Brake failure

John Kallend · Post by **John Kallend** » Tue Feb 07, 2017 7:28 am

I think you underestimate just how cold the US upper midwest can get in January. (-32) degrees C would need more than "a drop". _____________________________John KallendProfessor EmeritusDepartment of Mechanical, Materials and Aerospace EngineeringDepartment of PhysicsIIT, Chicago

On Tue, Feb 7, 2017 at 8:52 AM, Norman Verona norman@frenchblat.com> wrote: John, drop of anti-freeze will cure that. May rot the rubber seals but the brakes would still work until then.[u][/u][u][/u]
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[b]Norman Verona[u][/u][u][/u][/b]
La Foie, 49520, Noellet, France[u][/u][u][/u]
Tel: 0033 (0)2 41 92 73 44[u][/u][u][/u]
Mob: 0033 (0)7 70 70 23 79[u][/u][u][/u]
Website: www FrenchBlat com (put dots in the spaces)[u][/u][u][/u]
[u][/u] [u][/u]
[b]From:[/b] John Kallend [mailto:kallend@iit.edu] [b]Sent:[/b] 07 February 2017 15:44 [b]To:[/b] Norman Verona norman@frenchblat.com> [b]Cc:[/b] Clive P Sherriff csherriff99@gmail.com>; Duncan morelists@yahoo.com>; MG T-Series List mg-tabc@yahoogroups.com>; James Davis burburyclose@yahoo.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure[u][/u][u][/u]
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Ummm. well, there is that FREEZING thing too. In a Chicago winter water might just be a problem.[u][/u][u][/u]
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_____________________________[u][/u][u][/u]
John Kallend[u][/u][u][/u]
Professor Emeritus[u][/u][u][/u]
Department of Mechanical, Materials and Aerospace Engineering[u][/u][u][/u]
Department of Physics[u][/u][u][/u]
IIT, Chicago[u][/u][u][/u]
[u][/u] [u][/u]
On Tue, Feb 7, 2017 at 8:40 AM, Norman Verona norman@frenchblat.com> wrote:[u][/u][u][/u]
The only reason we don t use water in our braking system is due to the corrosion that it would cause. I ve used water to get home after a roadside fix of a broken brake pipe (mole grips on pipe)[u][/u][u][/u]
[u][/u][u][/u]
[b]Norman Verona[/b][u][/u][u][/u]
La Foie, 49520, Noellet, France[u][/u][u][/u]
Tel: 0033 (0)2 41 92 73 44[u][/u][u][/u]
Mob: 0033 (0)7 70 70 23 79[u][/u][u][/u]
Website: www FrenchBlat com (put dots in the spaces)[u][/u][u][/u]
[u][/u][u][/u]
[b]From:[/b] mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]John Kallend kallend@iit.edu [mg-tabc] [b]Sent:[/b] 07 February 2017 15:05 [b]To:[/b] Clive P Sherriff csherriff99@gmail.com> [b]Cc:[/b] Duncan morelists@yahoo.com>; MG T-Series List mg-tabc@yahoogroups.com>; James Davis burburyclose@yahoo.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure[u][/u][u][/u]
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The bulk modulus of water is 2.15 GPa. For all practical purposes in a braking system it is incompressible..[u][/u][u][/u]
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Most commercial hydraulic fluids are in the same ballpark.[u][/u][u][/u]
[u][/u][u][/u]
_____________________________[u][/u][u][/u]
John Kallend[u][/u][u][/u]
Professor Emeritus[u][/u][u][/u]
Department of Mechanical, Materials and Aerospace Engineering[u][/u][u][/u]
Department of Physics[u][/u][u][/u]
IIT, Chicago[u][/u][u][/u]
[u][/u][u][/u]
On Wed, Feb 8, 2017 at 7:34 AM, 'Clive P Sherriff' csherriff99@gmail.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:[u][/u][u][/u]
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Duncan,[u][/u][u][/u]
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No, physics and chemistry don't work that way, in anyone's Lab.[u][/u][u][/u]
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Water in the system does reduce braking, but only because the water is more compressible than brake fluid. You could probably get quite reasonable braking by draining all the fluid and replacing it with water, or kerosine, or malt whisky, about any liquid in fact.[u][/u][u][/u]
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Anyway, even boiling does not release oxygen from water, it produces water gas (steam). [u][/u][u][/u]
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Could be fun though, because if it did and produced oxygen, it would also have to produce hydrogen Then the brake system may well explode ![u][/u][u][/u]
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Clive[u][/u][u][/u]
= ============================== ===[u][/u][u][/u]
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----- Original Message ----- [u][/u][u][/u]
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[b]To:[/b] mg-tabc@yahoogroups.com ; burburyclose@yahoo.com [u][/u][u][/u]
[b]Sent:[/b] Tuesday, February 07, 2017 9:14 AM[u][/u][u][/u]
[b]Subject:[/b] Re: [mg-tabc] Brake Failure[u][/u][u][/u]
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Might have never been properly bled when brakes last serviced. And remember that H2O contains oxygen, and H20 will get into the TC system's fluid, and it does not require a chemistry lab or textbook perfect boiling of the brake fluid to liberate some of oxygen from the water. It just happens, from pressure and other things.. Another good reason to flush your system every couple years and put in fresh brake fluid. It is good to be constantly paranoid about potential brake problems in these cars, as the brake system is not all that great from a modern safety standpoint. The TC parking brake, on the other hand, is superb. Duncan- CA To: "Mg-Tabc" mg-tabc@yahoogroups.com> Date: Monday, February 6, 2017, 2:02 PM .----------------------------- --------------- On Mon, 2/6/17, James Davis burburyclose@yahoo.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote: Subject: [mg-tabc] Brake Failure Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston [u][/u][u][/u]
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Steve S · Post by **Steve S** » Tue Feb 07, 2017 8:28 am

