clutch slave operational function - BMW Luxury Touring Community
 
LinkBack Thread Tools Display Modes
post #1 of 29 Old Oct 4th, 2011, 11:01 am Thread Starter
Senior Member
 
tenrocky's Avatar
 
Join Date: Apr 2011
Location: Lansdale, Pa, USA
Posts: 131
clutch slave operational function

A lot is written about the clutch slave cylinder . Could someone please to me in total layman's terms what is the function of this piece of equipment so I can better understand my bike. Thank you

Don't waste a day wishing you rode!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

------------------------
2002 K1200 LTC
1984 kawasaki ZN700 LTD
tenrocky is offline  
Sponsored Links
Advertisement
 
post #2 of 29 Old Oct 4th, 2011, 11:19 am
Senior Member
 
shoswell's Avatar
 
Join Date: Apr 2008
Location: Nashville, TN, United States
Posts: 1,425
Garage
Re: clutch slave operational function

From the backside of the tranny through to the center of the clutch is a steel rod about the thickness of a Sharpie inkstick...

One end rests against the pressure plate on the clutch, the other inside the Slave. When you pull the clutch lever it pushes in the rod (pin) thus pushing in your clutch....

Your end of the lesson..

Hoss
'Stupidity has a knack of getting its way.' --Albert Camus
'05- K1200LT - Gretchen
R.I.P. - '00- K1200LTE- "Barbara" - Retired at 168K 9/2011
MOA, IBA, EXR & RCB and TMI
shoswell is offline  
post #3 of 29 Old Oct 4th, 2011, 11:22 am
Senior Member
 
bigbear's Avatar
 
Join Date: Dec 2005
Location: Winnebago, IL, USA
Posts: 1,178
Re: clutch slave operational function

The slave cylinder replaces the older mechanical linkage to release the clutch. It has been decided by OEM's like BMW that it is easier to run a small hydraulic line Vs a cable and mechanical arms, pivot points, etc..

Does this explain it??

Roy Gregersen

Ride Slow, Ride Fast, Always Ride Safe
85 K100RT sold
02 LTC DOA 9/21/14
12 R1200RT
bigbear is offline  
 
post #4 of 29 Old Oct 4th, 2011, 1:23 pm
Senior Member
 
casualemt's Avatar
 
Join Date: Jun 2009
Location: Oak Harbor, WA, USA
Posts: 676
Re: clutch slave operational function

Master and slave....What the master wants, the slave does...When you pull on the clutch lever on the handle bar, it is connected to a hydraulic master cylinder, which is a pump of sorts, it pumps pressure into the hydraulic line that runs from the handlebar to the clutch... at the receiving end of that hydraulic line is the clutch slave cylinder, it uses the pressure that you pump into the line with the clutch lever, and pushes a rod into the clutch pressure plate that engages or disengages the clutch. As was previously stated this hydraulic system replaces the old clutch cable, springs, levers, in the less technical and older bikes. As is most noted in discussions on this forum, a big problem that plagues us LT riders is leakage of the slave cylinder seal. You see, the hydraulic fluid creates pressure in the slave cylinder and that pressurized fluid pushes the rod that operates the clutch pressure plate. There is a seal that keeps the hydraulic fluid inside the cylinder yet allows the rod to move in and out of this cylinder. If this seal fails, and hydraulic fluid leaks past the seal and into the clutch area, it eventually contaminates the dry clutch with a lubricant which makes the clutch slippery and won't hold tight anymore. (yea, its ruined) The idea of drilling a weep hole is designed to allow any hydraulic fluid that leaks past a failing seal, to run down the outside of the clutch housing thereby eliminating contamination of the clutch, and saving a huge headache (and don't forget big $$) of replacement of the clutch...Man! I can be long winded!!!

RICH CANNON
2000 K1200LT "a great ride"
2002 GL1800 powerful, but boring..(gone)
1979 XS1100 (gone)
1986 VT500 Ascot (gone)
1972 Honda 500-4 (gone)
1961 Lambretta (way gone)
1962 Allstate Compact (gone but not forgotten)
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
casualemt is offline  
post #5 of 29 Old Oct 4th, 2011, 4:55 pm Thread Starter
Senior Member
 
tenrocky's Avatar
 
Join Date: Apr 2011
Location: Lansdale, Pa, USA
Posts: 131
Re: clutch slave operational function

So ,just as holding the clutch lever in on a cable system will generally wear out the cable faster, will holding in the lever needlessly on this system wear out the slave cylinder quicker ?

