Brake failure

[Peter Roberts]

Ok Listers, Here is a puzzler. When I put TC 0604 in cold storage, the brakes were fine. When I went to take it out, the pedal went to the floor. There where no leaks on the floor. I am using silicone which would have left a stain. Since then, I have rebuilt the Master Cylinder. The MC is working fine. The pedal still goes to the floor. In the meantime, can anyone explain where the fluid went? Even vigorous pumping does not produce any leaks. Tomorrow, I will persuade my trusty assistant to help bleed the brakes. _Peter

[FDShade@aol.com]

In a message dated 5/9/2005 2:38:44 PM Pacific Standard Time, mgtc@comcast.net writes: can anyone explain where the fluid went? Peter - Since it didn't leak out - it must still be there. Perhaps your brake linkage is not connected to you MC ? Jim Shade, West Covina CA [Non-text portions of this message have been removed]

[Terry Sanders]

Peter, it will go to the floor is you have a lot of air in the system...careful bleeding is in order. Are you sure that one of your wheel cylinders isn't leaking? Terry in Oakland Peter Roberts mgtc@comcast.net> wrote: Ok Listers, Here is a puzzler. When I put TC 0604 in cold storage, the brakes were fine. When I went to take it out, the pedal went to the floor. There where no leaks on the floor. I am using silicone which would have left a stain. Since then, I have rebuilt the Master Cylinder. The MC is working fine. The pedal still goes to the floor. In the meantime, can anyone explain where the fluid went? Even vigorous pumping does not produce any leaks. Tomorrow, I will persuade my trusty assistant to help bleed the brakes. _Peter Yahoo! Groups Links [Non-text portions of this message have been removed]

[eworpe]

Sudden brake failures are rare but when the underlying cause may not be, then I hope you'll agree it seems justified to reveal concerns. My TC's brake failure seemed to be due to fluid leaking past the cup seal in the master cylinder, only slight resistance could be felt as the foot pedal sank to the floor, time and time again without any fluid being lost. Dismantling the M/C revealed a polished bore free from any wear or corrosion (silicon fluid) and a cup seal that seemed intact but a little stiff. The special metal, multi fingered cup washer that splays out the cup seal was absent and replaced by a plastic buffer secured to the return spring. A comparison between a genuine Lockheed cup seal and the cup seal that failed, revealed that the stiffness at the sealing edge was partially due to the very edge of the cup being quite thick (1+mm), whilst that of the Lockheed cup was feather edged. It seems that the combination of a thick edge to the cup seal and the absence of a splaying out washer could result in the seal's lip lifting away from the wall of the M/C's bore, allowing fluid to leak past and possibly setting up a positive feedback situation where the fluid leaking past the seal's lip, forces the lip even further away from the wall of the bore. This home spun theory could explain why even when the brakes were applied forcefully, generating a sudden pressure pulse which would normally help the cup to seal to the wall, no such enhancement was produced. Fortunately the handbrake was effective, but if my reasoning is valid, then some replica M/C brake spares are suspect. Any thoughts welcome, Regards, Eric.

[Clive P Sherriff]

Eric,   A similar situation has been known when refilling with Silicon Brake fluid after using "normal" fluid, without replacing the master cylinder (and wheel cylinder) seals at the same time.   Clive = ==========================

