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Thread: Kevlar vs Composite - Which clutch material is best?

  1. #1
    Join Date
    Feb 2009
    Posts
    11

    Default Kevlar vs Composite - Which clutch material is best?

    Hello,

    I am planning to replace the clutch on my 1918 Harley. Kevlar is the same price as composite and it is advertised to be much more durable. However, I'm told that most people go with the non-Kevlar composite clutch. Can someone tell me the down side of Kevlar?

    Thanks,
    Steve

  2. #2
    Join Date
    Jul 2012
    Location
    Inman, South Carolina
    Posts
    14

    Default

    Steve,
    Haven't tried them in your application, but on my WR the Kevlar were very "grabby" and put a lot of shock on the drive train. I prefer the stock fiber discs as they allow for a smoother take off and slipping the clutch if necessary. The stock discs, I assume, are similar to the composite ones you're looking at. Maybe someone else here has tried the Kevlar in your application and can give you some more info.
    Ralph

  3. #3
    Join Date
    Jan 2003
    Location
    England
    Posts
    636

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    Dear Steve, the original clutch linings were asbestos and still occasionally found nos, while the new ones are a bonded material not containing asbestos. I've tried the Kevlar linings on my '34 sprint bike but could not feel any difference. I've now made my own clutch plates which have a bonded-on modern lining (so no rivets) and about 50% more surface area as the lining goes further inwards towards the clutch hub. No problems with these.

  4. #4

    Default

    Most material application specs for kevlar state that it is best suited as a wet clutch application. So that rules out pre 60s harleys.

  5. #5

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    I agree kevlar is grabby ,tried it and took mine out soon after install

  6. #6
    Join Date
    Feb 2009
    Posts
    11

    Default

    Thanks for all of the inputs. It sounds like either material will work but based on what I see here, I am going to go with the composite.

    I also have a Model-T Ford and the transmission bands are available in either composite or Kevlar. People seem to have extreme feelings ,pro and con, for both materials. It's nice to see that the decision is much easier in this case.

    Regards,
    Steve

  7. #7
    Join Date
    Aug 2006
    Location
    So Cal
    Posts
    747

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    Hey Steve, a fellow model T'er too :-) I have Kevlar in my Henderson, wet clutch - but it's the only Henderson I have ridden. So I can't really compare it to anything - it seems to be working fine though. Good luck with the Harley - ps. I have not tried Kevlar in my model T's.

  8. #8
    Join Date
    Jan 2008
    Location
    S.E.N.Y. State American side of Hudson River
    Posts
    284

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    I just replaced the clutch plates on one of my 57 pans. A couple years ago I had replaced the plates on another one of my pans using the Barnett composite plates with bad results. Grabbing, jerking, hard shifts and stress on the driveline and couldn't seem to get it right. Took them out and and found some decent used ones that I cleaned up and they ran fine. The ones I just used on my other 57 were the same type Barnett composite wet or dry. Used 4 plates. My buddy gave me a hint to soak them in auto tranny fluid for about 15 mins before installing and wiping them off after soaking. Installed them and took the bike for a ride and they worked better than any clutch I've ever had. Maybe that was the trick or I just got lucky.
    Last edited by D.A.Bagin; 11-07-2012 at 08:21 AM.
    D. A. Bagin #3166 AKA Panheadzz 440 48chief W/sidecar 57fl 57flh 58fl 66m-50 68flh 70xlh

  9. #9
    Join Date
    Dec 2010
    Location
    Lamoille County, Vermont
    Posts
    945

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    Best material... asbestos by a country mile. Unfortunately, if you use it, Al Gore will come by your house with Jacoby and Myers and beat your motorcycle into pieces with a spotted owl...

    Kevlar is a good material, but it can cause damage if mis-adjusted or set up wrong. Lots of Model T-ers have destroyed their drums with Kevlar bands because original bands would wear out or self-destruct before causing harm... but Kevlar bands just eat what they touch and end up fine...

    Sometimes it's possible to find NOS/OEM asbestos clutch disks around. But I would recommend you consider a composite. Also, check with whoever is making your disks/plates and see what they are recommending... Most of the non-asbestos clutches do tend to be grabby and nowhere near as smooth as the originals.

    If it were MY bike, I would scour the earth for asbestos linings first, then go with composite if I could not find OEM linings.

    FYI, there is a great place to buy 'raw' lining materials of all kinds in CT. I think they are in Middletown. I'll get the number tomorrow. They will cut shapes, thicknesses, sell you sheets, etc. All kinds of materials. I think they are called Industrial Friction Linings. We get clutch materials from them for all kinds of vintage car applications.

    Last, if your bike has its original linings (ie asbestos) clean the dust out w. a spritz bottle full of water. Don't use an air hose and blow the dust up. Just wipe, toss the paper towels and drive on. Or mail them to Al Gore. He appreciates that kind of thing.
    Hope this helps,

    Cheers,

    Sirhr

  10. #10
    Join Date
    Dec 2006
    Location
    Idalou, Tx
    Posts
    76

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    I bought the Barnett wet/dry clutch plates back about 1980something and they came with a small (about 2" X 4") instruction sheet that said to soak them in transmission fluid whether they would be used wet or dry. Also said if run dry, they may need to be re-soaked if they get grabby. Have run these clutch plates with no issues many, many miles in a 52 FL and have never had to re-soak them and they have run very dry due to running a belt primary.

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