Plastic button/valve at bottom of brake reservoir - What does it do? - BARF

_Chris_ · 01-06-2019, 09:30 PM

Hello everybody,

I just wanted to flush the front brake on a new to me 2018 BMW G310R. Upon opening the reservoir, I discovered a white plastic button/valve. I've never seen something like this before, I'd assume it regulates the brake fluid flow towards the cylinder. As you can see, it is surrounded by a spring-style ring and it came out of the housing at the bottom of the reservoir. I wonder if a) anyone knows its purpose/has seen it before b) can tell me which side is up/down ( it's asymmetrical ) and c) if there is any trick or tools required for inserting it back into the housing.

Thank you so much,
Chris

ST Guy · 01-07-2019, 12:26 AM

I believe it's simply a cover or cap over the intake and compensating ports. During use, brake fluid can shoot out of the ports with a fair amount of force which has the possibility of introducing air into the fluid. By keeping any turbulence below the air at the top of the resevoir, the fluid stays air free.

I may be wrong.

kuksul08 · 01-07-2019, 07:12 PM

Quote:

Originally Posted by ST Guy

I believe it's simply a cover or cap over the intake and compensating ports. During use, brake fluid can shoot out of the ports with a fair amount of force which has the possibility of introducing air into the fluid. By keeping any turbulence below the air at the top of the resevoir, the fluid stays air free.

I may be wrong.

Also, some have a cover on them to keep brake fluid from squirting up and out onto your paintjob while pumping the lever when bleeding brakes.

ST Guy · 01-07-2019, 07:35 PM

Quote:

Originally Posted by kuksul08

Also, some have a cover on them to keep brake fluid from squirting up and out onto your paintjob while pumping the lever when bleeding brakes.

Yes, another purpose.

EastBayDave · 01-08-2019, 01:26 PM

or keeping you from squirting yourself in the eye...

ST Guy · 01-08-2019, 01:46 PM

When cleaning out the reservoir, it's always a good idea to pop the cap/cover off and make sure it's clean underneath. (As you have done, OP.)

_Chris_ · 01-08-2019, 05:47 PM

Thank you everybody for the feedback.

For future references, there is only way how you can insert it ( round side up ), here is the picture:

dravnx · 01-09-2019, 04:55 AM

Why are you doing a flush on an almost new bike?

01-06-2019, 09:30 PM	#1
_Chris_ Newbie Join Date: Jun 2014 Location: Palo Alto Motorcycles: Triumph Name:	Plastic button/valve at bottom of brake reservoir - What does it do? Hello everybody, I just wanted to flush the front brake on a new to me 2018 BMW G310R. Upon opening the reservoir, I discovered a white plastic button/valve. I've never seen something like this before, I'd assume it regulates the brake fluid flow towards the cylinder. As you can see, it is surrounded by a spring-style ring and it came out of the housing at the bottom of the reservoir. I wonder if a) anyone knows its purpose/has seen it before b) can tell me which side is up/down ( it's asymmetrical ) and c) if there is any trick or tools required for inserting it back into the housing. Thank you so much, Chris Last edited by _Chris_; 01-06-2019 at 09:31 PM..

01-07-2019, 12:26 AM	#2
ST Guy Veteran Join Date: Nov 2006 Location: South Bay Motorcycles: Honda ST1100 ABS (tweaked here and there) Name:	I believe it's simply a cover or cap over the intake and compensating ports. During use, brake fluid can shoot out of the ports with a fair amount of force which has the possibility of introducing air into the fluid. By keeping any turbulence below the air at the top of the resevoir, the fluid stays air free. I may be wrong. __________________ It's not the answer that enlightens, but the question. - Eugene Ionesco Let us not pray to be sheltered from dangers but to be fearless when facing them. - Rabindranath Tagore A mind all logic is like a knife all blade. It makes the hand bleed that uses it. - Rabindranath Tagore

01-08-2019, 01:26 PM	#5
EastBayDave - Kawasaki Fanatic - Founding Member From the heart Join Date: May 2002 Location: San Lorenzo, CA "The Mudflats" Motorcycles: ZRX1200 Name: "Dave"	or keeping you from squirting yourself in the eye... __________________ Enjoy the ride!

01-08-2019, 01:46 PM	#6
ST Guy Veteran Join Date: Nov 2006 Location: South Bay Motorcycles: Honda ST1100 ABS (tweaked here and there) Name:	When cleaning out the reservoir, it's always a good idea to pop the cap/cover off and make sure it's clean underneath. (As you have done, OP.) __________________ It's not the answer that enlightens, but the question. - Eugene Ionesco Let us not pray to be sheltered from dangers but to be fearless when facing them. - Rabindranath Tagore A mind all logic is like a knife all blade. It makes the hand bleed that uses it. - Rabindranath Tagore

01-09-2019, 04:55 AM	#8
dravnx Veteran AMA #3018349 Contributor +++++++ Barf Roadside Angel Join Date: Dec 2012 Location: santa rosa, ca Motorcycles: '12 DL650A '15 FJR1300A Name: Jeff	Why are you doing a flush on an almost new bike? __________________ bike X miles=smiles smiles ÷ bike=miles miles ÷ smiles=bike. It's simple math. https://www.directavionics.com/

01-08-2019, 05:47 PM	#7
_Chris_ Newbie Join Date: Jun 2014 Location: Palo Alto Motorcycles: Triumph Name:	Thank you everybody for the feedback. For future references, there is only way how you can insert it ( round side up ), here is the picture:

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode