The car is a 51 Chevy. I just installed a ECI disc brake kit. The car has a small power booster under the floor, and a new 70's style full size chevy disc/drum master cylinder. I have a 2lb residual valve in the front and a 10 lb in the rear. I also have an adjustable prop valve on the rear. The problem that I am having is that I cannot get a firm pedal. It is soft and goes strait to the floor. If I pump it, its slightly better, but still falls to the floor. I made a mistake by not bench bleeding the master first, but there must be some way to get this right. I have bled a full quart of fluid thru it. How can I get this working?
You have air trapped in the system. Keep bleeding but do not push the brake peddle all the way to the floor that can destroy the master cylinder. You may open all of the bleeders and let it gravity bleed this works well also. Keep the mast full or you will have air again.
is there any way to tell if its the front or rear brakes that need bleeding? Also, should the adjustable proportioning valve be all the way opened?
I don't know how you are bleeding the brakes, but I was always taught to start farthest away from the master cylinder - typically the RR first, then the LR, then the RF, and lastly the LF. Don't know if that's part of the problem or not, but if not it'll help you. Hopefully it's just air in the system and not a bad master cylinder byp***ing off the shelf.
Ya thats the order I bleed in. Are the vacuum bleeders any good? HF has on for about $25. Looks like it puts a vacuum on the bleeder valve to pull fluid thru.
instead of pumpimg on the pedal and spreading the air bubbles, stop by any good parts supply store and get a one man VACCUUM bleeder tool. Fill the master cylinder and put the cap on. then apply a light coat of bearing grease around the bleeder valve on the brake wheel cylinder starting with the right rear wheel. as you pump the vaccuum tool air bubbles will appear in the fliud as it is PULLED thru the lines. when the air is gone the bubbles stop and you can do the next wheel . tools sell for under $30 at most stores. well worth the time and effort.
make sure your bleeders are at the top of the calipers. Also, make sure the caliper mounts have the bleeders high enough to be the highest part of the calipers.
Ya the bleeders are at the top. I am going to go buy a vacuum bleeder. I did some poking around under the car and I found that the PO put some loops in the hard lines. I am SURE there is air trapped there. Hopefully the vacuum bleeder will pull it out. If not then I will probably need to get new hard lines. It still amazes me that someone will do something so stupid to save a few minutes to get the correct length lines...
We had this problem on the Wayfarer, bled it many times and still couldn't get a pedal. It turned out that the piece inside the booster that contacts the master cylinder was out of adjustment and wasn't engaging the master cylinder to push enough fluid. You could pump it once and it'd firm up, but it would never get firm on it's own. Adjusted it a little longer and it's had a firm pedal for 5 years now.
How do you adjust it? Does it thread in and out? I read somewhere that there should be 1/64 inch clearance between the booster push rod and the master, but it didnt say how to adjust it.
DO NOT mess with that booster to M/C adustment untill all other possiable problem areas have been checked and taken care of. If you do do it note exactly how much you turn/change the length of the push rod. With a dual M/C ALWAYS bleed the side closest to the pedal first no matter which set of brakes that side works. If you have any vertical loops in the hard lines that is most likely your problem as it works like a "P" trap in your house plumbing. If you can bend them to lay flat at least untill you can replace them, then try bleeding the system again. I just helped a guy out with the same kind of problem and after making the loops flat bled out just fine.
If I understand your situation correctly, you said you have a small power booster under the floor. I ***ume that the master cylinder is also under the floor. If the master clylinder is lower than thewheel cylinders/ calipers, you can't gravity bleed the system. It is also very difficult to bleed it by someone pumping the brakes. The vacuum systems and or power bleeders work good especially in these situations. The other thing to try is raising one end of the car until the mater cylinder is above the wheel cyl.Then bleed those cyl. Let the end down and raise the other end and do the same thing on the opposite end, but it's a whole lot easier with the vacuum bleeder and faster.
I lieu of a vacuum bleeder/ power bleeder etc - I have had sucess with a couple low buck methods. A big honkin syringe makes for a budget vacuum bleeder. I have also simply cracked the bleeders - stuck some small hose on the ends of the bleeders - free end stuck into a jar of brake fluid and then slowly cycled the brake pedal. The jar serves several purposes. First you can watch the fluid go into the jar. Always good when you're bleedign an old system as you can watch the color change as the fresh fluid goes in. Next you can monitor the amount of fluid you've actually REMOVED from the M/C - good reminder to fill it before you induce more air. lastly with the end submerged you can see the air bubbles or hopefully lack of. It's nicer to have a clear hose - as you can watch to see IF you are cycling the fluid back and forth - if it does that and I'm by myself - instead of tightening bleeders - I will just pinch off the hose while I retract the brake pedal - same as closing a bleeded but alot faster. That syringe also comes in handy for "prebleeding" your brake lines - new systems can be a pain to "get going" by prebleding them you can make alot more progress more quickly.