The master cylinder does not have to be empty for brake failure to occur. Failure of the internal rubber components will do the same thing, with or without a leak. I still suspect the master cylinder is the issue but there are several causes possible. If there is still fluid in the reservoir then it has to be either air in the system or the master cylinder internals. I suspect we will soon find out.

On a related note, one time when my TC had been sitting for about a month, the brakes went almost to the floor at the end of my street. A few additional presses of the pedal returned normal braking and it never had that problem again. I have my suspicions about the cause but I never positively identified it.

- Steve Simmons, TC8975

On February 7, 2017 1:25:41 AM "Norman Verona" norman@frenchblat.com> wrote:

Steve, the point is the OP said there was no signs of a leak. To get total brake failure the master cylinder must empty completely. And to get sudden total failure the leak must be substantial. I have suggested that before going for the unusual, with the master cylinder the wheel cylinders and the brake pipes are inspected. It would appear we are talking a substantial leak so it should be clearly visible.

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 09:25 [b]To:[/b] 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

It takes very little air to cause massive brake fade. When you bleed the brakes, each pump yields a lot of fluid with a small amount of bubbles. However the brakes go from soft to firm. If you somehow had enough air coming in from below to displace 3/4" of fluid in the cylinder and overflow it, you'd probably completely empty all four cylinders and half of the hard lines! - Steve Simmons, TC8975
On 2/6/2017 11:49 PM, 'Norman Verona' norman@frenchblat.com [mg-tabc] wrote:

Steve,

In which case the fluid would be overflowing from the master.

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 02:48 [b]To:[/b] MG tabcgroups MG-tabc@yahoogroups.com [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Agreed. Air can definitely come in past the wheel cylinder cups. No leak necessary. If the master cylinder returns faster than the brake shoes, air can be pulled in. Ensure the brake springs are all in correct working condition to prevent it from happening. - Steve Simmons, TC8975
On 2/6/2017 5:26 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote:

I had a continual problems with air entering the braking system, likely coming via wheel cylinder(s) that may have been seeping slightly, don't discard that end of the system as the problem. Bleeding would result in a hard peddle that over time would become softer in use.
Steve TC2911

[b]From:[/b] "James Davis burburyclose@yahoo.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com [b]To:[/b] Mg-Tabc mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, February 6, 2017 5:02 PM [b]Subject:[/b] [mg-tabc] Brake Failure

Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston

Benny Grumer · Post by **Benny Grumer** » Tue Feb 07, 2017 8:39 am

Norman,

If the cup seal in the m/c is defective brake fluid will "run" from the front of the seal to the back without a outside leak the level in the M/C will remain the same…

Benny

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Norman Verona · Post by **Norman Verona** » Tue Feb 07, 2017 10:35 am

Steve,

You haven t read all my posts on the subject. I also said to check the wheel cylinders and brake pipes. The master cylinder would be my last port of call.

The master cylinder may have had very little fluid in it the day before then ran out overnight.

I have to take the events as posted, if not how can we ever help.

[b]Norman Verona[/b]

La Foie, 49520, Noellet, France

Tel: 0033 (0)2 41 92 73 44

Mob: 0033 (0)7 70 70 23 79

Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] Stephen D Stierman [mailto:morgan7709@sbcglobal.net] [b]Sent:[/b] 07 February 2017 15:56 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Norman,

I am not necessarily debating your premise that the MC is at fault, what I am saying is before the OP decides that is the problem, he ought take a good close look at the rest of system to be sure nothing else has gone south. Unless of course all the hydraulics have just been rebuilt/replaced which still doesn't guarantee that there is not a problem. Additionally you are taking his description of events at face value and his explanation may not be quite the same as mine should I experience a similar situation.

