Kevlar sprockets?

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  • #41645
    Mike Jansen
    Participant

    Once again I stand in the infield and cheer my competitors after suffering a mechanical DNF. To finish first, first you must finish.
    :bang

    I just started using the extron kevlar sprockets and i had one fail Saturday in practice. No off track excursions or anything adverse but a saw with literally NO teeth. Same thing happened on Sunday that led to my DNF. What gives? I had proper chain tension, lubrication and alignment. We attributed Saturday’s to a new chain and possible stretching of the new chain as the culprit. I have no idea to Sunday’s failure. All I know is I’ll practice on the kevlar since they’re easier on the chain but race day i’ll use the Aluminum. My front driver sprocket looks BRAND NEW.

    Does anyone have any idea as to why this is happening? Thanks in advance!
    PS I did check the fetzer valve so I know that’s not the problem….

    #54568
    Doug Welch
    Participant

    We’ve been using them for quite some time and have found out a couple of things about them

    Chain tension is very important. While we don’t see as much chain stretch and that chains last longer, If we go out too loose, it eats teeth. And once they start to go, it peals every tooth off.

    Sprocket alignment is much more important. If it is pulling even slightly off, it eats teeth.

    Lubrication is very, very important. I use Motul off road. Lub it every time you go on track.

    At the first sign of a hot or stiff chain. New chain. Don’t run it even one session.

    The chain we had on Greg’s kart had 3 race weekends on it. Its still fine. The sprocket has many race weekends on it.

    #54569
    Mike Jansen
    Participant

    thanks for the feedback Doug. So, how much tension is just enough chain tension? That is the only thing I can figure since everything else was followed to the T.

    #54570
    Doug Welch
    Participant

    We set it so that we have about 1/4″ to 3/8″ deflection. For Aluminum sprockets, some might consider it on the tight side. There maybe an issue with the heavy weights of masters. Several times I saw the rear ends of the karts coming off the ground this weekend. That can cause spikes in the rpm. Did you see any spikes in your data?

    #54571
    Mike Jansen
    Participant

    Yes I did on the infield section and only once on the entry into the main straight when I hit the bump instead of around it…

    I guess that means Bandimere is out of the question too eh? 😆

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