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PostPosted: September 18, 2017, 2:37 pm 
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Joined: September 2, 2013, 9:12 am
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I just bought this car last week and am trying to solve an issue. The issue is the chain keeps smacking the tunnel opposite side of the sprockets (see pic) and makes a terrible racket (the car is loud enough already),what I have a question about is should what to use to stop it? I was thinking about a spring loaded tensioner that would ride on the bottom of my new cutout with a wheel or maybe you guys have a better idea? Thanks Rich


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PostPosted: September 18, 2017, 10:48 pm 
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The top run of the chain is the one that's under tension when you're on the throttle, so you don't want your slack takeup device (I'm avoiding using the term "chain tensioner" 'cause that's not really your problem--the problem is the chain is only tense on one side). You might well be able to solve the chain slap issue with an acetal (Delrin is a popular brand) rub block on the bottom of your chain tunnel. And oh yeah, you need a secure cover on that tunnel--in event of chain failure, you won't like having a broken chain thrashing around in the cockpit with you.

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PostPosted: September 19, 2017, 8:08 am 
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If you decide to go the rub block route, think about what Jack just said. The chain will be tense on one side, the top during acceleration. That means the top will be slack during deceleration. You may find you need to add a rub block to the underside of the cover that you're gonna put on it to keep the chain from beating against that during downshifts.

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PostPosted: September 26, 2017, 2:02 pm 
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Joined: March 30, 2011, 7:18 am
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Location: central Arkansas
Years ago a company called ATK sold a chain tensioner. This was back when dirt bikes started using longer and longer swingarms, which translated to better lap times for the motocross guys, until they started having chain problems. Eventually the engines got modified to put the sprocket centerline closer to the swingarm centerline, but in the meantime people experimented with various types of tensioners.

The one ATK sold was a spring-loaded "dogbone" with an upper and lower roller that ran on the chain. It didn't try to keep all the tension on the drive side; instead, it tried to keep the chain tight on the sprockets, so it wouldn't strip teeth on the front sprocket or beat up the rollers on the chain. I *think* the springs biased it more toward the slack side, to keep tension on the drive side of the chain, though.

Actually, you might not need anything so fancy. Just a single idler would do, and you could make a remote adjuster for it if you wanted.


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