Bad day on brakes..........

[Hedgehog]

Today I thought it was the end or close to an end to my front axle swap to a front disk brake system.

The front is mechanically on.

New rotor, new rubber hoses, new master cylinder, new proportioning valve. The old lines were cut and flared, new lines were spliced in to the proportioning valve that is now up attached to the master cylinder.

Reay to go. The master was plumbed with short lines routing fluid back into the MS reservoirs. The master was "bench" bled in the vehicle. !!cool! The lines were attached to bleed the entire system. Working the slaver cylinders in the traditional way ....pump .... pump .... pumppumppumppump ... Nothin'!

So off to the store to get a vacuum bleeder. suck ... suck ... suck ... NOTHIN! And to add to the frustration now the pedal stroke is catching and not right.

........ Not a good day. Where to next?

 

[Bent]

It sounds like you did the research on the conversion, and you know what a vacuum bleeder is, so I assume you have the rear outlet on the MS going to the front brakes and the front going to the rear. It sounds like the proportioning valve is off set. Try opening all bleeders and stomping on the brake pedal. Then close all the bleeders try the vacuum bleeder again starting on the wheel furthest from the MS.

 

[Torxhead]

Hedge, I am going to agree with Bent on this one. As many posts I have read on replacing prop valves, your issue is not uncommon. I would suggest keep bleeding until you get a good pedal. Although Bent's suggestion about stomping on the pedal is one that I have not tried yet, not enough bleeder bottles I guess. I have been using just one of those plastic bleeder kits for my brake work.

 

[Lumpy Grits]

The p'valve has been trip'd.
Your gonna have to bleed the rear wheels to reset it.
LG

 

[Hedgehog]

Okay - Would bench bleeding it again open up the prop valve? At this point I have no fluid moving anywhere. Frustrated doesn't even begin to cover how I'm feeling right now.

 

[Hedgehog]

another bench bleed of the MS/proportioning valve showed that ALL lines were squirting. Then I tried using the manual vacuum bleed pump on the right rear. Nothing. Then had a helper help me with traditional bleeding. Nothing. Then tried combining the two using vacuum AND traditional bleeding. Nothing, well I did get a little fluid to come through. Then I tried the open ALL valves and slam on the brakes a few times and back to bleeding. Nothing. Now I'm trying to see if there is a vacuum bleeder that uses an electric pump for continuous vacuum. Errrrrrrrr! By-the-way, I appreciate all your help. I'm not inexperienced at this sort of thing, I've done several MS swaps, caliper swaps, mostly motorcycle brake line swaps with little trouble, this is different.

 

[Lumpy Grits]

Have you tried a pressure bleed? You can make one yourownself from a spare lid off the MC and 2 tire valve stems.
What did you do to get them all to 'squirt'?
FWIW: I have never had much luck with a vacuum bleeder. I have seen vacuum bleeders 'trip' a p'valve because of psi drop in the brake line.
LG

 

[mriplaybass]

Don't known if you tried this yet. You say that all lines are squirting. With a helper, pump the pedal several times, then hold it down. Then instead of opening the bleeders, loosen the brake lines at the wheel cylinder/caliper. If the bleeders are plugged, fluid can still escape via the loose connection. If this doesn't produce results,you may want to try the same procedure at the proportioning valve.

 

[Hedgehog]

How did I get them to squirt. I made up short brake lines that terminated back in the MS reservoir, I.E. a bench bleed.

I have considered making up a bottle to fill the brake lines and slave cylinders with fluid. Is it possible to fill the lines, then do a conventional bleed?

I am becoming more and more convinced that the problem is in the proportioning valve.

