I've got a stock 28 coupe in the shop right now, someone at some point did a juice brake conversion, and it did not work. Removed everything, put a new 39-48 master cylinder, all new 1/4" brake lines, and 4 new wheel cylinders (39-40 backing plates). Bled everything and have no air coming out at all, yet it still has no pedal. I can pump it up, and after about 3 strokes it has pedal, and holds, but once I let go and step on the again, it just goes right to the floor. I'm stumped. Any ideas?
Thats what I was thinking, but all the wheels are adjusted with a little bit of drag when free wheeling? At the first stroke, when it goes to the floor, you can still turn the wheels by hand, after the second stroke, the lock up as normal, however the pedal is still low. Third stroke, their locked up, and the pedal is about 3" from the floor board
Just experienced the same issue. Check that there is sufficient travel to activate the master cylinder. My application called for 1 1/2" of travel. I had to fab new linkage to obtain that amount of travel. After installing the "new and improved" linkage, had all kinds of pressure. Hope this helps. Ken
maybe the rod length,meaning not enough stroke or could still be air- rebleed lines,they say longest line first.
narrow it down, when it is up as far as it gets, how firm is it? If it is fairly firm, it's not air. If it's spongy, try "flow bleeding". Crack one bleeder at a time a bit, then slowly push it down while someone watches for air. Then let it come back super slow, or have your guy shut the bleeder, but still go slow. You are not pumping the pressure up, just flowing the fluid out on each stroke. last thing is, did you place a shoe inside the drum to match the curves of the drum and shoe? It could be so far off, that the shoe is bending to fit the bigger radius.
OK, so I feel like an idiot now, but yes they were just out of adjustment. First thing I did when the car first came in was adjust them all, starting with the bottom two and then the top two. Just found out one of my employees went and adjusted them again, after me, and had them out of whack. Just adjusted them again, and their fine now. I knew it had to be something simple. Two many hands in the pot. Anyways problem solved! Back to your regular programing
Does the pedal actually "go to the floor", it shouldn't, master should bottom out before pedal hits the floor. If you are getting full stroke on the master and the air is gone maybe try readjusting the brake anchors and cams, the fluid has to be going somewhere. Lots of room on the '39-'41 brakes for lost movement if not adjusted completely.
OK! Back to the drawing board. Yesterday after adjusting them again, I had good pedal, and everything was fine. Road tested the car, and the pedal would come and go. Adjust them again (new shoes and drums) and it was good again. Drove it around for a few hours, adjusting them as I went, and although it was stopping, it didn't feel "right". About 8:30 last night, I parked it in the shop, went home and let it sit over night. Came back around 5:30 this morning, jacked it up, all the wheels had drag on them, gave them a quick tweak (just the upper two adjusters this time), step on the pedal, and it went right to the floor. Two pumps it's back up and holding. Resevoir is full, no leaks, after two pumps it has normal pedal height, and holds. WTF? Measured the pedal stroke, and it's 1 3/8". Pedal has about 1/8" of free play before it starts actually pushing the piston. Bottoms out in the master about 1/4" from the floor board.
Try some bleeding right at the MC...looks like you can reach everything at once to make it easy. Loosen bolt at fitting ***embly with a bit of pressure on pedal, see if there is any fizzing...keep on light pressure throughout so nothing gets i before you tighten. If you see/hear anything, repeat till all quiet, then also bleed at the two line connections there. That area can be a hidden trap...also it looks like MC is slightly uphill, enhancing that effect, though the uphillness might be just from photo.
Going by the top pic, it looks like the stroke is not enough to use the full depth of the master. Take the pin out and see if the cylinder can move much beyond where the pedal bottoms.
Are the wheel cylinders higher than the master? If so, your fluid may be draining back into the master. Thats why "they" say you need residual pressure valves in these systems that have the master under the floor. I installed a 10 lb RPV in the front, and the same in the back. Use the good br*** ones from ECI. http://ecihotrodbrakes.com/discbrake_kit_components.html
Jacked the car up like 2 feet in the front, so the pushrod end of the master is higher than the rear. Pumped it and bled the block, then the fittings after the block. No Air came out of the fittings, however bubbles did bubble up to the resevoir. The car is still sitting like this, and every 5 minutes I've pumped them up, and then let it sit to see if the air will bleed out through the master. As of now the pedal is feeling good. I'm going to let it sit for 10 or 15 minutes jacked up and see how it feels. As for the pushrod stroke. The pedal in the up position has about 1/8" of free play, and the pedal bottoms out about 1/4" before the floor board. I took the front floor board out, and the pedal is not bottoming out on the bellhousing or anything. The master is getting full stroke.
So after letting it sit jacked up, the pedal seemed fine. Let it back down to take it for a road test, and the pedal went straight to the floor again. I don't get it. I have the exact same setup on my roadster, as well as two other vehicles in the shop right now. They all bled and work fine.... The only difference between this one, and the other three, is the other ones all have 39 pedals, this one still has the model A pedals, however the master is still getting full stroke? The master is lower than the wheel clyinders, but the lines are higher in some areas
Did someone accidentally pull the stock residual out of the MC? The original ford MC's have a residual so I am told and perhaps a fitting was replaced and now it's gone or maybe it defective or jammed up? The reason why it feels good on the lift is the wheels drop and are lower then the MC but when it's on the ground it reversed that. Just brainstorming.... I would pull that MC and see if there is something clogging the residual with a paperclip.
39-48 masters have a residual valve built in, as was stated earlier. Drove the car around some more, one red light it stops great, the next one it needs to be pumped. They keep coming and going. Also, the pedal pulsates, like warped rotors on a disc brake system? I'm thinking now of taking the master off another car, that I know works, and trying it. The master on the model A is brand new, but may be defective, as Jeffery James suggested.
2178 here: http://www.vanpeltsales.com/FH_web/...s/Flathead_Brakes_mastercylinder_1939to46.jpg My suggested next check was about possible trapped air in the 2076 neighborhood. Do check on the valve...current cylinders are coming from China, and sometimes details slip their minds... One current repro I have seen was lined with stainless...the bore had a very vivible and palpable spiral showing from hasty boring.
Swapped the master for an identical one off another car. The pedal instantly felt better, before bleeding the lines. After the lines were bled the pedal is nice and high, feels solid and the car will lock up all four wheels with ease! Thanks for all the help guys. And remember to keep buying communist parts so I can spend another 3 days fixing something that should take a few hours!
The good old days were back when your new parts from the store were likely to be better than the ones you just tossed in the trash can!
Unless you are sending it back, or shoving it up someone's...., how about take the guts out to see WTHeck was wrong? I wonder if it was a missing valve at the front end of the spring? or stuck open.
Took the old master apart, and accourding to the diagram Bruce posted everything is there. I dunno? What I do know, is it's going back to the supplier!
So the car is in getting it's inspection, and the inspector just called me, the right rear wheel cylinder, that is now 4 days old, started leaking. Once again thumbs up for offshore parts!
Repro hubcaps from China were one thing...brake cylinders quite another! Get in touch with Richard at Early Ford Garage...he wrote this tuff up recently. Apparently USA brands of brake stuff for early Fords are China made now, but there are two sources and he believes one to be better than the other. China stuff is as good as the company setting the standards, and at least that stuff is via a normal Brake company and noy a plain white box item from Mac's. Richard is an expert on Ford brakes ans sells this tuff.
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