[jclyman]

I'm a little confused ... and, I didn't just fall off a turnip truck.

I thought the ALL cars nowadays, had two brake systems (each system operates two wheels). I can surely understand you having MAJOR brake failure, but TOTAL brake failure? Not sure how that happens when just one line fails.

Explain please.

 

[Panos]

I'm a little confused ... and, I didn't just fall off a turnip truck.

I thought the ALL cars nowadays, had two brake systems (each system operates two wheels). I can surely understand you having MAJOR brake failure, but TOTAL brake failure? Not sure how that happens when just one line fails.

Explain please.

That was my first thought as well. Shouldn't the front brakes maintain pressure in this situation?

 

[Diny]

It's an Euro spec car, brakes are all reversed :haha2:

 

[farquy]

I'm a little confused ... and, I didn't just fall off a turnip truck.

I thought the ALL cars nowadays, had two brake systems (each system operates two wheels). I can surely understand you having MAJOR brake failure, but TOTAL brake failure? Not sure how that happens when just one line fails.

Explain please.

I am afraid I have no idea. Would a leak no loose all brake fluid, or are there two complete systems?

I lost complete braking power. The pedal just sank to the floor with very little resistance.
It is a Euro car... MY01.

I am off to the dealers first thing to explain why my car is there and to get it repaired, I am sure he will explain.

 

[RemBrant]

First...thank god you're OK.

Next...Take a good look at the last pic you posted. a) The rear swaybar bracket is busted clean off, and b) it looks like the threaded end of the bolt for the swaybar is rubbing on the brake hose. It should be nowhere near the hose.

I'm not saying that caused it, but it looks like it may have contributed.

Maybe invest in the Billet sway bar brackets right away so this never happens again! :M5thumbs:

 

[RICKROSS]

split system so one front and opposite rear should still have worked???

 

[Need4Spd]

Yow! I'm glad you are ok. It sure looks like the broken sway bar bracket helped split the hose. Normally there are at least several inches clearance. It's a good practice to inspect all the brake lines at every oil change or certainly at each Inspection interval, especially if you have braided steel lines.

As for why one brake hose failure resulted in total failure, this is expected. When you bleed brakes and open just one bleed screw (same effect as a broken brake line), the pedal goes all the way to the floor, now, doesn't it? But, I can't explain what failure mode would result in only one of the two brake circuits failing. I never could figure out how having two circuits would help in the event of a brake failure and what kinds of failures it would work on. Maybe someone else could explain.

 

[whatheheck]

Yeah, I noticed too on your last photo that your rear sway bar bracket is completely broken. Make sure you get that replaced with some heavy duty ones so you wont have to worry about replacing it again.

Stock rear sway bar brackets are known to be a weakness.

Also, you may want to possibly upgrade to stainless steel brake lines. They are a worth investment and gives you a better pedal feel.

Glad to hear you're safe.

 

[Cousinvin11]

I'm a little confused ... and, I didn't just fall off a turnip truck.

I thought the ALL cars nowadays, had two brake systems (each system operates two wheels). I can surely understand you having MAJOR brake failure, but TOTAL brake failure? Not sure how that happens when just one line fails.

Explain please.

The two brake systems still use one master cylinder reserve tank. I am guessing once too much fluid comes out...no systems will have pressure eventually

 

[m5 deamon]

personaly i think it was weeping way before the total brake failure and that was the final staw. if i were you my friend i would upgrade the sway bar brakets and put 4 braded brake lines . here in the states were breaking the law big time doing 150but in germany on the autobahn you can do that speed at will withthe proper conditions. think about how 200 or 300 euros could save you life with these two items this board has metioned. glad all worked out and ur safe

 

[whatheheck]

- Stainless steel braided brake lines: Here's what I have installed on mine:

http://www.beastpower.com/Merchant2...T-BEALL-SSLINES&Category_Code=&Store_Code=BMI

- Rear sway bar brackets: Here's what I have installed:

http://www.beastpower.com/Merchant2...PROD&Store_Code=BMI&Product_Code=TC-BE39-RSBB

Very happy with both items above.

 

[jclyman]

The master cylinder (at least in the US) has a separator between two "pools" of brake fluid. Even if one line was totally disconnected, there would be fluid supporting the other two (wheel) brakes. Unless it was very low already from brake pad wear. The master cylinder is difficult to get to, so probably not checked very often, but I would expect a light on the dashboard warning of a low fluid condition. Also, the clutch uses the same master cylinder. And, if the clutch still worked there would have to be fluid available for it.

In short, pumping the brake pedal should have worked somewhat.

Very strange.

farquy, you ought to ask Dave Zeckhausen.

 

[KBK]

Yes, the sway original sway bar brackets on these cars are a "100% MUST inspect item, once every month, at a minimum.

I let one of mine go for about 2 months, not thinking it was a big deal. I finally got around to buying two new ones.

When I crawled underneath the car to inspect the blown one, and replace it (and the other at the same time)..I found a brake line that was worn half way thorough! Holy crap batman!