Steve TC2911

[b]From:[/b] "'Norman Verona' norman@frenchblat.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Stephen D Stierman' morgan7709@sbcglobal.net>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Sent:[/b] Tuesday, February 7, 2017 9:19 AM [b]Subject:[/b] RE: [mg-tabc] Brake Failure

Steve, I agree. However the report said the pedal was hard one day and no brakes at all the next. A master cylinder with mixed air and fluid will give a spongy pedal which will pump up to hard is pumped. However a cylinder which is completely empty will have a pedal which goes to the floor and will not pump up.

Do you disagree?

[b]Norman Verona[/b]

La Foie, 49520, Noellet, France

Tel: 0033 (0)2 41 92 73 44

Mob: 0033 (0)7 70 70 23 79

Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] Stephen D Stierman [morgan7709@sbcglobal.net] [b]Sent:[/b] 07 February 2017 12:19 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Not so Norman,

As Steve points out and I have found personally, enough air entering via wheel cylinder(s) and a bit of loss at the same place, will cause a peddle to become softer over time, eventually causing brake actuation to become almost nil.

Steve TC2911

From: "'Norman Verona' norman@frenchblat.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Sent:[/b] Tuesday, February 7, 2017 4:25 AM [b]Subject:[/b] RE: [mg-tabc] Brake Failure

Steve, the point is the OP said there was no signs of a leak. To get total brake failure the master cylinder must empty completely. And to get sudden total failure the leak must be substantial. I have suggested that before going for the unusual, with the master cylinder the wheel cylinders and the brake pipes are inspected. It would appear we are talking a substantial leak so it should be clearly visible.

[b]Norman Verona[/b]

La Foie, 49520, Noellet, France

Tel: 0033 (0)2 41 92 73 44

Mob: 0033 (0)7 70 70 23 79

Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 09:25 [b]To:[/b] 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

It takes very little air to cause massive brake fade. When you bleed the brakes, each pump yields a lot of fluid with a small amount of bubbles. However the brakes go from soft to firm. If you somehow had enough air coming in from below to displace 3/4" of fluid in the cylinder and overflow it, you'd probably completely empty all four cylinders and half of the hard lines!

- Steve Simmons, TC8975

On 2/6/2017 11:49 PM, 'Norman Verona' norman@frenchblat.com [mg-tabc] wrote:

Steve,

In which case the fluid would be overflowing from the master.

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 02:48 [b]To:[/b] MG tabcgroups MG-tabc@yahoogroups.com [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Agreed. Air can definitely come in past the wheel cylinder cups. No leak necessary. If the master cylinder returns faster than the brake shoes, air can be pulled in. Ensure the brake springs are all in correct working condition to prevent it from happening.
- Steve Simmons, TC8975

On 2/6/2017 5:26 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote:

I had a continual problems with air entering the braking system, likely comi! ng via wheel cylinder(s) that may have been seeping slightly, don't discard that end of the system as the problem. Bleeding would result in a hard peddle that over time would become softer in use.
Steve TC2911

[b]From:[/b] "James Davis burburyclose@yahoo.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com [b]To:[/b] Mg-Tabc mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, February 6, 2017 5:02 PM [b]Subject:[/b] [mg-tabc] Brake Failure

Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston

Norman Verona · Post by **Norman Verona** » Tue Feb 07, 2017 10:38 am

Having spent two weeks in Chicago in February I know how cold it gets with the wind blowing across the lakes. One night we came down to the car and found rock hard rain droplets on it. It had rained then froze solid. When my host got us to his home he had no idea how to drive on ice and nearly turned the car over as he tried to get up his drive to the garage. We ended up sliding sideways into his front garden.

[b]Norman Verona[/b]

La Foie, 49520, Noellet, France

Tel: 0033 (0)2 41 92 73 44

Mob: 0033 (0)7 70 70 23 79

Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] John Kallend [mailto:kallend@iit.edu] [b]Sent:[/b] 07 February 2017 16:29 [b]To:[/b] Norman Verona norman@frenchblat.com> [b]Cc:[/b] Clive P Sherriff csherriff99@gmail.com>; Duncan morelists@yahoo.com>; MG T-Series List mg-tabc@yahoogroups.com>; James Davis burburyclose@yahoo.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

I think you underestimate just how cold the US upper midwest can get in January. (-32) degrees C would need more than "a drop".

