Home › Forums › Motorcycle Tech Talk › Same clutch, different problem!

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  • Anonymous
    Inactive
    12/02/2011 at 10:17 am
    Post count: 42
    #3566

    Hi, I am back with another mystery issue.  After fixing the problem of no hydraulic line pressure I am now have the opposite!  When the motor is cold the clutch feels normal, but after 10 kms or more the clutch lever has no forgiveness, and will start to slip with extra throttle.  Left for a few hours it will return to normal. Could the clutch fluid be expanding with heat? My first thought is to bleed the clutch and replace the fluid, unless someone has another suggestion.  All ideas are welcome, thanks!

    Murray
    Participant
    13/02/2011 at 3:24 am
    Post count: 487
    #14714

    From your description, it is most likely the clutch slave cylinder and it would explain the stiff action of the clutch…o-ring gone. Try a clutch fluid flush first…easy to do…make sure you use a good quality clutch fluid then change entirely every two years on your Rockster, as per the service schedule.

    Dave Ross
    Moderator
    13/02/2011 at 4:16 am
    Post count: 2310
    #14715

    When the slave cylinder on my 1150 started leaking, the clutch action had very little resistance and certainly wasn't slipping. You would have changed your clutch fluid only recently, after you changed your master cylinder. Is that correct? Is it leaking around the slave cylinder? Do you slip your clutch a lot during low speed maneuvers?

    Anonymous
    Inactive
    13/02/2011 at 8:38 am
    Post count: 42
    #14716

    The clutch fluid was replaced in November by Jeff Gray in Chch, they reported finding bits of swarf in the fluid, but that may have been my fault from trying to reverse flush the line with a poorly fitting bleed nipple, as I had stripped a couple of threads. Since the service the clutch has been working normally, until i went to overtake a truck on the Whangamoa Hill recently and the motor started to spin out. The clutch normally takes up when the lever is about halfway out, but now, when hot, it will slip as soon as I pull the lever and I can feel the difference in the line pressure.  The resistance in pulling the lever hasn't changed, but there it feels like there is too much pressure in the line. Cheers

    Anonymous
    Inactive
    13/02/2011 at 8:55 am
    Post count: 42
    #14717

    P.S. No sign of any leaks.

    Dave Ross
    Moderator
    13/02/2011 at 5:38 pm
    Post count: 2310
    #14718

    Could be an internal leak. Clutch fluid can travel along the push rod and foul the clutch. Do you have handguards on your bike? They've been known to twist and put pressure on the clutch lever.

    Anonymous
    Inactive
    13/02/2011 at 6:17 pm
    Post count: 42
    #14719

    That is an interesting possibility that I will look into, thanks!

    Anonymous
    Inactive
    19/02/2011 at 1:58 am
    Post count: 42
    #14720

    UPDATE- Just returned from a ride to Rai Valley with the clutch slipping again. The slave appears to have leaked, the fluid level has dropped in the reservoir but no leak is apparent, so the theory of it leaking internally seems correct. If the friction plate has been fouled this adds considerably to the complexity and cost, I was reading up on the procedure in mt Clymer manual, and with the various tools needed I am almost resigned to taking in to the dealer, either in Chch or Lower Hutt.  Any recommendations?  If the problem is simply replacing the slave that would be great, can anyone suggest how to tell if the friction plate is fouled?I read in the newspaper that Henry Cole has arrived in NZ, perhaps the big group of riders I saw heading East this afternoon are a welcoming committee to greet him at the Ferry?

    Dave Ross
    Moderator
    19/02/2011 at 2:29 am
    Post count: 2310
    #14721

    You could remove the starter motor to have a look. But don't get your hopes up, you'll only get a glimpse of the clutch. I would change the slave cylinder and then see what happens. Once you have the rear shock out, it's a fairly straight forward procedure, but access is tight. Changing the clutch is a mission on the 1150. I've done it on an R80, where it's a two to three hour job. The 1150 probably takes more than 8 hours, but I am just guessing here. People who do it for a living, will probably disagree. Clutch parts are also expensive. You'd probably want to change all the wear items.Do a search on advrider, they have tutorials on the subject. Hope you'll have it sorted soon, good luck.

    Anonymous
    Inactive
    19/02/2011 at 4:32 am
    Post count: 42
    #14722

    Thanks for that, I had arrived at a similar opinion after reading this post: http://www.r1150r.org/board/viewtopic.php?f=3&t=16815&p=155010&hilit=clutch#p155010I pulled the starter out, rotated the motor and what I could see appeared to be in order, and I do not want to pull the clutch apart.  I did enjoy replacing the clutch on the R60/6 but the R1150 looks like a mission to Mars.I appreciate your help, Cheers!

    Anonymous
    Inactive
    06/03/2011 at 7:13 am
    Post count: 42
    #14723

    🙂 New slave arrived from Motorworks and with a bit of bleeding the problem seems to be sorted, no evidence of contaminated friction surfaces and full throttle is no issue. Yahoo!

    Dave Ross
    Moderator
    06/03/2011 at 8:59 am
    Post count: 2310
    #14724

    Thanks for reporting back and I am pleased you've solved your problem.

    Anonymous
    Inactive
    31/03/2011 at 7:11 am
    Post count: 42
    #14725

    Interesting how often I need to eat my own words. All was going well and then the return of the clutch slip! It feels as though there is too much pressure that builds up in the line during a run. Not good news for someone contemplating towing a trailer camper. My son thinks I should revisit the master cylinder and ensure all is clean there. Any other thoughts?

    Anonymous
    Inactive
    13/05/2011 at 10:39 am
    Post count: 42
    #14726

    Several hundred k's later, I think the clutch surface might have become a wee bit contaminated, and seems to be a reducing issue.

    peter.trub
    Participant
    17/05/2011 at 9:42 am
    Post count: 267
    #14727

    Not one hundred percent up with the play on the BMW hydraulic clutch sustems but as a guy who plays with things from time to time it sounds to me like (pauses for breath). A compounding effect  ;DNothing to do with heat, after all how much heat is the system subject too? Sometimes (for various reasons) when the clutch is activated upon release the fluid can be restricted from returning to the Master Cylinder reservour. (ok so I cant spell that word) Which means it stays in the line and holds pressure on the release bearing, ta da, clutch slip  😮Things to check; initial adjustments, angles affect stroke and force thats why they need to be correctly set up. Master Cylinder, if it has a foot valve make sure it is operating correctly, clutch lever returning to the fully released position.Start with the simple things then work in from there  ;D

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