Quote:
Originally Posted by Durbs
FFS, you'll never guess what 
Its pretty full but seemingly invisibly so from outside. ****.
Theres a wierd black rubber noddy within the reservoir so it aint just a cup full of fluid, and that noddy helpfully squeezes brake fluid all over the place when you try and replace the cap. |
That black 'noddy' is there so as to expand as the fluid disappears down the lines when the brake pads wear. It's to stop air getting in the lines. It gets sucked down by the vacuum it creates leaving the air on the other side.