----- Original Message ----- [b]From:[/b] E.Worpe@surrey.ac.uk [mg-tabc] [b]To:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Friday, July 22, 2016 4:34 PM [b]Subject:[/b] [mg-tabc] Brake failure   Sudden brake failures are rare but when the underlying cause may not be, then I hope you'll agree it seems justified to reveal concerns. My TC's brake failure seemed to be due to fluid leaking past the cup seal in the master cylinder, only slight resistance could be felt as the foot pedal sank to the floor, time and time again without any fluid being lost. Dismantling the M/C revealed a polished bore free from any wear or corrosion (silicon fluid) and a cup seal that seemed intact but a little stiff. The special metal, multi fingered cup washer that splays out the cup seal was absent and replaced by a plastic buffer secured to the return spring. A comparison between a genuine Lockheed cup seal and the cup seal that failed, revealed that the stiffness at the sealing edge was partially due to the very edge of the cup being quite thick (1+mm), whilst that of the Lockheed cup was feather edged. It seems that the combination of a thick edge to the cup seal and the absence of a splaying out washer could result in the seal's lip lifting away from the wall of the M/C's bore, allowing fluid to leak past and possibly setting up a positive feedback situation where the fluid leaking past the seal's lip, forces the lip even further away from the wall of the bore. This home spun theory could explain why even when the brakes were applied forcefully, generating a sudden pressure pulse which would normally help the cup to seal to the wall, no such enhancement was produced. Fortunately the handbrake was effective, but if my reasoning is valid, then some replica M/C brake spares are suspect. Any thoughts welcome, Regards, Eric. [img]https://ec.yimg.com/ec?url=http%3A%2F%2Fstatic.avast.com%2Femails%2Favast-mail-stamp.png&t=1522510607&sig=x0SDtJcC3w0T7bGT3uQnMg--~D[/img] This email has been checked for viruses by Avast antivirus software. www.avast.com

[Norman Verona]

Eric,  I've seen that before but on very old cylinders where the seal has perished.  Do you know where this cylinder came from? It may help others about that supply.

Norman Verona French Blatting Company mob: 0033 (0)770702379 home: 0033 (0)241927344 web: [url=http://www.frenchblat.com]www.frenchblat.com[/url]

Sent from BlueMail

On 22 Jul 2016, at 18:39, "'Clive P Sherriff' csherriff99@gmail.com [mg-tabc]" mg-tabc-noreply@yahoogroups.com> wrote:   Eric,   A similar situation has been known when refilling with Silicon Brake fluid after using "normal" fluid, without replacing the master cylinder (and wheel cylinder) seals at the same time.   Clive = ========================== ----- Original Message ----- [b]From:[/b] E.Worpe@surrey.ac.uk [mg-tabc] [b]To:[/b] mg-tabc@yahoogroups.com [b]Sent:[/b] Friday, July 22, 2016 4:34 PM [b]Subject:[/b] [mg-tabc] Brake failure   Sudden brake failures are rare but when the underlying cause may not be, then I hope you'll agree it seems justified to reveal concerns. My TC's brake failure seemed to be due to fluid leaking past the cup seal in the master cylinder, only slight resistance could be felt as the foot pedal sank to the floor, time and time again without any fluid being lost. Dismantling the M/C revealed a polished bore free from any wear or corrosion (silicon fluid) and a cup seal that seemed intact but a little stiff. The special metal, multi fingered cup washer that splays out the cup seal was absent and replaced by a plastic buffer secured to the return spring. A comparison between a genuine Lockheed cup seal and the cup seal that failed, revealed that the stiffness at the sealing edge was partially due to the very edge of the cup being quite thick (1+mm), whilst that of the Lockheed cup was feather edged. It seems that the combination of a thick edge to the cup seal and the absence of a splaying out washer could result in the seal's lip lifting away from the wall of the M/C's bore, allowing fluid to leak past and possibly setting up a positive feedback situation where the fluid leaking past the seal's lip, forces the lip even further away from the wall of the bore. This home spun theory could explain why even when the brakes were applied forcefully, generating a sudden pressure pulse which would normally help the cup to seal to the wall, no such enhancement was produced. Fortunately the handbrake was effective, but if my reasoning is valid, then some replica M/C brake spares are suspect. Any thoughts welcome, Regards, Eric. [img]https://ec.yimg.com/ec?url=http%3A%2F%2Fstatic.avast.com%2Femails%2Favast-mail-stamp.png&t=1522510607&sig=x0SDtJcC3w0T7bGT3uQnMg--~D[/img] This email has been checked for viruses by Avast antivirus software. www.avast.com

[eworpe]