 

[Lumpy Grits]

Why don't you put the old p'valve back in and try it. Are the line fittings the same??
Then you'll know for sure.
You may well be 'rite' about the p'value be'n the issue here.......
Who made this valve?
LG

 

[hdgapeach]

Hey Hedge,

Don't know what your p-valve looks like but, if it has the provision for the screw in tool on top (like a Ford p-valve), obtain one of those and install it while you bleed the brakes. The pin on the end of the tool holds the p-valve safety plunger in place and keeps it from tripping. Once all 4 brakes are bled, you just remove the tool from the p-valve and seal it back up with the screw in cap. The one I got is made of a type of plastic and cost me a whole dollar! Best dollar I've ever spent on a tool. I was at wits end trying to do the exact process you're fighting, 'cept mine was on my '77 Ford truck.

 

[jammer1]

I've had it happen where the vacuum bleeder wouldn't work till I had brake fluid run through the line. I usually start the bleeding by loosening the pass rear bleed screw (with M/C cover off) and let it gravity bleed. In bad cases I've had to walk away and come back 40 min or more (just make sure the m/c doesn't run dry). Once I get it to flow, then the vacuum gauge does a good job. I've done like you and pumped the handle like hell and couldn't get it to flow.

 

[Hedgehog]

Lumpy -
my old P-valve is for a drum/drum system. Now I have a disk/drum ... not same/same

One of those p-valve centering pins is definitely in my future. I'm also going to get a reverse bleeder ... adds fluid from the brake to the MC. Very cool idea that simply makes sense. This doesn't mean that I won't bleed the system the conventional way too. I need to get over this hump first.

I'm no sure how this gravity bleed thing works. Do you prop the brake pedal down and open the valve bleeder open until gravity drops the fluid down where it should be?

 

[jammer1]

Just remove the M/C cover, fill the m/c and loosen one bleed screw. The m/c is higher and gravity usually will allow the brake fluid to drain down the system. Usually it takes (on a bone dry system) around 10 min to get to flow. On my CJ7 during the rebuild the rear took longer (and I was starting to think it wasn't going to work). Once it started to flow if your lucky, you won't even have to use the vacuum pump. As a boy my father taught me that (grandfather owned a ford auto repair shop, father grew up as a auto mechanic). When brake pumping and vacuum pump failed, gravity worked. Just may take some time (worth case put a pan under the bleeder screw and let it bleed overnight. You'll see in the morning that it did work through, you'll just have to refill the m/c and let it bleed again since the m/c would go dry.). Hasn't failed me yet, hope it helps you.

 

[Lumpy Grits]

HH-If the line fittings are the same size. It will work. DTDT.......
Are you leaving the lid OFF the MC when your making a 'pull' with the vacuum system?

 

[jammer1]

It's worked for me on many occasions. You can also do it piece meal. Loosen the brake lines going into the proportionate valve. Gravity bleed till you get a good flow out the fitting. Then tighten. Loosen the line going out of the proportionate valve and bleed till you get a good flow. Then go to the rear pass and finish the gravity bleed. You can also do both the front and rear at same time (might help with centering the valve shaft). This way you'll see results sooner. Lumpy, it's harder to pull air than a fluid with the vacuum pump (especially if their is any leak in the brake lines ex. would be a fitting that didn't seat good).

 

[99jpxj]

It is easy to make your own reverse pressure bleeder. Just use a large catheter tip syringe (not a luer lock tip- I use a 60ml) and a section of vinyl hose. Slide the hose over the syringe barb and bleeder screw, and add fluid slowly. Careful to not overflow the master, these systems don't hold much volume. I usually do this when I can't one to gravity bleed or the vacuum bleeder won't work.

 

[tarry99]

Try this:

1. Get brake lines horizontal, manually bleed, engine off.
2. Pull calipers, block with a piece of wood. Raise calipers as high as possible and bleed manually!

Meaning jack up the rear and get the system as horizontal the best you can..........start bleeding at the rear........

The orifices in the W/C are too small to move enough volume to get the air out of the lines. Speed bleeders will not work either.

 

[Hedgehog]

Yesterday after work I cracked open the bleeder (both front and rear), yes I left the top off the MS. ......................................today ...........................wait for it .........................................................................................NOTHING!.......................

 

[Lumpy Grits]

Sounds like you may need to make a positive pressure bleeder.
Can you post a picture of the p'valve? Who sells it and what's the PN?

LG