KTM 790 - Rekluse TorqDrive .Vs. KTM OEM Clutch pack

Discussion in 'Parallel World (790/890)' started by windblown101, Feb 6, 2020.

  1. windblown101

    windblown101 Long timer Supporter

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    Rekluse Versus KTM head to head build comparison: There are some interesting differences between these clutch packs in regards to the number of plates, materials used, the spring rates of the clutch springs, and total weight. I'll be offering up a few personal theories regarding the differences and how they may affect performance. I'm keen to hear others opinions and theories as well!
    Photo 01.jpg

    The KTM OEM clutch pack uses 8 friction disks with an aluminum base and steel drive plates. The Rekluse uses thinner plates and has 11 friction disks of which 8 of them have a steel base and 3 with an aluminum base. The three aluminum friction disks took me by surprise. One of the reasons I wanted to try this clutch was I was under the (incorrect) impression it used steel plates throughout. However the plates are positioned at the front and back of the pack where heat build up tends to be less.

    KTM clutch plates
    Photo 03.jpg

    Rekluse clutch plates
    Photo 02.jpg


    Drive plate differences: The KTM drive plates have a dimpled surface. The ReKluse plates are smooth. I'm uncertain if there is any practical difference between the surfaces. I suspect the KTM plates may retain a bit more oil? But whether that in fact happens and if so is good or bad I couldn't say.
    Photo 04.jpg


    Clutch pack weights:
    There's been some speculation as to what the weight differences would be between the clutch packs. I didn't have access to a precision scale so a postal scale that measures in .1 lb increments had to suffice. The OEM clutch pack weight vacillated between 1.5 & 1.6 lbs on my scale. The Rekluse wieghed in at 2.0lbs. That makes the Rekluse between 6 to 8 ounces heavier based on my scale. In my book that's a plus! A bit of additional flywheel affect on this motor for my use will not be a bad thing.

    Photo 07 KTM.jpg Photo 08 Rek.jpg



    Clutch pack springs: I took the clutch springs to a local machine shop to test the springs. Measurements were taken using 1.25" (32mm) as the installed spring height. All 3 springs were tested form each clutch pack and the results were very consistent from one spring to the next within each set. ReKluse / KTM
    Photo 05 ReK.jpg Photo 06 KTM.jpg

    The Rekluse springs each measured a consistent 37 lbs at 1.25"
    The KTM OEM springs each measured a consistent 46 lbs at 1.25"

    Woah... I was not expecting that! That's a huge difference and I'm a puzzled ReKluse opted to use a LIGHTER spring rate. I have to believe they did so with good reason. My theory is this: Since the PASC system uses the opposing ramps between the inner hub and pressure plate as the primary means to achieve clutch lock up the need for a stiff clutch spring to handle acceleration loads is negated. The lighter springs should make the slipper function occur under lighter deceleration loads which ReKluse may have deemed an advantage. Keep in mind the Rekluse is also designed for the 790 Duke and it may have been track use they were considering when they chose spring rates. Bottom Line: I'm going to email them and ask! :)

    Clutch pack thickness:
    The OEM pack measured 36.42mm
    The Rekluse measured 36.68

    The repair manual calls for 35.60 - 36.50 with a wear limit of 34.8mm. The ReKluse measured a hair over spec, but not so much that I will worry about it.

    So there you have it. The side by side of the two clutch packs. I hope folks find it informative if not also a bit puzzling. I will be installing the Rekluse in a the next day or two and look forward to seeing how it feels.
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  2. 1coolbanana

    1coolbanana Long timer

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    Great info :clap
    I guess you could always re-use your original springs?
    #2
  3. windblown101

    windblown101 Long timer Supporter

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    Indeed. And I may. I've already sent Rekluse an email inquiring about the reasons for the lighter springs. I'll wait to see what they say.
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  4. Velociraptor

    Velociraptor TrackBum Super Supporter

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    My OEM clutch pack was fine but I installed the Torq drive clutch pack anyway. Only big difference I noticed is that now it is harder to find neutral. I emailed Rekluse about it and they said their pack has a bit more drag and it may wear in and get better. I am interested to see if you have the same issue.
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  5. 1coolbanana

    1coolbanana Long timer

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    Id consider this an option but the clutch kit is nearly $1000 AUD here in Shitsville :(
    #5
  6. windblown101

    windblown101 Long timer Supporter

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    It is an expensive option. I'm hoping it will work well and last a very long time! The stock clutch pack is fine and will be on the spare parts shelf if needed.
    #6
  7. windblown101

    windblown101 Long timer Supporter

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    Regarding Spring Rates:

    I got the following response this morning from Rekluse.

    Based on their response I'm going to go with their springs, at least for now. After all, they build clutches for a living and I don't. :D

    It's a cold windy day outside. Good day to do a clutch install!
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  8. ramirin

    ramirin Ready to push

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    Thanks for nice un-boxing info @windblown101

    Awaiting for installation tips & tricks as well as first feels ..
    #8
  9. windblown101

    windblown101 Long timer Supporter

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    Not much to say so far which is a good thing I reckon! :)

    The install went smoothly. Instructions are good. I did find a variance between the diagrams and written instructions. The diagram was based on an earlier version for the 790 which only used two different thickness drive plates. The kit has been updated and has 3 different thickness drive plates. The written instruction lays out the new order for the plates. The revised clutch pack is a total of .024" thicker (1.435" nominal versus 1.411" nominal for the earlier version).

    The only place I varied from their instructions is:
    1) I got the footpeg bracket out of the way so I had better access to the cover bolt at the rear of the clutch cover. The instructions recommend leaving the footpeg bracket in place and using a wrench on the hard to reach bolt. I hate turning a bolt 1/8" turn at a time... so the bracket came off so I could use a socket.

    2) The instructions call to install the last two thick friction plates and the thickest drive plate onto the pressure plate side and then put the pressure plate in place. This was awkward IMHO so I placed one friction disc and one drive plate on the pressure plate side and the last thick friction disc I slipped into the basket before slipping the pressure plate into place. Everything ends up in the exact same spot regardless. Personal preference....

    The test ride felt great but was short. I could tell the clutch pull was slightly lighter as they said it would be. The engagement felt smooth and not grabby. Finding neutral was slightly trickier but the clutch isn't broken in yet. It reminded me a bit finding neutral on my 1190R, taping down from 2nd into neutral was easy, poping up into neutral from first required a very light touch. I didn't want to purposefully start abusing the clutch under heavy loads right off the bat but I did do a few intentional slip stalls with the front brake engaged while in the garage to get a feel for the engagement. Then I did some low power friction zone playing around in 2nd around the woods at the house, then I hit the pavement and did some WOT acceleration in 5th on the street to see if I could detect any slip. All seems good.

    Hopefully next warm spell I'll get back out for a longer ride! The real test will be how it holds up in the long run.
    #9
  10. Velociraptor

    Velociraptor TrackBum Super Supporter

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    Thanks for the report. Seems like you are having the same experience as me with finding neutral.
    #10
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