I've been searching for weeks and cannot find out what I have going on. speedway disc conversion to Ford spindles, 57 Chevy rear drums Disc drum master cylinder, mustang/Ford style. Chassis Eng. brake pedal to 36 Ford frame. 2 ln res press valve in front and 10 in rear. I have had 2 different pushrods in this, and with both I have to pump my brakes once to get a good pedal... Without the pump brake pedal goes low and it does not stop the same. once I pump it is great. Rear drums are adjusted just free with slight drag. Pedal has some play so the pushrod is not too long. bench bled the master and bled the lines over and over. same thing, one pump to get a firm pedal...any ideas? Also today I checked the front wheel bearings to see if they were too loose, and now my pass front caliper/pad is hanging up now and again...help...
You may try and adjust the rear brakes up all the way then bleed the rears and see if you get some air some times when you bleed with slack in the brake shoe adjustment once you open the bleeder the wheel cylinder will push the fluid out the bleeder and will leave some air in the line.
Bleeders are at the HIGH POINTS right? Hoses are new? Brackets flexing? -By your comments I assume that this is a NEW system. Any chance you got some "low drag" calipers? Those required "special" m/c and will work like you mention without.
Have you tried bleeding with a pressure bleeder? Depending on the layout of the lines, it can be near about impossible to get all the air out by the pump up and bleed method. You can rig up a shadetree pressure bleeder pretty easy. Take a piece of plate large enough to cover the master cylinder reservoir and drill & tap for a 1/4"NPT air fitting. C-clamp the plate over the M/C using a piece of rubber sheet as a gasket. Set your air pressure to 15-20 psi and plug the air line onto the fitting. Then work your way around starting with the wheel farthest from the M/C. If air is trapped in a high area in the line the continuous flow will force it out rather than letting it move a ways and then back itself up to where it was when you have to pump up the pedal again. Just don't let the reservoir run dry or you're back to ground zero I've got a 69 Corvette I've owned for 40+ yrs, and you could pump a hundred gallons of fluid thru the system using the pedal and never get the air out. 10 minutes with my homebrew pressure bleeder and its good to go.
new hoses, I'll check the brackets the calipers bleeder screws are at the top 11" Ford/Mopar rotor and '69-'77 GM caliper to early Ford spindles
A correct brake pressure bleeder uses a bladder that prevents air from entering the fluid reservoir. Injecting compressed air directly into brake fluid is not good. I know $150-$200 for a special tool can sometimes be hard for some, but when you consider the value of the cars you own or are working on, the investment may be easier to make, especially brake system related, IMO.
My first read on this is wrong master cylinder for application. If brakes are adjusted correctly and you have to double pump to get pedal up, to me it indicates that the master cylinder is not displacing enough fluid to fill all brake piston bores on one stroke so the displacement is to small and you need a slightly larger master cylinder bore. What do you have now?
