Clunking from axle when spun?

Kyle Geddes · Joined: 19 Oct 2012 Posts: 12

Folks - curious if anyone has ever seen (er.. heard) an axle that makes a clunking noise when spun?

With just the bare axle on my kart, no chain/tires - if i rotate it it makes a clunk, clunk, clunk - 3 times per revolution as near as i can tell. You can almost hear it more from the floor plan as the noise resonates from it, but it's clearly from the axles/bearing since they are the only thing rotating - can this be bad bearings?

Any thoughts on a fix? (besides buying new bearings - can these be re-lubed?).

thanks!

TJ Koyen · Joined: 03 Oct 2004 Posts: 1417

Do you have a floating brake rotor on the axle or is that off too?
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Kyle Geddes · Joined: 19 Oct 2012 Posts: 12

Ken Schilling · Joined: 01 Dec 2005 Posts: 1345

If it's a shifter kart and has a reinforced axle, it may be the reinforcement that's worked itself loose. The reinforcement is basically a smaller axle a couple of inches long inside the axle and placed where the axle sprocket should be located. It's there to reinforce the axle due to the high loads from a shifter engine. I hope that makes sense...

Don't ask me how I know... Laughing

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Randy Mckee · Posted: Fri Jan 25, 2013 12:58 pm Post subject:

The others have made some good suggestions. I've also seen where the axle can slightly bind between the carriers and each rotation causes it to snap back to alignment making a knocking noise.

An easy test is to loosen one of the bearing carriers a bit so it's not locked to the frame. I usually loosen the center one. Turn axle and listen. If silent, then you'll want to carefully re-align the axle in all of the carriers.
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Tim Doll · Posted: Fri Jan 25, 2013 8:07 pm Post subject:

If you eliminate the other listed posibilities, it's almost certainly a bearing. Yes, you can re-lube them, but I'd recommend against it. If the bearing is 'clunking' - it means you've already damaged it. It's going to run hot, burn out the lube, and fail, with a good chance it'll damage the axle as well.

If you determine it's a bearing, replace it - they're not expensive (unless you get silly and get ceramic - a major waste of money) and you don't need to worry about it failing at a bad time.

Tim
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Gary M Smith · Posted: Fri Jan 25, 2013 9:43 pm Post subject:

Normally a bad bearing would give you clicking or a grinding noise, not a 3 clunks per rev. When my bearings need to be cleaned, I use a 2 pie pan method with mineral spirits, or paint thinner. I soaked the bearings in the first pie pan, spin the bearing repeatedly, blow compressed air into the bearing and repeat several times until the bearing seems free, then soak in the second pie pan with clean paint thinner and blow compressed air until clean. Lubricate with Dura Lube, and the bearings seem to be good as new. This process takes about 10 minutes per bearing and has worked for me for years.
Gary
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Walt Gifford · Posted: Wed Jan 30, 2013 11:18 pm Post subject:

Keith Buffo · Posted: Thu Jan 31, 2013 10:14 am Post subject:

Yeah, it's tough to tell exactly where those noises are coming from. Mike at CFMotorsports showed me a trick: Hold a screw driver to the caliper and each cassette and put your ear to the handle to help isolate the noise. More often than not, the noise is coming from the rotor.

Bearings do get dirty and can be cleaned. Once you have them in hand:
1.) Pop off the dust cover from the side away from the axle sleeve... use a very small/thin blade screw driver gently so you don't mangle the cover.
2.)Clean thoroughly. Do not allow them to move/spin much so you don't scratch up the internal surfaces. I've been lucky enough to have access to aqueous & mineral spirit washers... perhaps someone else can chime in with an at-home technique.
3.) Rinse with water. Then blow with compressed air until completely dry. If the blown out water is tinged, they're still dirty, so repeat 2 & 3 until clean. Again, do not allow them to move.
4.) Apply coat of spray grease. Allow to dry/set. Gently turn a little. Respray 3-5 times. At CFMotorsports we use Wurth HHS-2000.

This works great, and will save a relatively new set of bearings after a rain race or off-track excursion. None the less, I replace the bearings at least once a year. Hope that's helpful.
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bob prinzo · Posted: Sat Feb 09, 2013 8:56 pm Post subject:

its thebrake rotor
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Lawrence Doty · Posted: Sat Feb 09, 2013 10:37 pm Post subject:

Hub keys

Evan Fraser · Posted: Wed Mar 20, 2013 10:24 am Post subject:

I once had a seat strut and a set screw on the right bearing bumping into each other just enough to make a slight bump noise and slow the axle slightly. Wound up moving the seat strut to the other side of the bearing carrier.