I think your description of how to make a cover for the pressure bleeder is accurate. You might use a thicker piece of aluminum to make the plate and then put a relief in the bottom side to insure plenty of room for the fluid to pass either way. I remember a vehicle that I could not get the air out of....try as I might. I finally raised the rear of the vehicle before I bled it and after that I had no more problems. Possible that it was just enough to get air past some high spot........or my imagination.
Well, I may have been a little aggressive calling the pedal high and hard on the second pump. The first pump will not lock the brakes. The second pump will lock all 4 wheels. I guess at that point I quit pushing but the pedal is higher at that point. As has been said it has to be either air in the system or not enough volume delivery. Wilwood says that there is enough volume to operate the caliper with a 7/8" bore MC, if I indeed have full stroke at the MC. I am in the process of verifying and adjusting that right now. I am taking a break and my computer is right next to the car in the shop. I seem to require a lot more breaks nowadays. It is an underfloor MC.
Well, it does appear that I had full stroke, but it was close. I adjusted the pedal up a little bit just to make sure. Now I need to put it back together and try bleeding again. The whole time I was jacking the MC off checking for floorboard clearance etc. I had the bleeders on the calipers open with hoses down into fluid, so I should be pretty close already. Gonna try a bleed right at the MC first, the go to the full bleed. Got my fingers crossed. If that don't get it I am back to square one.
I bled the brakes last night again for about the 367th time. I checked and adjusted the pedal and MC piston for full stroke. Bottomed out at full stroke, and against the clip when relaxed (loose push rod). It is getting full stroke. I checked the residual pressure valves to make sure they were installed right end to. I bled both lines right at the MC by loosening the nuts. I got no air. I then bled all 4 wheels again. I had the wife running the pedal. I got no air whatsoever from any bleed point. Plenty of fluid, but no air. I was dead wrong in the first post when I said I had a high hard pedal on the second pump. I have good brakes on the second pump, but I can push the pedal almost to the floor after any number of pumps. Sorry to mislead. But there is definitely air in the system somewhere. For some damn reason, it just won't bleed out with ordinary measures!!! I have been over all the brake lines inch by inch. The only air trap could be the hump over the center section in the rear, but that is a pretty common thing in a lot of brake systems. Should bleed through that. Maybe it isn't? The only other thing I know to try is a pressure bleeder, so my new one should arrive tomorrow. It doesn't come with an adapter to fit the Wilwood MC, so this morning I made up an MC cover and gasket with a 1/4" hose barb inlet. I should be able to adapt that to the new pressure bleeder. I'm a little skeptical of the pressure bleeder working either. I can't see any difference between pushing the fluid with pressure or pulling the fluid with vacuum. I'm about ready to rip out all the brake lines and start completely from scratch. All the components are from the same well known brake company. They have been engineered to work together. That leaves only what connects them... the brake lines. Hell I don't know. I'm completely lost at this point. We'll see tomorrow.
Dang, this is not good news. I'm not doubting your doing the process right but just to be clear. All your hard lines are 3/16" and not a leak in sight. Next is the actual bleed process. Where things are now, the Wife pumps the pedal 3 times and holds pressure on the pad while you crack the line, and she keeps pushing down. Before she gets to her stopping point you crack the valve momentarily and while fluid is actively moving close it tight and repeat that process. You do not leave the bleeder open until fluid stops running out. I will say there have been a couple projects over the years that presented a challenge but nothing that lifting an end of vehicle or tilting pass side up to keep fluid going uphill through loops due to owner not understanding normal plumbing routs. This don't sound like your issue. The only other thing that comes to mind is a compressed section not letting good fluid transfer to the wheels. In other words, a big restriction. Probably not your problem either. The cure is going to be interesting.
A sorry tale but you'll get there in the end!! Just because a master is new doesn't mean it is good. Probably worth using a pressure gauge to establish the pressures at the master outlets and at the calipers. Don't recall any suggestions of selectively clamping flexible lines to identify problems. Wont work with braided lines though! (Find an alternative way to block off ) Chris
Oh Jeez! Perfect example of CRS. About 6 months ago I bought a set of adapters and brake pressure gauges. I'll dig them out and see what they tell me. Man, I am really getting old. Can't believe I didn't remember that.
I am facing the same problem with a four wheel disc conversation on a 62 Ford Galaxie. Please post your findings with the gauge. I am thinking of buying one.
I fought this same problem forever on my Ford Fairlane after converting to disc brakes and tidying up some lines I wasn't happy with. Someone on here asked if I had a pressure switch for my brake lights and was it mounted in the original factory position. I did and it wasn't, I had it mounted vertically. He said it would always hold air like I had it. I changed the position , reblead everything and it solved my problem. A couple of years later I upgraded to a master cylinder/proportioning valve combo because it looks so much better. The problem came back and I chased it until one day I gave up. It's still like that 5 years later. Argh!
Just a thought, instead of relying on Wilwood's numbers; maybe calculate the calipers requirements and the master's volume yourself and see if they jive. Seems to me with discs the pedal should be right there unless something is making the pistons retract excessively.
Look on the bright side; at least you remembered you'd bought some already instead of finding out after having purchased a (second) set!!! Chris
Another issue out there is Rotor to Pad alignment. Many kits out there have issues and cause the pads to retract further that they should on release. This requires more fluid movement to get good clamp force.
Yes hard lines are all 3/16". It is hard to tell the skill level of some random guy on the internet, but believe me even the wife is an old hand at brake bleeding after 43 years of being around me. I haven't tried tilting the car yet. Don't know which way to tilt it.
When trying this just do what you can to get the master low and the hard lines going uphill as much as possible. Air wants to rise with the fluid movement.
The pedal doesn't go down like it's bleeding. It eventually hits a soft bottom. I'm 99% sure it is air in the system. Almost 60 years of bleeding race car and hot rod brakes and the occasional DD experience tells me it is air.
I have my proportioning valve (Wilwood) mounted upside down. At least the words on it are upside down. The way the inlet and outlet are arranged on the valve the outlet is above the inlet and there is a space below the inlet in the knob end. This makes me wonder if there is a possibility of air there. Never had a proportioning valve apart.
This is all good. Checked when installed. These are floating calipers. Not quite as picky as fixed calipers.
one thing that hasnt been mentioned. maybe plug off the front brakes at the MC . see what happens. if the pedal is still soft cap the rear like you did the front . if the pedal is better you've at least narrowed down which end is the culprit. seems every project ive had ive always had a brake issue . one was a too short rod from brake pedal to MC. my coupe im working on now had a soft pedal that i tracked down to me forgetting to adjust the back (drum) brakes out after installing the drum.
Okay. I think that is reasonable. Let me measure the total stroke of the MC and I'll get back to you.
Did you check to see if your bleeders are at the very top of your wheel cylinders? Just trying to think of something crazy! Bones
7/8" bore MC moves .60 cu. inches with 1/4" movement for approximately 1/8" of caliper piston movement. I think the piston actually moves a lot less than 1/8". Total stroke of the MC is approx. 1" for 2.40 cubic inches. So less than 1/4" stroke at the MC. There is plenty of volume to stroke the piston 1/8 inch.
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