A gripe about Master cylinders

Mechanical brakes are going to return. Car manufactures always return to an old design. If you have pedal you have brakes with a mechanical system. I am thinking on how to convert the 89 OLDS right now. The emergency brake on the 89 has never failed and the hydraulic brakes have never failed and the car has 400,000 plus miles. You fellas have me worried now.

 

This thread has now been elevated to the official HAMB 'pissing contest' category.
Over to you Porkchop.

 

My '95 one ton van, since gone to scrap, blew a line on me when this ass in a rollback truck cut me off over near Utica. I was on my way to the junkyard with a guy following me to scrap another car.

Now those do have two seperate pots on the top, and this thing had the stupid dead 4-wheel ABS unit so it had like a mile of extra lines under it. But, I was able to stop - not nearly as well - and I nursed it in low gear to an auto parts store, where I spent about three hours under it replacing the line and at the same time plumbing the ABS unit out of it. It did not stop well, but I was able to safely stop and I drove it well past probably where I should have.

I've had some too where the front and rear are entirely seperate circuits.


On the other hand, my '91 Suburban blew a line and I had nothing. That one is supposed to have a valve in the master that closes when pressure is too low on one side, but the pedal in it is useless. I haven't fixed it yet. Did I mention I'm sick to death of fixing brake and fuel lines under rusty New York vehicles? Oh, well I am.

 

Let's not forget, in a panic situation of brake failure dual or single hopefully we have all built back into our rides the e brake system........that's what it was designed for and works when applied.

 

I lost a line recently on my 1999 F150. It was a bit scary , but I did have brakes. Not great brakes , but enough to stop the truck .

 

I assure you it was nothing personal.

 

A single master is stupid? on the hamb, which is about preserving tradition? Geez. Just because a person does not know how to inspect and maintain an older system, brings forth the "stupid" comment?

Edit; "lost a rear wheel cylinder"...you are adding drama. That wheel cylinder did not loose all it's ability to hold fluid in an instant. That cyl was leaking for a long,long time, and you just never knew it. It finally leaked enough to drain the reservoir for the rears, and lost that circuit. Facts are facts. and drama is silly, especially based on bs

 

Just to chime in - I was recently thinking of picking up a 1995 Taurus SHO as a daily driver replacement. This was a reasonably well maintained car, by the look of it. I went for a test drive. On the test drive (owner riding alongside), the pedal felt spongy. I thought something wasn't right. Tried to get it back to the guy's house. Very soon, the pedal went to the floor. All the way to the floor. As in, only pumping did anything, and very little at that. There was no place in the pedal travel that gave any firmness or resistance.

Upon (barely!) making it back without crashing, we figured out that it had sprung a leak at a single fitting on one of the rear brake lines, on the body, ahead of the rear wheel.

(It should be obvious that this was a modern, dual master cylinder system. The typical Ford thing is to tie one front and one rear together - diagonal.)

So, it's true that the car did not lose all brakes instantly. But it certainly didn't work as neatly as some people would have you believe. It's not at all like half a normal braking system. I didn't have a firm pedal at any point. I didn't have 50% braking power. I might have had 5% braking power. It was a scary experience that I don't want to repeat.

Now, might a single pot master cylinder have been even worse? Maybe - I don't know. I haven't actually driven one, let alone had a failure while driving one. But I do know that a loss of fluid from one half of a dual master cylinder is a serious, major, potentially catastrophic event!!!

I also don't see why yelling at people is necessary in this thread. Do some people think their fellow posters are just brainless, or that they are lying about their past experiences? Come on, there are several people with similar experiences, all in this one thread.

 

The one's doing most of the yelling are those stating illogical/irrational/untrue remarks, like "bolt face lie", "both piss out brake fluid if one is out", "when one goes, it all goes", and my favorite, "government conspiracy". REALLY???
Many that don't understand something find it easier to blame someone else for their ignorance rather than try and learn what's real and true.
What's real sad is so many still do not understand vehicle brake systems that have been around for over 45 years, including many that sell brake components.

 

Is there a (simple replacement)for single pot to dual.47 ford tudor.Have body off.Now would be the time.I have been reading these type threads for awhile.Someone said pre 75 were internally(Proportioned?)Would this simplify things?Thanks for any and all help.
AKMARTY

 

I have an aftermarket (Wilwood) dual (not duel, the circuits are not fighting each other) circuit master cylinder. It is set up from the factory to have the two reservoirs separate from each other. If one goes dry the other will still maintain braking function however diminished it is in accordance to it's position on the vehicle, i.e. front or rear circuit.

I can tell you from bleeding the system when I installed it that the pedal got pretty firm after the rear was bled and really solidified after the front was bled. That leads me to believe that if either circuit fails I will be able to stop my truck without incident (provided I am not tailgating, speeding or having to perform some other form of panic stop.)

