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clutch frustration on P11 ranger 750

Discussion in 'Norton P11 Motorcycles' started by mark fisher, Sep 24, 2018.

  1. mark fisher

    mark fisher

    Joined:
    Sep 21, 2018
    The clutch on my p11 ranger refuses to play ball! when I got the (restored) bike from Baxters the clutch would slip and drag which was very annoying! on inspection I discovered a pretty tired looking clutch with warped plates so I replaced them and the springs. I also fitted new cush drive rubbers as these had turned into a sticky goo. I also replaced the very worn primary chain. All this was odd because everything else on the bike looked to have bee renewed. After this work there was an improvement but it would still slip occasionally, and the oil level has to be kept low. After a while things degenerated and some dragging resumed. I went in again and replaced everything else, hub, basket, backplate etc. now it works fine until it gets hot and it tries to creep forward and of course there is more cable slack once it's hot, the action is kind of horrible too particularly as you pull the lever back to the bar. I think I'm missing something fundamental here....any ideas anyone?
    thanks mark
     
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  2. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    a worn push rod?
     
  3. p400

    p400 VIP MEMBER

    Joined:
    Jul 14, 2014
    You might want to assure yourself that the clutch is running in the period correct oil. Certainly the chain and sprockets could not care less, but the clutch does care. Changing or mixing oils has certainly caused me problems with off road race bike clutches.
    Dinosaur oil was all the rage in the 60's, I am not sure you buy that stuff anymore.

    Wide range viscosity with lots of long chain polymers have certainly been on my list of do not use on a clutch.

    P11 also required me to learn about 7/8 pivot clutch levers, the exact correct gearbox clutch pivot piece for a P11 gearbox and overfilling a P11 gearbox with oil.

    Please post pictures, as I tire easily with forum posters who don't offer me their time/effort to do so. A picture is worth a thousand posts.
     
  4. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    I run Type F ATF in the primary. It is said to have 35% higher coefficient of friction than oil when clutch plates become wetted. If this extra c.o.f. does not resolve the slippage, then increase spring tension, and use a Venhill Teflon lined clutch cable to keep the clutch lever pull manageable.

    BTW .... Type F ATF will not turn the cush drive rubbers to goo. Venhill Teflon lined cables are said to reduce clutch lever pull by 25% ..... worth using even if increased spring tension is not needed.

    Slick
     
    Last edited: Sep 24, 2018
  5. elefantrider

    elefantrider VIP MEMBER

    Joined:
    Apr 6, 2013
    Second the Type F ATF. Cheapest brand available.
    If the plates are now glazed, scuff them up.
     
  6. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    If my memory serves me, even the pre-production P11A provided by the factory for the press to test was plagued by the clutch to slip ..... I believe this was a common problem with all Atlas-powered hybrids. The clutch torque capacity is marginal for this engine. Have you tried Surflex or Barnett plates? Barnett claims their friction plates are better with ATF than others. Wetting them before fitting is recommended. You don't say who was the supplier of parts was. Please beware of buying cheap parts not up to spec.

    Correct friction plates for the P11 have p/n 043192.

    As for the dragging problem, you need to check your plain plates for flatness. I trust you have fitted dimpled plates with tangs not dragging in the clutch housing?

    I don't understand why there should be any significant cable slack once the clutch is hot. I mean, how hot can it become? Maybe you have an abnormal amount of heat generated due to ongoing clutch slip? If so, your clutch springs (040358) may be the culprit. Did you replace those with OEM quality replacements? Have you verified that your pressure plate (043362) lifts squarely?

    Is your clutch operating lever (inside the cover), p/n 040029 the correct one? The one used on the Commando is different and gives an unfavourable lifting ramp.

    Did you fit a 1/4" bearing ball and a two piece clutch pushrod? It's an old trick to improve clutch action.
    http://forum.ozvmx.com/index.php?topic=33926.0

    Fitting a clutch mainshaft seal (Dynodave's invention) to prevent ingress of gearbox oil contaminating your clutch friction plates is a very good improvement. Look up "Atlantic Green Norton" in your browser if you want to order one.

    Pls. read this thread as the poster seems to suffer similar problems to yours:
    http://www.jampot.com/forum/viewtopic.php?f=20&t=5522&sid=7f6f9efa20aa0da019f4e5d1de2e203b&start=10

    Beware of the danger of mixing new and old parts of unknown origin. For instance, the pressure plate changed over the years.

    If all this doesn't help, you should try to reduce the gearing by fitting a larger crankshaft sprocket - go from 21 teeth upwards. The taller the gearing (42/19, 42/17, etc.) the more load on the clutch.

