Author Topic: Sticky clutch (Read 12140 times)

jensk · « **on:** June 28, 2015, 01:14:42 PM »

I have just bought a '92 K75rt with 65kkm on the clock and full service history. This is my first beemer so please bear with me if the answers to my postings are well known to others than me.

I had a leak on the left fork so first job was to get the forklegs of and renew the seal. Stancion tube seemed fine without dents or scratches. I was very carefull sliding the new seal down on a piece of plasticbag. But it still leaks. I wonder if the bushings are worn even though i can't feel any play grabbing the forklegs antrying to rock them back and forwards. I guess a new seal job is required.

My major problem is a sticky clutch. Sticky in a way so that sometimes when i ride on the highway and pull the clutch lever all the way in to the handlebar the clucth doesn't disengage so the engine is running 2000 rpm and i can't get it out of 5'th gear. At all other times the clutch disengages fine. If i have it on centerstand with engine running and pull the clutch, put it in gear the rear wheel stop without a mess.

I have changed all oils i engine, gearbox, final drive and lubed the final drive splines. Gear and final drive oil is Castrol 75w/90. I haven't inspected the clutch splines but the clutchlever is easy and even to pull.

What is the possible cause of this strange clutch behavior?
/Jens

rbm · « **Reply #1 on:** June 28, 2015, 01:59:31 PM »

Have you followed the clutch adjustment procedure, including setting the 75mm free cable length at the actuator arm, setting the 2mm clutch handle freeplay and setting the adjustment screw at the end of the actuator arm? The procedure is detailed on page 21-09.0 of the OEM manual.

jensk · « **Reply #2 on:** June 28, 2015, 02:34:01 PM »

I will adjust tomorrow - it's getting late here.
What bothers me is that the clutch in all other respects seem to be working fine. No problems getting it in 1'st gear when stopped by a light. I was a bit worried since this problem occurred after i changed the gear oil. I used 1 liter od Castrol 75w-90 gear oil. Its API GL-4/5 semi synthetic. Is this oil ok?

rbm · « **Reply #3 on:** June 28, 2015, 02:38:51 PM »

Should be fine. I use an equivalent synthetic gear oil -- Royal Purple Maxgear 75-90 in my transmission and final drive. I believe it has similar properties to the Castrol, conforming to API GL-4/5.

jensk · « **Reply #4 on:** June 28, 2015, 02:41:12 PM »

Thats good with the oil then. I will look at the clutch cable and arm adjustment tomorrow when i get home from work.

pallum · « **Reply #5 on:** June 28, 2015, 08:01:25 PM »

If it's still sticking after the clutch cable adjustment (a properly adjusted clutch cable is a wonderful thing, never overlook it) you're probably due for a clutch spline lube.

jensk · « **Reply #6 on:** June 29, 2015, 06:48:28 AM »

I read an article or view'ed a youtube video somwhere with a guy that did his clutch spline lube without taking the gearbox completely of. He had it hanging in 2 longer bolts that he mounted in stead of the normal clutch bolts. This way he could pull back the gearbox 4 - 5 cm's without dismounting it.

I can't find this posting, article, video. Any clues to where it is?

The Mighty Gryphon · « **Reply #7 on:** June 29, 2015, 07:30:41 AM »

I don't have the link, but have done my bike that way. All you need to do is get two 6mm bolts that are about 100mm long and cut the heads off.

Remove the bolts on each side of the transmission and replace them with the new bolts. Slide the transmission back about two inches and get in there with a parts cleaning brush with a bit of spline lube on it. When done, slide the transmission forward and replace the bolts.

Inge K. · « **Reply #8 on:** June 29, 2015, 08:15:48 AM »

Quote from: The Mighty Gryphon on June 29, 2015, 07:30:41 AM

I don't have the link, but have done my bike that way. All you need to do is get two ~~6mm~~ bolts that are about 100mm long and cut the heads off.

