Brake Master Cylinder Overhaul

[Roger Muir]

After having had a steady small leak from my brake master cylinder on my TA whilst on the recent MG Car Club Midland Centre's Welshe Rallye, I have now obtained a new seal kit. Has anyone any tips they may like to pass on to me, and indeed to anyone else contemplating this job. Thanks all Roger Muir MGTA Bromsgrove UK

[Peter Roberts]

Roger, Presumably, the TA MC is similar to my TC. A couple of thoughts: 1. Clean everything. Examine the bore of the cylinder, it should be bright and shiny. A brake hone on a portable drill works dandy. 2. Madhu warns that some kits have a flat washer, the one that goes at the far end of the cylinder, that is too thick. This will prevent the piston from completing its full travel on the downstroke. I cannot suggest a way to determine if you have this. Perhaps Madhu has a suggestion. 3. Be sure you reassemble in a perfectly clean environment and dip all parts in fluid before assembly. Double, double check the order of assembly. 3. Make sure you have new copper washers for the banjo fitting. This will go towards eliminating leaks at the banjo. _Peter...in the midst of rebuilding his TC brake system

----- Original Message ----- From: "Roger Muir" rogermuir@btinternet.com> To: "mg-tabc" mg-tabc@yahoogroups.com> Sent: Thursday, May 19, 2005 9:33 AM Subject: [mg-tabc] Brake Master Cylinder Overhaul > > > After having had a steady small leak from my brake master cylinder on my > TA > whilst on the recent MG Car Club Midland Centre's Welshe Rallye, I have > now > obtained a new seal kit. > > Has anyone any tips they may like to pass on to me, and indeed to anyone > else contemplating this job. > > > Thanks all > > Roger Muir > > MGTA > > Bromsgrove UK > > > > > Yahoo! Groups Links > > > > > >

[Ian Linton]

Roger, I rebuilt my TA MC last month (see photo - if any lister wants a copy, please email me). It was a new unit bought around the time I last ran the car (1965 - doesn't time fly!) but never used. The unit on the car was almost corroded away. So I bought a new heat shield unit from Moss (top left), had the knuckle shaft plated and blackened and fitted it to the chassis, which is under complete restoration. However, having thought about it for some time, I decided to replace the rubber seals as I intend to use silicone brake fluid. I understand from others that swelling of rubber parts is different for silicone than for conventional brake fluid. It appears to be essential to start with new dry rubber parts if changing to silicone. So I bought a kit from Octagon and set about it. Very easy with a decent pair of circlip pliers (Draper, under 10, several combination of ends). Just as well I did it because the very thin metal washer inside had largely corroded away in storage - see lower washer. No metal washer came with the kit, and no suppliers appear to offer this part. So on an inspiration I hacked apart what was left of my old MC, and to my amazement out came a similar washer in excellent condition - see upper washer. The rest is straightforward. Just keep clean, soak each item in whatever brake fluid you intend to use, and it should go together easily. Apart from the circular seal over the piston, which takes some persuasion. I didn't remove the threaded section of the MC, nor did I have to hone the internal bore as the latter was still smooth and clear. I'm slightly surprised your MC leaks. If it does, it can only be washers at joints or there is a pinhole in the can. Unless fluid is passing the piston seal, of course. Changing the seals - except for the last one - would not stop a leak?? Finally, the washer that Madhu is concerned about is shown bottom left. It does appear thickish. I made sure the little pinhole for pressure relief was clear by poking a thin wire through it. If I get problems once on the road, I know where to look. Best of luck, Ian Linton TA 3120, East Sussex, UK

----- Original Message ----- From: "Roger Muir" rogermuir@btinternet.com> To: "mg-tabc" mg-tabc@yahoogroups.com> Sent: 19 May, 2005 14:33 Subject: [mg-tabc] Brake Master Cylinder Overhaul > > > After having had a steady small leak from my brake master cylinder on my > TA > whilst on the recent MG Car Club Midland Centre's Welshe Rallye, I have > now > obtained a new seal kit. > > Has anyone any tips they may like to pass on to me, and indeed to anyone > else contemplating this job. > > > Thanks all > > Roger Muir > > MGTA > > Bromsgrove UK > > > > > Yahoo! Groups Links > > > > > > > [Non-text portions of this message have been removed]

[Roger Muir]

Thanks Ian. Super detail and the photo is a great help too. Now I have run silicone for most of the time I have owned the car, BUT I used silicone fluid copiously to flush out the original brake fluid. i suspect problems may have occurred as a result of not using new seals to start with. Incidentally I have no problems with the wheel pistons... Pinholes? well possibly but as I haven't removed the MC yet I can't tell. I had no problem with pressure only with a leak from the brake push rod end. And I need a new copper washer for the banjo end. Thanks all Roger......... 19/5/05 4:07 pm, Ian Linton at cars@castle-energy.co.uk wrote:

> Roger, > > I rebuilt my TA MC last month (see photo - if any lister wants a copy, > please email me). It was a new unit bought around the time I last ran the > car (1965 - doesn't time fly!) but never used. The unit on the car was > almost corroded away. > > So I bought a new heat shield unit from Moss (top left), had the knuckle > shaft plated and blackened and fitted it to the chassis, which is under > complete restoration. However, having thought about it for some time, I > decided to replace the rubber seals as I intend to use silicone brake fluid. > I understand from others that swelling of rubber parts is different for > silicone than for conventional brake fluid. It appears to be essential to > start with new dry rubber parts if changing to silicone. > > So I bought a kit from Octagon and set about it. Very easy with a decent > pair of circlip pliers (Draper, under 10, several combination of ends). > Just as well I did it because the very thin metal washer inside had largely > corroded away in storage - see lower washer. No metal washer came with the > kit, and no suppliers appear to offer this part. So on an inspiration I > hacked apart what was left of my old MC, and to my amazement out came a > similar washer in excellent condition - see upper washer. The rest is > straightforward. Just keep clean, soak each item in whatever brake fluid > you intend to use, and it should go together easily. Apart from the > circular seal over the piston, which takes some persuasion. I didn't remove > the threaded section of the MC, nor did I have to hone the internal bore as > the latter was still smooth and clear. > > I'm slightly surprised your MC leaks. If it does, it can only be washers at > joints or there is a pinhole in the can. Unless fluid is passing the piston > seal, of course. Changing the seals - except for the last one - would not > stop a leak?? > > Finally, the washer that Madhu is concerned about is shown bottom left. It > does appear thickish. I made sure the little pinhole for pressure relief > was clear by poking a thin wire through it. If I get problems once on the > road, I know where to look. > > Best of luck, > Ian Linton TA 3120, East Sussex, UK > > > ----- Original Message ----- > From: "Roger Muir" rogermuir@btinternet.com> > To: "mg-tabc" mg-tabc@yahoogroups.com> > Sent: 19 May, 2005 14:33 > Subject: [mg-tabc] Brake Master Cylinder Overhaul > > >> >> >> After having had a steady small leak from my brake master cylinder on my >> TA >> whilst on the recent MG Car Club Midland Centre's Welshe Rallye, I have >> now >> obtained a new seal kit. >> >> Has anyone any tips they may like to pass on to me, and indeed to anyone >> else contemplating this job. >> >> >> Thanks all >> >> Roger Muir >> >> MGTA >> >> Bromsgrove UK >> >> >> >> >> Yahoo! Groups Links >> >> >> >> >> >> >> >