clutch hydraulics or clutch itself?

[two2tone91]

certainly sounds similar.

i wish i had spent the time doing this before i dug into it as it would have been a nice side by side comparison.

in your first video it looks like the clutch cover plate moves in with the friction plate to begin with? then gets pushed back out as the clutch re engages? might just be my eyes deceiving me though!

if the cover plate has movement in it, independent of the plate its mounted onto you could have your culprit? especially if the mechanic didn't replace the bolts (apparently stretch bolts to be replaced every time they're removed)

 

[roamer]

If you are confident in the hydraulics etc , it does look like you may be splitting the bike,
There is debate on lubricating splines, as the o/p found it gummed up, do you know if the input shaft was lubed ?
The diapragm needs to lift evenly, cracks and finger wear can cause drag as it stays in contact slightly,
You could measure plate clearance clutch held back with a tie, through the starter hole with feeler blades near each drive strap,
It may prove the diapragm integrity , either way pulling the gearbox off may be the only option,
I dont have the wealth of gs experience some have, but dry clutches need to be just that,
a smear of grease can cause exactly your and the o/ p troubles as it turns to tar,
Good luck to both of you for a sucessfull repair��

 

[ferguscawley]

certainly sounds similar.

i wish i had spent the time doing this before i dug into it as it would have been a nice side by side comparison.

in your first video it looks like the clutch cover plate moves in with the friction plate to begin with? then gets pushed back out as the clutch re engages? might just be my eyes deceiving me though!

if the cover plate has movement in it, independent of the plate its mounted onto you could have your culprit? especially if the mechanic didn't replace the bolts (apparently stretch bolts to be replaced every time they're removed)

Hmmm

Good point re fixed plate. Am wondering if I can replace the bolts via the upper plastic cover on the clutch by doing them one at a time while rotating the flywheel around ? Can that cover come off without splitting the bike ?

Fergus

 

[two2tone91]

there are 6 bolts on it so if you swap them one by one you should be fine. the torque isn't much from memory which surprised me as it wouldn't result in much stretch, but apparently they do come loose if they arent replaced. i think ive seen someone who has managed it through the starter hole, but i might be wrong??

here's a little google album of the few photos i took once it was stripped back

https://photos.app.goo.gl/fP4Hck8j7uVoq2Bh7

in there is a crap photo of my gearbox input splines before i cleaned them off, and only then realised the photo was terrible... note how the grease has dried and clumped making it almost look like the splines have teeth along them. i'm hoping that this gunk was where my issue was coming from, but i wont know until i get it back together this weekend im afraid. other than that and the usual surface corrosion i couldn't see any reason i would have issues. all cleaned up a treat with some brake cleaner on a rag.

 

[ferguscawley]

I've just been out to the local BMW dealers to order 6 new bolts. To my disbelief they had them in stock

So later I will remove the starter (again) and see if the bolts can be replaced via that ope or not. Hopefully they can be.


Fergus

 

[ferguscawley]

Update

Bolts could possibly be replaced via the starter motor opening but they can't be renewed and torqued as the only way to get them out would be using a ball-headed Allen key. (There is no clear exit nor the ability to fit a torque wrench at 90 degrees to the bolt)

So instead I went around all 6 bolts to see if any were loose by using said ball-headed allen key and a 10mm ring spanner to see if they could be tightened up.

Unfortunately all were tight / snug so I don't know what the issue may be

 

[(RIP) Bin Ridin]

Fergus, have you tried filling the hydraulic system from the bottom to top?

 

[ferguscawley]

I have done. It was 11 months ago. But I may just try it again.

I have some time off today so will give it another go.

 

[ferguscawley]

Fergus, have you tried filling the hydraulic system from the bottom to top?

OK - an update. I made some progress today. Here's what I did:

I removed the slave cylinder from the back of the gearbox (keeping all hydraulic lines intact- and thereby allowing the slave cylinder to fill completely with fluid as the pushrod was no longer keeping the piston mid-stroke). I then swapped my master cylinder out for my original one that I had kept in the shed (always thought it felt better than the used replacement one I sourced on ebay).
I then used the slave cylinder as the syringe - i.e. I pushed the piston back in slowly thus forcing fluid and air bubbles back into the master cylinder (to which I had added a few ccs of fluid). I did this a few times and got a firm lever almost immediately.

I refitted the slave and went for a wee test run.

The transmission feels much better than before. Much better. Gearbox not near as crashy and I can find neutral when stopped with engine running. I have yet to test it on a longer run with everything up to temperature but am hoping I have solved my issues. (I hate getting my hopes up (on live TV) though)

I'll update again after a longer run.

 

[Steptoe]

i.e. I pushed the piston back in slowly thus forcing fluid and air bubbles back into the master cylinder (to which I had added a few ccs of fluid). I did this a few times and got a firm lever almost immediately.

I've posted a few times previously that if bleeding the clutch remove the slave cylinder from the rear of the gearbox (but keep the lines attached) and using a socket force the slave piston back into the slave housing and clamp it then bleed the system.
So basically you're bleeding the system with the slave cylinder housing containing no fluid and with no chamber to trap any air in the system.

 

[Pukmeister]

I've posted a few times previously that if bleeding the clutch remove the slave cylinder from the rear of the gearbox (but keep the lines attached) and using a socket force the slave piston back into the slave housing and clamp it then bleed the system.
So basically you're bleeding the system with the slave cylinder housing containing no fluid and with no chamber to trap any air in the system.

Obviously a sound method, but why not first try with a mityvac or similar vacuum bleeder on the slave nipple if you have one and simply suck the air out under negative pressure relative to the master cylinder ? I bled mine successfully this way.

If you get the air out it saves the spanner work unbolting the slave. If not, carry on and unbolt it.

