to a tee for the front brakes, and one should come out and go the the back brakes...............also, seriously consider replacing all rubber brake lines, they will cause pulling too.

if you need a picture of the way the master cyl and prop valve should look, let me know.

hope this helps

[gerfunken]

I agree with the rubber lines.... right before my rt front split the truck was tugging to the left. Might be that they're starting to expand a little bit, and can only encourage you to replace them before they go.

Another thought, I've seen symptoms of this (not sure how bad it's pulling to one side) when the ball joints go out. 4x4's are harder than anything to check, but when you apply stopping pressure, it would torque the bottom ball joint back, and with how the steering geometry is set up, it would change the right front tire to "toe out", and may cause it to dart that way as well.

[RustyParts]

Your calipers are on the wrong side, bleeder valve should be on top.

[glock35ipsc]

Doh, I never noticed that!!

[sandking]

Originally Posted by RustyParts

Your calipers are on the wrong side, bleeder valve should be on top.

Good call!! I did not notice that before.

[Classic Heartbeat]

I missed that one too..lol It wouldn't cause the pulling while braking though. I stand by my diagnosis. You can't have one brake line running through the proportioning valve and the other not. The fluid in the rear resivour (unless it is empty) has to be going somewhere. It definately isn't being lost out of the broken line, or you would see fluid all over the rear end. So that tells me that the line from the mastercylinder is not connected to it. (Again unless the rear resivour is empty) I think that he has the two lines plummed one to each caliper. WES

[donelan07]

I have the master cylinder set up right but I need to replace some broken lines. Everything is so rusty it doesn't want to come apart.

So the calipers are on the wrong side?

My rear broken line and the hose that I can't break loose from the broken line.

[glock35ipsc]

The new line from the MC to the PV looks to be kinked in at least two places. I would have someone with a tubing bender twist one up for you, or buy the proper pre-bent tube.

I say replace them all right now. You don't want those rusty steel lines to fail when you need to hammer the brakes hard.

The calipers are still on the wrong sides too.

[sandking]

You really, really need to replace all of the brake lines in order to get this right. Broken and kinked lines will never work correctly and will sacrifice your safety.

[donelan07]

I planned on tearing the pickup all the way down to the frame anyways. Would you recommend inline tube for new lines?

[donelan07]

My work for the weekend.

[sandking]

Good call!!!

[glock35ipsc]

Nice!

[Beefcake]

i was just going to suggest that!! did wonders for me- plus, there right around the corner from me.