clutch hydraulics or clutch itself?

two2tone91

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afternoon all,

i've been having some gear changing issues for a while now, they've been slowly getting worse and yesterday a short ride out with my brother had me arguing with the gear lever to get it into and out of gear. i've spent today trying various different quick fixes to no avail, then tried to move the wheel when it was in gear with the clutch pulled in. hey presto, the clutch is barely disengaging and its very tough to spin the rear wheel by hand. i immediately pulled the clutch slave away from the engine casing expecting to find a load of fluid in there but there was nothing, it was spotless with no signs of a leak. the master cylinder feels normal, and doesn't allow the clutch to slowly re engage if held in. so i'm left with questions:
1)can a clutch master cylinder be failing to provide enough fluid to disengage the clutch fully, but maintain whatever pressure it has when its held to the bar (i.e. not allow the clutch to re engage fully. but still drag heavily?)
2)is there another way the slave cylinder would be failing without having any visible fluid leaks? (note that the master cylinder hasnt been losing fluid)
3)clutch is not slipping as far as i can tell and ive done my best to provoke it!
4)could some corroded or gunked up clutch splines be pinning the clutch in place? my assumption was that it would drag but slowly loosen if this was the case?
5) is there a reliable way to test the master cylinder?


any help massively appreciated, the bike is parked now until i can suss the issue, or end up getting impatient and tear it down to the clutch anyway (only to find it wasnt that!)
 
You say you are having trouble changing gear, I would have thought that whilst in the move the gear changes would be pretty slick even if the clutch is dragging,
Or do you mean you are struggling to get it in gear or in neutral when stopped?
You have checked that the gear lever moves freely on its pivot through the frame, they have been known to get stiff and cause gear change problems.
 
I've checked, cleaned and lubricated the linkage as part of the quick fixes this morning to no avail. the clutch is dragging badly and I have proof of that by having the bike in gear, engine off, bike on its main stand. I then pull the clutch lever in and it barely frees up the rear wheel enough to rotate by hand. I can vouch that in this situation, the gears do not change smoothly at all!

It's definitely hydraulic or clutch related, I just wondered if anyone had any answers to help me pinpoint the issue
 
check the fluid level

As the clutch wears, the fluid rises, is it overly full?

You could drop the slave cylinder, it's only two bolts, a bit awkward, but see if that frees the clutch....

Roger.
 
Too much fluid would make the clutch slip not bind.

Have you tried bleeding the clutch? I don't see you mentioning it but it might be what you consider a quick fix.

Sounds to me that your problem is most likely in the Hydraulic part rather than the mechanical clutch part.
 
Has somebody topped it up with DOT4 instead of mineral oil and buggered the seals ??
 
I've already tried taking a little fluid from the system (pre realising the issue) through bleeding a small amount out. No air to speak of and the fluid looks perfect.

Also as mentioned before I have had the slave off of the gearbox and there were no apparent leaks to say the slave has/is failed. And removing it does the opposite of free the clutch, it pins the clutch in place.

Anyone had a clutch master cylinder fail and can confirm my symptoms? I think I'm agreeing with marki that it's more likely hydraulic and most likely the master cylinder. but I'm confused to why the pressure wouldn't leak back to the reservoir whilst I held the clutch?

And no... I haven't put dot 4 in it...
 
1. You need to bleed the master cylinder (handlebar) first, before bleeding the slave cylinder) see youtube video at bottom of this post.I suspect the slave cylinder is your problem area, get a one way valve brake / clutch bleeding kit ( speed bleeder) and bleed the slave cylinder ( after first bleeding the master cylinder) with a tywrap over the rubber pipe on the bleed nipple, only unscrew the bleed nipple a very small amount so can bleed under pressure from handlebar. these can be a pain to bleed if just opening and closing bleed nipple. I had similar problem after fitting a new clutch, i decided to fit a new slave cylinder in preparation for a 6000 mile trip to Norway, the new slave cylinder i bled perfectly, after a 100 mile test the clutch was not disengaging properly.

2. i then suspected the hydraulic clutch line may be bulging somewhere, new clutch line was over £100 and on a 4 week delivery from BMW, i needed one within a week, I removed the clutch line, measured it, photographed it, Hel performance delivered me a custom replacement within 24 hours for less than £50, Fitted that, still same problem, bled again all worked ok, after another 75 - 100 miles gear change problem again, this time noticed small drips of clutch fluid on bleed nipple of slave cylinder, so removed slave cylinder, removed bleed nipple, under magnifyer saw hairline crack in threaded area, this was letting air in and a minute amount of fluid out, turns out many new slave cylinders fitted to bikes and available in dealers had a manufacturing fault and were subject to a recall.

