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Sprocket Bolts Loosening and Damaging the Hub

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I have an 07 EXC 450 and just ruined my second hub due to sprocket bolts coming loose. After replacing the first hub I put on new sprockets and chain with new bolts. After every ride I would find one or two loose then tighten all to the proper torque spec then even tighter when they would loosen. Then I put new bolts again with red lock tite and they still came loose. After checking the countersink angle the bolt and the chamfer on the sprocket match at 90 degrees. The chain is kept within the manufacturer's suggested slack as well.

Are there any remedies? Should I try an aftermarket hub?

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I kow you are measuring it but sounds like a tight chain could be the problem. Did you pull the shock and check for 1/2" chain slack at tightest point?

My chain tensioning method is to have at least one guy tell me its too loose at every race!

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I kow you are measuring it but sounds like a tight chain could be the problem. Did you pull the shock and check for 1/2" chain slack at tightest point?

My chain tensioning method is to have at least one guy tell me its too loose at every race!

+1 .. can't think of anything else it could be... I adjust mine then sit way back on the rear fender to compress the rear shock as much as possible. Then check it again. If it feals the least bit snug I loosen it more.

I have the same bike and only use blue Locktight, no issues.

Had one budy destroy the rear hub. He had forgot to put any locktite on the sprocket bolts :smirk:.

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+1 on chain tension check.

I have over 8k on my bike with no drive train problems- neither should you.

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Are you torqueing the bolts by using a wrench on the head of the bolts? If so you won't get the bolts tight since they are tapered and will bind on the sprocket and will give a false torque value. Try tightening everything with a wrench on the nut.

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After adjusting the chain sit on the bike and see how much slack it has. It should have 1-2 inches. Looser is better. Or remove the shock and check that way. Its a thight chain thats causing your problem.

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I never have sprocket bolts come loose on my jap bikes but on my KTM's it was a common problem.I adjusted the chain to the specs and I have even tried running with more slack then the book says and they would still come loose.My final solution was to buy stainlees steel bolts and nylock stainless nuts with thin washers.I also used lock washers and blue loc-tite.Using this combo solved my problem.Maybe it's overkill but I destroyed two stock hubs after trying numerous types of hardware

and chain adjusting methods.The past two years I have been on a Kawi but recently bought a 2011 XC300 and just after my first month the bolts started to come loose.

I don't know why it happens.My personal theory is that KTM swingarms are thinner and they flex more putting more tension on the sprocket.I would like to know what the factory KTM mechanics use.I never tried the titanium hardware but my stainless combo worked in the past so I'm going back to it.

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