Alright, who is stealing my front brake fluid. Stop It!

[..]

Filled up the reservoir 2 weeks ago to the line on the sight glass.

Now after about 500 miles the fluid is down to the bottom of the sight glass.

Yes I had the reservoir flat and level when I filled it up.

[bill-jr]

Close your bleeder paul ....

[Bighead]

Or put new pads on .

[..]

Or put new pads on .

Pads half dead

[Gryphon Rider]

If your pads were spread apart (i.e. caliper pistons pushed in) when you added the fluid, using the brake to bring the pads to their normal position next to the rotor will require some of the fluid to move down to the pistons, thus lowering the level.  Pad wear will cause the level  to drop over time, as well.

[..]

If your pads were spread apart (i.e. caliper pistons pushed in) when you added the fluid, using the brake to bring the pads to their normal position next to the rotor will require some of the fluid to move down to the pistons, thus lowering the level.  Pad wear will cause the level  to drop over time, as well.

Didn't touch pads.

[..]

Put a splash more in and will see what happens when next I ride.

Took the caps off the bleeders and there's no moisture I can see.

[Daniel Meyer]

You should never have to add once bled/etc...the pads wear, the fluid goes down a bit (but not below line), ya add new pads, fluid goes back up.

You have a leak. Fix it. Sudden failure of a caliper seal or master cylinder is trouble you don't want...

[..]

You should never have to add once bled/etc...the pads wear, the fluid goes down a bit (but not below line), ya add new pads, fluid goes back up.

You have a leak. Fix it. Sudden failure of a caliper seal or master cylinder is trouble you don't want...

[Firefighter]

If you are leaking fluid it should be all over everything, it doesn't go away without cleaning.

[..]

If you are leaking fluid it should be all over everything, it doesn't go away without cleaning.

That's what's puzzling  ???

[..]

You should never have to add once bled/etc...the pads wear, the fluid goes down a bit (but not below line), ya add new pads, fluid goes back up.

You have a leak. Fix it. Sudden failure of a caliper seal or master cylinder is trouble you don't want...

No discernible leaks form bleeder, hoses or junctions.

Next step remove calipers and check for a leak?

[hubcapsc]

You should never have to add once bled/etc...the pads wear, the fluid goes down a bit (but not below line), ya add new pads, fluid goes back up.

You have a leak. Fix it. Sudden failure of a caliper seal or master cylinder is trouble you don't want...

No discernible leaks form bleeder, hoses or junctions.

Next step remove calipers and check for a leak?

I've never had a leaky caliper that I know of, but if one of those piston
seals was leaking just a little, maybe your level would go down and
all the "action" happening at the caliper pistons might make it harder
to see a leak than if it was happening at one of the junctions.

I've had a junction leak once or twice, even if you can't really see it,
that brake fluid will find its way out if there is one... I could feel
the fluid, more than see it, at the leaky junction.

-Mike

[..]

You should never have to add once bled/etc...the pads wear, the fluid goes down a bit (but not below line), ya add new pads, fluid goes back up.

You have a leak. Fix it. Sudden failure of a caliper seal or master cylinder is trouble you don't want...

No discernible leaks form bleeder, hoses or junctions.

Next step remove calipers and check for a leak?

I've never had a leaky caliper that I know of, but if one of those piston
seals was leaking just a little, maybe your level would go down and
all the "action" happening at the caliper pistons might make it harder
to see a leak than if it was happening at one of the junctions.

I've had a junction leak once or twice, even if you can't really see it,
that brake fluid will find its way out if there is one... I could feel
the fluid, more than see it, at the leaky junction.

-Mike

Ill do a feel and tissue test.

[..]

Touch test done all the way from the reservoir to the calipers.


Nuttin.

[Valkpilot]

Touch test done all the way from the reservoir to the calipers.


Nuttin.

Is there any difference in lever and braking "firmness" before and after the apparent loss?  Is it possible there was air in the line that worked its way out to the master cylinder?

[..]

Touch test done all the way from the reservoir to the calipers.


Nuttin.

Is there any difference in lever and braking "firmness" before and after the apparent loss?  Is it possible there was air in the line that worked its way out to the master cylinder?

Don't think so.

[Ricky-D]

Well then, if there is no indication of a leak I would think you must have been mistaken in you observation and assumption.

***

[The emperor has no clothes]

If your pads were spread apart (i.e. caliper pistons pushed in) when you added the fluid, using the brake to bring the pads to their normal position next to the rotor will require some of the fluid to move down to the pistons, thus lowering the level.  Pad wear will cause the level  to drop over time, as well.

Didn't touch pads.

I always have to spread the pads a little to ease in reinstall.

[..]

No more theft of brake fluid. After 200 miles today and 200 last weekend the level in the window is as it should be.