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Discussion Starter #1
So if the brake fluid in our master cylinders and resevoirs is SEALED how does the fluid get contaminated by moisture?

Is the culprit condensation?

Is the 24 month window pretty much rule of thumb for brake fluid flush and refill / line and banjo fitting inspection ?
 

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Condensation, yes. The brake fluid gets hot with medium to hard short brake application periods, then cools down when the brake is released. So the cycle continues. If one rides applying the brake lightly, the fluid will eventually boil, to the point where it fails totally... no braking ability on that system. Luckly there are two master brake cylinders, one for the front brake and one for the rear brake. The front brake is 70 - 90% of your brake stopping power.
The rubber seal just under the top cover, on the master cylinder has a track / vent to allow air to escape. Often this is sucked into the master cylinder when cranked down too tight. Open the master cylinder cover with care not to spill fuild or disturb the seal and see for yourself, if there is any brake fluid on top of the rubber seal.
The 24 month is recommended by the brake fluid manuafacturer. They have done a lot of extensive testing and hence their advice is worth listening to. I know of some who don't change the brake fluid as often, but that is their choice. If something goes wrong with the braking system, detailed service records would help you prove that the brakes on your ride was in a roadworthy condition.
 

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Two year replacement interval? I'm guilty of the 10 year interval. I got Brake Bleeders from Kirby ( Kirby's Brake Bleeders) for the '04 650 and the task was very quick to accomplish. Even the rear reservoir was easy enough to access with a bit of care.
Yes it did make a difference.
For comparison, the BMW dealer charged about $100 and the speed bleeders cost $50? And I didn't have to go to the dealers.
 

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So if the brake fluid in our master cylinders and resevoirs is SEALED how does the fluid get contaminated by moisture?



Is the culprit condensation?



Is the 24 month window pretty much rule of thumb for brake fluid flush and refill / line and banjo fitting inspection ?


Not to split hairs too much, but it's Hygroscopic, not Hydroscopic.

hy·gro·scop·ic
/ˌhīɡrəˈskäpik/

adjective
(of a substance) tending to absorb moisture from the air.

@Gert - Nicely answered Sir.

The secondary impact of not changing your brake fluid every couple of years or more often is the potential to have a ring of corrosion occur around the brake caliper pistons. This is especially prone to bikes that sit over the winter, or longer. The problem becomes evident when you go for a ride, apply the brakes and the piston doesn't retract due to the corrosion. Shortly your brake rotors start to glow from the heat generated by the dragging pads and you end up with expensive repairs.

On ABS bikes this can occur for the solenoid piston inside the ABS block. That gets really expensive! $4k for a repair like that recently on my wife's GSA due to the dealership charging for service they didn't do. We paid them for flush/bleed of the brakes, they didn't do it. Didn't realize it until the ABS failed, caliper dragged and it ended up being ABS block, rear rotor, pads and a plastic guard that melted. Aftermarket extended warranty replaced it. The wife lets me service her bike now instead of relying on the dealer.

Detailed service records would be helpful to someone in the US that had an extended warranty and was making a claim. I've had bikes with well over 100k miles that still were under factory extended warranty. One claim, (CCT), the Mothership asked for receipts for my owner service. The dealer scanned the pages in my owner's manual with my service log, where I had added lines going well past where the original ones left off, and detailed everything done, and the tire log I had kept on the bike since new. The Mothership took one look and never asked for receipts again. The dealer told me about this after the fact, and laughed at the response he got from the Regional rep about it later. :ROFLMAO: They aren't used to people that actually ride their bikes and maintain them.
 

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Discussion Starter #6
Thanks for the replies, I will be in the 24 month window in july this year. Thankfully my bike is garaged and ridden
fairly often. And so far no issues with anything after almost 3000 miles.
 

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Prove to who?
Anyone, from lawyers, to law enforncement, to a new buyer.... Something positive can turn to a negative in a blink of an eye. Sad enough that a motorcyclist has to have eyes in the back of his / her head, but to cover one's arse from a legal point of view, is just as important for any rider..
 
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