_____________________________

John Kallend

Professor Emeritus

Department of Mechanical, Materials and Aerospace Engineering

Department of Physics

IIT, Chicago

On Tue, Feb 7, 2017 at 8:52 AM, Norman Verona norman@frenchblat.com> wrote:

John, drop of anti-freeze will cure that. May rot the rubber seals but the brakes would still work until then.

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] John Kallend [mailto:kallend@iit.edu] [b]Sent:[/b] 07 February 2017 15:44 [b]To:[/b] Norman Verona norman@frenchblat.com> [b]Cc:[/b] Clive P Sherriff csherriff99@gmail.com>; Duncan morelists@yahoo.com>; MG T-Series List mg-tabc@yahoogroups.com>; James Davis burburyclose@yahoo.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Ummm. well, there is that FREEZING thing too. In a Chicago winter water might just be a problem.

_____________________________
John Kallend
Professor Emeritus
Department of Mechanical, Materials and Aerospace Engineering
Department of Physics
IIT, Chicago

On Tue, Feb 7, 2017 at 8:40 AM, Norman Verona norman@frenchblat.com> wrote:
The only reason we don t use water in our braking system is due to the corrosion that it would cause. I ve used water to get home after a roadside fix of a broken brake pipe (mole grips on pipe)

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]John Kallend kallend@iit.edu [mg-tabc] [b]Sent:[/b] 07 February 2017 15:05 [b]To:[/b] Clive P Sherriff csherriff99@gmail.com> [b]Cc:[/b] Duncan morelists@yahoo.com>; MG T-Series List mg-tabc@yahoogroups.com>; James Davis burburyclose@yahoo.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

The bulk modulus of water is 2.15 GPa. For all practical purposes in a braking system it is incompressible..

Most commercial hydraulic fluids are in the same ballpark.

_____________________________
John Kallend
Professor Emeritus
Department of Mechanical, Materials and Aerospace Engineering
Department of Physics
IIT, Chicago

On Wed, Feb 8, 2017 at 7:34 AM, 'Clive P Sherriff' csherriff99@gmail.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:

Duncan,

No, physics and chemistry don't work that way, in anyone's Lab.

Water in the system does reduce braking, but only because the water is more compressible than brake fluid.   You could probably get quite reasonable braking by draining all the fluid and replacing it with water, or kerosine, or malt whisky, about any liquid in fact.

Anyway, even boiling does not release oxygen from water, it produces water gas (steam).

Could be fun though, because if it did and produced oxygen, it would also have to produce hydrogen    Then the brake system may well explode !

Clive
= =================================

----- Original Message -----
[b]From:[/b] morelists@yahoo.com+[mg-tabc]
[b]To:[/b] mg-tabc@yahoogroups.com ; burburyclose@yahoo.com
[b]Sent:[/b] Tuesday, February 07, 2017 9:14 AM
[b]Subject:[/b] Re: [mg-tabc] Brake Failure

Might have never been properly bled when brakes last serviced. And remember that H2O contains oxygen, and H20 will get into the TC system's fluid, and it does not require a chemistry lab or textbook perfect boiling of the brake fluid to liberate some of oxygen from the water. It just happens, from pressure and other things.. Another good reason to flush your system every couple years and put in fresh brake fluid. It is good to be constantly paranoid about potential brake problems in these cars, as the brake system is not all that great from a modern safety standpoint. The TC parking brake, on the other hand, is superb. Duncan- CA To: "Mg-Tabc" mg-tabc@yahoogroups.com> Date: Monday, February 6, 2017, 2:02 PM .-------------------------------------------- On Mon, 2/6/17, James Davis burburyclose@yahoo.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote: Subject: [mg-tabc] Brake Failure Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston

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Norman Verona · Post by **Norman Verona** » Tue Feb 07, 2017 10:43 am

Steve,

I m aware of seal failure in master cylinders. However wheel cylinder and brake pipe leaks are more common so that s what I would check first.

I have no idea what the problem is, I m only offering a systematic testing procedure. If the car was in front of me I may be able to diagnose better than over the internet, but as that isn t the case I offer my experience in checking the system for the fault.

Of course, there may not be a fault, the fluid in the master may have evaporated through heat from the exhaust, especially if the heat shield is missing. I ve lined my shield with exhaust wrap.

[b]Norman Verona[/b]

La Foie, 49520, Noellet, France

Tel: 0033 (0)2 41 92 73 44

Mob: 0033 (0)7 70 70 23 79

Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 17:28 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] RE: [mg-tabc] Brake Failure

The master cylinder does not have to be empty for brake failure to occur. Failure of the internal rubber components will do the same thing, with or without a leak. I still suspect the master cylinder is the issue but there are several causes possible. If there is still fluid in the reservoir then it has to be either air in the system or the master cylinder internals. I suspect we will soon find out.