I had this information on how to narrow down a brake pedal travel problem. Maybe it will be of some help to narrowing down your condition ...... The Most Common Reasons for a Poor Brake Pedal: The bleeder screws on the calipers are not facing up. The master cylinder was not bench bled or was not bled completely. Defective rebuilt master cylinder with pitted cylinder bore or defective pressure seals. Master cylinder bore size too small for the system volume requirements. Use of a disc/drum master for a 4 wheel disc system. Master cylinder lower than the calipers or wheel cylinders. Lines or components near a heat source. Lines that loop up higher than the master cylinder and then come back down. Will trap air. Low drag metric calipers without the use of a quick take up master cylinder. No residual valve to rear drum brakes. Drum brake wheel cylinders too large. Silicone brake fluid ( it can tend to trap air and cause seals to swell). Rear caliper parking brake / pistons not set properly with a rear disc system. Rear calipers not being bled properly. Most brake problems with four wheel disc cars comes from the rear. Improper pedal adjustment with too much free play. Old or inferior quality brake hoses. How to Properly Diagnose a Brake Problem: If you have very poor brakes, a spongy pedal or no pedal at all you will have to do some diagnostics to determine where the problem is in your braking system. Is it in the master cylinder, the front brakes or the rear brakes? These tests assume that your system is properly installed and bled. Perform these simple tests to find where the problem is. Once you know where the problem is it will be much easier to fix. Disconnect the brake lines from the master cylinder while leaving it on the vehicle. Obtain solid tapered plugs for the master cylinder outlets with the correct thread pitch. These are available at any good automotive auto parts store. You may also use our supplied bleeder kit. Plug the master cylinder outlets. Step on the pedal and hold pressure for about 30 seconds. If the pedal remains firm then the master cylinder is good.If the pedal sinks to the floor then the cylinder is bad. If the master cylinder is fine, connect the line to the front brakes. If the pedal remains firm then the problem is not coming from the front brakes. If the pedal sinks to the floor or is excessively spongy then the problem is with the front brakes. Connect the rear and if the pedal goes bad then the problem is in the rear. You may also check whether your lack of a pedal comes from the front or the rear quickly this way. If you are sure the master cylinder is good, clamp off the front rubber hoses and try the pedal. If you get a good pedal then you know the problem is from the front calipers. Be very careful not to damage the hoses and try to protect them from damage by placing the hose between something smooth. There is a special tool sold in auto parts stores for this purpose. Try it on the rear if the front is fine.
I am a firm believer in "pressure bleeding" but have taken a bit different approach. I bought a quart capacity pump handle oil can and attach a short length of clear vinyl tubing to the nozzle. I start at the farthest wheel cylinder bleeder, attaching the tubing to the bleeder 'nipple'. I 'crack' the line fitting at the 'Tee' and pump fluid until it flows without visible bubbles. Then tighten the 'Tee' fitting and onto the remaining rear wheel cylinder. Pumping fluid into that bleeder valve sends fluid to the master cylinder and any air along with it. I then do the same procedure on the front calipers. I have no quarrel with the pressure bleeder tool that is available insofar as effectiveness, but only as to price. Also, I 'borrowed' the idea of doing it from the wheel cylinder end from light aircraft repair where the master cylinder is well above the brake cylinder/caliper and access to the M/C is very restricted. The cost of the pump can is usually under $10.
If you can pump the pedal up and have a firm pedal, there is no air in the lines. I would look for something mechanical, the tip to adjust the drum brakes up on the tighter side rather than the looser side is good. How is the master mounted? It has to be real solid with no flex of where it gets mounted to. Bob
Having to pump the pedal to get a firm pedal results from a displacement problem, caused by air, fluid volume capacity, caliper retraction, drum adjustment, or a combination. First, does the pedal have it's own return spring that brings the pedal back firmly? Check and/or adjust the push rod for about 1/16" min. 1/8" max clearance. Can the master be fully stroked? If it can't, the problem has to be corrected. Bleeding method is sometimes is the problem. The master should be slowly full stroked during bleeding. With a dual system, it really doesn't matter where you start; just make at least three rounds of bleeding each brake. The master may be too small for your system as already mentioned, but I would try things that don't cost money or require parts changing first, and push rod setup/proper bleeding are priority.
This is the master cylinder http://www.speedwaymotors.com/Dual-Feed-Master-Cylinder,1985.html I have a return spring, on my pushrod, it is a new pushrod and i will adjust it tonight. The master bolts to the chassis eng pedal mount and to the frame and it is secure. I will snug the rear drums up as well. As an aside when I let it site over ngiht and hit the brakes this am it did them same thing, low pedal on first pump and hard after...