Hi Clive, The whole system was renewed about 10 years ago, the seal doesn't looked perished or bloated so I suspect the real culprits are the absence of the splay-out washer and lack of a feathered edge on the cup. I ought to look at all the wheel cylinders now that my confidence in the brakes has been shaken not stirred. Regards, Eric. ________________________________________ From: 'Clive P Sherriff' csherriff99@gmail.com A similar situation has been known when refilling with Silicon Brake fluid after using "normal" fluid, without replacing the master cylinder (and wheel cylinder) seals at the same time. = ==========================

----- Original Message ----- From: E.Worpe@surrey.ac.uk [mg-tabc]E.Worpe@surrey.ac.uk Sudden brake failures are rare but when the underlying cause may not be, then I hope you'll agree it seems justified to reveal concerns. My TC's brake failure seemed to be due to fluid leaking past the cup seal in the master cylinder, only slight resistance could be felt as the foot pedal sank to the floor, time and time again without any fluid being lost. Dismantling the M/C revealed a polished bore free from any wear or corrosion (silicon fluid) and a cup seal that seemed intact but a little stiff. The special metal, multi fingered cup washer that splays out the cup seal was absent and replaced by a plastic buffer secured to the return spring. A comparison between a genuine Lockheed cup seal and the cup seal that failed, revealed that the stiffness at the sealing edge was partially due to the very edge of the cup being quite thick (1+mm), whilst that of the Lockheed cup was feather edged. It seems that the combination of a thick edge to the cup seal and the absence of a splaying out washer could result in the seal's lip lifting away from the wall of the M/C's bore, allowing fluid to leak past and possibly setting up a positive feedback situation where the fluid leaking past the seal's lip, forces the lip even further away from the wall of the bore. This home spun theory could explain why even when the brakes were applied forcefully, generating a sudden pressure pulse which would normally help the cup to seal to the wall, no such enhancement was produced. Fortunately the handbrake was effective, but if my reasoning is valid, then some replica M/C brake spares are suspect. Any thoughts welcome, Regards, Eric.

[eworpe]

Hi Norman, The master cylinder was renewed about 10 years ago, and I imagine it was the standard version available at all the MG spares outlets. I might have the receipt somewhere, but I don't want to go through them all as I could find myself entering a phase of clinical depression at the realisation of how much I've spent. At one level I don't want to make too big an issue of the brake failure lest it spoils enjoyment of driving the TC, but at another level it seems responsible to mention potential problems, especially when it seems possible to identify the causes. The splay-out washer is an all important component of both the Master and wheel cylinders. Best wishes and congratulations on restoring your TC. Eric. ________________________________________ From: Norman Verona norman@frenchblat.com Eric, I've seen that before but on very old cylinders where the seal has perished. Do you know where this cylinder came from? It may help others about that supply. ---------------------------------------------------- Eric, A similar situation has been known when refilling with Silicon Brake fluid after using "normal" fluid, without replacing the master cylinder (and wheel cylinder) seals at the same time. Clive = ==========================

----- Original Message ----- From: E.Worpe@surrey.ac.uk E.Worpe@surrey.ac.uk Sudden brake failures are rare but when the underlying cause may not be, then I hope you'll agree it seems justified to reveal concerns.

[Norman Verona]

Eric,  i hadn't realised it was that old.  I used dot 5.1 fluid as I'm old fashioned and know it well.

The rear seal problem is interesting.  I wonder how many others have the same problem.

Actually i was not happy about not doing it propery and removing the crank,  but now realise I would have had to turn the flywheel down even if i had packed the housing from behind by removing the crank.