On a related note, one time when my TC had been sitting for about a month, the brakes went almost to the floor at the end of my street. A few additional presses of the pedal returned normal braking and it never had that problem again. I have my suspicions about the cause but I never positively identified it.

- Steve Simmons, TC8975

On February 7, 2017 1:25:41 AM "Norman Verona" norman@frenchblat.com> wrote:

Steve, the point is the OP said there was no signs of a leak. To get total brake failure the master cylinder must empty completely. And to get sudden total failure the leak must be substantial. I have suggested that before going for the unusual, with the master cylinder the wheel cylinders and the brake pipes are inspected. It would appear we are talking a substantial leak so it should be clearly visible.

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 09:25 [b]To:[/b] 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

It takes very little air to cause massive brake fade. When you bleed the brakes, each pump yields a lot of fluid with a small amount of bubbles. However the brakes go from soft to firm. If you somehow had enough air coming in from below to displace 3/4" of fluid in the cylinder and overflow it, you'd probably completely empty all four cylinders and half of the hard lines! - Steve Simmons, TC8975
On 2/6/2017 11:49 PM, 'Norman Verona' norman@frenchblat.com [mg-tabc] wrote:

Steve,

In which case the fluid would be overflowing from the master.

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 02:48 [b]To:[/b] MG tabcgroups MG-tabc@yahoogroups.com [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Agreed. Air can definitely come in past the wheel cylinder cups. No leak necessary. If the master cylinder returns faster than the brake shoes, air can be pulled in. Ensure the brake springs are all in correct working condition to prevent it from happening. - Steve Simmons, TC8975
On 2/6/2017 5:26 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote:

I had a continual problems with air entering the braking system, likely coming via wheel cylinder(s) that may have been seeping slightly, don't discard that end of the system as the problem. Bleeding would result in a hard peddle that over time would become softer in use.
Steve TC2911

[b]From:[/b] "James Davis burburyclose@yahoo.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com [b]To:[/b] Mg-Tabc mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, February 6, 2017 5:02 PM [b]Subject:[/b] [mg-tabc] Brake Failure

Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston

Norman Verona · Post by **Norman Verona** » Tue Feb 07, 2017 10:47 am

Benny, my experience is that you still get a pedal if it’s pushed sharply. The pedal normally only goes to the floor when pressed slowly.

But, I agree it can lead to total brake failure. All I’m saying (getting boring repeating myself) is to thoroughly check for leaks as the OP said there was air in the system.

I must add that this seems to be an amazing system that allows enough air into it for total failure but has no leaks at all.

[b]Norman Verona[/b]

La Foie, 49520, Noellet, France

Tel: 0033 (0)2 41 92 73 44

Mob: 0033 (0)7 70 70 23 79

Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Benny Grumer jaguarb@inter.net.il [mg-tabc] [b]Sent:[/b] 07 February 2017 17:43 [b]To:[/b] mg-tabc@yahoogroups.com [b]Subject:[/b] RE: [mg-tabc] Brake Failure

Norman,

If the cup seal in the m/c is defective brake fluid will "run" from the front of the seal to the back without a outside leak the level in the M/C will remain the same…

Benny

__________ Information from ESET NOD32 Antivirus, version of virus signature database 14898 (20170207) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