Ordered another slave cylinder, fitted, bled, hey presto all problems cured.

3. If point 1 above does not cure the problem, remove the clutch slave cylinder and remove the pushrod, roll it on a piece of glass, ensure its is not bent and does not have wear marks on it or corosion, they get hot and can stick if bent or not clean. If damaged order a replacement. If dirty clean with emery cloth and meths, let dry, lubricate only a little with oil (should be a felt pad on it if i remember. Also its vital the slave cylinder is fitted carefully (square and bolts gently screwed in equally and torqued up to the specific torgue setting) any misalignment will cause pushrod to foul inside its shaft and stick)

4. If necessary check that the master cylinder (on handlebar) operates the clutch slave cylinder satisfactorily under pressure ( put slave cylinder in a workmate or similarbut be careful not to blow the seals).

If all above fails, full bike strip down and complete new clutch assembly is recommended. Join the BMW club to hire the tools to do the job. Very very cost effective and the service is excellent.

see https://1200rt.com/index.php?topic=2215.0

https://www.bmwsporttouring.com/topic/86683-clutch-slave-cylinder-recall/

https://forums.bmwmoa.org/showthread.php?64334-07-R1200GS-clutch-issue

https://www.youtube.com/watch?v=mLqsry3QPDw must watch this !!!

Regards

Steve
 
I remember that the TC had a problem in that air was trapped in the clutch line, very hard to bleed. The line was routed slightly differently (dealer did it but it was simple, no disconnection) and it solved the issue. If you eyeball the line you might see the problem. Ideally it should rise all the way from the slave cyl back to the master.

Here's a paste from another guy about filling bottom up:

Hi all,

A tip for those who may not know and apologies for egg-sucking advice for those that do know:

When the clutch system is drained, get a good quality medical syringe and attach a clear plastic hose to the 'needle' end. Load it with about 15ml of clutch fluid (mineral oil, not brake fluid) and expel all the air like the doctors do. Cable ties the clear plastic hose to the bleed nipple on the clutch slave cylinder, crack the bleed nipple and squeeze the plunger on the syringe. When the fluid appears in the clutch master cylinder reservoir, the system is bled - hey presto!

I did this on 2 of my mates' bikes after spending an hour bleeding my clutch system having simply filled it from the master cylinder reservoir.

Cheers,
BeenAround
 
thanks both, i'm away for the week but i'm compiling a list of checks to run before i commit to the tear down over the weekend.

good note on checking the pushrod for any bowing, it seemed free enough when i had the slave off previously but i suppose you never know whats going on when its all buttoned up.

i think when i drop the slave away from the gearbox that i should be able to test the pressure at the lever once the slave piston has nowhere to go (is hard up against the C clip). any air or sealing issues should be apparent through sponginess or any motion towards the bar with some even pressure. i also forgot to check the bearing on the front when i had it off so that's on the list.

i also spoke with a tech from bahnstormers that was very helpful. after i discussed the checks id done already his assumption was that it is likely a stuck/sticking pressure or friction plate in the clutch itself, but ill double and triple check that i haven't missed anything easier than that. worst case its damaged or stripping gearbox splines i suppose. but i'll cross that bridge as/when it comes to it.

i haven't looked into the BMW club yet (only owned the bike for 6 months) but i'm fairly tooled up anyway having done all the wrenching on cars and bikes needed for a decade or so. fingers crossed i wont get caught short!!!
 
Can you try pumping the clutch lever a few times and see if pressure builds up? I was with a guy whose new R1200GSA "lost pressure" in the clutch hydraulic, he could pump it enough to change into gear and cure was hose reroute / bleeding.
 
evening all, just back home for the weekend now so have been running through some of the checks discussed.

im now pretty confident its not the hydraulics. the slave is absolutely pristine, the bearing is spinning beautifully and once removed the clutch lever goes rock solid, not even the slightest hint of air to be compressed. (i've got some of the v10 fluid to bleed/flush it anyway and will do that in the morning before i fully commit to the tear down)

its lovely and quiet around here for some reason too, very few cars going passed. and when i was attempting to pump the lever as per bin ridin's suggestion i could hear a clicking or pinging noise from the bell housing. its more and more looking like something is amiss in there :-(

assuming a bleed/flush doesn't work miracles i'm going to pop the starter off and have a nosey inside the clutch housing. then get following the various guides on removing the back of the bike. aim being to diagnose and order everything necessary to reassemble and test over the mayday weekend. (and desperately hope it doesn't turn out to be the gearbox input splines :-/)

thanks for the suggestions this far

wish me luck!
 
