Ok guys, I have a question related to brakes and residual valves. Here ya go: My deuce has an under floor master cylinder. No residual valves. Previous owner said the brakes were just fine when he owned it. (He was the one who trashed the thing! It was originally built as a static showroom piece displaying the company's body. Many corners were cut to get it to a static display. Then sold many years later to the guy I talked to.) I have built many rods with under floor master cylinders. I always ensured that there were no residual valves in the master cylinder and used a GM proportion valve with separate residual valves. (2 and 10 psi) plumbed into the system. The front portion of the master cylinder going to the front brakes and the rear portion to the rear. I have never had a braking problem with the system as described. I have used the "Dial your balance" valves and to me they are a pain getting them set right. Always under the car and the pitts to get to. Recently I had the need to put the car up on jack stands as there was a slight problem with the brake pedal. As I'm lying on the creeper, I can't understand how the hell the brakes are working. Using the brakes as is, are similar to the mechanical brakes on the old Fords, PLAN AHEAD! So, we're going to re-plumb the system. Any suggestions or ideas? All the lines are 3/16ths and the existing system is plumbed as the front bowl is going to the rear brakes and the rear bowl is to the fronts? That doesn't make any sense to me as the GM proportion valve has always been in the reverse. In other words, the front of the master cylinder is plumbed to the front of the valve and that goes to the front brakes, hence the dual outlet ports. So throw your two bits in as I do appreciate the various thoughts.
you can not always go by front/rear location .........which reservoir is bigger? do you have disc/drum or 4-wheel disc?
If all the lines are 3/16 it has to be a disc front and rear but you didnt say so you might have the wrong master cyl or combo valve
You can use 3/16 line on disc and drum You need to look at the master, the larger reservoir is for disc brakes, smaller for drum. Some masters have the larger esevoir to the rear.
Its disc/drum. All the lines are 3/16th. What I was told many- - many years ago was that the larger reservoir was for the rear drums as it took more volume to activate the drums than the disc in the front. Also that it was a shorter run to the front, hence the smaller bowl.. They usually said that the brake systems were engineered for best application. I.E., GM runs the front reservoir for the front disc brakes. I'm not one to re-engineer something that was already done by folks way smarter than me. Remember, the typical disc brake on most hot rods are not typical automotive as manufactured by the big three but rather small aftermarket units requiring less volume but more pressure. Interesting isn't it? Please see attached photos as for common applications.
I have understood that the first piston on the pushrod end of master cylinder is the primary for the front brakes.
Texas Drifter, you have been miss informed. The reason for one large and one small res on Disc/Drum masters is this. Rear drum brakes do not need to have Fluid added as the shoes ware. That side of the Hyd. system maintains the same amount of fluid once bled. Now front Disc constantly need fluid added to system as the pads ware due to the pads not being mechanically adjusted like the rear shoes. The Wizzard
Just got back from cruising thru a bone yard. Looked at lots of master cylinders. Yup--the old guys were right. I just never paid any attention to the master cylinders. The larger bowl was to the front and the smaller was to the rear. GM likes to do a trippy thing with the castings in that the rear has a sloping bowl floor. Hmmm- - - learn something new everyday huh? Then it would seem like the tops were inverted or installed backwards by previous owners? Oh well. We're going to just do a complete brake system rebuild and install power brakes, residual valves and a proportion metering valve. We're going to obtain a complete set of rear backing plates with self-adjusters and really bring the old car into the new world. Looked into that a while back and none of the parts people around these parts had any idea of the correct parts to add self adjusters to the 1957 Ford backing plates. Anyway, then I won't have to "Plan Ahead" as though it still has mechanical brakes. Thanks for the input guys. Opened my old eyes for sure!!
just saying GM did have an equal bowl front and back in 76 at least I am sure there are others.I installed 2 on a friends 39 ford rod.first one started leaking into booster after a couple of years fun finding that no damp on pulling it off booster.summer driven only luckily.off shore shit also front to front rear to rear port. discs front and rear mish mash of parts calipers etc.
