Condom in brake fluid top up chamber ?

[headache56]

Well not exactly a condom but both my front and rear brake fluid reservoirs have a kind of black sheath inside the chambers.

What are these for ? Should I remove them ?

They make it difficult to see - externally - whether the fluid needs toping up.

Do I need them ?

 

[greg]

you should be able to fold them up, they are a moveable membrane that allows the fluid to be sealed, but allow air to fill the volume as it is pumped out.

You can fold it up before putting the lid on.

 

[Motogiro]

Are you talking about the thin expandable rubber gasket at the top of the reservoir?

That expandable gasket reduces air exposure in the master reservoir as fluid is used.

You need it! Leave it then alone. Maybe bleed your system with new brake fluid.

Brake fluid is highly anhydrous, meaning it sucks up moisture from the air when exposed. Moisture is brake fluids enemy and reduces it's hydraulic properties hence reducing efficiency in braking performance. If it has absorbed enough moisture, that moisture in turn becomes air in your brake line. So even a small amount can reduce your braking ability.

 

[dpaul007]

Are you talking about the thin expandable rubber gasket at the top of the reservoir?

That expandable gasket reduces air exposure in the master reservoir as fluid is used.

You need it! Leave it then alone. Maybe bleed your system with new brake fluid.

Brake fluid is highly anhydrous, meaning it sucks up moisture from the air when exposed. Moisture is brake fluids enemy and reduces it's hydraulic properties hence reducing efficiency in braking performance. If it has absorbed enough moisture, that moisture in turn becomes air in your brake line. So even a small amount can reduce your braking ability.

x2 I didn't feel like typing all that so I waited for someone else to

Leave it there! or you'll be changing you brake fluid a LOT more often.

 

[yamihoe]

leave it there!!!

brake fluid attracts water, it can rust your calipers and lines from the inside out!

 

[Carlos840]

Well not exactly a condom but both my front and rear brake fluid reservoirs have a kind of black sheath inside the chambers.

What are these for ? Should I remove them ?

They make it difficult to see - externally - whether the fluid needs toping up.

Do I need them ?

It's hard to know for sure without seeing a picture, but the only thing i can think off is that the level of your master cylinders has run low and what you are seeing are the seals/ diaphragms as they get sucked down into the reservoir.

You need to stop riding the bike and sort it out.

There are two possibilities:
Your level went down because your pads are worn, check them, if bad change, replace brake fluid, bleed.
Your fluid went down because you have a leak. Rebuild calipers, new fluid, bleed.

Odds are you only need new fluid and a bleed, but you really should not be riding the bike until this is sorted.


Is this what you have:

brake master cylinder resevoir rubber diaphragm?

If yes then just fold it back properly and do what i mentioned before.

If it's something else take a picture and post it!

 

[Botch]

Brake fluid is highly anhydrous, meaning it sucks up moisture from the air when exposed.

Hygroscopic, not anhydrous…

 

[Motogiro]

Hygroscopic, not anhydrous…

Anhydrous - Wikipedia, the free encyclopedia

The process that removes the water I believe is exposure to hygroscopic elements which is the process that creates an anhydrous product. So yes brake fluid is an anhydrous product that is hygroscopic.

 

[headache56]

Thanks guys - really useful. I never knew this - I Goggled it following your tip. Google suggests that, as well as what you say, the membranes have another purpose - that is the membrane-baffle unfolds-expands, to take up any "gap" left in the reservoir if any fluid is used up. Without this, allegedly, the unfilled gap would introduce an unwanted bit of a vacuum or pressure in the braking system. Fascinating. I have bled the brakes and used new fluid - after replacing the "old" membranes x 2 but I will now get some new membranes (£13.50 + VAT) before I use the bike again.

None of this is in the 432- page manual.

 

[Carlos840]

Thanks guys - really useful. I never knew this - I Goggled it following your tip. Google suggests that, as well as what you say, the membranes have another purpose - that is the membrane-baffle unfolds-expands, to take up any "gap" left in the reservoir if any fluid is used up. Without this, allegedly, the unfilled gap would introduce an unwanted bit of a vacuum or pressure in the braking system. Fascinating. I have bled the brakes and used new fluid - after replacing the "old" membranes x 2 but I will now get some new membranes (£13.50 + VAT) before I use the bike again.

None of this is in the 432- page manual.

Did you check your pads and your calipers for leaks?

Unless the level is going down there is no reason for the diaphragm to be sucked down.
The only time i have ever had that happen was on a car with massive caliper leaks.
If your brakes are working properly your level should not go down low enough and fast enough for the diaphragms to do what they are doing, unless your pads are really worn down!

 

[aclayonb]

Calipers rust? Most calipers I've seen are aluminum..... Never seen one rust before. Seem some serious oxidation (yes, technically aluminum rust) but not what I consider rust...

 

[Carlos840]

Calipers rust? Most calipers I've seen are aluminum..... Never seen one rust before. Seem some serious oxidation (yes, technically aluminum rust) but not what I consider rust...

I guess it depends what they are made of...
Don't know about the FZ6 but the calipers of my C3 are steel and show outside rust! It would probably take a hundred years to rust through, but it does rust!

 

[FinalImpact]

Without the cap liner in there, use over rough terrain can aerate the fluid and you could suck air and loose brake pressure. Not to mention all the air water moisture rust issues ^^^...

If you chuck it, be sure to update you Obamination care policy and get life insurance! You may need one or both! J/K lol

Edit: out of the US... Never mind...