Monday, July 11, 2011

Master cylinder rebuild

The BMW still sits with its braking issue. Since the last brake lines swap (from Goodridge 1 into 2 to Goodridge 2 into 2), it had several fluid bleeds and it didn't change anything. The brake lever feels harder for a couple of days after a bleed and then the bike sits still for another 2 days and the lever ends up feeling completely soft, hitting the right clipon.

I had bought a master cylinder rebuild kit from BMW several weeks ago just in case the lines weren't the issue. With the last result being a spongy lever, the brand new master cylinder piston has had a go.

"The master cylinder rebuild kit" consisting of a piston and a spring ...
The whole hand brake assembly has been removed, inspected and cleaned. Comparing the old and new pistons, I had reasons to be hopeful.

Old and new master cylinder pistons

I could put the master cylinder together with its new piston rather easily. Unfortunately, the brake lever feeling is still as spongy as ever. Now, the brake lines have been swapped twice with new complete kits, the master cylinder has been refreshed and the whole assembly has seen more fresh brake fluid than the pan contains oil. Next in sight are the calipers.

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