    -Knut
     
    Last edited: Sep 25, 2018
  7. mark fisher

    mark fisher

    Joined:
    Sep 21, 2018
    ok guys thanks for all your replies. I did not take any pictures while i worked on the clutch so I'm no help there sorry. Ok ALL plates are new they came from baxter cycle ( that's who I bought the bike from) and I think that are barnett plates, I assume they made the plain ones too. The question about wetting them is interesting as I have to do that when fitting new plates to my Ducatis, so I asked baxter about that and they said not to do it, so I didn't. Maybe that was bad advice? There are NO old parts left in this clutch other than the pressure plate, spring screws and the pushrod, all parts from Baxter. Pressure plate looks good and lifts pretty evenly however it wouldn't hurt to take another look at the pushrod. it isn't slipping right now but it definitely gets hot and then drags. I did notice that the lever on the bar has 1 1/8 centres and I beleive they should be 7/8, could this make a difference?
    mark
     
  8. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    I fitted Barnett plates
    I fitted Barnett plates to my Atlas DRY, and after letting the bike sit for several months while I chased other issues, I could not free up the clutch. I was forced to pull the primary cover, remove the plates and pry them apart with a sharp edged tool. After assembling wet with ATF, the clutch still locks up, but frees up after several kicks. With the original Norton clutch plates, I never had to free up the clutch, even after winter layover.

    The spring nuts should be tightened until flush with the studs. If you have 1- 1/8 centers on your lever, and proper tension on the clutch nut springs, then your clutch pull ought to be extremely heavy. Even with 7/8 centers, the pull is very definitely four finger.

    Slick
     
    Last edited: Sep 26, 2018
  9. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Just because Baxter Cycle supplied the parts doesn't mean you've got the right parts. Do your homework!

    I read somewhere that wetting was an instruction issued by Barnett. The clutch is essentially a wet clutch as it runs in an oil bath, thus wetting can't be wrong. As for Slick's comment on the need to free up the clutch, this has to do with the greather COF for the Barnett plates when using the ATF lubricant, which is essentially a good feature.
    Having to free the clutch before setting off by applying the K/S is common practice. Surely the cause of dragging is a clutch pressure plate not lifting sufficiently? You will have to verify that all actuators are correct, starting with the handlebar lever. Do check that the plain plates are free to move in the clutch wheel. Sometimes the plates will rub and cause them to "hang". If so, you need to trim the tabs.

    Definately. As Slick stated, a lever pivot radius of 7/8" is correct for all AMC clutches and gearboxes. In addition I recommend a Venhill teflon-lined clutch cable which will reduce wire pull force by approx. 25%.

    -Knut
     
  10. mark fisher

    mark fisher

    Joined:
    Sep 21, 2018
    Ok so I never said that Baxter had supplied the RIGHT parts, just that they had supplied the parts, as this is basically a warranty issue. Having said that everything seemed to fit just fine, however the plain plates seemed a little tight on the new hub so I had to work on them. I think you are right about wetting the plates so I'm going to do that when I go back in to tighten the springs so that they are basically flush with the tops of the studs as per various manuals, then of course I'll have to re-check that the pressure plate is lifting square. This will be in conjuction with a change to a 7/8" lever and a cable change, as I don't think the one fitted is teflon lined. Also, Mike at Waldridges has sent me an actuator to compare with mine just to make sure that it's not a commando type. I guess I'll check the pushrod while I'm at it. All of this may have to wait until after Barbers now as I want to take the Ranger there, it's still rideable but it could be better as far as the clutch is concerned. I WILL get there in the end! Thanks for everybody's help and advice.
    mark
     
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  11. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Mark, when you've sorted your clutch woes, please let us know the bugs you corrected.

    -Knut
     
  12. mark fisher

    mark fisher

    Joined:
    Sep 21, 2018
    ok so I did wet the plates, I changed the bar lever to 7/8" centres, I changed the activating lever in gearbox to the correct one and I tightened the springs and checked for square lifting. I also changed the oil to SAE 20 from ATF. I took the bike to Barbers and rode around a fair bit. The upshot of all this is that the slipping is gone HURRAH and the action/feel is much improved. However there is still some dragging when warm, its as if the plates are sticking together. So now I'm going to replace the new Barnett plates with new surflex plates to see if that works....we shall see. I rode it to work to today in much cooler weather 57 deg and it still dragged eventually but not as bad, this is the first time I've rode it with temps of less than 85 deg. Anyhow we'll see if surflex plates help...who knows.
    mark
     
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  13. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Mark, good to hear your clutch action is improving. I trust you have fitted dimpled steel plates. Running the primary in an oil bath of SAE 20 oil is asking for trouble. SAE 20 of the 60's had a different composition to SAE 20 as of 2018. The CoF will drop significantly if and when your friction plates becomes wetted, thus the slipping problem will most likely return. ATF type F is still the recommended primary oil, but not too much - the primary chain should just skim the surface of the oil bath.

    Please check slack in your clutch cable, adjust to 1/8" free play maximum. Check primary chain for tight spots, adjust as needed (a rocking clutch basket will also cause it to drag). I am sceptical to using the single OEM gearbox adjuster on the P11 - having twin adjusters as per G80CS would be better, considering the alloy engine plates will not allow effective pre-tensioning, thus there is a risk of the gearbox and clutch going out of alignment.

    Did you fit the mainshaft seal recommended earlier? It's very effective in preventing gearbox oil entering the clutch as this *will* cause the clutch to drag.

    If these measures doesn't cure the dragging, then dismantle the clutch plates, wash off with paraffin, dry them, assemble with a very thin smear of bicycle oil rather than ATF, which when used liberally tend to cause bonded plates to stick to the steel plates. Use this procedure on the Surflex plates also.

    -Knut
     
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