8mm

The Mighty Gryphon · « **Reply #9 on:** June 29, 2015, 12:58:14 PM »

Ouch! Memory is worse than I thought. Thanks for the correction.

jensk · « **Reply #10 on:** June 29, 2015, 05:42:00 PM »

Sorry for the delayed answer - I was out helping a friend who was about to buy a used R1100R.
I did the clutch adjust today. measure free inner cable length, set it to 75mm (it was ~80mm) adjusting the clutch pressure bolt so that it just touches the clutch pin and lock it with the locknut.
I had trouble to turn back the locknut so i took the bolt completely out of the clutch arm. Then il strated to drip out of the hole for the bolt. When i remounted the bolt and adjusted it to barely touch the clutch pin and locked it the dripping stopped. is this normal?

After adjustment i tried and had almost no freeplay at the clutch handte so i ajdusted the cable to allow 1,5 mm slack at the handle.

The problem with sticking 5'th gear remained there so next up might be a spline lube at the clutch splines.

BTW when i changed the gearbox oil i gave it 1 liter of new oil. Now i read in Clymers that the gearbox only needs 0,85 liter. Could the extra 0,15 liter affect gearshifting?

jensk · « **Reply #11 on:** June 30, 2015, 09:47:18 AM »

Checked the measurement at the end of the clutch cable again today as weel as the freeplay at the handle 1,5 mm.
I will take it for a spin tomorrow morning to se if it has helped.

I wold beliewe that if it is in need of a clutch spline lube that I would feel it as the clutch handle would be difficult to pull or it would not feel smooth to pull. But when i pull the handle it work easy and smooth all the way in. Is my assumption right about smooth handle pull indicates that cluth spline lube is ok or???

motodude · « **Reply #12 on:** June 30, 2015, 10:00:26 AM »

The need for a clutch spline lube will not present as a stiff clutch lever. It will usually present as difficult down shifting.

The tool kit has a bayonet gauge for measuring transmission lube level. As indicated, it is less than a liter.

Tom

rbm · « **Reply #13 on:** June 30, 2015, 10:10:21 AM »

When you were fooling with the adjustment screw, did you feel how easy or difficult it was to pivot the actuator arm with the clutch cable removed? It may be possible that a stiff feeling clutch could be caused by frozen roller bearings in the actuator arm. I have my doubts that it contributes to gear problems in 5th though. It may be the shift drum in the transmission needs looking at; but first do the clutch spline lube. You could use the trick of using M8x120mm bolts (with the heads cut off) and sliding the transmission out on those bolts. This exposes the clutch splines enough to be lubricated. Don't expect instantaneous smoothness after lubricating the splines. It might take a few days for the feel at the clutch lever to lighten up.

TimTyler · « **Reply #14 on:** June 30, 2015, 10:22:06 AM »

Quote from: jensk on June 29, 2015, 05:42:00 PM

... Then il strated to drip out of the hole for the bolt. When i remounted the bolt and adjusted it to barely touch the clutch pin and locked it the dripping stopped. is this normal?

That's because you overfilled your gearbox fluid.

TimTyler · « **Reply #15 on:** June 30, 2015, 10:24:13 AM »

Quote from: jensk on June 28, 2015, 01:14:42 PM

I have just bought a '92 K75rt with 65kkm on the clock and full service history.

Is there a clutch spline lube included on the service history?

jensk · « **Reply #16 on:** June 30, 2015, 11:03:43 AM »

The full service history consists of a original BMW servicebook with all stamps by the original dealer for every 10.000 km op til 60.000. 60.000 km was in 2006. The service book is in german which I do not understand and I can't find anything about kupplung (german for clutch) in the service book.

Since 2006 it has only run 6.000 km because the PO didn't have time to use it.

My assumptions is that for at least 9 years and 6.000 km it hasn't had a clutch spline lube. So is it time for a clutch spline lube yes/no?

