Front brake reservoir 'insert'
- Thread starter Sunny Jim
- Start date
As far as I understand - its there as a seal and also to allow expansion/contraction of the fluid.
Yes, it's a diaphragm to allow fluid level changes such as pad wear/replacement etc. And also seal against fluid escaping from the cap and it helps to keep moisture out.
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Do you mean the foam insert, rather than the rubber seal? The Haynes manual recommends changing it when the fluid is changed. I didn't as I'd already changed the fluid and bled the lines by the time I read that bit, so far so good everything is working ok. I'll replace it next time I service the bike.
The foam insert is to take up space and stop the fluid from frothing.
Chuck it away. Is does nothing of any value.
my 2010 had the sponge, when Mikeyboy serviced the bike I got him to chuck it away 
I don't know about the sponge but I always thought (assumed) the bellows/diaphragm thing was to fill the air gap between oil and cap to prevent splashing and bubbles forming which could then get pushed into the hydraulics. The bellows/diaphragm gets "sucked" down as the oil level drops as the brake pads wear so it's always sitting on top of the oil.
I assume the sponge does something similar. Perhaps any bubbles cling to the sponge rather than dispersing through the oil. Dunno. Making it up now.
I assume the sponge does something similar. Perhaps any bubbles cling to the sponge rather than dispersing through the oil. Dunno. Making it up now.
Did a little bit of digging when I say my 2010 had one, and it seems that they only fitted the sponge on 2008-2010 bikes, and some have them, some don't.
I was told that it was because owners complained that they didn't like to see the brake fluid sloshing about through the clear reservoir
Not had a bike with a sponge in the reservoir apart from this one.... and that's why it's gone in the bin. The brakes still work
I was told that it was because owners complained that they didn't like to see the brake fluid sloshing about through the clear reservoir
Not had a bike with a sponge in the reservoir apart from this one.... and that's why it's gone in the bin. The brakes still work
Stop. You're all talking about something completely different.
Later reservoirs fitted with the sponge insert still have the bellows/diaphragm fitted as per normal.
Bendy toy
Registered user
My 08 has the bellows but never had the sponge. Brakes work fine.
I have a farkle cover over the reservoir to keep light fingers at bay so can't see the level.
I have a farkle cover over the reservoir to keep light fingers at bay so can't see the level.
Tis so, my 2011 TC has both.
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