Don't waste a day wishing you rode!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

------------------------
2002 K1200 LTC
1984 kawasaki ZN700 LTD
tenrocky is offline  
post #6 of 29 Old Oct 4th, 2011, 8:47 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,131
Re: clutch slave operational function

Quote:
Originally Posted by tenrocky
So ,just as holding the clutch lever in on a cable system will generally wear out the cable faster, will holding in the lever needlessly on this system wear out the slave cylinder quicker ?
Holding a lever on a cable will not wear it out faster, nor will it wear out the slave faster. There is a small "throwout" bearing the rod rides in at the end of the slave piston. It is always spinning whether you have the clutch pulled in or released and it is always under some pressure. It just does not make any difference.

By the way I always stay in gear at the lights with the clutch pulled in - 71K and no issues so far.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #7 of 29 Old Oct 4th, 2011, 8:58 pm Thread Starter
Senior Member
 
tenrocky's Avatar
 
Join Date: Apr 2011
Location: Lansdale, Pa, USA
Posts: 131
Re: clutch slave operational function

Thanks for helping me to understand things a little better. By the way, 54000 miles with no problems, just trying to learn all I can.

Don't waste a day wishing you rode!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

------------------------
2002 K1200 LTC
1984 kawasaki ZN700 LTD
tenrocky is offline  
post #8 of 29 Old Oct 4th, 2011, 9:46 pm
Senior Member
 
K100Dennis's Avatar
 
Join Date: Jul 2008
Location: Railton, Tasmania, Australia
Posts: 876
Re: clutch slave operational function

John, do you know what the failure mode(s) is/are for the clutch slave (when fluid eventually leaks) ? I had mine off my '05 to drill the weep hole and looked at the thrust bearing as much as I could see without removing it from the bike, very small. Being a small diameter bearing the surface speed will never be very high, and the bearing looks to be sealed ?? So does the bearing eventually seize, causing the slave piston to rotate and wreck the piston seal ?
I pressed a little moly lube in around mine while I was in there, it may or may not help. I note the slave cylinder unit is by Magura, but obviously not available from them, only as an OEM part from BMW. Not rebuildable according to Clymers ?

Dennis
1987 Yamaha TY250R
1991 Aprilia Climber 280
1988 K100RT (the pack horse)
2005 K1200LTE Light yellow metallic
K100Dennis is offline  
post #9 of 29 Old Oct 4th, 2011, 11:37 pm
Senior Member
 
rhawk's Avatar
 
Join Date: Nov 2007
Location: Wilsonville, OR, USA
Posts: 438
Re: clutch slave operational function

Here's another one,

Let's say that you've got the clutch operating rod with the groove for the felt piece.

If you put a new felt thingy in there ............... should you also put a couple drops of engine oil on it to help it slide inside the xmsn shaft ?

I'm doing the weep hole mod as we speak.
rhawk is offline  
post #10 of 29 Old Oct 5th, 2011, 9:49 am
Senior Member
 
zippy_gg's Avatar
 
Join Date: Jun 2004
Location: Kennesaw, GA, USA
Posts: 8,110
Re: clutch slave operational function

Quote:
Originally Posted by jzeiler
By the way I always stay in gear at the lights with the clutch pulled in - 71K and no issues so far.
+1 This one good habit to develop, along with keeping an eye in the rear view mirrors.
I see many riders struggle to get in first gear when the light turns green, with impatient cagers right on their tail... Not the safest combo!

Gilles & Kathy
BMWMOA# 154719
IBA# 71594
2011 Ostra Gray RT
06 Mercedes-Benz E350 Estate (parts and people hauler)
2012 BMW X3 (parts and people hauler)
86 Porsche 911 Cabriolet (my "new" baby)



For her I climbed the highest mountain!
For her I swam across the deepest ocean!
For her I walked through the largest desert!
And then she left me... She said I was never home!!!


