Stem nut keeps getting loose

[MrN2OBelvedere]

Hey guys I have a little problem not sure what is the cause. 

 

The steering stem nut and the triple clamp nuts keep getting loose. Probably 1 hour of moto practice will make it come loose. Any way to prevent this? I tighten the bearing adjuster nut until I begin to feel drag on the steering, then loosen the top triple where it clamps to the forks, then tighten the triple nut, then tighten up the fork tube clamps. I just can't see where I'm going wrong here. Do I just need to safety wire these to keep them where they need to be?

[handreasen]

Hey guys I have a little problem not sure what is the cause. 

 

The steering stem nut and the triple clamp nuts keep getting loose. Probably 1 hour of moto practice will make it come loose. Any way to prevent this? I tighten the bearing adjuster nut until I begin to feel drag on the steering, then loosen the top triple where it clamps to the forks, then tighten the triple nut, then tighten up the fork tube clamps. I just can't see where I'm going wrong here. Do I just need to safety wire these to keep them where they need to be?

You can use a touch of lock tight, yes wife/girl friends nail polish, or a sharp pin punch and hammer blow to the side flat of the nut

[mec500]

Your either missing a tabbed washer or other part .a bearing or race may not be seated all the way .or not assembling correctly.

[gimped up]

Or carefully check the bearings and the triple clamps for cracks.

[ScootMcGoot]

Did you torque the 32mm on the top of the clamp to spec?  I believe the spec is 80 ft-lbs.  If that was not torqued properly I could see how the spanning nut underneath (which you don't set that tight) could loosen up.

[MrN2OBelvedere]

Did you torque the 32mm on the top of the clamp to spec?  I believe the spec is 80 ft-lbs.  If that was not torqued properly I could see how the spanning nut underneath (which you don't set that tight) could loosen up.

 

I'll go back and check the spec. I'm paranoid about torquing aluminum nuts but it looks like it may be necessary. 

 

As far as missing washers/other parts there are no issues at least when I compare to the OEM exploded parts diagrams.

 

There aren't any grooved washers/etc to prevent this sort of thing.

 

When I originally got the bike I went through the bearings and the stem bearings/races were a bit pitted and galled but they still roll more or less smoothly. I'll go ahead and check for further deterioration of these parts.

[rodgini]

 I always torque it factory spec, drill a hole and safety wire it. Then it can't move. make sure your upper triple clamps nut is torqued to spec and safety wire it as well.   

[frdbtr]

That nut on the top of my 94 CR125's torque spec was 108 foot lbs.  I don't think it is going to move if you torque it to spec.  The one on my 06 250 is 80 foot lbs. 

 

Edit:  I was starting to doubt my numbers so I went and double checked them for the 125.  Not sure why it is so tight, took a 24" breaker bar to loosen that thing though and the book confirmed my numbers. 

Edited September 10, 2013 by frdbtr

[stroker]

I always draw a black line with a sharpie, across the bottom of the nut and the shaft, and the top of the triple clamp, so if it gets even a little loose, you can see it right away.

Edited September 11, 2013 by stroker

[OneLapWonder]

If the previous owner rode with worn bearings too long, it's possible the head tube may have ovalized. I've seen this several times on bicycles - presumably it could happen to mx bike as well.

[MrN2OBelvedere]

If the previous owner rode with worn bearings too long, it's possible the head tube may have ovalized. I've seen this several times on bicycles - presumably it could happen to mx bike as well.

 

Nah they aren't that far gone. I'll eventually just replace the bearings and races but they do roll around and aren't cracking or anything. I clean them out and re-grease every 15-20 hours.

[seanmx57]

Check the front of the frame for cracks. Vertically between the upper and lower bearings. Seen at least 2 of em crack there.

 

Torque it to spec for sure. I've never had one loosen up with no precautions other than correct torque.