BMW could get their butts sued off here, on this one. It would actually be possible to have BMW make a better mount,and give it away to everyone who owns a E39M5. Or an E39 or any kind, for that matter.

This is a very serious situation for BMW. These things happen and I'd have to say that far worse things have happened with other companies.

But a penchant for having E39 M5's blow their own brake lines is very serious indeed.

I realize this is an older car, and BMW's obligations to its customers have largely and correctly ended..but....

....Killing them is definitely not on the menu of considerations that they can walk away from.

And that's the one they can be nailed on.

As these E39 cars get older..more and more of this will happen.

So BMW had better nip this in the bud. As it is only going to become far more expensive in the long run.


For example, some litigious (rhymes with religious) a-hole from the ambulance chasing crowd could attempt to make this situation into a career move of a sort, and start compiling evidence in BMW E39 'brake failure claim' accidents. And then use the whole pile'o'stuff to start a class action suit. That's the kind of thing that just might happen in the future on this one. Perhaps I'm totally off base, here. But somehow I doubt it.

 

[MarkQC]

scary thought - no brakes...

...let me know when you go to the ring this spring - most the Brits I see there are E34 etc...

 

[Dr Pooface]

The master cylinder (at least in the US) has a separator between two "pools" of brake fluid. Even if one line was totally disconnected, there would be fluid supporting the other two (wheel) brakes. Unless it was very low already from brake pad wear. The master cylinder is difficult to get to, so probably not checked very often, but I would expect a light on the dashboard warning of a low fluid condition. Also, the clutch uses the same master cylinder. And, if the clutch still worked there would have to be fluid available for it.

In short, pumping the brake pedal should have worked somewhat.

Very strange.

farquy, you ought to ask Dave Zeckhausen.

I think you are completely mistaken. Lets think about this logically. When you bleed brakes the pedal goes to the floor, right? I'm not sure where you get your information from.

 

[DouglasABaker]

Brakes have 2 semi-independent circuits

I think you are completely mistaken. Lets think about this logically. When you bleed brakes the pedal goes to the floor, right? I'm not sure where you get your information from.

I'm guessing he looked here, here, or here.

Sorry folks, John is right - there are 2 separate circuits in brake systems and he should have had stopping power on his front left and rear right wheel.

Remind me not to let any of you guys work on my brakes

Oh, and to answer the question about bleeding, the pedal goes all the way to the floor slowly because you are also clamping down on the other wheels - hence the distributed brake force all 3 articles reference. No one is saying that you don't lose pressure out the ruptured brake line, just that you are also sending pressure down the remaining good brakes.

I haven't looked into our master cylinder specifically to verify we have 2 circuits, but it certainly seems likely...

d-

 

[DouglasABaker]

As for why one brake hose failure resulted in total failure, this is expected. When you bleed brakes and open just one bleed screw (same effect as a broken brake line), the pedal goes all the way to the floor, now, doesn't it? But, I can't explain what failure mode would result in only one of the two brake circuits failing. I never could figure out how having two circuits would help in the event of a brake failure and what kinds of failures it would work on. Maybe someone else could explain.

Only on a single circuit vehicle, which I do not believe (although I could be wrong) includes the M5.

The pedal goes to the floor during bleeding because you have a circuit open and are losing pressure - that part is normal. BUT, try rolling the car during your next bleed - you won't be able to because you are still sending pressure to the other brake circuit. Which, in this particular case, should have helped to stop the vehicle.

I concur with John, it would have required pumping, but he should have had stopping power on 2 wheels.

My guess is that he will either find that he has a failure in the 2nd circuit as well (unlikely) or will have learned to pump the brakes rapidly to build pressure if this ever (hopefully not!) occurs again.

d-

 

[Panos]

The two brake systems still use one master cylinder reserve tank. I am guessing once too much fluid comes out...no systems will have pressure eventually

Makes sense. Learn something new everyday.

So I guess those sway bar brackets are more dangerous than I thought.

This post should help sell a few of those reinforced aftermarket ones ;-)

 

[Panos]

Remind me not to let any of you guys work on my brakes

Oh, and to answer the question about bleeding, the pedal goes all the way to the floor slowly because you are also clamping down on the other wheels - hence the distributed brake force all 3 articles reference. No one is saying that you don't lose pressure out the ruptured brake line, just that you are also sending pressure down the remaining good brakes.

I haven't looked into our master cylinder specifically to verify we have 2 circuits, but it certainly seems likely...

d-

I guess you wont be working on mine either

First of all the 2 circuits are separated front to back. Front wheels on one and the rear two on the other. The reason for this is so that the abs can bias the pressure distribution front to back. The rear caliper pistons are smaller and require less pressure compared to the front.

2nd, Vin is right.

Sure if the right rear ruptures as you are pressing the brake than there will still be pressure until empty that circuit and the reservoir. At this point the only help that the seperate circuits has given you is in leaving fluid in the 2nd circuit. However, remember that the master cylinder dumped everything it had into the open circuit, leaving nothing behind to pressurize the undamaged circuit. So there you have it.

Farquy,

You got come good advice here. Get the beefier brackets and SS lines! Good luck!