 

Well, Bob, I went and looked up the federal standard you referred to. I found a few things of interest.

First, here is the requirement for partial failure (hydraulic):

Table II is represented by an image, and, humorously, the link is broken. (What is the spec for partial website failure? ) I found an older version (2010) on another site.

So here are the maximum stopping distances you can expect for a brand new car, with its only defect being a sudden hydraulic failure in one of the lines.

30 mph - 114'
40 mph - 155'
45 mph - 202'
50 mph - 257'
55 mph - 317'
60 mph - 383'
80 mph - 458'
95 mph - N/A
100 mph - N/A

This sounds kind of okay ... although stopping from 60 mph in 383' would be iffy, and anything higher would be really dangerous. Of course, these are the maximum specifications, so maybe your car would stop a little better than that. But these are also for new cars in perfect shape otherwise.

But, Bob, here's something that bothers me. The federal standard leaves some vagueness here. It says the other system "shall continue to operate", but it does not say for how long. Does this standard apply to only one stop, or does it apply indefinitely?

Now, when you look at the standard for reservoirs, here is what you find.

Now, since the Taurus I drove has only one brake fluid filler cap, it obviously falls under the portion of the specification pertaining to reservoirs with a common supply to the subsystems. In theory, each side of the MC should have had enough fluid to allow a firm pedal on the half of the system that didn't have a leak.

But my experience was that there was decent braking power at first, but it disappeared after a few presses, leaving me with almost nothing. I realize that is not how it is supposed to work. So there must have been some flaw. Maybe it was a design flaw, although one would think Ford should know its way around at this point. More likely, it was an unseen flaw that developed in that particular car over time. Maybe leaky seals in the master cylinder let fluid from the "good" side leak over into the "bad" side and then out of the system, eventually resulting in air inside the second part of the MC. I don't know.

But the flaw was not evident when looking at, or initially driving, the car. So how would anyone know that they were one leak from a wreck?

Are you saying we should all open a brake bleeder and drive around every few months to make sure that the backup is working?

If you're not going to do that, then you may have a false sense of security from the knowledge that you have a dual MC, but completely miss the fact that it may not work as you expect in an emergency.

That's all I was saying. It's better than a single MC, undoubtedly. But it can give a false sense of security.

 

An interesting thread to be sure. As a [retired] certified mechanic, I understand the mechanics of the dual master cylinder. I was very surprised to read about some of the guys here losing all their brake pedal when blowing a line on one end of the car. If there was an internal leak between master cylinder resevoirs, I can understand it but in a case like that, the pedal would have been mushy and spongy for some time before blowing the line, indicating a problem with the brakes. In a newer car it would have lit the "brake" light that has a sliding piston with a switch that detects un-even brake pressures and lights the dash light.
If there was only one guy or even two guys having this problem, I'd understand the probability of 2 out of many thousands having this trouble but there are 4 or 5 guys reporting this on this thread. I personally have only lost brakes with a single resevior M/C [twice] and know the panic that ensues. I'd love to inspect a dual chamber, 2 circuit master cylinder that completely failed on both chambers.
If this is true, there needs to be a good look taken at the reason for this problem. After all, the entire reason the MFGR's went to dual chamber master cylinders was to prevent this life-threatening problem.
BTW, in my many years as a mechanic for the local municipality, I've had a few dual chamber master cylinders fail in one circuit and the brakes had dimished capability but they were able to stop with the other circuit...good enough to get the vehicle back to the shop..
Not calling anybody a liar...just wondering why the second chamber and circuit didn't work.

 

The remaining brakes were marginal, for one reason or another, or else they would not have gone away, unless you expected too much and brought about fade, depending on how long and fast you drove after the first failure.
Keep the complete brake system in good operating condition by checking fluid levels, repairing ANY leaks, keeping pad/shoe linings well within specs, making any necessary caliper park brake or drum brake adjustments, and they will work as designed.

 

Here are a few I've run into. I know anything is possible, and catastrophic failures can and will occur, BUT most complete master failures are the result of:

Seat not adjusted properly as stated previously.
Poor maintenance.
Physical limitation not allowing full leg movement or pedal stroke.
Poor maintenance.
Water bottle, thermos or other items allowed to slide under or behind the brake pedal.
POOR maintenance!

 

Well. Tom P64 is yet, again, for the 7th time on this single little-old-thread, another person who has had no pedal on a dual master system after losing a line (plus his friend, as well, according to the thread). Regardless of what people are writing and think they are proving - true experiences don't lie. Maybe it's not a government conspiracy; maybe we 7 are plants for a new car company that is trying to tarnish the credibility of big car company names! Yeah! That's it! It's amazing how many Hamb members accept messed-up, old, and non-stock brake systems in their daily drivers.

 

Boils down to maintenance given the system is designed correctly. When I did the brakes on the Dart, I replaced everything and sprung a few extra bucks for the stainless steel line kit. Just in fitting the lines it was worth the extra bucks - SS lines much easier to form. I had to add a full loop at the master cylinder and it was easily done - no way could I of formed regular lines 360 degrees without kinking them.

My wife's 2010 MINI Cooper has already had it's brake fluid flushed at the dealership - MINI says every 2 years. I have never flushed brake fluid in any other vehicle that often - something that often is not on people's maintenace radar.

 

I guess if the OP is letting brake lines rust out, there's no changing his mind about much to the benefit of common sense anyway.

 

As a mechanic myself I do appreciate the added safety of a dual system and will be including one in my '53 'Binder. However if you take the precaution of inspecting your system you will have reduced the possibility of brake failure probably in half. Mine will be built with stainless steel lines, all new flex hoses, new wheel cylinders in back, rebuilt up front, and DOT 5 brake fluid to avoid water contamination.

 

I drove less than a mile, with very careful braking, planning ahead as much as possible, knowing that the brakes had something wrong.

I am skeptical about brakes fading under those conditions.

The rotors and pads appeared to be fine, and no other leaks were apparent. However, I cannot tell you the exact maintenance history of the car, since it wasn't my car. (After that mishap, I elected not to buy it, since my wife had witnessed the goings on, and would have been unlikely to accept that car in the driveway. )

It is possible that there may have been internal leakage between circuits in the MC. Or even leakage between portions of the reservoir that are supposed to stay separate. But that is a subtle problem that might not be detected until one of the circuits failed completely. How else would you know?

 

I will NEVER build a car without dual circuit brakes. I've been in more than one car with failed brakes on a single circuit master. Luckily the most damage was the pucker mark in the seat covers.
The ONE time I had a hose brake on a dual circuit system, it was VERY obvious something was wrong, but I was able to drive in traffic to a parts store to get it fixed.
My 2 cents, or what its worth.

 

Laughing, shaking head...

 

After I lost a rear brake line on my 99 F-150 and saw how ineffective half the brakes were ( even with dual master ) I have a new appreciation for a good working E-brake.

 

I have an 02 GMC and when the brake line popped, it was the front, at 55 mph. After I layed on the brakes and pulled my shorts out of my ass, I limped home. By the time I got 5 mile, nothing.

 

Cars stop pretty well with just front brakes but don't stop well at all with just rear brakes. For that reason, newer cars are being built with diagonal split(one front & opposite rear), which works pretty well.

 

They can work, but in a split second decision, you'll never get to it. I'm not talking about brakes going out 200 feet before you have to stop, I'm talking about you're on the freeway and the guy 50 feet in front locks his up. When you slam on that pedal and nothing happens, chances are you've already crashed or you're screaming and bracing for collision. PANIC will negate all safety features.

At best, it's a PARKING brake. THAT'S what they were originally made for. Over the years people started calling them emergency brakes, but they are not. That's due to practical reaction times.

 

Falcon, you bring up a good point and refreshed my memory about one of my junkers.
Years ago, I had a late 70s VW rabbit and I blew a rear brake line. That broken line, however, had come hot on the heels of many other repairs. I cut the back line to the master with a set of snips, and then flattened, bent, flattened, bent, flattened bent the line to close it out. I then put it back into the rear of the master as a plug. By the end of the week, a friend at the yard (V&V) had lined up an 84 Riveria, with a sunroof, for 350.00 (what style).
Long story short, I drove the car to V&V (the local junkyard in my hometown); but since I was 18 then, I picked my friend up and we drove around town locking the front wheels up at each stop sign. We scared the pejesus out of a lot of people.
Anyway, in that case, with the rear of the MC sealed, the fronts did work. Sure, she walked left to right a little when stopping, but she did stop.
I guess, like so many things in life, there are many variables. Meaning, on some cars, my story being proof, the system works fairly well. Yet, on others…
Funny thing, your story and thinking of that Rabbit made me recall my friend and I sitting up one night with beers and counting the cars that he and I owned since high school. He stopped at 22, and I at 36, and both of us knew that we had missed a few in between.
So, as accused by someone earlier on this thread, yes, I have owned a few jalopies in my time.

 

It has all been said here before.
When you build your car with aftermarket brake parts.And if with no fluid in the system and you cant' bottom out the master cylinder completely, because the the pedal hits the floor 1st then your dual brake system won't work. I have failures with single and dual systems, Its a bad feeling. The dual systems were marginally better.



Ago

 

I blew a flex line on a 88 Honda and flew through a red light, no brakes what so ever...

I also lost my wheel cyls on my DD but was able to continue driving it, and our 54 pontiac has blown rear wheel cyls and I still have brakes too.

 

I blew a rusted line on my winter driver with a dual chamber master cylinder. Pedal to the floor after a few pumps. Take the time to check and maintain you old style brake system regularly to prevent failures and you'll have years of trouble free cruisin (and stopping).