A gripe about Master cylinders

I had a brake line blow out from rust in my 96 s10 pickup.It was the factory brake system so nothing was improperly installed.I had NO brakes ! not evan a little no extra pumps, Nothing ! There was no warning, no loss of pressure prior to the failure no indication of a problem.No Brakes.I had to drive up an embankement to get it stopped.Bob

 

A topic I've often pondered on. You should have some safety advantage running a dual circuit system assuming you also have the accompanying distribution block with a warning light switch to tell you that one end is loosing pressure. Would even this save your ass in a total failure or just a slow leak? I've always been a real stickler about suspension and brakes and inspect them regularly. Can't say for sure if a dual master behaves any differently with a blown hose, etc. but having bled a few and felt the pedal with only one end done, it wouldn't suprise me if the result was the same. True, a slow leak or pinhole would still allow some braking but so should be the same with a single unit. Always wanted to test this out with one end wide open but have yet to find the right victim and venue.

 

With one side failed and the other side still working, the pedal will go lower than normal, sometimes very close to the floor, then the functioning half will work. If it's not a diagonal split, and the fronts fail, you still aren't going to stop very well with just the rears, but it's better than nothing.

 

I don't think any of us can argue that a dual MC does have the advantage of giving at least some emergency braking if one half craps out. That is the reason every new car I know of has a dual system as opposed to the old single system. That being said, I am running a single MC from a 66 Chevy pickup on my 27 with half of it operating my clutch. It has been on there for over 24 years but when I redid the car a few years ago I bought a new one (same model) just because of the age of the old one. I feel I have some margin of safety as my 27 is a stick shift and I could always drop down into first gear if the brakes ever did go out.

One time in my life I did have a single system fail on me and it wasn't pretty. I parked my 57 Pontiac on a hill and when I came out to go to work one morning I put it in gear and started down the hill. Unbeknownst to me, overnight one of the wheel cylinders has leaked and all the fluid ran out.

When I hit the brakes there were none, and I had a stop sign and was entering a cross street. I ran through the sign and yanked the wheel hard to the right, just missing oncoming traffic. People were blowing their horns and yelling, but I was just happy to be alive. From that day on I always tested the brakes by stepping on the pedal before I put the car in drive.

Don

 

Duel master is far superior.

 

With over 40 years as a dealership line tech i can tell you that a dual system is better than single one. If one side fails you will lose a lot of pedal but not all of it. All those who say they had no pedal after a one side failure either had a poor brake system to start with or are full of shit. The auto industry didn't spend the time to design this just to dupe the public. It as designed to get your ass out of a jam and it works. You won't stop in the same distance, but you will stop. Better than the way I stopped my 67 Barracuda when the front wheel cylinder let go about 25 years ago. Coming up to a busy intersection with people in the crosswalk. Cut the wheel and took a tree. It was real ugly. Ken

 

"brakes are gone no point in steering now, eh?"

 

When the first half of the brake system fails you are supposed to fix the brakes. If you keep on truckin till the second half fails, yes you are right they are no better than a single MC.

 

I agree with Kennb, and Rusty, If you lost all brakes at once on a dual master cylinder, it just means that one half of it was already inoperable.

 

I have been in several cars, when a line or a hose blew, with a dual pot, and besides the few pumps that slowed me down enough to get to the side of the road, it will bleed all out if you keep pumping. The larger res. will get you three four, maybe 5 more pumps, which will save your life in the correct situation. There are five people on this post alone who have said they popped a hose or line on a stock, unmod'ed system, and they went up on the grass. Again, I can agree that four or six pumps, compared to 2 or 3 is a better scenerio, but there is way too much confidence out there that the big four actually give a shit about our saftey. If such were the case, a thing like brake lines would be mandatory stainless from the factory- so they never rotted. Think about that for a minute, 25,000 for a cheap car today and they can't put 100 bucks more material in stainless lines! It was a patent that was great and they never followed after it or pushed the manufac. to continue with the saftey. I am not being wise; but next time you flush your brake fluid (flush, inspect, refill, and bleed), leave one line off and pump about 5 or six times, maybe 10-11 total; it will pump until both pots are empty. Why is that?

 

Utter bull dust ! Duel systems are completely independant of each other. If you had ever taken the time to pull a cylinder apart and work out the mechanics of the internals you would not write such drivel.
Sure, we have all read about people out there that have experienced a 1/2 system failure and then cried in court that they had NO BRAKES AT ALL when their GM/Ford/Toyota ran up the back of the car stopped in front of them.! Let me tell you that most of those people probably had their seat adjusted so that they could not even reach the floor pan when the pedal went low. Most modern brake systems run a 60/40 split front to rear ratio meaning that the loss of front system means you are trying to pull up a vehicle with an, at best, 40% effective system .
Let me tell you as an ex GM Quality Engineer with 20 years experience looking at 'failed' brake master cylinders returned under warranty I have never seen a dual failure of a master cylinder.
And EVERY master that failed in the field under warranty was reviewed in a test and teardown to determine the validity of complaint in front of me.
Next time you feel like experimenting try locking off the front hoses on your shitbox daily driver with half worn brake pads/shoes and see just how far it takes you to stop from say 30 miles an hour!

