'09 GSA Clutch and Brake questions

[Grout]

Brake - I was changing the tires on my bike yesterday and noticed that the brake rotors have some play in them. The rotors can be moved slightly on a plane parallel to the wheel (not in and out). Is this normal? Both rotors have the same amount of movement and the discs themselves are properly torqued.

Clutch - The clutch fluid level is below the Min mark. In reading the manual it says to use mineral oil, but it is not allowed to pour fluid in! How do I replenish the clutch fluid then?

Thanks for any help you can offer.

[marc]

I believe the current version of the front rotors are semi-floating which means they should move a bit. Not the rear, thought.

The "don't pour" is for a flush or first time install. In that case you put the fluid in a syringe and push it into the system from the bleed valve at the slave cylinder. To top off you can add some to the master cylinder.

But.... Low fluid would bother me. A lot. Where did it go? As the clutch wears the fluid RISES. The usual problem is that you have to remove some fluid over time. I'd be looking closely at my slave cylinder for proper operation and indication of leaks. I might go so far as to remove the slave for a closer look. You certainly don't want hydraulic fluid near your clutch, someplace it may go if the seal in the slave cylinder goes.

[pdxrmccgs]

My take on the owners manual instruction: You may "add" mineral oil
by pouring some into the clutch fluid reservoir but do not add
"hydraulic fluid" which is generally distinguished from mineral oil.

Jim Von Baden is very specific on this point in his material in that you
do not use brake fluid but mineral oil.

The procedure for "clutch bleeding" is usually thought of as
bleeding the existing fluid out of the system and replacing with
new mineral oil with no air bubbles. At first it is a complex procedure
but when the light bulb goes on pretty easy to understand. There are
quite a few good posts on the forums on the procedure. The difficulty
is making sure there are no air bubbles in the system or your clutch
is squishy.

Welcome to the forum.

[marc]

Originally Posted by pdxrmccgs

My take on the owners manual instruction: You may "add" mineral oil
by pouring some into the clutch fluid reservoir but do not add
"hydraulic fluid" which is generally distinguished from mineral oil.

Minor nit. "Hydraulic fluid" is a generic term that includes mineral oil. It includes any fluid used to control a hydraulic system which could be water. In the particular instance of the BMW clutch the hydraulic fluid happens to be some kind of mineral oil. It used to be the same as Magura Blue Blood used for bicycle braking systems, but I don't if that is still true on later model bikes.

[pdxrmccgs]

I worked in the mobile and industrial hydraulic industry for several years
and the only "stuff" we used to power pumps valves
and cylinders was called "hydraulic fluid". It was several years later
that I heard the term "mineral oil" in a engine break-in discussion and
I asked and have asked for many years what is mineral oil?

The normal feedback I get is something about natural oil...no additives etc.
So...I have asked anyone who seems interested and knowledgeable: If Abdul pulls
a bucket of water up for his camel Husef from a oasis well 10 miles from
a Shell complex in the Saudi Arabian desert and finds oil floating on the
top...is that mineral oil? Most peoples response is something to the effect
that maybe I should consider counseling and walk away as fast as they can.

[Grout]

Originally Posted by marc

I believe the current version of the front rotors are semi-floating which means they should move a bit. Not the rear, thought.

The "don't pour" is for a flush or first time install. In that case you put the fluid in a syringe and push it into the system from the bleed valve at the slave cylinder. To top off you can add some to the master cylinder.

But.... Low fluid would bother me. A lot. Where did it go? As the clutch wears the fluid RISES. The usual problem is that you have to remove some fluid over time. I'd be looking closely at my slave cylinder for proper operation and indication of leaks. I might go so far as to remove the slave for a closer look. You certainly don't want hydraulic fluid near your clutch, someplace it may go if the seal in the slave cylinder goes.

Thank you for your help. I went to my local Dealer and wouldn't you know, someone (before I bought the bike) "topped off" the clutch with DOT 4 :-( The Dealer is recommending a system flush with mineral oil and inspection in case the DOT 4 damaged any part of the clutch system. Seems like sage advice to me.