Wilsons Sandbox

On Wednesday, August 28, 2019, 04:24:30 PM PDT, norman verona norman@frenchblat.com [mg-tabc] mg-tabc-noreply@yahoogroups.com> wrote:

My 1946 MG TC has a brake problem that is somewhat enigmatic to me, considering my past experience (limited). Initially, when I depressed the brake pedal I got no brake action. There are no visible hydraulic leaks. So, I opened the master cylinder reservoir, and it is full. I then closed it. After that the brakes worked. Is the master cylinder intermittent? Is that something that can occur? I've never encountered that before. == Alex in Maine, TC 1321 --- This email has been checked for viruses by AVG. https://www.avg.com

On 8/28/2019 7:54 PM, Eric Worpe E.Worpe@surrey.ac.uk [mg-tabc] wrote: > Hi Alex, > It's tempting to suggest that the air bleed hole in the lid is blocked > and that this somehow effects the seal between the cup washer in > front of the piston and the bore of the master cylinder. > I admit I've not been able to reason why a build up or absence of > pressure in the reservoir should have such an effect, but removing > the lid would allow normalization of the pressure, which seems to > return the braking function. > Another possibility comes from the use of a non-Lockheed rubber > sealing cup washer. I've found that some replacement rubber seals > have a quite thick edge to the cup, unlike the original Lockheed seals > which are feather edged and are flexible enough to maintain contact > with the bore. > A further issue could be the absence of the special dished washer > that resides in the cup and whose splayed out fingers help press > the side of the cup washer against the bore. > The combination of a non-Lockheed cup seal and absence of the > dished washer have resulted in an inability of the cup washer to seal > against the bore and consequently present as a brake failure. The pedal > can be pushed to the floor, but is unable to pressurize the hydraulic > system as fluid simply flows past the cup seal. > When your brakes fail, does the brake pedal go to the floor? > Regards, > Eric. > ________________________________________ > From: AlexM alexmm@roadrunner.com > > My 1946 MG TC has a brake problem that is somewhat enigmatic to me, > considering my past experience (limited). > > Initially, when I depressed the brake pedal I got no brake action. > > There are no visible hydraulic leaks. > > So, I opened the master cylinder reservoir, and it is full. I then > closed it. After that the brakes worked. > > Is the master cylinder intermittent? Is that something that can occur? > I've never encountered that before. > > --- This email has been checked for viruses by AVG. https://www.avg.com

More than once I've seen this happen on a TC that has sat for a while. One of the cylinders ends up with air in it and the pedal goes to the floor on the first press, then slowly builds as you panic and hit it a couple more times. Try bleeding the brakes to see if one cylinder expels a bunch of air. It's also possible to suck in air if you have a sticky wheel cylinder, or if the shoe return springs are missing or weak. - Steve Simmons, TC8975 On 8/28/2019 3:56 PM, AlexM alexmm@roadrunner.com [mg-tabc] wrote: My 1946 MG TC has a brake problem that is somewhat enigmatic to me, considering my past experience (limited). Initially, when I depressed the brake pedal I got no brake action. There are no visible hydraulic leaks. So, I opened the master cylinder reservoir, and it is full. I then closed it. After that the brakes worked. Is the master cylinder intermittent? Is that something that can occur? I've never encountered that before. == Alex in Maine, TC 1321 --- This email has been checked for viruses by AVG. https://www.avg.com