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
zippy_gg is offline  
post #11 of 29 Old Oct 5th, 2011, 6:12 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,131
Re: clutch slave operational function

Dennis,

It is a small bearing and when it does lock up it will spin the slave pistion. The diameter of the rod is tiny and you are right it does not spin fast but it is under a certain amount of pressure all the time. A little dab of lube can't hurt the bearing.

rhawk

I would leave it dry - you should not have any trouble sliding it into the shaft. Its purpose is anti -rattle not anti oil contamination.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #12 of 29 Old Oct 5th, 2011, 7:11 pm
Senior Member
 
K100Dennis's Avatar
 
Join Date: Jul 2008
Location: Railton, Tasmania, Australia
Posts: 876
Re: clutch slave operational function

Thanks John, I suspected that may be the failure mode. Sounds like a PITA, but I might just make a point of going in there occassionaly and doing a regrease of the little bearing.
I assume that the clutch actuation rod has a hardened end on it ? I didn't examine it too closely when I did my weep hole. That being the case, I presume the clutch rod normally survives the slave failure.

Dennis
1987 Yamaha TY250R
1991 Aprilia Climber 280
1988 K100RT (the pack horse)
2005 K1200LTE Light yellow metallic
K100Dennis is offline  
post #13 of 29 Old Oct 5th, 2011, 10:15 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,131
Re: clutch slave operational function

Yeah, The air heads used to weld them selves to the release disk. Not the case with the LT the tip goes through a hole and a shoulder rests on the release spring. I don't think the slave end get damaged when the piston starts spinning. At least I don't remember David Shealy mentioning that when his spun.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #14 of 29 Old Oct 6th, 2011, 5:49 am
Senior Member
 
Roamrider's Avatar
 
Join Date: Feb 2011
Location: North-central Florida
Posts: 196
Re: clutch slave operational function

Years ago hydraulic clutches, and brakes, replace cables or rods to connect the motion of the control.....a handle or pedal......to the motion of the component.....a clutch or brake.

Imagine two large syringes. Remove the needles and have the two ends connected by a long tube. The syringes and the tube are filled with water. If you pressed on the plunger of one syringe, the plunger on the connected syringe would move out. You're pressing on the "master" cylinder piston.....and the "slave" cylinder piston is moving. The cool thing about this system is that it doesn't care how long the tube is, within reason. So, if I want something that I do with my hand.......ie squeezing the clutch handle, to result in mechanical motion somewhere else on the bike, in this case a clutch assembly, I simply hook up a piston with a plunger to the handle of my clutch....the master cylinder......by a long hose filled with oil.....to a companion piston with a rod attached......the slave cylinder.

When the rod on the slave cylinder moves, it actuates the clutch mechanism.

To complete the system, you need a spring on the clutch to "push back" when the clutch is to be reengaged. This all works because the oil flows in the lines when pushed, but because the system is sealed and there are no air bubbles in the system, what happens at one end, is immediately happening at the other end.

Push the master piston rod....the slave piston rod moves. Let go of the handle moving the master piston rod, the spring on the slave piston assembly pushes everything back where it was.

Some time ago folks decided that such a system, long term, was more reliable and easier to maintain than a flexible cable, or a series of complex rod linkages.

JD

Jeff Dunkle
Ocala, FL
2000 LT - Motorvation Formula II
1995 R100GS
2004 Burgman 650 (wife's)
Roamrider is offline  
post #15 of 29 Old Oct 6th, 2011, 7:08 am
Senior Member
 
New2rt's Avatar
 
Join Date: Jun 2009
Location: Kingston, PA, USA
Posts: 728
Re: clutch slave operational function

They'll also use a larger diameter piston on the slave for less effort at the master. You will loose travel on the slave piston as compared to the master but you don't need much.
Self adjusting to boot.

The downside, they can leak
New2rt is offline  
post #16 of 29 Old Oct 6th, 2011, 6:16 pm
Senior Member
 
dshealey's Avatar
 
Join Date: Apr 2002
Location: Dandridge (Near Knoxville), TN, USA
Posts: 12,165
Re: clutch slave operational function

Quote:
Originally Posted by jzeiler
Dennis,

It is a small bearing and when it does lock up it will spin the slave pistion. The diameter of the rod is tiny and you are right it does not spin fast -------------------------------.
It spins at whatever the engine RPM is, I consider this quite fast. Most standard electric motors only spin at 1,700-3,600 RPM, the LT engine idlesat around 1,750, and goes up to near 8,000.