Oh, and good luck with your ratrod running Drum front and disc rear setup too..idiot!!
http://www.jalopyjournal.com/forum/showthread.php?t=543055

Sorry for the rant , I'll go back in my box now.

 

....... or, the seal on the secondary piston was bad and gave no symptoms.

I think what often happens is that the driver freaks out and doesn't push the pedal down far enough to energize the good half of the system.

 

Whether the poster or the response is right or wrong, these kind of responses aren't helpful and they promote disputes.

 

One thing that I haven't seen mentioned in this debate is an "emergency" brake. Back in the stone age when I took driver's ed., you were taught to apply it full on in case of a brake failure, and steer around any traffic if possible, you will stop!

Today they are known as "parking" brakes, but I view mine as my ace-in-the-hole in case my stock single-pot brake system ever were to fail. I see a lot of cars being built today without a working emergency brake - something I would never do.

It worked for grandpa, and dad, so far it's working for me too.

Fire extinguisher at the ready - flame away!

 

The single pots have worked fine for me!

 

You bring up an excellent point with the Ebrake. When building a car from scratch, try to put whatever Ebrake/Parking brake system you have, right where you can get at it quickly and firmly.

Pay heed to where those older cars had the handle; a real long one for leverage, and right next to the shifter.

 

I live in Ohio.

A long time ago I had a brake line pop in a 65 Impala and had nothing....scared the crap out of me.

I currently have as a dd a 97 Dakota that is totally clean and looks new. I never would have anticipated a brake line pop.....but that's what happened - long line to both rear brakes.

The only way I knew was the pedal now went halfway to the floor before any braking was felt. But the truck stopped just fine.

I drove a 65 vette for over 30 years with a single pot mc but I was VERY careful about the condition of the lines. On any car where originality isn't an issue I think you're an idiot if you don't avail yourself of the extra margin of safety a dual mc provides.

 

Fools can yell all they want and rant in an uneducated tone to feel better about things; but such behavior just proves they are similar to the plural noun and introduction word in this sentence. As usual, regardless of proven accounts by numerous people, including myself, what I wrote is not a lie. What's truly sad is the attempting to validate a view or point with foul and derogatory blurts which can&#8217;t be respected. Oh, and some twenty cent "thirty year Inspector" flack doesn&#8217;t add to the credibility line either. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

Waldo, you are right about the Ebrake thing. When I was getting my license, they told us to consider our Ebrake as a real brake in the event you ever lost your pedal. My niece, who just got her license a few months back, never even knew about such a thing as "e-braking it." When we were younger, my friends and I goofed around ebrakin.'

 

This point of the post seems a good time to bring up an idea... I may not trust the big 4 or the dumbass novice rat rod builder, but guys on the HAMB pay a hell of alot more attention to automotive safety than any certified such and such. This is also a forum of master engineers and builders. Can't we come up with a new system that IS safe for our hot rods? It's gotta be a lot less complicated than casting your own manifold in your garage....?


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And don't forget "engine braking" in addition to the e-brake. If your brakes shit the bed, jam the trans into 1st and kill the ignition while in gear.

 

IF you have the time. A fair question to ask would be, "How many people tailgate or don't compensate for the age of thier braking system."

 

All very valid points.

 

My first car was a 32 3 w and I installed a single master cyl.Bad choice knocked a brake line off crashed the car at over 75 mph. just about killed my older brother. took over 17 years to get back on the road w my new 3w that has 4 w disc brakes w 4 piston calipers w tilton swinging pedel and mechanical bias control ps did I mention that I scared the shit out of myself.

 

Iv been diving mostly 65 and older single master cars since the mid 70’s.
The only time ever I lost a brake line was in my 67 elcameno (w duel master) and I hit the fuckin car in front of me anyways.

Duels are overrated .... you dont stop to good w only rears.

 

What he said ^

 

Utter bull dust ! fixed it for you CutawayAl.
Oh, and thanks for being in agreement.

 

Brakes are pretty important. A one pot is stupid.

I lost a rear cylinder in my RV, going down hill, into trafic. Its a heavy mother fucker.
If I would have had a one pot I would have killed someone for sure. Maybe me.

The rear section was empty from pumping, but I stopped, because I had fronts.

There is no argument here.

 

Porkchop;
you started out this thread by stating that you drove junk cars and had many complete failures in 2 pot braking systems which lead you to believe that the cylinders where somehow connected. And you were probably right in saying that if the piston seal between primary and secondary was scored/cut or just worn out. The M/cylinder would act normally and apply pressure to all 4 wheels , until you had a brake line fail, in which case the good half of the system would pump fluid past the damaged seal into the failed side of the system.
A good way to prevent this is to flush out the fluid every 2 years which will eliminate the corrosive action of water vapour buildup which as we all know is caused by brake fluid being hydroscopic. Corrosive buildup will eventually wear away seals in junk cars.


I'm sorry to hear about your dyslectic condition.

 

I've lost the brakes twice with dual masters once on my 67 Ranchero when the rear brake line broke and once on my 53 ramptruck (79 F350 chassis) when the caliper bracket bent and tossed the caliper. Pedal went all the way to the floor and i tried several times.

A friend lost all braking on his 92 Ford pickup when it burst a front caliper seal when the truck was just a couple years old, same thing.