That master should work fine, but make sure the larger (primary) chamber goes to the fronts. Some caution with the push rod return spring. I also tried to use one, but found the spring would bind and prevent full travel if adjusted to fully return the pedal. I trimmed the push rod spring to only retain the alloy dust boot retainer, and installed another spring to return the pedal. JFYI
thsi is the pedal http://www.chassisengineeringinc.com/brake-pedal-kit-1935-1940-ford/ this is the kit I have http://www.speedwaymotors.com/Brake...er-to-Early-Ford-Spindles-Chevy-B-P,2005.html if you look at the pic they have the bleeder facing down, and mine are facing the top... click on the pictures on the link above actually i had the worng one this is my bolt pattern http://www.speedwaymotors.com/Brake-Kit-1969-77-GM-Caliper-to-Early-Ford-Spindle-Ford-B-P,2004.html
Do you just have to pump it once at the begining of the day and then it is fine for the rest of the day, or do you have to pump it before every ride during the day, or before evey stop during a ride?
its is pump once to get a good pedal all the time...sometimes the hard pedal will stay for a few lights etc, but the longer i go without a stop it wil l need a pump i drive with my other foot pumping as i approach a stop...like I said i get a lower pedal that will stop it the first time, but no where as firm or good a stop with the "second pump"
Jack up the front , rotate the frt wheels , is there pad drag on the wheels? If so the front's probably o.k. . Jack up the rear , can you access the rear adjuster.s ? If so crank them out till the shoes lock , then back them off just enough to be free , were these new drums & shoes ? sometimes the drums have worn so that it leaves a ridge that comes in contact w/ the edge of the shoes & you're not adjusted out nearly as far as you think. Also if the drums have been turned excessivley , the arc of the shoe is off so much you get poor contact/low pedal dave
I would look into this suggestion and rule it out before making too many other changes ... There is more info on them here if you aren't familiar with the low drag calipers ... http://www.remaninc.com/pdfs/lowdragcalipers.pdf
I am looking into it, speedway calipers are as follows: Easily installs 11" Ford/Mopar rotors and 1969-1977 midsize GM single piston calipers to your 1937-1948 Ford passenger car spindles. No machine work needed. Great for street rods based on 1932-1948 Fords, however, these kits are much too large and heavy for a T-bucket or an early roadster from what I've read the low drag calipers are from 80 and up...however that does not mean I don't have them. I removed the spring, adjusted the pushrod out so that most slack is gone from the pedal. I adjusted the rears more and re bled the rear, as I bled the front yesterday. now have a higher pedal, and firm and it stops good, but if I sit in the car and just pump the pedal it goes like this.....first pump has more travel than the second, then if I pump-pump-pump it will sink like the first and then pump harder again....may be the master is bad? I can lock the rears and the front grab too but something is goofy
Your master may be bypassing. You can usually make it do it by just sitting in the car and pressing on the pedal. Pump it up and leave your foot on the pedal lightly, sometimes it will sink after a few seconds, sometimes you have to tickle it a bit with your foot, or with the car idling, do it and drop it into drive. They can be quite elusive and other times you get one that will mimic other issues. Bob
I can hear the driver side drum/spring...something when I hat the brakes...I am going to pull that wheel off as the noise corresponds to the pedal it seems...I can hear a squeak type of noise
the master cylinder pushrod is right on. However I pulled my rear drums off and found that the drivers side rear shoes are worn out...I cannot get a good adjustment on the as the shoes are pretty far gone, so I can get new ones at Autozone... could the fit between the shoes and drum be what is causing the pedal to have to be pumped? I am thinking that the bottom part of the shoes is adjusted out so far to get the drag I need that the top of the shoe has to go futher than the wheel cylinder wants or can hold. does this make sense?
I had much the same system on my roadster a few years ago when it was first built. Another Dooley told me my lines running to the rear were to high. I re-routed the line from the under floor master to the rear flex line and lowered the high spot. It was trapping air up there even during bleeding.
put the new rear shoes, adjusted the rear on the tight side. re bled the front and back again, still get a one pump pedal. if I sit in the car and push the pedal it will go from hard to low to hard if I pump it continuously. I am going to try a new master cylinder. Anyone have a part number for a manual Ford disc drum that I can use? On NAPA'S website they have Ford disc drum for Mustang but they say it is for power brake, can I use that as a manual system?
picked up a new master cylinder, bench bled it and hooked it up an bled all wheels, same thing. think I may have cooked the front 2lb rpv as it was close to the exhaust. will pick up a new one...
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