Stephen D Stierman · Post by **Stephen D Stierman** » Tue Feb 07, 2017 10:48 am

That is fine, great minds think alike.Steve TC2911 [b]From:[/b] "'Norman Verona' norman@frenchblat.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Stephen D Stierman' morgan7709@sbcglobal.net>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Sent:[/b] Tuesday, February 7, 2017 1:34 PM [b]Subject:[/b] RE: [mg-tabc] Brake Failure Steve, You haven t read all my posts on the subject. I also said to check the wheel cylinders and brake pipes. The master cylinder would be my last port of call. The master cylinder may have had very little fluid in it the day before then ran out overnight. I have to take the events as posted, if not how can we ever help. [b]Norman Verona[/b]La Foie, 49520, Noellet, FranceTel: 0033 (0)2 41 92 73 44Mob: 0033 (0)7 70 70 23 79Website: www FrenchBlat com (put dots in the spaces) [b]From:[/b] Stephen D Stierman [mailto:morgan7709@sbcglobal.net] [b]Sent:[/b] 07 February 2017 15:56 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure Norman,I am not necessarily debating your premise that the MC is at fault, what I am saying is before the OP decides that is the problem, he ought take a good close look at the rest of system to be sure nothing else has gone south. Unless of course all the hydraulics have just been rebuilt/replaced which still doesn't guarantee that there is not a problem. Additionally you are taking his description of events at face value and his explanation may not be quite the same as mine should I experience a similar situation. Steve TC2911[b]From:[/b] "'Norman Verona' norman@frenchblat.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Stephen D Stierman' morgan7709@sbcglobal.net>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Sent:[/b] Tuesday, February 7, 2017 9:19 AM [b]Subject:[/b] RE: [mg-tabc] Brake Failure Steve, I agree. However the report said the pedal was hard one day and no brakes at all the next. A master cylinder with mixed air and fluid will give a spongy pedal which will pump up to hard is pumped. However a cylinder which is completely empty will have a pedal which goes to the floor and will not pump up. Do you disagree? [b]Norman Verona[/b]La Foie, 49520, Noellet, FranceTel: 0033 (0)2 41 92 73 44Mob: 0033 (0)7 70 70 23 79Website: www FrenchBlat com (put dots in the spaces) [b]From:[/b] Stephen D Stierman [morgan7709@sbcglobal.net] [b]Sent:[/b] 07 February 2017 12:19 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure Not so Norman,As Steve points out and I have found personally, enough air entering via wheel cylinder(s) and a bit of loss at the same place, will cause a peddle to become softer over time, eventually causing brake actuation to become almost nil.Steve TC2911 From: "'Norman Verona' norman@frenchblat.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Sent:[/b] Tuesday, February 7, 2017 4:25 AM [b]Subject:[/b] RE: [mg-tabc] Brake Failure Steve, the point is the OP said there was no signs of a leak. To get total brake failure the master cylinder must empty completely. And to get sudden total failure the leak must be substantial. I have suggested that before going for the unusual, with the master cylinder the wheel cylinders and the brake pipes are inspected. It would appear we are talking a substantial leak so it should be clearly visible. [b]Norman Verona[/b]La Foie, 49520, Noellet, FranceTel: 0033 (0)2 41 92 73 44Mob: 0033 (0)7 70 70 23 79Website: www FrenchBlat com (put dots in the spaces) [b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 09:25 [b]To:[/b] 'MG tabcgroups' MG-tabc@yahoogroups.com> Subject: Re: [mg-tabc] Brake Failure It takes very little air to cause massive brake fade. When you bleed the brakes, each pump yields a lot of fluid with a small amount of bubbles. However the brakes go from soft to firm. If you somehow had enough air coming in from below to displace 3/4" of fluid in the cylinder and overflow it, you'd probably completely empty all four cylinders and half of the hard lines!- Steve Simmons, TC8975 On 2/6/2017 11:49 PM, 'Norman Verona' norman@frenchblat.com [mg-tabc] wrote:

Steve, In which case the fluid would be overflowing from the master. [b]Norman Verona[/b]La Foie, 49520, Noellet, FranceTel: 0033 (0)2 41 92 73 44Mob: 0033 (0)7 70 70 23 79Website: www FrenchBlat com (put dots in the spaces) [b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 02:48 [b]To:[/b] MG tabcgroups MG-tabc@yahoogroups.com [b]Subject:[/b] Re: [mg-tabc] Brake Failure Agreed. Air can definitely come in past the wheel cylinder cups. No leak necessary. If the master cylinder returns faster than the brake shoes, air can be pulled in. Ensure the brake springs are all in correct working condition to prevent it from happening.- Steve Simmons, TC8975 On 2/6/2017 5:26 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote: I had a continual problems with air entering the braking system, likely comi! ng via wheel cylinder(s) that may have been seeping slightly, don't discard that end of the system as the problem. Bleeding would result in a hard peddle that over time would become softer in use.Steve TC2911 [b]From:[/b] "James Davis burburyclose@yahoo.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com [b]To:[/b] Mg-Tabc mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, February 6, 2017 5:02 PM [b]Subject:[/b] [mg-tabc] Brake Failure Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston

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Clive P Sherriff · Post by **Clive P Sherriff** » Tue Feb 07, 2017 11:44 am

Steve, you say >> Unless of course all the hydraulics have just been rebuilt/replaced I'd say that was the most important reason to check absolutely everything ! (Unless I'd rebuilt them of course ! Clive = ==================================

