| usapro | -- 01-10-2012 @ 4:44 PM |
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Having replaced everything - there no leaks- no air in lines, etc. brake shoe adjustment is good. However, I still do not have what I would called great peddle- If I slightly tap the peddle first the brakes are great.I have done brakes before without this challange. I really do not know how I found this mess. Is there a critical point with the bypass valve portion of the master cylinder and the peddle adjustment. Thanks in advance for your help. Digit
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| 37RAGTOPMAN | -- 01-10-2012 @ 5:08 PM |
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Do you have 1 inch of free play in the brake peddle ? what kind of brake fluid are you using,? when you hit the brakes for the first time,is the peddle high ? and is lower the second time,? let us know,. 37RAGTOPMAN
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| supereal | -- 01-10-2012 @ 7:08 PM |
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See my answer to a brake problem below. This message was edited by supereal on 1-10-12 @ 7:10 PM
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| usapro | -- 01-11-2012 @ 6:55 AM |
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Superreal I could not find you answer below. Please add it to your message or tell me how to dig it out. Pedal Free play The pedal has about 3/4" play. If you push down hard in goes almost to the floor. A slight tap prior to pushing the pedal you have super brakes - in that case the positive brake activation is two inches from the top position of the pedal. Thank you I appreciate your efforts on my behalf. Digit
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| supereal | -- 01-11-2012 @ 7:23 AM |
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There are several reasons why pumping the brakes is necessary. First, the manual adjustment of the brake shoes at each wheel must be correct. If too loose, the stroke of the master cylinder may not be sufficient. The system may contain air, in spite of extensive bleeding. That is particularly true if DOT 5 (silicone) fluid is being used. It "entrains" air, making it nearly impossible to get all air out. The residual valve in the master cylinder may be leaking. This is an internal valve that retains a slight pressure in the system as the pedal is released to prevent the need to pump up the system, particularly after idle periods. Replacement of the master is the cure. The amount of pedal free play should be about an inch. but lack of free play usually causes dragging brakes when the fluid can't return to the master cylinder reservoir. That doesn't seem to be your problem. Bleeding the brake system in old Fords can be tricky, as the wheel cylinders are above the master cylinder. The old "pump and hold" method commonly requires lots of fluid to be bled to get a reasonable "pedal". At our shop, we use a bladder-type bleeding machine to get the job done quickly. Any small amount of air in the system will cause a soft pedal. If you get a hard pedal, but pumping is required after the car sits awhile, I'd suspect the master cylinder.
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| TomO | -- 01-11-2012 @ 7:30 AM |
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It sounds like you have some air in the system. Try bleeding the brakes without pumping the pedal. Have your helper press on the brake pedal and open the bleeder at least 1/2 turn, close it when the fluid stops coming out, release the pedal and check the fluid level. Tom
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| 37RAGTOPMAN | -- 01-11-2012 @ 1:39 PM |
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usapro slide the master cylinder rubber boot back and see if you see any signs of any brake fluid,on the inside of the boot or on the master cylinder let us know, 37RAGTOPMAN
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| usapro | -- 01-11-2012 @ 4:16 PM |
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This has a new master cylinder. We bled brakes by keeping hose from fitting buried at the bottom jar of fluid to eliminate air in system. There is no leak from master cylinder. We are using regular DOT 3 fluid. Brakes are not dragging. We adjusted for slight brake shoe touch on drums I agree it feels like air, but just a slight tap on the pedal is much better than when you have air in the system and hit the brakes. Thanks for all your help -Seems I am left with one choice - go back to square one replace the new master cylinder. Digit
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| supereal | -- 01-11-2012 @ 7:01 PM |
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The residual valve is an interal device in the master cylinder, and any leak is not visible on the exterior, or in the boot. It could be hung up on rust or other contamiinant. Just because a part is new, doesn't mean it is good. Today, those of us in the trade send back new defective parts very often. Much is due to the fact that they are foreign made. The fact that it is "new" is a strong indicator that it may be the cause of your problem, particularly if all other parts of the system have been found to be OK. If you are sure that something is good, it probably isn't. I learned that years ago. Even parts marked "USA" are more often than not, from offshore.
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| TomO | -- 01-12-2012 @ 10:46 AM |
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Before removing the master cylinder, try bleeding one more time. Tom
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| juergen | -- 01-12-2012 @ 12:46 PM |
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I have used a MyTeeVac in combination with pumping the brakes to aid in getting rid of the air. Instead of just applying pressure at the master cylinder, it applies a vacuum through the bleeder at the brake cylinder. You build up a vacuum, open the bleeder while your partner pushes on the brake pedal followed by closing the bleeder as the vacuum returns to near zero. Repeat until the bubbles disappear. You can get it at most auto parts stores for about $30.00.
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| supereal | -- 01-12-2012 @ 1:21 PM |
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You have better luck than we do with that tool. The last time we tried it, we went thru a gallon of fluid before getting near a good pedal.
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| shogun1940 | -- 01-12-2012 @ 6:18 PM |
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If you pump up the brakes and hold it down , does it go down slowly indicating a bypassing mc seal.