That is fast for most any normal bearing.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
dshealey is offline  
post #17 of 29 Old Oct 6th, 2011, 7:28 pm
Senior Member
 
K100Dennis's Avatar
 
Join Date: Jul 2008
Location: Railton, Tasmania, Australia
Posts: 876
Re: clutch slave operational function

David, my reference to the bearing speed is based on its diameter. "Fast" is a relative term only. I'm well aware of the potential engine rpm's, but this bearing is extremely small in diameter, so itssurface speed (m/min, ft/min) will be quite low. If someone can quote me the bearing number I can do some calcs on surface speeds and potential (theoretical) L10 life for the bearing. Remember, there is a point very close to the centre of every circle where there is virtually no velocity but there's plenty at the outside diameter. rpm's will always be the same though.

Dennis
1987 Yamaha TY250R
1991 Aprilia Climber 280
1988 K100RT (the pack horse)
2005 K1200LTE Light yellow metallic
K100Dennis is offline  
post #18 of 29 Old Oct 6th, 2011, 9:43 pm
Senior Member
 
dshealey's Avatar
 
Join Date: Apr 2002
Location: Dandridge (Near Knoxville), TN, USA
Posts: 12,165
Re: clutch slave operational function

Quote:
Originally Posted by K100Dennis
David, my reference to the bearing speed is based on its diameter. "Fast" is a relative term only. I'm well aware of the potential engine rpm's, but this bearing is extremely small in diameter, so itssurface speed (m/min, ft/min) will be quite low. If someone can quote me the bearing number I can do some calcs on surface speeds and potential (theoretical) L10 life for the bearing. Remember, there is a point very close to the centre of every circle where there is virtually no velocity but there's plenty at the outside diameter. rpm's will always be the same though.
It is a ball thrust bearing, not a radial bearing, I do not think there is a replacement bearing available, as it it pressed into the piston. It is about 12-14 mm outside diameter, from memory, have not measured one. The ball race is likely around 10mm diameter.

I MAY still have the piston that failed, will have to look this weekend to see if it is still in my LT junk box.

That bearing does not have to get very "tight" to cause the piston to spin, which pretty rapidly destroys both the piston and cylinder.

Here is the picture of my "spun" piston/cylinder
.
Attached Thumbnails
Click image for larger version

Name:	PistonCylinder.JPG
Views:	323
Size:	146.2 KB
ID:	33128  

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
dshealey is offline  
post #19 of 29 Old Oct 6th, 2011, 11:17 pm
Senior Member
 
K100Dennis's Avatar
 
Join Date: Jul 2008
Location: Railton, Tasmania, Australia
Posts: 876
Re: clutch slave operational function

Thanks for the info David, looking at it in the SKF General Catalogue, if it's a thrust ball bearing of your approximate OD it is possible that it's a BA-5 or a BA-6. It may of course be some modified derivative, as these things sometimes are when the OEM does a deal with the supplier of the parts. However, that bearing won't be a sealed type bearing (not possible for this type), so there is probably some dust seal arrangement built into the Magura assembly and the bearing has some lube applied during assembly, who knows. That being the case, it may be possible to get some fresh lube in there if one was serious about preventing the failure. For the record, both those bearings mentioned have designated limiting speeds of 24000 and 28000 rpm respectively. Man, the seizure sure does a number on the piston and cylinder !

Dennis
1987 Yamaha TY250R
1991 Aprilia Climber 280
1988 K100RT (the pack horse)
2005 K1200LTE Light yellow metallic
K100Dennis is offline  
post #20 of 29 Old Oct 7th, 2011, 7:15 am
Senior Member
 
dshealey's Avatar
 
Join Date: Apr 2002
Location: Dandridge (Near Knoxville), TN, USA
Posts: 12,165
Re: clutch slave operational function