----- Original Message ----- [b]From:[/b] morgan7709@sbcglobal.net [mg-tabc] [b]To:[/b] norman@frenchblat.com ; mail@mgnuts.com ; MG-tabc@yahoogroups.com [b]Sent:[/b] Tuesday, February 07, 2017 2:56 PM [b]Subject:[/b] Re: [mg-tabc] Brake Failure Norman, I am not necessarily debating your premise that the MC is at fault, what I am saying is before the OP decides that is the problem, he ought take a good close look at the rest of system to be sure nothing else has gone south. Unless of course all the hydraulics have just been rebuilt/replaced which still doesn't guarantee that there is not a problem. Additionally you are taking his description of events at face value and his explanation may not be quite the same as mine should I experience a similar situation. Steve TC2911 [b]From:[/b] "'Norman Verona' norman@frenchblat.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Stephen D Stierman' morgan7709@sbcglobal.net>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Sent:[/b] Tuesday, February 7, 2017 9:19 AM [b]Subject:[/b] RE: [mg-tabc] Brake Failure Steve, I agree. However the report said the pedal was hard one day and no brakes at all the next. A master cylinder with mixed air and fluid will give a spongy pedal which will pump up to hard is pumped. However a cylinder which is completely empty will have a pedal which goes to the floor and will not pump up. Do you disagree? [b]Norman Verona[/b] La Foie, 49520, Noellet, France Tel: 0033 (0)2 41 92 73 44 Mob: 0033 (0)7 70 70 23 79 Website: www FrenchBlat com (put dots in the spaces) [b]From:[/b] Stephen D Stierman [mailto:morgan7709@sbcglobal.net] [b]Sent:[/b] 07 February 2017 12:19 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure Not so Norman, As Steve points out and I have found personally, enough air entering via wheel cylinder(s) and a bit of loss at the same place, will cause a peddle to become softer over time, eventually causing brake actuation to become almost nil. Steve TC2911 From: "'Norman Verona' norman@frenchblat.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> [b]To:[/b] 'Steve S' mail@mgnuts.com>; 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Sent:[/b] Tuesday, February 7, 2017 4:25 AM [b]Subject:[/b] RE: [mg-tabc] Brake Failure Steve, the point is the OP said there was no signs of a leak. To get total brake failure the master cylinder must empty completely. And to get sudden total failure the leak must be substantial. I have suggested that before going for the unusual, with the master cylinder the wheel cylinders and the brake pipes are inspected. It would appear we are talking a substantial leak so it should be clearly visible. [b]Norman Verona[/b] La Foie, 49520, Noellet, France Tel: 0033 (0)2 41 92 73 44 Mob: 0033 (0)7 70 70 23 79 Website: www FrenchBlat com (put dots in the spaces) [b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 09:25 [b]To:[/b] 'MG tabcgroups' MG-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure It takes very little air to cause massive brake fade. When you bleed the brakes, each pump yields a lot of fluid with a small amount of bubbles. However the brakes go from soft to firm. If you somehow had enough air coming in from below to displace 3/4" of fluid in the cylinder and overflow it, you'd probably completely empty all four cylinders and half of the hard lines! - Steve Simmons, TC8975 On 2/6/2017 11:49 PM, 'Norman Verona' norman@frenchblat.com [mg-tabc] wrote: Steve, In which case the fluid would be overflowing from the master. [b]Norman Verona[/b] La Foie, 49520, Noellet, France Tel: 0033 (0)2 41 92 73 44 Mob: 0033 (0)7 70 70 23 79 Website: www FrenchBlat com (put dots in the spaces) [b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]Steve S mail@mgnuts.com [mg-tabc] [b]Sent:[/b] 07 February 2017 02:48 [b]To:[/b] MG tabcgroups MG-tabc@yahoogroups.com [b]Subject:[/b] Re: [mg-tabc] Brake Failure Agreed. Air can definitely come in past the wheel cylinder cups. No leak necessary. If the master cylinder returns faster than the brake shoes, air can be pulled in. Ensure the brake springs are all in correct working condition to prevent it from happening. - Steve Simmons, TC8975 On 2/6/2017 5:26 PM, Stephen D Stierman morgan7709@sbcglobal.net [mg-tabc] wrote: I had a continual problems with air entering the braking system, likely comi! ng via wheel cylinder(s) that may have been seeping slightly, don't discard that end of the system as the problem. Bleeding would result in a hard peddle that over time would become softer in use. Steve TC2911 [b]From:[/b] "James Davis burburyclose@yahoo.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com [b]To:[/b] Mg-Tabc mg-tabc@yahoogroups.com [b]Sent:[/b] Monday, February 6, 2017 5:02 PM [b]Subject:[/b] [mg-tabc] Brake Failure Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston

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Clive P Sherriff · Post by **Clive P Sherriff** » Tue Feb 07, 2017 11:50 am

I definately does happen, and not just on T Types. A significant suction of air into the M/C is catastrophic, and the reservior fluid rise after the air is expelled through the bleed hole is virtually Zero, but the cylinder remains full of air. As you say. End of thread ! All best, Clive mm mmmmmmmmmmmmmmmmmmmmmm

----- Original Message ----- [b]From:[/b] norman@frenchblat.com [b]To:[/b] csherriff99@gmail.com ; burburyclose@yahoo.com ; mg-tabc@yahoogroups.com [b]Sent:[/b] Tuesday, February 07, 2017 2:35 PM [b]Subject:[/b] RE: [mg-tabc] Brake Failure Clive,

But what you describe, in my 50 years of experience, would not give a pedal that went to the floor. It would give a spongy pedal. For the pedal to go to the floor with no brakes at all the master cylinder must be empty so the cylinder is pumping pure air and no fluid at all. Even if 1cc of air is introduced the level in the master cylinder will rise. The area you talk of would fill with fluid on the next pump. If it didn t the brakes wouldn t work at all.

In my experience if the fluid was leaking slowly the brakes would become spongy. You would not get a firm, hard pedal one day and no pedal the next.

I think the best thing is for you to believe what you do and I ll believe what I do, because folks are probably getting fed up with the argument. (or highly entertained)

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] Clive P Sherriff [mailto:csherriff99@gmail.com] [b]Sent:[/b] 08 February 2017 14:26 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'James Davis' burburyclose@yahoo.com>; 'Mg-Tabc' mg-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Hi Norman,

Yes, I Disagree, it takes very little air in the master cylinder seal space, say about 1to 2cc (compared with the comparitively huge volume of the reservoir) to completely foul things up.

Additional sucked in air would perhaps go back in the reservoir, but then just bubble to the surface and out of the vent hole. You would see no difference in the reservoir level at all without very detailed measutement. Even a couple cc of air would lift the level less than 1mm when spread accross the large reservoir fluid surface area.

Clive
= ========================================
----- Original Message -----
[b]From:[/b] norman@frenchblat.com
[b]To:[/b] csherriff99@gmail.com ; burburyclose@yahoo.com ; mg-tabc@yahoogroups.com
[b]Sent:[/b] Tuesday, February 07, 2017 7:44 AM
[b]Subject:[/b] RE: [mg-tabc] Brake Failure

Clive, in which case the fluid would be coming out of the top of the master. All I m saying is that if a system is full of fluid to get air in some fluid must come out. Do you disagree with this?

[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)

[b]From:[/b] Clive P Sherriff [csherriff99@gmail.com] [b]Sent:[/b] 08 February 2017 00:46 [b]To:[/b] Norman Verona norman@frenchblat.com>; 'James Davis' burburyclose@yahoo.com>; 'Mg-Tabc' mg-tabc@yahoogroups.com> [b]Subject:[/b] Re: [mg-tabc] Brake Failure

Norman, If as I suggested at the start, there is a problem with the master cylinder seals, then it's quite possible that air has been sucked into the master cylinder by the pedal strokes.

Clive
m mmmmmmmmmmmmmmm

----- Original Message -----
[b]From:[/b] norman@frenchblat.com%20[mg-tabc]
[b]To:[/b] burburyclose@yahoo.com ; mg-tabc@yahoogroups.com
[b]Sent:[/b] Monday, February 06, 2017 10:42 PM
[b]Subject:[/b] RE: [mg-tabc] Brake Failure

Jim,
Something wrong with your statement. If there is air in the system then the fluid that was in there must have leaked out. I suspect you do have a leak otherwise the air cannot get into the system.
Think of a bottle which is full of water. To get more water in, or air, then the water in the bottle must overflow.
[b]Norman Verona[/b]
La Foie, 49520, Noellet, France
Tel: 0033 (0)2 41 92 73 44
Mob: 0033 (0)7 70 70 23 79
Website: www FrenchBlat com (put dots in the spaces)
[b]From:[/b] mg-tabc@yahoogroups.com [mg-tabc@yahoogroups.com] [b]On Behalf Of [/b]James Davis burburyclose@yahoo.com [mg-tabc] [b]Sent:[/b] 06 February 2017 23:03 [b]To:[/b] Mg-Tabc mg-tabc@yahoogroups.com> [b]Subject:[/b] [mg-tabc] Brake Failure

Thanks to all of you for your ideas. I checked the brake lines,MC, etc with no indication of leakage. Then I bled the line out. Much air in there. The brakes came back after bleeding. Perhaps when I tested the brakes HARD the day before, I explosed some intermittent crack etc in the system which only shows up with hard use. I plan to give it a rigorous test after my diff comes back from being worked over. I'm on pins and needles driving it now and will try to break the fault during the next hard test. I'll keep the group informed. Thanks again. Jim Davis TC 7225 Houston

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