790 Reported Clutch failures - My 12k mile examination

Discussion in 'Parallel World (790/890)' started by windblown101, Nov 10, 2019.

  1. windblown101

    windblown101 Long timer Supporter

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    Not sure of the number of crispy clutches found, maybe a dozen? Grenading friction plates maybe half that? There was another grenaded one with photos pop up on FB in the last day or so.

    I realize we live in an age where if someone gets a hangnail on the other side of the planet we hear about in social media but in all the various mc groups on the interweb the "noise" level regarding the clutch in the 790 advr is balanced by deafening silence of grenading clutches elsewhere in the industry, so I go back to something I said much earlier in this conversation - something is different about this clutch in this bike.
  2. 1coolbanana

    1coolbanana Long timer

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    So has nobody enlarged the oil jet on a 790?
    Seems unlikely no one has tried this since its so easy to do.
  3. kubcat

    kubcat Long timer Supporter

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    Thanks for the feedback, I hear ya. Still though, it seems more akin to measuring acceleration performance with the "seat of the pants" dyno rather than an actual dyno. And we all know what a comparison of those results would show:scratch
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  4. TrailTrauma

    TrailTrauma Nemophilist

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    Dude, I just checked for free movement in the Camel arm, and guess what? Zero play. %^&*

    So I actuated the arm to remove the wire just to see what movement is really has and without the wire attached it freely moves 1/4" at the end tip of the Camel arm, as it sweeps. I reattached the wire, and adjusted the clutch. Loosening it enough until I could actuate the Camel arm easily with just a few mm of movement. Next I adjusted my clutch lever back out, and tested getting in and out of gears, and into neutral while cold and parked in the garage. (4' of snow and all .. so no testing outside). Bit more slack in the clutch lever but I can probably get that out.

    So yeah, I guess it is easy for some, to overlook the aspect of a bit of free movement at the arm end of things. :thwak

    I'm grateful for the push to finally walk over and to check the arm.
  5. windblown101

    windblown101 Long timer Supporter

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    Ummm... sure. Hell everyone knows that.

    Off to Google I go....

    :lol3
  6. ramirin

    ramirin Ready to push

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    So to be safe.. clean oil jet between every ride and get rekluse friction discs?

    Half joke - rekluse claims their discs can take more beating though..

    I saw video for cleaning and inspecting the oil jet - it was not english, spanish maybe.. can't find it now maybe it was on fb.. easy to do within oil change or once a year

    it's a tough world with all the issues .. clutch and cruise control .. and all I wanna do is work on some clutch control
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  7. 1coolbanana

    1coolbanana Long timer

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    Would be interesting to know if clutch failures are associated with build dates or VINS or if random.
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  8. braaap!

    braaap! Long timer Supporter

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    Maybe a poll?
  9. windblown101

    windblown101 Long timer Supporter

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    @TrailTrauma & @Kinkysmurf

    Here's another one for the Hmmmm file.

    So I and a few others have mussed about whether the slipper function or the light springs may contribute to unwanted clutch slip and heat build up. Here's another possibility that came to me tonight.

    The PASC system uses opposing ramps to achieve full clutch lock up when the motor is under load rather than relying on spring pressure. This allows the nice light clutch pull we enjoy. At the base of the clutch pack is a rather stout "pre-tension" ring. With the clutch assembled and not under load it has the effect of making the static clutch pack assembly measure thicker. Of course cable free play gets less as clutch packs wear (get thinner), keep that in mind for the next part of my rambling...

    The "PASC" ramps need to compress the clutch pack enough to overwhelm the pre-tension ring (shown in parts diagram and photo below) in order to achieve full lock up. If there is not enough additional free-play in the clutch cable to allow the ramps to compress the pretension ring then full clutch lock up is not achieved. It may only allow a slight bit of slip under very heavy load as the clutch cable tension and ramps fight against each other but excess heat will kill the clutch sooner rather than later. Yet when the operator checks for clutch cable freeplay with the bike at rest the pretension spring is not compressed and free play might feel like it's "just" enough, when due to the clutch design it actually isn't.

    Another possibility is that under full load the ramps overwhelm the cable tension and do achieve full lock up but under light load the cable tension wins and causes what would be a very hard to detect light acceleration clutch slip that disappears when you pin the throttle...

    Keep in mind - I'm talking out my ass relying on a big old heap of unproven assumptions. Don't come at me (or KTM) with pitchforks based on my new wild ass speculation. LOL.

    Attached Files:

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  10. 1coolbanana

    1coolbanana Long timer

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    I was actually thinking along similar lines and that having more lever free play than less might be best.
    The free play may well be used up under load when compressing the clutch pack.
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  11. TrailTrauma

    TrailTrauma Nemophilist

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    I think for the sake of our sanity, we need to side step speculation and expand our audience to as many advanced gear heads as we can. @AdvRonski may be able to help. And I know we have some ktm mechanics kicking around here somewheres.