Quote:
Originally Posted by K100Dennis
Thanks for the info David, looking at it in the SKF General Catalogue, if it's a thrust ball bearing of your approximate OD it is possible that it's a BA-5 or a BA-6. It may of course be some modified derivative, as these things sometimes are when the OEM does a deal with the supplier of the parts. However, that bearing won't be a sealed type bearing (not possible for this type), so there is probably some dust seal arrangement built into the Magura assembly and the bearing has some lube applied during assembly, who knows. That being the case, it may be possible to get some fresh lube in there if one was serious about preventing the failure. For the record, both those bearings mentioned have designated limiting speeds of 24000 and 28000 rpm respectively. Man, the seizure sure does a number on the piston and cylinder !
And, the bearing was not reallied "seized", as it still turned, but with a little roughness. It does not take much torque to spin a lubricated piston in a cylinder. The seal is probably the only real resistance to it turning. When the hard anodize coating is worn away by the turning, the seal is then destroyed as it moves over the ridges. The coating is only a couple thousandths thick, and the base aluminum is soft.

In my opinion, I think that a great many of the failed slave cylinders, if not most, are because of this. Few have ever looked at a failed one to see.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
dshealey is offline  
post #21 of 29 Old Oct 7th, 2011, 10:08 am
Member
 
hd_ryder1964's Avatar
 
Join Date: Oct 2010
Location: Greer, SC, USA
Posts: 54
Re: clutch slave operational function

Quote:
Originally Posted by zippy_gg
+1 This one good habit to develop, along with keeping an eye in the rear view mirrors.
I see many riders struggle to get in first gear when the light turns green, with impatient cagers right on their tail... Not the safest combo!


Not such a good habit .... I personally saw a clutch cable break while a rider was sitting at a red light on an older Goldwing, it was years ago.. at Bike Week in Daytona. The bike lunged forward (he was the first one at the redlight!) just enough for him to be struck by a passing lifted 4WD truck. Not pretty!!! I stopped to administer what aide I could, there wasn't too much that could be done.
When his friends went to help load what was left of his bike onto the wrecker they noticed that his clutch cable had broken causing this fatal accident!
Unlucky... yeah... bad timing... yeah.... but me at a light.. neutral until it turns green. If I want to see if my clutch is slipping or dragging I'll check it anywhere but at a red light!!


Randy

47' Schwinn Whizzer H
50' Roadmaster Cycletruck Whizzer J
67' T-100R Triumph Tiger
83' CT100 Honda Trail
86' TR200 Honda Fat Cat
94' FLHR Harley Roadking
04' Von Dutch Cruel World
04' 1200KLT BMW
05' AN400 Suzuki Burgman
06' 250 Aprilla Scarabeo
07' 125 Yamaha Vino
11' Victory Vision

Not enough room to list the "sold" bikes....


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
hd_ryder1964 is offline  
post #22 of 29 Old Oct 7th, 2011, 10:49 am
Senior Member
 
dshealey's Avatar
 
Join Date: Apr 2002
Location: Dandridge (Near Knoxville), TN, USA
Posts: 12,165
Re: clutch slave operational function

Quote:
Originally Posted by hd_ryder1964
Not such a good habit .... I personally saw a clutch cable break while a rider was sitting at a red light on an older Goldwing, it was years ago.. at Bike Week in Daytona. The bike lunged forward (he was the first one at the redlight!) just enough for him to be struck by a passing lifted 4WD truck. Not pretty!!! I stopped to administer what aide I could, there wasn't too much that could be done.
When his friends went to help load what was left of his bike onto the wrecker they noticed that his clutch cable had broken causing this fatal accident!
Unlucky... yeah... bad timing... yeah.... but me at a light.. neutral until it turns green. If I want to see if my clutch is slipping or dragging I'll check it anywhere but at a red light!!

I always held the clutch in, and front brake on. At idle, a rapidly engaging clutch will just stall the engine, not enough torque at idle to overcome the front brake.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
dshealey is offline  
post #23 of 29 Old Oct 7th, 2011, 11:18 am
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,131
Re: clutch slave operational function

I am with David on this one. Front brake on, clutch in. Far more likely to get an impact from the rear that to have a failure of the clutch cable/slave!!!Like he said the engine will stall on rapid release if the brakes are applied.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #24 of 29 Old Oct 7th, 2011, 3:46 pm
Senior Member
 
pozo_izquierdo's Avatar
 
Join Date: Apr 2004
Location: Hyvinkää, , Finland
Posts: 1,583
Re: clutch slave operational function

Quote:
Originally Posted by jzeiler
Holding a lever on a cable will not wear it out faster, nor will it wear out the slave faster. There is a small "throwout" bearing the rod rides in at the end of the slave piston. It is always spinning whether you have the clutch pulled in or released and it is always under some pressure. It just does not make any difference.