I can't recall you mentioning the year/mileage on your hexhead? High mileage & I would have expected to be hearing about clutch slip, rather than drag were it internal.

In my experience of many bikes over the years, this problem has always proved to be hydraulics, particularly memorable in my KTM period, so this area is worth the further investigation you propose. Usually the first to play up would be the slave, given it's environment & replacement is usually the best medicine. Then comes the master - a new seal kit/rebuild maybe. I assume you have an OE clutch lever; aftermarket options sometimes lack sufficient throw. Then come the clutch lines - have you checked carefully for damage, particularly if you have been off-road. It can be absolutely microscopic, maybe just a tiny black tar like pimple on the line. Strange to hear your system doesn't pump up though, as Bin Ridin suggested - needs about 10 full pulls on the lever in quick succession & gives a brief period of almost full clutch movement whilst any air in the line is compressed.

Good luck finding the culprit.
 
quick update,

got the bike stripped down on Saturday afternoon, the friction plate seemed to be binding as i was trying to get the gearbox off, and some very dry lubricant almost looked like it had balled up on the splines. obviously given the dragging the pressure plate and cover are blued and hot spotted so i'm going to replace the whole assembly, as i don't plan on getting repeating this any time soon! all seals are fine and the splines all cleaned up like new so I've been lucky in that regard.

new bits are on order from motor works so fingers crossed ill be able to get the bike back on the road this coming weekend, pending some assistance from my brother to persuade the two halves back together without accidentally throwing the front end onto the garage floor!

I consider myself fairly competent as an amateur mechanic, but boy oh boy isn't this a mega job! ill certainly be glad when its all done and back together
 
Am very interested in this thread. My 2010 TC GSA had anew clutch fitted last year and I still have clear clutch drag. I've replace master / slave cylinders and clutch live.

Bled the bejaysus out of it. Still have dragging, especially when hot. Can push it around with clutch in when cold although there is still some resistance. I have done 6000 miles since clutch replacement.

Am dreading having to split the bike
 
I consider myself fairly competent as an amateur mechanic, but boy oh boy isn't this a mega job! ill certainly be glad when its all done and back together

Check the Clutch Push rod against the new diaphragm spring

There was an updated clutch arrangement but you had to have the new ball ended pushrod

I will be replacing the engine in my 1200 GS soon and have a new clutch to go in while I am in there and I have reminded myself umpteen times Check the Pushrod
 
Check the Clutch Push rod against the new diaphragm spring

There was an updated clutch arrangement but you had to have the new ball ended pushrod

I will be replacing the engine in my 1200 GS soon and have a new clutch to go in while I am in there and I have reminded myself umpteen times Check the Pushrod
You mean like this ??

I replaced mine last summer hoping to fix the slightly dragging clutch I have.

It didn't make a difference. The 'throw' of the pushrod is determined by the slave cylinder so the wear on the rod doesn't really matter
792df41170a74d64ac0ddf30b408548c.jpg
 
i'll double check it in case it was swapped for an old one by a previous owner, but from what i have read the push rod/pressure plate change happened in 06, and mines a 2010 so fingers crossed it should match nicely with the new kit when it arrives. (there was a warning about this on the motorworks site saying that older bikes would require the new pushrod)
 
The photo I posted shows the pushrod that came out of my 2010 GSA and the new one I replaced it with.

I was really hoping it would solve the issue for me but alas it didnt
 
Clutch drag 2010 GSA

Sorry to be hijacking this thread a bit, but the symptoms are kinda similar.

I removed the starter motor to have a look at the clutch action. I made 3 videos showing the clutch working

The first one here is of the pressure plate movement when the clutch lever is actuated. The movement is very small but it is visible.

https://www.youtube.com/watch?v=G0qUjBWyc2U


This one is with the clutch lever pulled in and rotating the rear wheel with the gearbox in 6th gear - there is some but really very little drag here

https://www.youtube.com/watch?v=Pt8ERmJ7LSE


This one is with the gearbox in first gear, and there is a lot of drag here compared to 6th (as would be expected)

https://www.youtube.com/watch?v=WThv3wpohH8


Anyone got any ideas why I am still getting drag. The clutch is in there for 6000 miles now and has been well used. The master, slave and clutch lines have all been replaced. System has been bled multiple times. When riding the bike, the gearbox is 'crashy' at times and neutral can be very difficult to find. It gets worse as the bike gets hotter

Is it likely that the friction plate is stuck on the gearbox splines ? Is there anything I can do without splitting the bike ?

Steptoe - any ideas or words of wisdom ?

Thanks

Fergus
 


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