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Luego brake master cylinder sizing
Streetfighterpete - 18/8/19 at 06:51 PM

Hi all, I'm having problems bleeding the brakes on my Velocity XT. I'm using the standard 0.7 rear and 0.625 front master cylinders. I have upgraded the front calipers to a Brembo big brake set up and cant seem to get any feel on the pedal. I used an eazibleed kit and dont appear to have any air in the system and have no visible leaks. I'm wondering if the front master cylinder is simply not big enough to displace enough fluid for the new front calipers. Anyone out there had any experience of this or got any ideas please?

rusty nuts - 18/8/19 at 08:13 PM

Canít help with the bore size but do you have rear docs? Is the bleed screw at the top of the calliper ? It isnít unknown for the callipers to be fitted with the bleed nipple at the bottom, in which case they need to be removed and a spacer fitted between the pads then inverted before bleeding . Also it helps to slacken off the handbrake adjustment before manually adjusting the piston to reduce as much clearance as possible between the pads and the disc without the brakes binding . If you have rubber brake hoses you can clamp them before trying the brake pedal to identify if your problem is the front or rear brakes . Also check the master cylinder push rods are adjusted correctly as well as the brake bias. What size are the Cali per pistons ? Are they much larger than the original callipers? If all of the above are OK then you may have to go up on size for the front m/cyl

Streetfighterpete - 18/8/19 at 09:45 PM

Hi, thanks for the reply. Bleed nipples are on top so no issue there. I've disconnected the handbrake cable and the levers seem to operate OK. I haven't checked the pushrods so I'll do that next. New calipers are 4 pots off a BMW with 320mm rotors, so my suspicion is the master cylinder, but I wanted to check I wasnt missing something obvious before I started changing it out.