By the way I always stay in gear at the lights with the clutch pulled in - 71K and no issues so far.
I woulld like to discuss this topic a bit deeper. The reason being that this past summer I was helping a friend who was on his way to do the Nordkapp- Gibraltar (from Northernmost point of Europe to Southernmost) run in 72 hours. His slave cylinder blew when he was riding North and he had to return back home over 1000 miles with a clutchless bike.
Luckily he had the weep hole drilled so his clutch was not lubed with clutch fluid and we changed his slave cylinder.
I talked with a BMW master technician about this incident and his comment was that sitting on the bike with clutched pulled in for instance in traffic lights wears out the slave cylinder faster. I respect the opinions of this technician as he has worked with BMW bikes since early 80's and he knows them like hs own pockets.

I don't want to discuss the safety point of this habit as I understand that in the US it is safer to have the bike on gear while waiting for the green light. Over here our traffic lights go from red to green through one second yellow so we get a little warning and actually time to put bike (or a car) on gear before rushing forward.

But technically, to me it makes sense that if the clutch is pulled in and thus the bearing (and piston around it) is under more pressure than when the clutch is released. I admit that the bearing is under some pressure all the time but when the clutch lever is pulled in the pressure becomes significantly bigger.
Does this make sense to anybody else...?

Regards

Ari "the Farkle-Freak-Finn" Ignatius

Hyvinkää, Finland
2004 ('05) LT, Dark Graphite, "Sunset Cruiser II"

Bike trip from Finland to USA:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


Pictures of various farkle projects:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pozo_izquierdo is offline  
post #25 of 29 Old Oct 7th, 2011, 10:17 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,131
Re: clutch slave operational function

I agree it is always under pressure pulled or not and it is under greater pressure when pulled. I don't see that as a problem. It is designed to do a job and does it well, but it will wear out. Can't calculate Just when it will happen though.

I will continue to hold mine in.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #26 of 29 Old Oct 8th, 2011, 7:27 am
Senior Member
 
K100Dennis's Avatar
 
Join Date: Jul 2008
Location: Railton, Tasmania, Australia
Posts: 876
Re: clutch slave operational function

So John, I'm drilling for a bit more info on the slave, do you know what the stroke of the slave is ? I'm thinking it may be possible to machine a longitudinal slot in the outer end of the piston and insert a guide pin into the wall of the cylinder to prevent the piston from being able to rotate when the bearing begins to bind. This then pushes the failure mode to another part though - the bearing and the clutch push rod, which I guess would end up being severely damaged before anything was noticed ?? So would I have wasted my time and effort ? Maybe we just run with the weep hole as the alert that the piston has been spinning, as you correctly point out, it would be rare to see a piston - cylinder assy fail without this (rotation) as the cause. I wonder if I can get some fresh lube into that little bearing ? Not too much work to take out the swing arm to get in there. Do we continue this thread, or just drop it ?

Dennis
1987 Yamaha TY250R
1991 Aprilia Climber 280
1988 K100RT (the pack horse)
2005 K1200LTE Light yellow metallic
K100Dennis is offline  
post #27 of 29 Old Oct 8th, 2011, 1:34 pm
Wrencher Extraordinaire
 
jzeiler's Avatar
 
Join Date: May 2004
Location: Hazel Green, AL, USA
Posts: 13,131
Re: clutch slave operational function

The stroke is very small but it moves over time. When I removed the slave in prep for the clutch replacement the piston was all the way to the rear. When I installed the slave following clutch replacement it was barely pushed back at all. I thought I had missed something during reassembly of the clutch. Based on that I don't think that idea would work.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jzeiler is offline  
post #28 of 29 Old Oct 8th, 2011, 9:34 pm
Senior Member
 
K100Dennis's Avatar
 
Join Date: Jul 2008
Location: Railton, Tasmania, Australia
Posts: 876
Re: clutch slave operational function

Yes, that's a good point. Idea exhausted I think. I may take the trouble to go in and attempt to relube the thrust bearing, I'll see. I've seen posts where some have over 100,000 Km's and no trouble with the slave, so I assume some bearings are better lubes initially than others, maybe. I'm done on this one I think.

