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Thread: '92 851 S3 - Clutch slippage and hard to find Neutral gear.

  1. #1
    Join Date
    May 2015
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    Default '92 851 S3 - Clutch slippage and hard to find Neutral gear.

    I'm a newbie to this bike, and going through all the basic steps of fixing the baby. So here we are its The Clutch!

    Problem Statement: Clutch would slip and drag when shifting from neutral into 1st gear. So, at every traffic light and stop... there was a problem dragging the gear, hearing that god awful sound, etc.
    So I took the plates off and here are the facts. Pictures attached.
    1- There are a total of 7 friction plates, 7 spacers plates one of which is a double and at far end. Overall stack height is 38mm. This according to spec is correct. (38.00mm +/- 2.00mm)
    2- I did not find the slightly wavy spring steel spacer disc in this stack set. Also, the most inner spacer is a double set. All that said, the entire stack is still the right height.
    3- There was moderate glazing on the friction pads. So I took 200 grit sandpaper and roughed up both sides.
    3- The hub (inner drum) has slight indentations where the discs sit. To me it looks acceptable. The outer basket has no noticeable wear and slotting.

    I reinstalled the stack and went for ride. Here are results :
    GOOD NEWS = No more slipping and dragging going from neutral into 2nd.

    BAD NEWS= Finding neutral is now nearly impossible. Again, making it very hard to use in any traffic. This was not a problem before!

    What can you tell me with the data? I need to be able to go into neural with ease.

    Thanks!!!
    -->FJ
    Attached Images

  2. #2
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    How far does the pressure plate travel, and what does the inside of the top hat thing that sits in the pressure plate bearing look like? I think its about 22.5-3mm of travel normally.
    Griff
    To infinity and.......

  3. #3
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    Make sure that when you pull in the clutch lever that your able to spin the pressure plate by hand. If your unable to start there as this will most likely be your issue. Bleed the clutch slave and adjust the screw on the inside of the clutch lever. I had the same problem but once I bleed and adjusted problem solved. If that's not it you might have a bent transmission fork? Does it have an aftermarket clutch salve? I found that some slaves have a deeper recessed plunger and the clutch rod itself is slight to short not allowing a full push on the pressure plate. Report back and let us know what you find?
    Last edited by Viper1; 06-23-2015 at 01:17 PM.

  4. #4
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    Quote Originally Posted by griff851 View Post
    How far does the pressure plate travel, and what does the inside of the top hat thing that sits in the pressure plate bearing look like? I think its about 22.5-3mm of travel normally.
    The pressure plate travels out around 2.5-3.0 mm when pulling and releasing the clutch lever.
    I can't quite decipher what you mean by "top hat thing that sits on pressure plate". The bearing, if that's your question; though suspect not, is fine and spins ok with no interruptions.
    -->FJ

  5. #5
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    Quote Originally Posted by Viper1 View Post
    Make sure that when you pull in the clutch lever that your able to spin the pressure plate by hand. If your unable to start there as this will most likely be your issue. Bleed the clutch slave and adjust the screw on the inside of the clutch lever. I had the same problem but once I bleed and adjusted problem solved. If that's not it you might have a bent transmission fork? Does it have an aftermarket clutch salve? I found that some slaves have a deeper recessed plunger and the clutch rod itself is slight to short not allowing a full push on the pressure plate. Report back and let us know what you find?
    The plate can be spun easily by hand when the clutch is pulled in with my other hand. It does not have any aftermarket clutch parts including slaves, etc, I'm aware of including asking previous owner. Visual inspection shows OEM from the surface as well.
    -->FJ

  6. #6
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    What is the role of the wavy spacer? I'm fairly sure there is no such item in my stack. Does that not create the slight separation and somehow related to neutral? I'm no expert.... perhaps daft question. Have at me!!

    The double spacers at the back end towards motor is the only different spacing. Again, the stack height in totally is within spec.

    -->FJ

  7. #7
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    I wouldn't say the spring plate is 'wavy' but more of a very shallow cone, it provides smooth pick up when pulling away. Two plain plates at the back is correct, nomally a pair of 1.5mm each IIRC.
    Check the lift of your clutch slave cylinder, it's easy to change gear but another thing if there is any drag.
    Last edited by stafford; 06-24-2015 at 08:39 AM.
    celeresracing.blogspot looking-back-at-2016-classic-tt
    Power tends to corrupt and absolute power corrupts absolutely.

  8. #8
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    I have gone through this on a few bikes, get neutral easy and others things pop up. Get clutch pull the way you like it and Neutral is gone. If you stick with it you can get both to your liking. Maybe some definitions are in order? When I think clutch "slip" I think engine overpowering the clutch and tranny not keeping up. When I think "drag", I think of being in 1st, with the clutch lever fully in and the bike still creeping forward because of lack of full disengagement. Normally I don't see both at the same time. One thing struck me right off. As a usual stack is usually bookended with two steel discs on the motor side and one on the pressure plate side, there is no way to have the same number of friction plates and steel plates. I think your picture clears this up as it shows 8 steels with one looking double width.
    I have taken apart 2 clutches on 2 Ducs I have bought and neither used the "wavy" steel plate. Indeed they are getting harder to even find to buy these days so I am thinking that is not your problem though it might help. Given that the pressure plate moves enough for full disengagement, at least with engine not running, and if you have adjusted the lever for more engagement, I'd just quickly bleed the cylinder and if that doesn't clear it up play with the stack height a bit if you happen to have spare steels lying around.



    Quote Originally Posted by SvenSven View Post
    I'm a newbie to this bike, and going through all the basic steps of fixing the baby. So here we are its The Clutch!

    Problem Statement: Clutch would slip and drag when shifting from neutral into 1st gear. So, at every traffic light and stop... there was a problem dragging the gear, hearing that god awful sound, etc.
    So I took the plates off and here are the facts. Pictures attached.
    1- There are a total of 7 friction plates, 7 spacers plates one of which is a double and at far end. Overall stack height is 38mm. This according to spec is correct. (38.00mm +/- 2.00mm)
    2- I did not find the slightly wavy spring steel spacer disc in this stack set. Also, the most inner spacer is a double set. All that said, the entire stack is still the right height.
    3- There was moderate glazing on the friction pads. So I took 200 grit sandpaper and roughed up both sides.
    3- The hub (inner drum) has slight indentations where the discs sit. To me it looks acceptable. The outer basket has no noticeable wear and slotting.

    I reinstalled the stack and went for ride. Here are results :
    GOOD NEWS = No more slipping and dragging going from neutral into 2nd.

    BAD NEWS= Finding neutral is now nearly impossible. Again, making it very hard to use in any traffic. This was not a problem before!

    What can you tell me with the data? I need to be able to go into neural with ease.

    Thanks!!!
    -->FJ
    Last edited by fstntq; 06-28-2015 at 07:18 PM.

  9. #9
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    May 2015
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    Quote Originally Posted by fstntq View Post
    I have gone through this on a few bikes, get neutral easy and others things pop up. Get clutch pull the way you like it and Neutral is gone. If you stick with it you can get both to your liking. Maybe some definitions are in order? When I think clutch "slip" I think engine overpowering the clutch and tranny not keeping up. When I think "drag", I think of being in 1st, with the clutch lever fully in and the bike still creeping forward because of lack of full engagement. Normally I don't see both at the same time. One thing struck me right off. As a usual stack is usually bookended with two steel discs on the motor side and one on the pressure plate side, there is no way to have the same number of friction plates and steel plates. I think your picture clears this up as it shows 8 steels with one looking double width.
    I have taken apart 2 clutches on 2 Ducs I have bought and neither used the "wavy" steel plate. Indeed they are getting harder to even find to buy these days so I am thinking that is not your problem though it might help. Given that the pressure plate moves enough for full disengagement, at least with engine not running, and if you have adjusted the lever for more engagement, I'd just quickly bleed the cylinder and if that doesn't clear it up play with the stack height a bit if you happen to have spare steels lying around.
    Excellent, clarification of statements towards common understanding. I've only had "drag". Me thinketh you have a few clearly interesting observations and suggestions thereof. I'll investigate, and expreiment, take high resolution pictures and return here if not able to resolve.
    -->FJ

  10. #10
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    Some hints and tips here Clutch Tips the disc spring plate or conical plate should always be used, in my experience a clutch without one grabs like a bastard.
    celeresracing.blogspot looking-back-at-2016-classic-tt
    Power tends to corrupt and absolute power corrupts absolutely.

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