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| juergen | -- 01-13-2012 @ 10:31 AM |
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Supereal, did you just use the vacuum or did the pushing at the pedal (manually or with your pressure unit) and the vacuum? It's hard to imagine how working both ends isn't better than working at one end. I saw my buddy successfully use it to bleed his 40 Ford brakes and his modern Merc while replacing the front calipers. I used it on my 39 Ford and when installing discs on my 64 GTO. Worked great for us. This message was edited by juergen on 1-13-12 @ 11:04 AM
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| supereal | -- 01-13-2012 @ 11:15 AM |
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I used it by myself, being careful to keep the master cylinder topped off. I thought it was a good way to do the job when I didn't have anyone to pump and hold the pedal (my wife is tired of that, any way) while I opened the bleeder screws. I can't tell you why that pumping the My-T-Vac didn't get all the air, in spite of giving it plenty of time. Normally, we bench bleed the master, then hook up our bleeding tank, and open the wheel cylinder bleed screws one by one, starting with the right rear, the farthest from the master. I didn't consider having someone pump the pedal while I worked the tool, as it seemed like it defeated the purpose. We use it mostly to test vacuum operated parts of a vehicle such as heater doors, etc. I've been doing brake jobs for many, many years.
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| carcrazy | -- 01-13-2012 @ 1:57 PM |
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I have had the best results in bleeding brakes using two people: one in the car to apply pressure to the brake pedal while another person opens the bleed screw on the wheel cylinder while pressure is applied to the pedal and then closing the bleed screw before the pedal is released. Keep doing this until all of the air is out of the line to the furthest wheel cylinder and then repeat the procedure for the other three brakes. I have had problems using the vacuum pump on the bleed screws to bleed brakes because of air leaks past the threads of the bleed screws when they are open.
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| misfit | -- 02-22-2012 @ 5:46 PM |
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I just finished putting on rebuilt wheel cylinder kits u.s made and rebuilt the master w/non u.s. kit. However I also have what seems to be a spongy peddle and will not stop the car easely. I'm using dot 3/4 from napa. I did not replace the brake lines they look recently replaced. The prevous owner said they used silcone in the system. I'm wondering if I need to replace the hoses because of that and did you replace your hoses. Before I did this project I had stoppable brakes that will lock up but some wheel cyls were frozen and the fluid looked like an algey pond. So tomorrow I'm going to bleed the brakes again. Len
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| supereal | -- 02-23-2012 @ 6:48 AM |
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Try bleeding the brake system until all fluid appears completely clear. Using a hose on the bleeder screws that empties into a glass container will help. DOT3 is alcohol based, and does not mix with silicone fluid. It is likely you have pockets of it in the system.. The best way to bleed your brakes is with a pressure bleeder. The last time we faced your problem, it took two gallons of fluid before we achieved a hard pedal. This is why we don't use or recommend silicone. If you don't have access to a bleeder, most shops have them, and can flush the system.
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| misfit | -- 02-23-2012 @ 1:44 PM |
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On my 40 Ford I found my problem with the spongy brakes and the peddle going almost to the floor. I want to share this with you a'll. It was the brake adjustment. I was doing it wrong all the time. After doing it the way the shop manual told me I was not having any luck. I contacted a person who knew the correct procedure witch is oposite of the ford manual alas it works. The whole time I thought it was air in the system I bled the brakes several times no help.I can sleep now and stop. Len
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| Stroker | -- 02-23-2012 @ 3:38 PM |
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39-48 brakes are very easy to bleed compared to most modern systems. For one thing, the master cylinder is down low, so you aren't having to push air bubbles downhill. I've always had good luck with the two-person, hose in a jar method (make sure there is enough fluid in the jar to cover the end of the hose). I also have an ancient Wagner "Fluid Ball" which allows me to do the job by myself. They came onto the market in 1939, but are still available (though pricey)new from Wagner; however you see them often on E-Bay. These are a spherical container that has a diaphragm at the "equator". You introduce a small amount of air pressure in the "upper hemisphere", and the fluid is thus pressurized in the lower "hemisphere" and then fed via a hose and adapter directly into the master cylinder under pressure. You never have to worry about re-filling the master cylinder, as the fluid level is always replenished by the Fluid Ball. Adapters are available for just about any master cylinder in existence. The diaphragm ensures that no air gets mixed with the fluid, so it also doubles as a storage container for unused hygroscopic-glycerin-based fluids (everything but silicone), since air/moisture are sealed out. They are also great for flushing a system, as they hold about 2-gallons of fluid. As an aside, cheap/ol' methanol racing fuel works great as a flush for glycerin fluids.
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| supereal | -- 02-24-2012 @ 11:09 AM |
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There are some reasonably priced brake bleeding units on the market. They are an adaptation of the "pump up" garden sprayers. At our shop, we use a bladder-type bleeder machine. Newer cars with ABS systems can't be bled without the proper equipment to cycle the system. Old Fords can often be tricky to fully bleed using the "pump and hold" method. Old bleeder screws on the wheel cylinders may not seal properly, allowing air to reenter, and old piston cups may do the same. If you are not installing new cylinders, pull back the boot and look for fluid, if you find some, toss that cylinder. When installing a new master cylinder, "bench bleed" it before putting it in the vehicle.
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