Leaky radial brake pump
Posted: Tue Apr 22, 2008 8:44 pm
Ok - here's the thing, for a while now I've noticed a brake fluid leak at the banjos on the master cylinder, not entirely acceptable! Recently I've been alarmed to find that I can occasionally pull the lever right back to the bar, but that it will pull back slowly and not spongily.... errrm!
Anyway, today I decided that enough was enough and having replaced the banjo washers without stopping the leak, I took the master cylinder off to have a closer look at it.
This is what I found!
The view is of the inside of the cylinder casting where it clamps to the handlebar. There are radial machining marks but there are also the longitudinal 'striations' that look like chatter from the boring bar - they are also on the clamp part of the casting. What you can see are drops of brake fluid that appear on the inside face of the casting when pressure is applied to the lever. I'm assuming that the f*cker is cracked as the weeping is from several points along the same line as opposed to just one point which might have indicated a porousity.
I'm going to call Lucas TRV in Germany tomorrow to see if there was a problem with any other castings, but I'm not going to hold my breath for a replacement.
The question is... is it salvageable? My immediate thought was to take it to my local welder and have him 'v' groove along the crack and tig weld it up. The only problem I can forsee is that the crack is doubtless bigger than it looks and may have propogated under the surface of the casting.
It's worth mentioning that the bar is a Gilles adjustable - just measured it to be 22.2mm., and the ID of the clamp is 21.9mm, so it's looking like a stress crack - bastard!
G
Anyway, today I decided that enough was enough and having replaced the banjo washers without stopping the leak, I took the master cylinder off to have a closer look at it.
This is what I found!
The view is of the inside of the cylinder casting where it clamps to the handlebar. There are radial machining marks but there are also the longitudinal 'striations' that look like chatter from the boring bar - they are also on the clamp part of the casting. What you can see are drops of brake fluid that appear on the inside face of the casting when pressure is applied to the lever. I'm assuming that the f*cker is cracked as the weeping is from several points along the same line as opposed to just one point which might have indicated a porousity.
I'm going to call Lucas TRV in Germany tomorrow to see if there was a problem with any other castings, but I'm not going to hold my breath for a replacement.
The question is... is it salvageable? My immediate thought was to take it to my local welder and have him 'v' groove along the crack and tig weld it up. The only problem I can forsee is that the crack is doubtless bigger than it looks and may have propogated under the surface of the casting.
It's worth mentioning that the bar is a Gilles adjustable - just measured it to be 22.2mm., and the ID of the clamp is 21.9mm, so it's looking like a stress crack - bastard!
G