Barry Kemp Posted March 13, 2018 Report Share Posted March 13, 2018 Ok so I've probably bled a cars brakes a dozen or so times in my life but I have a question that I am now surprised I have to ask. I hope this is not dementia coming on as I feel I should know the answer! Having pumped the brake pedal 3 or 4 times air bubbles come up from the bottom of the master cylinder when I release the pedal. Is this normal or a sign of a leaky seal in the M/c? Link to comment Share on other sites More sharing options...
JohnD Posted March 13, 2018 Report Share Posted March 13, 2018 Deffo should not happen! M/c rebuild? John Link to comment Share on other sites More sharing options...
Guest Posted March 13, 2018 Report Share Posted March 13, 2018 Barry. As you say, air is getting somewhere and it probably is the M/C as John has identified; you will have to check it out on the bench so an overhaul is the next step. What's the history of the unit ?? Regards. Richard. Link to comment Share on other sites More sharing options...
Barry Kemp Posted March 13, 2018 Author Report Share Posted March 13, 2018 I think the master cylinder was rebuilt about 9 years ago -so probably worn? Link to comment Share on other sites More sharing options...
Guest Posted March 13, 2018 Report Share Posted March 13, 2018 Reckon so Barry. I'm probably going to get shot down in flames here, but I'm not a big fan of rebuild kits for brake components and would rather purchase a new unit. Just depends on your stance with such things. Regards. Richard. Link to comment Share on other sites More sharing options...
JohnD Posted March 13, 2018 Report Share Posted March 13, 2018 And if you do, time to consider if you want to modify the system, or else just bring it uop to spec. The integral reservoir is a pain, IMHO, the old metal caps never fit. Modern M/cylinders come without and you can choose a plastic reservoir to screw in,in a vaiety of sizes or even remotely, if that were necessary (it's not, for a Triumph). And, you can consider a different bore to the M/c. Larger means less travel but more foot pressure needed, smaller the reverse. Available in a range from 0.625" - 1". All the other tweaks too. Best, again IMHO, are Aeroquip flexible hoses (nylon, braided metal sheath). No better than rubber, but fit and forget, though they do look spiffing at first! And vented discs, and MIntex 1155 pads, if you plan pass storming or similar. Otherwise Triumph brakes are as good as your tyres! John Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 14, 2018 Report Share Posted March 14, 2018 Barry, I'm guessing as you only bleed your brakes infrequently you're not racing your Triumph? If so you don't need vented disks, but Mintex 1144s will make a big difference. My master cylinder is 45 years old and the bore is still in good condition, but after 9 years certainly try a rebuild kit, dead easy to install and cheaper than a new master cylinder. Brake fluid absorbs water and should be replaced every two years. Now might be the time to consider silicone fluid which lasts almost indefinitely and doesn't eat your bulk head. Doug Link to comment Share on other sites More sharing options...
Darren Groves Posted March 14, 2018 Report Share Posted March 14, 2018 22 hours ago, classiclife said: Reckon so Barry. I'm probably going to get shot down in flames here, but I'm not a big fan of rebuild kits for brake components and would rather purchase a new unit. Just depends on your stance with such things. Regards. Richard. I agree....i always find rebuild kits to be a bit short-lived. Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 16, 2018 Report Share Posted March 16, 2018 There must be a small air bleed hole in the pushrod seal otherwise when you press and release the pedal you can get air past the End cup seal which will apear in the reservoir Should have a small 2mm hole in the end covering boot to allow the inards to breathe Pete Link to comment Share on other sites More sharing options...
Barry Kemp Posted March 16, 2018 Author Report Share Posted March 16, 2018 Sorry Pete, i don't quite understand your comments. Are you saying that the problem is in the pushrod seal, ie a hole that shouldn't be there? Barry Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 16, 2018 Report Share Posted March 16, 2018 The pushrod seal must have a small extra hole to allow it to breathe if there is no hole you will get trapped air to pass the piston seal lip and escape into the resevoir If this makes no sense im typing it in france on a wet holliday Pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 16, 2018 Report Share Posted March 16, 2018 Pete, My recollection is it rains where ever you go on holiday! Perhaps a schedule of your movements would help us all avoid wet holidays. Doug Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 16, 2018 Report Share Posted March 16, 2018 Suns out today Im saving the rain for your belated birthday bash , Pete Link to comment Share on other sites More sharing options...
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