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7 Plate clutch slipping on T140.

Discussion in 'Triumph (Classic)' started by Reggie, Jun 18, 2019.

  1. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    I fitted a 7 plate clutch to my T140 a couple of years ago, and the clutch has always slipped under high load. I fitted 650 springs at the same time as it is recommended, initially tightening the spring until the thread was just entering the straight groove in the spring cap for the screwdriver. To try to stop the slip, I tightened the springs more on two separate occasions so that there was a fair bit of thread protruding through the spring caps to no effect.

    So today I have stripped the clutch and found that the extra plain plate that was supplied in the kit is of the often found crap quality i.e. not flat. I have posted a picture of both sides of this plate and also of an original plate. It can clearly be seen where there are high spots. Unfortunately, I bought the kit nearly 3 years ago and so doubt that I can send this plate back. I didn't ride the T140 last year as it was at my sons which has caused a bit of the delay sorting this problem.

    I don't know why the clutch is slipping, unless this plate can be soley responsible, but I doubt it.

    Any suggestions where to buy a plain clutch plate from that is going to be completely flat? (Like the one's in the Barnett clutch kit for my Norton. Now they were flat).

    [​IMG]
    New plain plate.
    [​IMG]
    Other side of the new plain plate.
    Below, an original plate.
    [​IMG]
     
  2. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Is that the Hyde kit (going by the width of the mark left by friction material)?

    Should be plenty of good used ones about?

    The plain plate in the Aerco kit I bought needed the tangs filing before it would fit, so does that plate slide smoothly on the splines?

    I used the 750 springs slackened off about one turn.
     
  3. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    I bought the kit from TMS and they sell the Hyde 7 plate conversion, so I assume it is from Hyde.
    LAB said;
    The plate does slide in and out freely.

    I assume that it is correct that when the clutch plates are not assembled in the clutch and therefore there is not any tension on the bolts that the springs sit on, that it is correct that I am able to rock the sprocket/chainwheel housing a bit? Because I can on mine.
     
  4. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    "a bit" is probably normal.
     
  5. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    LAB said;
    Thanks.
     
  6. Matchless

    Matchless

    Joined:
    Dec 23, 2010
    I fitted a seven plate Hyde kit with 650 springs to my lightly tuned TR7. It slipped every time the motor reached 5000 rpm. I put the 750 springs in & that helped but it would still slip on hard acceleration. Eventually the friction material started to fall off the plates & then it really did slip! I ordered a new set of friction plates from TMS & these (Aerco) have been better than the Hyde ones. I think I ended up with the 750 springs screwed in until the threads reached the top of the nuts. Whilst this makes the clutch a little heavier to pull it doesn't slip. The simple fact is that the clutch is not up to the job, & whilst it was fine on the 650 engines it simply cannot cope with the extra torque of the 750. One day when I have finished all my other projects I will fit a Commando clutch. The only downside to this is the lack of cush drive.

    Martyn.
     
  7. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    Hi Martyn, that's quite interesting. I thought that I was nearly the only person having problems with the 7 plate clutch.
    I've ordered a new plain plate made by "Suflex," allegedly CNC made, so hopefully it will be flat, and I'll give it all another go. If this fails, I may look at getting some Aerco plates.
    I have read up on buying an alloy pressure plate, but it would seem that there is no advantage buying one over the standard steel pressed one, except it looks very nice and shiny when the primary chaincase is removed. Any other thoughts about this?
     
  8. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Both 7-plate kits (Hyde and Aerco) are supposedly made by Surflex.
     
  9. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    LAB said;
    That doesn't bode well. :( I will check when it comes.....and hope.
     
  10. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Have you tried flatting the new plate on a sheet of wet & dry paper?
     
  11. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004


    If the new plain plate was installed as the outer plate then check the pressure plate surface is flat and wasn't applying uneven pressure.

    Edit: And, just as a matter of interest, which year model T140 is this?

    Also, you might find the plain plate of the 7-plate kit is thinner Edit: (0.70") than the standard plain plates (0.80")?
     
    Last edited: Jun 19, 2019
  12. Matchless

    Matchless

    Joined:
    Dec 23, 2010
    My Aerco plates have a wider friction area than the Hyde type, but nothing like standard plates. I haven't tried the ally pressure plate as I agree that it's just bling. If the steel one is flat then it should work. One of the most important things to do is to adjust the springs to make the pressure plate runs true when kicking over with the clutch lever pulled in.
     
  13. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I had a chronically slipping 6 plate clutch in a 650 with Surflex plates. Like Mr Matchless above, it happened when the engine was about maximum torque.

    Fixed it by doing the very cheap Pete Russell 6.5 plate mod, relining the friction plates with cork mat.
     
  14. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    No, I haven't. I might try it tomorrow on my marble surface although I would think that it would take some time to do and ruin my fingernails at the same time. :)
     
  15. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    The pressure plate surface is flat. I checked it yesterday.
     
  16. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    It's a 1988 Les Harris Bonneville T140.
     
  17. Reggie

    Reggie

    Joined:
    Jul 24, 2006
    I've just measured the extra plain plate and it is exactly the same as the other plain plates which measure at 0.079".
    What would be the reason to make the additional plate thinner? The stack height? But would 0.0010" make much difference?
     
  18. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004

    Well, I did say "might" but, sorry, it was the late factory clutch that had seven 'thinner' plain plates and six (thinner?) friction plates with an additional friction lining attached to the inside the drum and was fitted to some late Meriden Triumphs so please disregard that piece of information.
     
    Last edited: Jun 19, 2019

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