Dennis
1987 Yamaha TY250R
1991 Aprilia Climber 280
1988 K100RT (the pack horse)
2005 K1200LTE Light yellow metallic
K100Dennis is offline  
post #29 of 29 Old Oct 9th, 2011, 2:43 pm
Lifetime Supporter
 
Voyager's Avatar
 
Join Date: Jun 2007
Location: Lawrenceville, PA, USA
Posts: 6,995
Re: clutch slave operational function

Quote:
Originally Posted by pozo_izquierdo
I woulld like to discuss this topic a bit deeper. The reason being that this past summer I was helping a friend who was on his way to do the Nordkapp- Gibraltar (from Northernmost point of Europe to Southernmost) run in 72 hours. His slave cylinder blew when he was riding North and he had to return back home over 1000 miles with a clutchless bike.
Luckily he had the weep hole drilled so his clutch was not lubed with clutch fluid and we changed his slave cylinder.
I talked with a BMW master technician about this incident and his comment was that sitting on the bike with clutched pulled in for instance in traffic lights wears out the slave cylinder faster. I respect the opinions of this technician as he has worked with BMW bikes since early 80's and he knows them like hs own pockets.

I don't want to discuss the safety point of this habit as I understand that in the US it is safer to have the bike on gear while waiting for the green light. Over here our traffic lights go from red to green through one second yellow so we get a little warning and actually time to put bike (or a car) on gear before rushing forward.

But technically, to me it makes sense that if the clutch is pulled in and thus the bearing (and piston around it) is under more pressure than when the clutch is released. I admit that the bearing is under some pressure all the time but when the clutch lever is pulled in the pressure becomes significantly bigger.
Does this make sense to anybody else...?

Regards
I have read the arguments on both sides of this practice and I prefer to shift into neutral and release the clutch at almost every light I stop at. The exception is lights that I believe are about to change or be very short. I do this for several reasons:

1. I beleive it lessens wear on the throw-out bearing.
2. It is easier on the hand, although the LT clutch effort is pretty light so this isn't a big deal.
3. I live in a rural area so I don't all that often have cars come up behind me at lights.
4. If a vehicle was coming up really fast, by the time you reall knew what was going to happen, I don't think most people could actually get out of the way in any event. Many would panic and pop the clutch stalling the engine.

If I see someone coming up at a high rate of speed, I can very quickly pop the bike back into gear and will occassionally do that. However, I am still not convinced that I could actually get out of the way by the time I know for sure that the person isn't going to stop.

A car approaching at 40 MPH is covering nearly 60 ft per second. So, if you decide whenthe person is still 120 ft away that they are not likely to stop, you have only 2 seconds to get out of the way. LTs don't launch all that fast. Go out and sit on your LT with it at idle and in gear. Have someone with a stopwatch stand 10 feet in front of you. Have them click the stopwatch and see how far you get in 2 seconds. I bet you will be lucky to past them. And moving 10 feet is probably the minimum to get out of the way enough to not get hit.

To me, the "keep it in gear so I can get out of the way" philosophy is great in theory, but I don't think it holds up in practice for most people in most situations.

2017 KLR650 "Mule"
2007 K1200LT "Starship Enterprise", VOICE II, Navigator V, Motorrad Communicator
1987 Kawasaki Voyager XII
1976 Kawasaki KH400
1973 Kawasaki 100 G5
1970 Rockford Chibi (the orange one)

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Voyager is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the BMW Luxury Touring Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Does tranny fluid take out Clutch Slave? mkiesel K1200LT 7 Mar 2nd, 2011 8:37 pm
Back on an LT after 3 years - clutch slave cyl question Bueller K1200LT 5 May 24th, 2009 7:58 pm
Slipping Clutch - Clutch Slave Cylinder lhendrick K1200LT 24 Mar 29th, 2009 7:02 pm
Unreliable clutch advice please cyclecamper K1200LT 11 Dec 1st, 2008 10:23 pm
latest clutch analysis cyclecamper K1200LT 17 Feb 27th, 2007 9:00 pm

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome