Sticking Clutch

Discussion in 'Technical Help' started by Crankypedals, Jan 31, 2018.

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  1. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Hi people, I'm looking for a bit of technical advice. Sorry for such a long post but it might cover off some of the basics.

    So here's the back story. I'm a mid-life-crisis guy who's just passed the direct access. In the weeks before my mod 2 test I bought a 2010 Sprint ST which went very cheap on ebay.

    One reason it went cheap is lack of service history. It's done 43K miles yet has no service stamps at all. The owner (from new) stated it had never had valve clearances checked though oil had been changed. Other than the lack of some maintenance/history it's pretty well immaculate for its mileage and looks original and true.

    I checked the valve clearances when I got the bike home, some bang on spec, all others well in tolerance.

    I changed the oil for Castrol Power 1 4T (10W-40). I fitted a K&N oil filter and K&N air filter.

    Two weeks later took my test, passed, jumped on and rode it .... First day I did 200 miles. Fabulous ride for the first 150 miles around the Peak District, never missed a beat, until …

    Got bogged down in traffic around Macclesfield and after a couple of minutes the gears became stiff to change to the point I had to stop the engine. After a minute or so I could change them again and so rode on, but each time that I had to slow and repeatedly use the clutch the gears stiffened up and wouldn't change. This repeated the next day after only 10 miles or so. I found I could ride around the problem to some extent by pre-selecting neutral before coming to a stop at traffic lights etc and ‘rest’ the clutch.

    It's basically the clutch not fully releasing with the lever pulled in and I'm guessing that sitting stationary for a while with it dragging is heating it and that's making it worse somehow. The cable is smooth in operation, routed correctly and adjusted to 1-2mm free play. Clutch engagement is smooth and progressive at about 3/4 released position. With engine off, bike on centre stand, first gear, clutch pulled fully in, the rear wheel is very stiff to turn by hand.

    I trawled the www for a solution. It would seem to be a fairly common problem. It also seems many have tried various 'fixes' only to have the problems reoccur and I can find no one who has convincingly cured it even after buying lots of new parts.

    So yesterday I removed and examined the clutch.

    Clutch housing and baskets fairly clean with very little residue. Release mechanism, hook and pin barely worn. All friction rings are with good service life 3.8/3.9mm and 3.2/3.3mm and all steel rings are flat and look virtually un-worn. On pulling out the rings most were fairly well stuck together, it took a little finger pressure to pull them apart.

    Their sequence (and I’ll add that it LOOKS very much like the three access covers have never been previously removed) was flat washer, spring washer, fat friction ring, then alternate steel/friction out to the final fat friction ring. The steels being 1.6mm for the first two, 2.0mm for the next four and 1.6mm for the outer three.

    Now, the friction rings look quite dark in colour, particularly the pad material and the steel rings all look a bit cooked; slight blueing and generally very dark but evenly coloured.

    I’ve used wire wool and brake cleaner to clean them all up and left the friction rings soaking in engine oil whilst awaiting new gaskets.

    So here’s some questions;

    1, Does it matter that the rings show signs of heating? It’s often cited that if they do they must be changed … is this true and if so can anyone tell me why? (They all appear to be perfectly flat, the clutch engages and drives well but the only problem seems to be that some rings ‘stick’ together when the clamp pressure is released)

    2, The friction plates are stamped ‘FP-MN4-11’ and similar. Are these OEM parts?

    3, Have I used the ‘wrong’ oil for this engine? (It states on the back of the bottle ‘Recommended by Triumph for all four stroke models’)

    4, Does the sequence of 1.6 and 2.0mm steels matter? I suspect the order I found them in is as fitted from the factory but it does not match what others on various forums have suggested. I’m wondering this as the five staggered rows of oil holes in the inner basket might need to be exactly aligned with the rings; difference of 0.4mm ring thickness is not much individually but over the stack in the wrong order it throws it all out by some margin.

    I’d best stop there before this becomes War and Peace!

    Any gurus out there willing to offer their thoughts before I throw it back together?
     
  2. Dozers Dad

    Dozers Dad Bushmills Chief Quality Controller
    Subscriber

    If the part number is KN-204?
    That's your first job mate. Throw that away & fit one without a 17mm nut on the end.
    Check out the thread near the top of the "Tech Help" section.
     
    • Like Like x 1
  3. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Just this moment been reading that! :eek:
     
  4. chuk

    chuk Senior Member
    Subscriber

    Jan 10, 2017
    266
    113
    neilston glasgow
    cheapest option firstly is replace the clutchplates give a good soak overnight at least in oil then refit and go from there.
     
    • Like Like x 1
  5. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Cheers for the advice chuck. That may indeed be my first action but I see many before me have done that with no improvement. I'd like to try to understand why it's sticking in the first place though.
     
  6. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Cheers Smilinjack.
     
  7. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Quick update:

    Spoke to Staffordshire Triumph, showed them the clutch plates and they suggested the steels look glazed with signs of overheating. I ordered a full set of friction and steel plates at £200 :sob: which are due in early next week.

    What I don't know is whether the clutch plates were already cooked by the previous owner through poor adjustment or riding the clutch etc or whether there is another fault which has caused it. So I'm a little concerned about throwing a new clutch and gaskets on without knowing the original cause.

    Guess I'll just have to ride it very carefully and stay local until I can be sure it's ok.
     
  8. Callumity

    Callumity Elite Member

    Feb 25, 2017
    2,803
    750
    Nr Biggar
    Just some general observations.
    The oil. Castrol market 2 versions in very similar packaging. The specs are pretty much identical but one is fully synthetic (Racing) and the other semi synthetic. The practical difference is the fully synthetic is more heat resistant and breaks down more slowly. For most of us it makes not a blind bit of difference.
    Bike clutches. If the plates look nice and flat on sheet glass the chances are they have plenty of service life in them, discoloured or not. Everything you have described sounds like an adjustment problem. When you pull the clutch lever you are overcoming the pressure of the springs and freeing up the mechanism. The clunk associated with selecting 1st gear is because of the drag between the plates caused by the oil bath it runs in.....entirely normal. If, however, you have a gear selection problem the clutch is not being sufficiently freed off and you are not overcoming a sticky oil film but some actual plate contact.
    The handbook will tell you to have a minimal slack adjustment at the handlebar; effectively just enough to know you have maximum clutch release but not with any pre-tension that would otherwise induce clutch slip.
    So, I would be inspecting the lever to lever operation of the actuation mechanism and the lever/rod arrangement inside the gearbox. That is the most likely source of your unwanted friction. You want maybe a .5mm gap between lever take up and full seated at its hinge and then take up (adjust out) all the play at the other end of the cable.
     
  9. Callumity

    Callumity Elite Member

    Feb 25, 2017
    2,803
    750
    Nr Biggar
    At the risk of stating the obvious, if you cannot adjust out all the slack you have a stretched clutch cable.
     
  10. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Pretty sure it's not an adjustment issue. The cable is fairly new, the in-line adjuster at the engine end is set around its mid-point and the lever is set with around 1mm free play. There is virtually no slack in the cable and the operation is smooth and free. The hook and release pin show minimal wear. Clutch disengagement occurs from around 1/3 of the lever movement leaving another 2/3 lever pull beyond that. It really looks to me as though some of the clutch rings are actually 'sticking' together after the pressure plate has been lifted. Having initially dismantled it and withdrawn the clutch pack half of the stack of plates could be picked up as a lump just by holding the end plate, the outer plates separated easily but those closer to the gearbox were progressively more stuck.

    When cold or having ridden open road the gear selection is sweet and normal though there is always slight clutch drag. It's after sitting half a minute with the lever pulled in at a junction or off/on a while in slow traffic that it all starts to seize up. The clutch drags more and more and then gear change is impossible.

    I don't have the experience with bike clutches to know what looks normal and what doesn't. Maybe the previous owner had left the oil in way too long and it's degraded and contaminated the pads such that they are prone to stick? Can that happen? I'll try to work out how to get a couple of photos up later to show you the colour and state of the bits.

    Thanks for your advice everyone.
     
  11. Callumity

    Callumity Elite Member

    Feb 25, 2017
    2,803
    750
    Nr Biggar
    As my mate Sherlock says ‘when you have eliminated the impossible, whatever remains, however improbable, must be the truth’

    There is also a possible clue in the newness of the clutch cable. If the clutch has been overheated through poor adjustment, abuse or oil neglect you may well be getting distortion as it warms up. Just check the bearings in there too.
     