I'll add two more comments here. (1) If you buy a Disc/Drum Ford master new it will already have the residual valve installed in it, you just can't see it. If you add a second in line one you just created a problem. (2) If you have 1957 Ford car rear drum brakes you don't need to change up everything. Just go buy a new 1965 and latter Spring kit from NAPA and it will have everything to convert those 57 Brakes to auto adjust, problem solved. Now, for what it's worth. I never use the Brass Manifold with the idiot light switch. That's just another Bologna program for hot rods. The after market Brake vendors are in business to make $$$. If you can't think past how/why the Factory did things, those guys will help you finish emptying your Wallet. The Wizzard
Thanks for the info on the spring kit for the 1965 up ford axles. We don't buy things if they aren't needed. The parts houses here aren't exactly a wealth of information. As for the master cylinder, it all depends on where you bought it. Besides, they are easily checked and removed if needed. And yeah- - - we do think past the factory! As for the brass manifold, its the proportion metering valve I like and not the damn idiot light. I usually get those out of the bone yard.
The reason for the larger reservoir in the front is that it takes a larger volume of fluid to move the piston(s) because they are a larger diameter than the wheel cylinders in the rear. As the pads/shoes wear and self adjustment takes place the fluid level in the MC drops because the pistons travel farther out in their bores and more fluid is required to fill the space. If adjustment takes place the amount of fluid needed to move the pistons doesn't change. Disc brake adjustment occurs because the piston seal distorts when the piston travels out and when you release the brakes it pulls the piston back only the distance that the seal needs to return to its original shape.
Another issue you may find is the brake line size at 3/16 is too large, drop it down to 1/8" and it will help with pressure, The truck in my avatar is manual brakes and will give any new vehicle a run for its money in the brakes department. Discs run the 2lb residual valve and drums run 10 lb. If you want to put the adjustable proportion valve in, crank it down half way to start with, that's where I always start mine at and go from there, normally 2 adjustments and I have some great brakes. Brake line size is always something to consider in re doing a brake system, power brakes I suggest going ahead to 3/16 anything manual stay 1/8 and it will give you great pedal feel.
Stubbs; Not trying to find fault in your statement at all. I found it interesting, so went on line to try to find 1/8" steel line or even 1/8" i.d. line nuts for inverted flair fittings. There don't seem to be anything out there in steel, only Copper and ferrel fittings. Also I have never heard of using 1/8" for brakes. Are you sure about this? Where do you get the product and does it come in 20' coils like the 3/16", 1/4" and 3/8"? The Wizzard
For one thing I've never seen or heard of 1/8" brake tubing, and secondly, this would not affect line pressure one bit. Where have you ever seen 1/8" brake lines, manual or power? I do agree with 2 lb. disc residuals, but only when the master cylinder is lower than the calipers.
The way I understand things is in using 1/8" line you will have much more pedal travel to move the amount of fluid it takes to charge the 4 corner cyl's. The 4 corner cyl's still need the same amount to apply pressure needed to stop the car. To me pedal ratio is much more important to what it takes to apply the Brakes than line size. The Master cyl will only output X amount of pressure, what is done past the first line connection only dictates how much fluid charge travels to the end of the line. The Wizzard
I've been working on my brakes recently (under floor disc/drum on a model A) I found I had a 68-74 Bronco master and these didn't use discs until later, so I'm thinking this is a drum/drum master. It does have a small/large chamber, so I'm a bit confused. I bought wilwood residuals and adjustable proportioning valve and am about to get a new master. Any ideas for what to use 78 f150? 79 Camaro? Wilwood? Also.....when you get a new master which side has a built in residual valve?
my mistake thought that was 1/4" so 3/16 is perfect. Found with too large of line you find spongy pedals... my mind was off this morning.
The installed residual valve installed in a master is just a small rubber bladder behind the Brass seat for the brake line. When in doubt you can very carefully use a piece of 1/16" welding wire and slip it into the line hole. The bladder will stop the wire just as it enters the hole. On the Disc side the wire will slip in about 1/4" to 3/8" depending. Be aware you can damage the bladder if you stuff the wire through it. On projects like yours I have always chosen a Master to match up with the front Disc brakes and not worry to much about the rear Drums. So far so good. Mix-n-Match is an imperfect science. The Wizzard
So I have GM discs from around 79? A matching 79 master should work. In a factory new master it sounds like there would be a residual built into the disc side only, right?
The diameter of the brake line will not change the pedal feel unless there is air in the line. With a smaller line the fluid just moves faster through it. With a larger line the fluid just moves slower. At the end of each line the same amount of fluid comes out, and at the same pressure. This is a common misconception.
In reply to Pist-in-Broke, it took me several hours on several parts house's websites to ascertain the components for self adjusters. Measured the shoes (11 x 2.31)on the 1957 Ford Ranch Wagon 9 inch rear axle backing plates and finally came up with the following: Duralast Brake Drum self-adjusting kit-rear Drivers side # H2544 and passenger side # H2545. Complete spring kit for both sides: H7101 and then riveted brake shoes # 263 I I will try to find some bonded ones as I really don't like riveted ones. All this from Auto-Zone, fitting a 1970 Ford Ranch Wagon, 5.0L, 2bbl OHV This all in case someone else could use the information. Then not all the other parts houses could correlate the parts to their selections or even had all the parts. I was surprised that Auto-Zone had all the components. One just cannot go into a parts house and simply tell them that you need a self-adjuster set up for a something that didn't have it. If it's not in their stupid computers, they can't find it. Then they look at you like "What planet did you come from?" Ahhh- - - so much fun huh?
Been thinking about the power brake thing. I've built numerous cars with disc front and drums rear. No power assist. All the vehicles were lightweight, 2400 lbs average. Never had a braking problem. So, I'm thinking I will forgo the power brake thing. The coupe weighs as much as my "40 did and it didn't have power assist. Let's not get into weight bias as generally any vehicle provides 60% braking on the fronts. We will be ordering a new master cylinder (GM) and components from Speedway to keep it all in the family. Winter project coming up!
Maybe I should have been a bit more clear. First off never tell a parts idiot your doing a modification, Never refer to what your going to use the parts on if you are. They just give you that Deer in the Headlight look and go take a brake (even if they are still standing in front of you). So I decided to get you the complete parts package part # such as Wagner F78528S only to learn you can't get there anymore. As you mentioned it is a search for each part. Springs, adjusters L & R then cable kit. What a blister. Sorry for the bad info or in this case outdated. I came from a time when you could just go get things if you knew what it was, now you gotta know how to ask for it also. I feel bad for you young guns. The Wizzard
You need a slightly smaller dia. M/C for non power, and 6 to 1 pedal ratio. Many after market pedals are 5 to 1, and keep the master under one inch. Smaller M/C = more pressure to brakes. Opposite on the caliper end. Larger caliper dia. = more pressure to brakes. Non power works fine if diameters of the system are selected correctly. Too much bolt in, and and forget it. Then wonder why brakes don't work good. Another thing: For the dual M/C safety to work correctly, the pedal has to bottom the M/C without any fluid in it before pedal hits the floor. Many cars running around that the dual M/C won't save you!
Young Guns? hahahaha- - - We have been at this thing since I was 13 and I'm now 72! The "Deer in the headlight look" is usually the kids behind the parts counter! Yup- - -having to search various sites for all the parts does take time and eventually one will get all the needed information. Just keep at it. I've got a couple of parts houses trained, I just give them the sheets with parts and their numbers listed. Saves time. They now don't ask what I'm working on, year- -model and make - -etc--etc. It's always interesting to read what others have to say concerning any mods done to just about anything. Opinions vary greatly. What works for one may not work for another. But there is always something to learn isn't there? Thanks Buddy!
The Jalopy Journal