I went and got a vacuum bleeder. I will give that a try tomorrow. Unfortunately I cant flatten out the coils in the hard lines. They coil around the trans. IDIOTS!!!
replace those coiled lines if a line is left loose and not secured you will always have a spongy pedal and when the line flexes it could also loosen. Had a 35 chevy in last week with almost no brakes found lines with coils in them replaced that and bleed the brakes now works fine. Hope this helps RED
No ****ing way that will work, every time you let up on the pedal, air will be ****ed in to the system. To the OP, you mentioned you didn't benchbleed your MC, I'd do that first, not sure if you can get the air out of the MC otherwise, in short order.
You really ought to go back and REREAD my post - the AIR doesn't get ****ed IN because the end of the hose is SUBMERGED in the jar of brake fluid. Originally Posted by HemiRambler have also simply cracked the bleeders - stuck some small hose on the ends of the bleeders - free end stuck into a jar of brake fluid and then slowly cycled the brake pedal. . If you then went further and read the REST of my post I ALSO mentioned if the fuild cycles back and forth - you pinch off the rubber line - I've done it this way when I either forgot to bench bleed the system OR when I was simply too lazy to prebleed lines - it works just fine.
I have done it this way as well......works well when working by yourself.....no fancy brake tools needed.........Littleman...I forgot to mention I have a small check valve that I put on so I can do it myself if I need to..
I wouldn't do another thing before replacing the "looped" lines that dipstick put in the system! AND, be sure and take good clear pictures of the lines looped around the transmission even if is just arounf the transmission crossmember. GAWD, don't you just hate ignorance and laziness? Brakes and steering ignorance and laziness can KILL! Correct that problem and smile as you drive.
Yeah when you're as CHEAP as me - I just end up sticking the hose against the bottom of the jar - it sorta acts like a one way valve. On systems with a TON of AIR I find that cracking bleeders is a pain - I've also used that hose and just pretended my thumb was the bleeder valve - I'm gonna enter the HIGH END CROWD and try my "new" (read: used HGR) hand vacuum pump on the next one. We'll see what works better. On brake systems - basic bleeding isn't rocket science - any motor manual will tell you the traditional method of bleeding brakes. Sometimes you learn little tricks - like one I recently learned from a buddy of mine - he called it "walking the bubble" - on a MC mounted HIGHER than the other components - you can literally "walk the bubble" and basically bleed your system without cracking a single bleeder. My mechanic friend told me they used to do this when replacing m/c's on rusty cars where cracking a bleeder was certainly gonna be a PIA. They'd bench bleed to m/c - toss it on. Naturally they'd get some air in the lines. By SLOWLY depressing the pedal and quickly releasing it they could literally move the bubble towards the m/c until they got it to come out completely. He swore it saved him LOTS of frustration. Sometimes it pays off to try different methods - different brake systems will react a little differently - sometimes.
OK guys this is really starting to puzzle me. I got a vacuum bleeder, but it is just ****ing air between the bleeders and the caliper, I can hear it. Almost NO fluid is coming out. I double checked that the residual valves are in right and they are. I still cant get a good pedal! Also, the booster has to travel about 15 thousanths farther before it contacts the master now, is that enough to make a soft pedal?
bttt, I have been trying to bleed it more with the vacuum bleeder. It is just ****ing air between the bleeders and the caliper. Is there a trick to this that I dont know?
Greetiings, I just read briefly through the posts and I believe you need to go back to square one, you'll never get a hard pedal or push any fluid through the lines without bench bleeding the master first. Take off both lines on the MC and run a line from each outlet back into the reseviors of the MC making sure the ends of the tubes are below the fluid level. Pump slowly untill you see no more air bubbles coming out. You should have gotton a bleeder kit with the cylinder when you got it with 2 clear plastic lines and a clip to hold the lines under the fluid level of the MC. Once you have the bubbles out, hook up your front and rear lines and continue to bleed. Right rear first, left rear, right front, left front.
Ya thats what I am going to do. I will leave the residual valves and the proportioning valve on the waster when I bench bleed it, that way there will be no air in them too...
I am going to get the loops out of the hard lines while I am in there too. I dont have a flaring tool. Whats the best way to deal with the extra length?
Yeah on those bleeders - sometimes they leak at the threads when they're loose as the threads aren't intended to seal. You may want to address that before goign further with the vac bleeder. Bench bleeding is a good idea, but not the end of the world either if/when you don't remember. Take a peek inthe M/C - make sure the pistons are retracting PAST the fluid inlet port. If anything prevents the m/c piston from fully retracting past that port - the vac bleeder ain't gonna work for ****. Look at BOTH pistons.
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