Disc Rear Drum Front

I think if I push down the pedal and the fluid then goes from the master cylinder, through the lines to the calipers and wheel cylinders, the car will begin to slow down. The variation in stopping will arrive from the variety of pedal position and just how hard I push with my big toe or the ball of my heal; that is, unless I am wearing a sneaker or a boot. In that case, it won't be as hard on my foot, because the barrier of my shoe fabric (whichever fabric that is) will be a damper. I think.

The Pork

 

I still want to know where the "Donkers" come up with all these super clean assed cars that they try and make into Grave Diggers?????

 

Of course the guy that has this setup will tell you it works just great. Pork, spend a few extra bucks and do it right. The first time you use this setup in a hard stop and swap ends you will feel the wrath of the physics gods.

 

All of the ones built with clean cars had big budgets ... I'd be willing to bet there are plenty of them out there packed with bondo.

 

From what I've seen, Discs need higher line pressures than drums.

Thats why they usually come with boosters, and why ( with front disc /rear drum setups ) there is a pressure regulator on the rear brakes .

So with a reverse setup like that you'd have to put the regulator on the front, which means you are limiting the brake capacity on the axle that is supposed to do the most work, to balance it with the axle that does the least work.

The main advantage of discs is that it gets rid of the heat much better than drums.
So that means that the axle that works the hardest will retain its heat much longer than the one that doesnt.
( so you could run into a situation where you'd have stone cold rear brakes and hot fronts, which can give another inbalance problem )

I cant imagine it would be the cheapest option either ( once you count all the extra time to figure it out, and pay for the regulators, etc )


All in all, it seems like a bad idea to me.


And even if you can get it to work ( which you probably could if you spend enough time and money ), it wouldnt be as good as a 4 wheel Disc, a front Disc/Rear Drum, or a 4 wheel Drum setup.

 

Well ive always thought drums had more stopping power, they just heat up quick. I would do it it just may take some playing with to get it right.

 

This type of thinking makes me wonder what I'm driving next to on the street. Not to be taken the wrong way, not a jab at anybody. But it does affect me directly, since we share these 'public' streets. I won't die worrying, but it's food for thought!

 

Probably doesn't drive it in the rain because the rear brakes lock up when the road is wet. Just because it's been done, doesn't make something a good idea.

The "bragging arse" probably either:
A) didn't build his brake system and/or his car
B) really had no clue how brake systems work
C) was too proud to admit faults in his own work
D) a mixture of all of the above

I bet it could be done right but I'd think you need small rear discs and a lot of work to get it right and safe for all conditions.

 

I wonder where you got the idea that just because its a lite car it would be easier to stop with this setup.You lock up the rear tires on a lite car and you will lose control alot faster.If you are putting this setup on the Dodge you"re building you aren"t going to have any weight on the rear anyway.Do it your way man,just be safe.

 

HAHAHAHAHAHA come on man.

 

I have just read this post over several times and almost didn't bother posting after reading your responses back to other posters.

According to my Google search, residual check valves were used with drum brakes to maintain a 6 to 12 lb line pressure (hence the 10 lb specification for aftermarket inline ones) with the brakes at rest to keep cup seals in the wheel cylinders expanded, thereby preventing fluid loss. Around the time front discs were coming into popular use, the addition of spring expanders in wheel cylinder seals negated the need for residual check valves and they were for the most part eliminated from braking systems.

Two pound residual check valves are used in disc brake circuits when the master cylinder is lower than the caliper to prevent fluid syphoning (draining) out of calipers and into the master cylinder reservoir. Dry calipers and fluid on the ground under an over filled master cylinder reservoir is generally considered detrimental to good braking performance.

Do youself a favor, before you end up with something that will work marginal at best, heed the advice of a couple of the posters and take yourself back to school (at least about automotive braking sysems).

You could make your life simple by selling off the disc brake kit, rebuilding the drum brakes on your nine inch, and ending up with a simple well balanced drum setup all the way around that works far better on your 1800 lb car than you could ever imagine. Just make sure you pick a master cylinder with the right diameter piston size for your pedal ratio and you'll get good pedal travel without too high a pedal pressure. This allows your right foot to modulate the application pressures to get the most out of the drum brakes without locking them up.

 

Wow, this is something new..a newbie asks a questionable question and seeks input, then has the balls to get testy when some of the folks question the what, why and how parts of the project...

Just because it can be done does not mean it should be done, for many reasons. If it was a good idea then one of the car companies would have tried it. Car companies... ya know, those operations with engineering budgets deep into 9 figures.

Please put some kind of flashing light on it so we can see ya coming.

.

 

? yhW

 

V8 Bob, who quoted from Wiki? Just a few words to those using Wikipedia; don't us it. It is far from credible and loaded with inaccuracy. I sure as hell wouldn't use it or trust it as there are too many clowns who feel they know it all and won't take other peoples suggestions!

The Pork

 

.[/QUOTE] questionable question?

Wouldn't that still just be a question?

 

Maybe I'm blind, but it appears to me that V8 Bob didn't mention using Wikipedia anywhere in his post....

 

Advice to Porkchop4464............"when you find yourself in a hole..stop digging"


Ray

 

Dont think you have an ideal set up, can be done.
I'd say sell the set up you have, find some circle track guys, theyll usually give you the drums if theyre building a new rear.

