Clutch problem , slipping

[SJK]

Hi All,

Please could I ask your advice , I cant seem to get my clutch adjusted on my K75.

The rear clutch piston seems to be very far out(12mm) towards the back wheel, and not flush in the gearbox housing as most of the examples I see. As a result If I attach the clutch cable to the arm it is pushing the push rod in and engaging the clutch without me pulling the clutch lever at the handle bars , even with the cables adjusted at way more then the recommended 750mm.

Does anyone by any chance now why the throwback piston is so far back?? :dunno

your help will be greatly appreciated   

[SJK]

This is the deepest it goes in without pressure

[Filmcamera]

Have you or anyone else taken the transmission off recently?

[SJK]

HI, yes sir.

This bike has never run since I bought it two years ago, and long story short It has had many issues and I have no record of who did what :yow

 The last was a leaking main seal that is now fixed. The latest is now this issue with the clutch piston but has been like that before my main seal work,but I know only know is a problem

[Filmcamera]

I would remove the transmission and clutch plate and start again - I guess something somewhere isn't seated properly.  Err hold on, where is the spring?  From that picture it looks like you have the spring behind the bearing not in front of it.


Check out Chris Harris' videos on you tube on a spline lube, in it he covers removing the tranny and shows how everything goes together.


https://youtu.be/HZJdZ1HszkA?list=PLMqo5VIG0mVv0vdF8JDrAoeQoWxBm3CtR

[SJK]

nope the spring is not behind ,its lying on my workbench .that picture is of the piston in with only the pushrod forcing it out.

I have watched this video of Chris before when I did the main seal repair, and Ive removed and rechecked everything a few times now :dunno2:

I took all the parts to our local BMW to confirm my parts and sizes as well today .....but no avail .
I was hoping the owner before might have installed the wrong Pushrod but it ended up being the right one (253mm)

[Motorhobo]

There are two different possible parts for that, if I remember correctly. One is a one-piece puck, the other is a two-piece one. All three of my K75s have the one-piece puck and they're all 94-95. I don't know if it makes a difference. Yours looks like the one-piece puck...are you sure you have it in the right way around? I can't remember myself which way it goes...but I do remember reading something about someone putting it in the wrong way around and wondering why it wasn't behaving as expected.

Anyone confirm that's the way it's supposed to go?

[Filmcamera]

I have a one piece puck, same as that- It goes the way he has it but with the spring after the puck

[SJK]

Yes thanks, that was also one of my doubts, but did confirm the puck instead of two piece piston other ones I've seen on pictures , as well as the direction of it.

I also need to add that with gearbox out there is no front pressure on the pushrod and the piston(puck) slips right into the housing with ease , so there isn't obstructions around that area , must be something more in front of the gearbox to the clutch area.....

[Motorhobo]

The only thing I can think of offhand is that if your clutch spring isn't centered properly, the front end of the pushrod won't seat properly. The clutch parts align so that there's a hole where the pushrod end goes in. If the clutch spring is out of alignment, the pushrod won't go in all the way and you might not notice it because it looks like it's in all the way. If the pushrod isn't all the way seated in the clutchpack, then it will protrude out the rear end of the transmission more than it should. Having said that, if it's not seated all the way, I'm not sure you'd be able to get the transmission on at all....

Anyway, it's something to look at. Read through this thread, I describe the problem with the pushrod not going into the hole all  the way in detail and give you some measurements to work with.

Hang in there...

MH

[SJK]

 If the pushrod isn't all the way seated in the clutchpack, then it will protrude out the rear end of the transmission more than it should.

yeah it must be something in this line of fault , I also tried inserting the pushrod into the clutchpack assembly then marked it with a permanent marker to show if it moves and then slid the gearbox into position while peeping in thru the side as long as possible to look if it shifts. but it still pushed the piston puck out the back.
will jump back in there tomorrow when spirit is higher ad look again 

[The Mighty Gryphon]

You may have a slightly bent rod that is not going into the pilot bushing in the output shaft.  Or the clutch pack is not centered.  I vaguely recall one of my bikes doing that after a clutch spline lube.  Had to remove the transmission and recenter the clutch pack. 

Can the rod be pushed in?  Or is it hard against a stop?

[Filmcamera]

I think it is the clutch pack as well, I have just changed my clutch and without a clutch centering tool it tool me a few attempts to get it perfectly centered

[SJK]

Morning, Thanks for the info guys , I got stuck in this morning removed the gearbox to have a nice good look again, unfortunately all seems to be in place and correctly aligned. The pushrod goes all the way into the holes and the sleave of the pushrod is up against the clutch spring plate. I was thinking maybe the very back Clutch housing was too far forward or something stuck behind hindering it from going back all the way, but no luck, if it goes back anymore the six clutch pressure plate bolts will scrape the bell housing.


Does anyone know for sure if this is the right pushrod (253cm) and piston(puck)??
 
I'm attaching photos

[Laitch]

Maybe you have inserted the rod backwards. Strange things happen out there.

[The Mighty Gryphon]

Laitch has a good point.  The K100 and k75 transmissions are not the same.  One has the rod go in from the back, while the other has the rod go in from the front.  I can't remember which is which.  The rods are also different. 

I have a K100 rod in my spares and a K75 transmission in the garage.  I can take some measurements later this morning when it warms up a little.  In the meantime, I would suggest double checking your manual to see if you were following instructions for the wrong model.

[SJK]

thx for the reply guys but nope, the pushrod I have is in the correct way, it can only be removed via the front of the gearbox. it has this shoulder rim that prevents it from sliding thru the back.

Thx Gryphon that would help eliminate that question for me if you can confirm the measurements
-Overall length=253mm
-Back to shoulder rim=217mm
-Shoulder rim to Front tip 35mm

I have read up that a worn out clutch friction plate could cause the diaphragm spring to push forward more on the pushrod? could this be the cause of the extended piston/puck?

[Laitch]

thx for the reply guys but nope, the pushrod I have is in the correct way,

Which side of the rod in the attach photo is being inserted in the clutch pack, the left side or the right side?

[SJK]

Left ( where the shoulder rim is)

[The Mighty Gryphon]

I just checked my K75 pushrod, and your dimensions are correct. 

Have you tried pushing the rod into the pilot bearing in the end of the output shaft?  I suspect that something is preventing the rod from going in there.

Is the rod staright?  When you roll it is there any runout?

Did you use an alignment tool to center the clutch pack?

[SJK]

Ok thx for checking Gryphon, yes the rod is not bent and goes into the piolet hole when the clutch pack is installed on the clutch housing. The shoulder rim goes all the way in against the diaphragm spring hole. I've also left the Pushrod in max position...marked the Pushrod with a marker to make sure there is no movement and slid the gearbox over, but still the Pushrod comes out too far at the back of the gearbox  :dunno

[Filmcamera]

I assume that with the clutch pushrod left out everything fits properly all the way in?

[Laitch]

Have you verified that there is no bushing in the assembly forward of the puck?

[The Mighty Gryphon]

Are you using a pair of 8mm x 100mm headless bolts to support and guide the transmission onto the rear of the engine to assure alignment?  A tiny bit of tilt in the transmission during installation will mess up the alignment of the splines and the pushrod.

I am pretty sure that you are not getting the forward end of the rod into the pilot bushing in the engine output shaft when you install the transmission.  That is the only thing that would force the rod as far back as you are experiencing. 

How did you center the clutch pack? 

[SJK]

I assume that with the clutch pushrod left out everything fits properly all the way in?

yes that is correct