 

[roamer]

Using Steptoes method has worked for me on many occasions ,
with difficult to bleed Clutches and brakes,
Then bled with a mityvac

 

[two2tone91]

my bike is back together now and working thus far... time will tell if something rattles loose (cue months of riding paying too much attention to any weird and wonderful noise, assuming its some catastrophic failure...)

the pressure plate and cover plate kit id bought from motorworks wasnt happy in the bike at all. when installed the pressure plate springs were compressed too far, meaning that when i got the gearbox back on, the push rod was so far in that the slave cylinder was maxed out onto its retention clip and there was no more room for it to actuate the clutch. i thought this was user error to begin with, so stripped and reattempted 2 or 3 times, re-evalutating my approach each time to try and spot an issue but i couldnt. decided in the end to trial fitting the old plates with the new friction disc and hey presto, the push rod sits in there perfectly. so i removed the gearbox, torqued everything to spec and continued to reassemble.

one epiphany id had during the week was potentially using some ratchet straps to pull the front and rear of the bike back together (looped through the tank crash bars and the rear pillion peg hangers), and with a bit of wiggling this approach worked perfectly, meaning i didnt have to call in any family assistance, and had ample time to move around the bike bit by bit to assess the situation and route cables etc. i also decided to leave the driveshaft out for the remating, and then re install by dropping the final drive which removed the need to wiggle and rotate that to fit half way through the process. obviously a bit of faff as i had to mess with the final drive but removing snag points at that stage was more important for me at least.

i decided against reusing the oem throttle body clamps in favour of some blackened stainless steel worm drive clamps for ease of use (and some tarty aesthetics!). a few thousand cable ties and the bike was back together.

a quick re check of the clutch symptoms and... Sierra Hotel Indigo Tango... still misbehaving... some choice words later and half a bottle of the v10 bmw fluid, bled in every single different way and angle imaginable and the bike now seems to be behaving...

so now i have stressed myself over the issue, spent two weekends fettling and will now have a season of riding worrying about and constantly rechecking the bolts... for what might just have been some persistently trapped air

i normally enjoy fettling with the bike but i've also had to repair a few things on the car to get it through an MOT, and now it needs a steering rack... so needless to say i'm a bit sick of wrenching at the moment!

fingers crossed motorworks will take a return of the plates i found issue with, and i will try to build enough trust in the mechanicals of the bike to take it somewhere scenic over the summer

bloody bikes... who'd have them!

 

[ferguscawley]

my bike is back together now and working thus far... time will tell if something rattles loose (cue months of riding paying too much attention to any weird and wonderful noise, assuming its some catastrophic failure...)

the pressure plate and cover plate kit id bought from motorworks wasnt happy in the bike at all. when installed the pressure plate springs were compressed too far, meaning that when i got the gearbox back on, the push rod was so far in that the slave cylinder was maxed out onto its retention clip and there was no more room for it to actuate the clutch. i thought this was user error to begin with, so stripped and reattempted 2 or 3 times, re-evalutating my approach each time to try and spot an issue but i couldnt. decided in the end to trial fitting the old plates with the new friction disc and hey presto, the push rod sits in there perfectly. so i removed the gearbox, torqued everything to spec and continued to reassemble.

one epiphany id had during the week was potentially using some ratchet straps to pull the front and rear of the bike back together (looped through the tank crash bars and the rear pillion peg hangers), and with a bit of wiggling this approach worked perfectly, meaning i didnt have to call in any family assistance, and had ample time to move around the bike bit by bit to assess the situation and route cables etc. i also decided to leave the driveshaft out for the remating, and then re install by dropping the final drive which removed the need to wiggle and rotate that to fit half way through the process. obviously a bit of faff as i had to mess with the final drive but removing snag points at that stage was more important for me at least.

i decided against reusing the oem throttle body clamps in favour of some blackened stainless steel worm drive clamps for ease of use (and some tarty aesthetics!). a few thousand cable ties and the bike was back together.

a quick re check of the clutch symptoms and... Sierra Hotel Indigo Tango... still misbehaving... some choice words later and half a bottle of the v10 bmw fluid, bled in every single different way and angle imaginable and the bike now seems to be behaving...

so now i have stressed myself over the issue, spent two weekends fettling and will now have a season of riding worrying about and constantly rechecking the bolts... for what might just have been some persistently trapped air

i normally enjoy fettling with the bike but i've also had to repair a few things on the car to get it through an MOT, and now it needs a steering rack... so needless to say i'm a bit sick of wrenching at the moment!

fingers crossed motorworks will take a return of the plates i found issue with, and i will try to build enough trust in the mechanicals of the bike to take it somewhere scenic over the summer

bloody bikes... who'd have them!

Great post Max.

Am intrigued that the new plates were so different than the originals. That's weird.

Could it have been that you needed to upgrade the pushrod to match ??

Hope everything turns out great.

Fergus

 

[(RIP) Bin Ridin]

Please see below snap of route of clutch hyd line. I think it may have been re-routed as part of PDI, to raise the lowest point to level of the slave cyl and not lower.

 

[Steptoe]

Obviously a sound method, but why not first try with a mityvac or similar vacuum bleeder on the slave nipple if you have one and simply suck the air out under negative pressure relative to the master cylinder ? I bled mine successfully this way.

If you get the air out it saves the spanner work unbolting the slave. If not, carry on and unbolt it.

Because It’s far quicker removing the two bolts that hold the slave cylinder in place then cleaning the mineral fluid out of the mytivac/compressor vacuum bleeder pump after using it to bleed the clutch.

 

[Pukmeister]

I use an inline catch pot between mityvac and slave, its part of the mityvac kit. Emptying takes seconds as its a bayonet fit to remove.