    My MME clutch lever was a royal PITA because setting it up was crucial and a bitch. It would seem way off cold and forget about finding neutral but when hot after a mile it would seem ok. But if you tuned it for rolling the bike across the garage or just tested it by taking a short boot up the road no bueno. So I have a passing knowledge of warm vs cold clutch tuning.

    Today I discovered I had no free play at the end of the arm, but what I didn't document or calculate or really even observe was whether (when the wire was connected) I was already beyond the biting phase. I think I was on the very cusp so I got lucky. Next season when I can get out again, I'll begin as @Kinkysmurf does, and push on the arm before riding off, (and manage the free play at the lever so it's optimal without undue slop.)

    I now would encourage others to try what I did, and push the arm counter clockwise to disconnect the cable. Once that is off the arm, push the arm again counter clockwise to reveal what it's free movement should fee like .. how much force it takes to push it. Then reconnect the cable and try pushing it again. You should still be able to push the arm easily a few mm. Not as far as you did with the cable disconnected, but still a few mm at least. If not (as was my case) then move up to the clutch lever and adjust the cable so it has more slack. It took quite a bit of adjustment on mine to see it loose enough at the arm end so that I could push the arm easily a few mm with just finger pressure. Then adjust your clutch lever outwards to compensate for the loosening of the cable so your lever has enough throw to fully disengage. Test as desired. Not sure if there is a cold test beyond shifting and rolling across the garage floor or if you need to test it all hot. Thats what I'd like input on.
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  12. Kinkysmurf

    Kinkysmurf Adventurer

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    @windblown101
    Im gonna use my phone a friend card. But

    You raise some interesting examples/ possibilities . I think I can test some of those.
    If there is variation in freeplay under loads, light or heavy it should be perceivable with a soft left hand.

    @TrailTrauma
    Nice work.
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  13. ramirin

    ramirin Ready to push

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    I haven't put in liquids yet on my hydraulic clutch .. almost afraid to do so as it's my first ever conversion. I will report how it goes..
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  14. windblown101

    windblown101 Long timer Supporter

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    Maybe we could get someone with a dyno to compare free play at the motor under load/no load. My mind wanders way too much when it's below freezing outside. :)
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  15. Kinkysmurf

    Kinkysmurf Adventurer

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    I phoned a friend, Independent, Ex race team mech. 40 years exp. Wife and him own/run a small shop.

    He says, " you wouldn't believe how many people swear the clutch has freeplay, and when they bring it into shop, no freeplay."
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  16. TrailTrauma

    TrailTrauma Nemophilist

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    Tell him he still owes me $50 for the model release form I signed off on, for the poster in his shop I posed for. . .aka "The No Freeplay Poster Child". :D
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  17. Kinkysmurf

    Kinkysmurf Adventurer

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    And a mean looking poster it would be. Couldn't believe your 5'10" , you look bigger than Hulk Hogan.

    Your not a orphan with freeplay. But I'm glad you checked and was man enough to say. respect.
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  18. TrailTrauma

    TrailTrauma Nemophilist

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    It's all pizza and beer ;)

    Yeah, it's weird, the whole free play thing. I thought I followed that video to a T. You probably saved me a clutch this season! Much appreciated.

    On a cautionary note, I wonder if I 'did' have free play, but as the clutch wore over the season, that free play was consumed. If that's the case, it makes a strong argument for checking the arm before each ride or 3 to keep on top of it.

    :beer
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  19. gearheadE30

    gearheadE30 @LC8Adventures Supporter

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    @TrailTrauma how many miles do you have on yours now? While it doesn't take a lot of wear to move the clutch position a bit, I guess having even that much wear in a season seems unusual unless you're really piling on the miles.

    @windblown101 that pretension ring idea is very interesting. I've seen it on plenty of other bikes too, including my 950, but never really considered what it would mean for a cable clutch. That theory does seem logical, especially the bit about slipping at light load but locking up as load increases to where no slipping is felt. I know Chris at Rottweiler has his 790 on the dyno pretty regularly; he's the only one I can think of in a place to try to test that in a controlled setting. Wes also raced Chris's 790 at the Parker 250 recently, so I know the bike has seen some abuse. Would be interesting to know if he's still got the original clutch in it.

    Re: Rekluse durability. Their fibers are apparently bonded to steel instead of the stock bonded aluminum parts. I can't speak to the friction material quality vs stock of course, but at least the steel plate should not fracture like a few have seen the aluminum ones do. Aside from higher risk of basket notching, I can't really think of a downside if the friction material is good. The added inertia wouldn't hurt on this engine, either.
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  20. windblown101

    windblown101 Long timer Supporter

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    I've been looking at the TorqDrive clutch they offer for the 790 because my lack of trust of the aluminum used on the OEM friction plates in the stock unit. Apparently it comes with steel sleeves that slip over the basket fingers to prevent notching the softer material? I hadn't considered the heavier weight, that could be a plus! :)
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