Clattery when cold
Join Date: Feb 2012
Location: United Kingdom
County: Greater London
"Brimming"? You need air space in the brake fluid reservoir else for the brakes to work properly once the cap is on. No air space means the master cylinder will struggle to draw fluid to compress. Air is elastic, fluid is not. You should siphon out any excess fluid above the max line. If no siphon, clean paper towel will soak it up (but don't let it drip on paint, or hot exhaust - it can ignite).
I've not yet tangled with AR brakes but I have seen an overfilled reservoir pretty much stop brakes from working. There is usually an air bleed hole to prevent the fault, but not always, and also they can get blocked.
There is probably more to what's going on here, pads not seated properly or something...