Keep an eye on your older flywheel weight

[mtnmanseth]

I'm not sure if this is a common problem with this product, but while pulling the motor to do a bottom end job because a terrible metal-on-metal sound made me think a major bearing was exploding, I found that it was actually the flywheel weight had somehow spun itself off the mounting bolt. Can't tell if it was originally welded, pressed, or machined as one piece. Regardless, the sound this little bastard makes while spinning on the outside of your crankshaft will make you think you bike is about ready to melt down. If you have 2005ish bike, keep an eye on any cracks or fatigue on this piece...

Now I need to decide whether to just install the new flywheel weight from Checkpoint Offroad and ride it, or continue with the teardown and do the bottom end while I have it half way apart and all the parts in my hands. We'll see...

 

[Leo]

This central bolt just losened.
Screw it back again and ready to ride again.

 

[mtnmanseth]

I don't think that's correct advice... I doubt they would design this as a simple friction securement. Admittedly, I never inspected this flywheel weight too closely, but I'm pretty sure it was once welded, pressed, or machined as one piece. Regardless, it's coming off for a new 12 ouncer from Checkpoint this weekend.

 

[Leo]

Please, refervto this instructions. Look like yours is the same
http://www.steahlyoffroad.com/skin/frontend/default/steahly/PDF/gray-instructions.pdf

 

[cbutler]

That does not look stock. I have a weight on mine the weight threads on like a nut then the nut screws on top.

Just querulous if the weight came loos mine would just eat threw the plastic cover. Can you move your flywheel up and down?

 

[mtnmanseth]

Please, refervto this instructions. Look like yours is the same
http://www.steahlyoffroad.com/skin/frontend/default/steahly/PDF/gray-instructions.pdf

Well, that's a different design overall... the Steahly weight/disc itself has it's own threads, then the "Special Nut" acts as a lock, right? On mine, the whole black disc i.e. weight part is now just flopping around on the end of the crankshaft. It might look like a big gap in the photos, but if I pull the weight back to contact the nut there's really only about 1/8" clearance between the FFW and the flywheel. I think mine broke, but I could be wrong...

 

[Neil E.]

It sure looks broken to me. I expect that the nut/hub piece is pressed into the disc part then welded on the inside. After that it is put on a mandrel for final machining so the disc runs true to the threads. It was probably not having much flywheel effect with a broken weld. Certainly would be noisy.

 

[mtnmanseth]

To close the loop on this, it was definitely broken. To the best of my knowledge, it was an original part, so after 10 years of (light) use it must have vibrated itself free of the weld or the machined material failed because it was barely/slightly/sorta off balance. That's my theory anyway.

I zipped off the mounting bolt easy enough using a pneumatic impact wrench, then installed one of these from Checkpoint Offroad, reassembled the whole bike, then rode 200 miles of singletrack over 3 days high in the Piute Mountains of California with zero problems.