I have sucked up 0.1 liter of oil from the gearbox. Now oil level is 11,5 cm down from the edge of the fill hole (it was 10,5 cm down before).

I will take it for a spin this evening to se how it disengages the clutch when in 5'th gear.

UPDATE:
so I gave it a spin. Gear shifts much easier now when cold. When warm shifting is a bit heawy/uneasy. The sticking of the clutch appears after about 12 km/8 miles driving. When the clutch sticks i can blip the throttle. This makes me able to shift down onto 4'th gear.

On the trip today my rpm meter locked several times - so a new topic to handle. Maybe it is due to he warm weather. I have to dig into this.

There are so many small issues on this bike that is beyond my experiences which is from old Hondas, Matchless and MZ (all between the 1950 and 1978) motorcycles

The Mighty Gryphon · « **Reply #17 on:** June 30, 2015, 02:55:43 PM »

I am going to guess that blipping the throttle is helping the clutch to disengage. The fact that it helps shifting makes me think that a clutch spline lube should be in your future plans.

jensk · « **Reply #18 on:** June 30, 2015, 03:23:53 PM »

Thank you - I will get the M8 100mm bolts and do a spline lube of the clutch spline. This is a great ressource for a motobrick newbie like me.

bocutter Ed · « **Reply #19 on:** June 30, 2015, 03:26:27 PM »

Quote from: jensk on June 30, 2015, 11:03:43 AM

I have sucked up 0.1 liter of oil from the gearbox. Now oil level is 11,5 cm down from the edge of the fill hole (it was 10,5 cm down before).

It should be 11,6-12,6 cm.

jensk · « **Reply #20 on:** June 30, 2015, 03:35:38 PM »

Quote from: bocutter Ed on June 30, 2015, 03:26:27 PM

Quote from: jensk on June 30, 2015, 11:03:43 AM
I have sucked up 0.1 liter of oil from the gearbox. Now oil level is 11,5 cm down from the edge of the fill hole (it was 10,5 cm down before).
It should be 11,6-12,6 cm.

I'll suck up a little more oil from the gearbox. I seems like that a little to much oil in the gearbox does make shifting a little rougher. With to much oil i had many false neutrals when shifting both up and down.
From my Hondas i'm more acustomed to easier and more nimble gearshifting than on this beemer. I will get used to this gearbox when ridin' more on it.

Engine and bike handling is fantastic except that it is a bit more heavy to handle at starting and low speeds. I allmost dropped it twice when maneuvering for parking.

motodude · « **Reply #21 on:** June 30, 2015, 03:37:08 PM »

+1 on the clutch spline lube.

The sticking tach may be due to a warped "dial back plate". If that is the case, the warpage should be visible.

Quote from: The Mighty Gryphon on June 30, 2015, 02:55:43 PM

I am going to guess that blipping the throttle is helping the clutch to disengage. The fact that it helps shifting makes me think that a clutch spline lube should be in your future plans.

rbm · « **Reply #22 on:** June 30, 2015, 04:52:50 PM »

The sticking tach needle might be due to warping of the face plate in the instrument cluster. The heat could be contributing to it (how much are you getting up there in Northern Europe??!). Look at the tach face obliquely and see if the gauge face looks buckled.

jensk · « **Reply #23 on:** June 30, 2015, 06:34:27 PM »

Today we have had sun and 25 degrees celsius but the bike had been standing so that the sun hit directly on the dials for a couple of hours. I will se if the dials are warped tomorrow.

Edited to remove faults introduced by spellchecking on my phone

The Mighty Gryphon · « **Reply #24 on:** June 30, 2015, 07:18:31 PM »

Two comments:

First, I will put my jacket or at least my ratty old gloves over the gauges when parked. For a long period I will put my cover over it. At home they sleep in the garage.

On my bikes the clutch spline lube made them shift very nearly as smoothly as Japanese bikes with none of the clunkiness that BMW's are supposed to have.

News:

Author Topic: Sticky clutch (Read 12140 times)