CNW Brembo master cylinder - leaky cap

Hi guys,

Does anyone have a sealing issue with the CNW brembo master cylinder ? I have had this on my Commando for years and since day one, brake fluid seeps out the top cap/lid. I now have the same master on my Ducati (installed by previous owner) and both the one for the brake and clutch leak the same way. (Yes they are tight). I wasn't too concerned because on both bikes the Masters were upright but I am putting clipons on the bike and they will be at a slight angle now.

Any suggestions? I assume that there is a replacement gasket that might be an option. But like I said, the one I got from CNW seeped from day one.

I would guess that you may be overfilling the master cylinder. If you fill it as much as possible then the act of tightening the cap down will compress the bellows in the cap, so when the fluid expands with heat , it has to go somewhere. Forcing it out under the cap is the only escape.

Try leaving a little more room for air in the reservoir.

Neither the Brembo clutch or brake master on my bike have shown any tendency to leak, unless I try to fill them to the brim. Jim

PS, DOT 5 fluid expands more with heat than Dot 3,4, or 5.1

Yup , all three of my bikes have the Brembo masters and I did experience a weeping once .... lowered level of fluid and all good for several years now ... only issue now is black fluid requiring frequent changes in Ducati Hyd. clutch res ....
Craig

Thanks guys. I lowered the fluid levels by about 5-6ml on each one and tightened them down. I'll see if that helps.

Mine were leaking just sitting in my cold garage. I took my bars off yesterday and used a ziptie to keep the masters from just hanging there. This left them both at an angle which caused the fluid to leak out.