Norman Verona French Blatting Company mob: 0033 (0)770702379 home: 0033 (0)241927344 web: [url=http://www.frenchblat.com]www.frenchblat.com[/url]

Sent from BlueMail

On 22 Jul 2016, at 20:58, e.worpe@surrey.ac.uk wrote: Hi Norman, The master cylinder was renewed about 10 years ago, and I imagine it was the standard version available at all the MG spares outlets. I might have the receipt somewhere, but I don't want to go through them all as I could find myself entering a phase of clinical depression at the realisation of how much I've spent. At one level I don't want to make too big an issue of the brake failure lest it spoils enjoyment of driving the TC, but at another level it seems responsible to mention potential problems, especially when it seems possible to identify the causes. The splay-out washer is an all important component of both the Master and wheel cylinders. Best wishes and congratulations on restoring your TC. Eric. From: Norman Verona norman@frenchblat.com Eric, I've seen that before but on very old cylinders where the seal has perished. Do you know where this cylinder came from? It may help others about that supply. Eric, A similar situation has been known when refilling with Silicon Brake fluid after using "normal" fluid, without replacing the master cylinder (and wheel cylinder) seals at the same time. Clive = ========================== ----- Original Message ----- From: E.Worpe@surrey.ac.uk E.Worpe@surrey.ac.uk Sudden brake failures are rare but when the underlying cause may not be, then I hope you'll agree it seems justified to reveal concerns.

[Duncan]

I know the bit Eric is talking about, and I have always had to re-use or improvise, as the "kits" do not include an equivalent "splay out" washer. The silicone DOT 5 is thinner viscosity. Thinner viscosity fluid and lack of splay out washer. I could see a potential problem. I think Eric is on to something. Or maybe a sturdier (rubber) cup --advisable with silicone fluid. Duncan- --------------------------------------------

On Fri, 7/22/16, E.Worpe@surrey.ac.uk [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote: Subject: RE: [mg-tabc] Brake failure To: csherriff99@gmail.com, mg-tabc@yahoogroups.com Date: Friday, July 22, 2016, 11:36 AM Hi Clive, The whole system was renewed about 10 years ago, the seal doesn't looked perished or bloated so I suspect the real culprits are the absence of the splay-out washer and lack of a feathered edge on the cup. I ought to look at all the wheel cylinders now that my confidence in the brakes has been shaken not stirred. Regards, Eric. ________________________________________ From: 'Clive P Sherriff' csherriff99@gmail.com A similar situation has been known when refilling with Silicon Brake fluid after using "normal" fluid, without replacing the master cylinder (and wheel cylinder) seals at the same time. = ========================== ----- Original Message ----- From: E.Worpe@surrey.ac.uk [mg-tabc]E.Worpe@surrey.ac.uk Sudden brake failures are rare but when the underlying cause may not be, then I hope you'll agree it seems justified to reveal concerns. My TC's brake failure seemed to be due to fluid leaking past the cup seal in the master cylinder, only slight resistance could be felt as the foot pedal sank to the floor, time and time again without any fluid being lost. Dismantling the M/C revealed a polished bore free from any wear or corrosion (silicon fluid) and a cup seal that seemed intact but a little stiff. The special metal, multi fingered cup washer that splays out the cup seal was absent and replaced by a plastic buffer secured to the return spring. A comparison between a genuine Lockheed cup seal and the cup seal that failed, revealed that the stiffness at the sealing edge was partially due to the very edge of the cup being quite thick (1+mm), whilst that of the Lockheed cup was feather edged. It seems that the combination of a thick edge to the cup seal and the absence of a splaying out washer could result in the seal's lip lifting away from the wall of the M/C's bore, allowing fluid to leak past and possibly setting up a positive feedback situation where the fluid leaking past the seal's lip, forces the lip even further away from the wall of the bore. This home spun theory could explain why even when the brakes were applied forcefully, generating a sudden pressure pulse which would normally help the cup to seal to the wall, no such enhancement was produced. Fortunately the handbrake was effective, but if my reasoning is valid, then some replica M/C brake spares are suspect. Any thoughts welcome, Regards, Eric. Posted by: e.worpe@surrey.ac.uk> Reply via web post Reply to sender Reply to group Start a New Topic Messages in this topic (6) Save time and get your email on the go with the Yahoo Mail app Get the beautifully designed, lighting fast, and easy-to-use Yahoo Mail today. Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage. Visit Your Group Privacy Unsubscribe Terms of Use .