Leaking Brembo Brake Cylinder

Bikepirate

Bikepirate

New member
Location
Brisbane Australia
I am currently renovating a 1973 SF2 which has Brembo front brakes. The LH back cylinder is leaking fluid due to corrosion in the piston bore. I have tried a new seal kit but no good. Any suggestions where I can get a replacement block + piston at a reasonable price? Anyone on the forum got one available to sell?
 
Not sure what you mean by 'LH back cylinder'? Is it the left hand caliper piston that's leaking? Kits readily available - in Oz, try Gowanlochs. If they're original steel pistons it's worth replacing all four with the later teflon coated ones. Should def do all four piston seals anyway.
 
That's quite a tricky problem to deal with, obviously new pistons/seals won't do any good if the bore is scored. In the past I've reclaimed a scored bore using epoxy and very careful application of a Dremel. I'm sure it must be possible to source a recon unit from somewhere.
 
motoddrob said:
Personally I'd try and recover the originals. They're rare to find these days and as Paul mentioned they're threaded for the Cerianis.
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Now that I understand the problem I agree with Rob - if they can be rescued it's worth the trouble. Maybe a Loctite or Devcon epoxy repair and line bore (a brake specialist could probably finish the bore)?
 
piranha-bro2 said:
Now that I understand the problem I agree with Rob - if they can be rescued it's worth the trouble. Maybe a Loctite or Devcon epoxy repair and line bore (a brake specialist could probably finish the bore)?
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I have reclaimed a number of calipers with corrosion in the seal groove, which is the usual problem I’ve seen. Some corrosion in the main bore is probably not much of an issue. I modified a small flat blade screwdriver to clean out the white corrosion and used JB Weld as a filler. Note the bottom of the groove is on a slant, not perpendicular to the sides, so need to be careful not to damage this feature.
Have done Brembo, Nissin and Tokigo calipers this way.
 
Corrosion in the seal groove is nearly the norm. One of the reasons they leak. A good scrape should suffice.
As usual, prevention by regular fluid changes is a good precaution.
Paul
 
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Thanks to all for your help. The corrosion is in the front part of the bore not in the seal groove which begs the question as to why leaking? The seal is new as is the front seal. The piston seems OK.
Never had any problem with my 1200 triple using the same Brembo callipers.
Good to know about the difference with the Ceriani's :)
 
Bikepirate said:
Thanks to all for your help. The corrosion is in the front part of the bore not in the seal groove which begs the question as to why leaking? The seal is new as is the front seal. The piston seems OK.
Never had any problem with my 1200 triple using the same Brembo callipers.
Good to know about the difference with the Ceriani's :)
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I have seen serious corrosion of the narrow land between the dust seal groove and fluid seal groove. Always means the critical side of the fluid seal groove is also corroded and I suggest this is causing the leak.
 
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