Ok. I've been knocking my head against the wall trying to figure out what is wrong and why I just can't get my front brake to feel right. So now I am seeking help and (grudingly) considering going to a garage, which my wallet doesn't like at this time . To begin, I have a '94 M600 and the front Brembo is of a single pin type. I've just had the caliper rebuilt as I noticed a weeping seal. I have a Goodridge hose with new banjo's top and bottom. I have stood my bike on the centre stand and put her on full left lock (something I learned this the hard way before when I originally replaced the hose as there is a high spot in the system if the bike is being bled while upright which causes an air lock. That left me pretty ticked off at the time ) then, having removed the leaver and using an appropriate rod for maximum piston travel, I pumped the cylinder until all the air has backed out of the reservoir. When I'm satisfied that all the air has been bled from the hose and reservoir, I've continued to bleed the system as normal, but I cannot get a solid feel to the lever. Waching the caliper as I squeeze the brake it seems that the force is working the inside of the wheel and not equal pressure. I took the caliper off again and openned up the bleed nipple and this time I held it so that the caliper was in a more upright position and tapped it to help any unwanted air. Checked the reservoir again, topped her up and still I have the spongiest lever ever. Now, the only thing that's not new is the Bleed Nipple (didn't even dawn on me that I didn't replace this) and I don't have any signes of issues with the master cylinder - no leaks, no odd noises, always pumps, etc. I'm not too sure about the adjuster on the brake lever, if it's better to have this wound in or out - winding the adjuster in means that the push rod doesn't open up beyond the second, outer hole in the reservoir and winding out means that it doesn't close beyond this feed hole. So, can anyone suggest anything for me to try please (other than go to a garage). I've done brakes a number of times throughout my life and never had this issue, with the exception of an old Bettle which we learned needed to be gravity bled and not forced. Has anyone else suffered this before and managed to resolve it?
sounds like you still have some trapped air in the caliper. You say you 'had caliper rebuilt' rather than doing it yourself - all four pistons should be free-ish to move and the only reason that they wouldn't move fairly equally other than trapped air would be if one or more of the pistons were binding. You can try (slowly) winding all four pistons in as far as they will go to evacuate as much air/fluid as possible to begin your next attempt at bleeding. Be aware that to do above you will either need to syphon some fluid from the m/cylinder reservoir or synchronise the undoing of the bleed nipple at the same time as winding each piston in. You will find that often the opposing piston will pump out in sympathy so it's quite a knack to restrain the others while you do above. As far as lever stroke is concerned, it's ok to leave it as normal - as long as you are achieving full stroke of the cylinder then it's fine.
you had NEW banjo bolts fitted did you check them with your old ones more so the master cylinder Brembo use a shorter banjo bolt, so if you fitted normal length banjo bolts it could be thread bound they nip up tight but just not tight enough and you can get what you describe. brian.
I will be double checking that tonight. Thank you very much Brian. I'll be livid if that's the case... Happy, but livid. I'll also be replacing the Bleed Nipple just to put my mind at ease there too.
Well......physics helps here....air is lighter than brake fluid, so all bubbles WILL rise....when you have bled the calipers, cable tie the lever tight to the bar overnight...the bubbles will be caught up at the right angle twixt master cylinder and brake line. Of course, it could also be easily that the master cylinder seals have gone.....and Brembo UK ( Mode Performance) wont sell you any.....public liability and all that....you may also find that your pads are contaminated....brake fluid, if in the pad material, can cause it to soften....
One thing I didn't think about was leaving the lever tied back over night. I'll sort that. And I've been doing myu best to keep the pads clean as much as possible. Nice thing is when I got home last night and had a look at her, the brakes were a bit better for having just sat still.