    • Like Like x 1
  12. GaryM

    GaryM It's him, you know who. Him from you know ....
    Subscriber

    Apr 28, 2016
    1,000
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    Patna , Ayrshire
    Photos is simple , use the upload a file button.
    It will give you the option to upload the full image or a thumbnail
     
    • Like Like x 1
  13. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Ah cheers for that. I'll have a go when I get home.:)
     
  14. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Here's pics of the rings as best as I can get. Bear in mind they've already been cleaned with wire wool and brake cleaner.

    20180202_175930.jpg

    20180202_175941.jpg

    20180202_180131.jpg

    20180202_175930.jpg

    20180202_180028.jpg
     
  15. Col_C

    Col_C I can't re...Member
    Subscriber

    Aug 5, 2015
    785
    300
    Cornwall
    Have a look at various posts from @Jody, he had a lot of problems with his clutch (Speed Triple but much the same engine).
    Here for example.
    Seeing your bike has had a shady service history I was wondering whether the previous owner has used the wrong oil at some time and contaminated the friction linings? (e.g. used a car oil not suitable for wet clutches)
     
    • Like Like x 1
  16. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    Cheers Col_C, I had read that, and disappointed to see he apparently never solved it :(
     
  17. chuk

    chuk Senior Member
    Subscriber

    Jan 10, 2017
    266
    113
    neilston glasgow
    i originally had problems with neutral selection that seemed to get worse after 20plus miles or so,i thought it was a clutch problem and sought advice on here r.e cable adjustment/chain slack etc,i got odd comments of sorts but bike now has no issues after (wait for the comments) filling the gearbox up to filler cap with oil/leaning it over to right side at angle for 2days,obviously i never turned bike over and dropped oil out and refilled to spec before making sure bike was always vertical in garage on stand,night and day after doing this never had a problem since touch wood and been this way for months.
     
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  18. Crankypedals

    Crankypedals Member

    Jan 31, 2018
    21
    8
    Staffordshire
    That sounds positive. I've read up about soaking the friction plates in oil before fitting and also the filling with oil to soak them in situ. Neutral selection does seem to be the first to go in my case too. Almost impossible to find at standstill with engine running.

    Re putting on centre stand, do you know if the clutch actually sits in oil on the stand? Seeing as I can take off the clutch cover without draining oil using the sidestand it looks marginal at best. But for the record it did sit for a couple of weeks on the side stand after I bought it and I do usually park it that way ...

    Well, the new clutch rings come next week, I'll soak them overnight and throw them in and see what happens. Either way I'll report back.

    Cheers for the input
     
    • Like Like x 1
  19. chuk

    chuk Senior Member
    Subscriber

    Jan 10, 2017
    266
    113
    neilston glasgow
    I'm not sure how long my bike lay on the sidestand from previous owner and dealer i bought it from,i only know since I've done things mentioned and kept bike vertical its been like a different bike imho I'm sure somebody more knowlegable will know oil level on plates etc.
     
  20. Col_C

    Col_C I can't re...Member
    Subscriber

    Aug 5, 2015
    785
    300
    Cornwall
    Crankypedals - look at your clutch plates compared to those in Jody's posts, I think it highly likely there's a contamination issue here, so your probably going to be fine with new plates. Just check the basket for burrs and that the new plates slide nice and free when you fit them (and yes fit them in the correct order). Jody also did some changes to the release mechanism, apparently there was a design change at some point so that may be worth looking into.
    On a far simpler note, have you got little hands? (somebody's bound to chip in with a smart comment here ;))
    The wife had a problem getting neutral sometimes on her Street Triple (clutch lever set to minimum span), I convinced her to set it a couple of clicks off minimum and problem cured. You're getting less travel on the release mechanism when set to minimum span and aftermarket levers might also make that problem worse. Personally I also set the cable slack a bit less than the recommended 3mm (as long as there's some).
    Chuk - so you gave your plates a good in situ soak and oil change which cured the problem (probably also some form of minor contamination IMO).
    Can't see keeping bike vertical or on side stand making any difference, clutch is still mostly out of the oil when vertical.
     
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