Get one of these, "Tune" your brake balance front / rear very carefully and very thouroughly.
http://www.google.com/search?q=adju...s:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7

 

Clowns that think they know it all and won"t take others suggestions. That only points right at you dude,so lose the attitude.Every time you get a legit responce you come back with the smartass remarks.

 

I would like to note, clearly, that I have not made an ill-regarded response to anyone who gave an honest and critical response. If you look back, I only responded rudely to those who had bad or sarcastic things to say. Important Life Rule: if you don't have anything nice to say, keep it to yourself. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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P.S. I have had as many people suggest it can be done as people who say it can't. That being said, with two people who said they know it can work, and the actual car and guy I saw at the show this summer, who, by the way, drove away from the parking lot, turned the thing sideways in a hand over hand over hand back again burn out, and then stop at the light at the corner. So, sadly, regardless of debate, I can attest to the fact that it does work. I can not, however, verify effectiveness or efficiency. But the question was never really will it work as much as the need for knowledge of pressures, fitting details, reservoir sizes, GM Master knowledge and disc and drum brake information.<o></o>
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The cool thing is that this thread has seen a lot of action and has actually become a pretty fun thread! If people are charged up, they are listening, sharing, thinking, and most importantly - they are learning. <o></o>
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I will load a pic or two.<o></o>
Happy Holidays!

The Pork

 

I understand but don't know if I agree with this quote, because such is the case for everything in life. To suggest that that working examples or known and driving cars, on the road, are dismissed as fodder or not acceptable is dangerous. I mean, how else ido you prove an idea, build, debate or point, courtcase?
The Pork

 

The fact that you saw the guy do a burn out in what it sounds like was an area where there was a show and then come to a stop, proves nothing ~ except that he was a moron to do this in a crowded area where it could have all gone wrong and put a black eye on rodding for all of us.
More to the point. I was having a problem with my Falcon's brakes last summer and the rears were locking up long before the fronts did much. I did drive it that way to an event and even autocrossed it, but honestly it was very dangerous and had it not been in a controlled area (and I was very aware of what was happening )I would not have driven it. But the truth is if I had been on the street and someone had pulled out in front of me it would not have ended well.
What I'm getting at is if your set up locks the rears first, it's DANGEROUS. If you diminish the fronts to make the rears less effective, then you have again caused a dangerous situation - why would you want LESS braking power.
I believe you really should re think this.

 

Give it up Don. He thinks he has a viable system even though he doesn't have a clue how it works so he will push on. At some point he will give it up but we will never hear about it.

.

 

Just because some else has this setup (and hasn't killed himself, and or other people "yet") doesn't make it right. Sell the front axle with the drum brakes, and get one with disks, or sell the disk rearend, and get one with drums.

The disk rear, front drum is like wiping your a$$ first then taking a dump.

 

That's because he will be dead in ditch somewhere, after he takes out a family in the other lane.

 

r o t f l m a o !!!!

 

You are aware of how a standard brake system works? Do you understand why discs are usually up front? Do you understand nose dive? Get in a bike and lock up the rear brakes. You slide right? I am asking all of this cuz I just got a hudson. 1940 4 door. Big ass car. The dipshit that built it had the same set-up you are talking about running. Fucker slid all over. And I can attest that it isn't safe. My fellow club member that bought it, almost died in a car wreck. The ass end locked up. and slid it all over the fukn place. Got hit by 2 cars as a result cuz it launched him over the median and placed him into oncoming traffic. If you are really convinced that this will work, go for it. See what we are all warning you about. But why ask, if you think it will work? Why ask opinions?

BTW what master cylinder are you ging to run with this?

 

You know for 3 bills, you can get a disc set up for the front as well? All bolt on? I have a set. Very easy install. Why not get this kit as well, and save ALL of your problems?

 

I think I could get the shoes and the drums for 80 bucks; but it makes no sense to take old tech and replace the new. If the discs are tuned well down, they will all-around be better than drums with a residual valve and an adjustable pro-valve.

For those PMing me, interested in the same content, here is some details I have dug up thus far. I guess I am niot alone with this idea.

METERING
The metering or hold off valve is used in the brake system to better balance the front to rear brakes. The valve does not allow the pressure to rise at the front disc brakes until the pressure at the rear drums has risen sufficiently to overcome the brake shoe springs. At this point the valve opens to allow full pressure to build at the front brakes.

PROPORTIONING
The proportioning valve modulates the pressure to the rear brakes. The modulation is necessary to minimize rear wheel lock up found in heavy braking and to compensate for the differences in braking conditions in front disc / rear drum systems. As pressure is applied to the system full pressure is allowed to the rear drums up to a certain point. Beyond that point the pressure to the rear is reduced preventing rear brake lock up.

RESIDUAL
There are two different residual valves. A ten pound residual valve will maintain a line pressure to the rear to keep the drum brake shoes out close to the drums giving a higher firmer pedal. Without a ten pound residual pressure to the rear you will experience a spongy pedal. A two pound residual valve is required whenever the master cylinder is lower than the calipers to prevent backflow of fluid from the calipers to the master.

COMBINATION
A combination valve incorporates metering and proportioning into one valve. These are available for disc/drum or disc/disc systems.

ADJUSTABLE PROP VALVE
The adjustable proportioning valve is used when you have a special rear condition that requires higher or lower pressure than a normal condition. You sould always use a metering valve to the front when using the adjustable.