Model D, two different noises, same reason?

[lhirsch]

Dear all,

my well maintained Model D has developed two issues lately:

- When running freely after an effort, at two specific flywheel speeds, I either hear a humming sound or feel a vibration through the seat.

- In the first third of the catch I hear a new "ratteling noise" coming from somewhere around the sprocket, the axel or chain idler.

The issues are minor and do not seem to influence the rowers performance, but seem to be progressing and are annoying.
Does anyone have any idea on the cause of the issues?

Thanks and Cheers,
Lutz

[Ombrax]

Something's coming loose or wearing out, but you probably already knew that... Sorry I can't be more specific, but I would guess a bearing.

How many lifetime meters are on the erg?

Good Luck

[jamesg]

Presumably your routine maintenance includes cleaning the fan and tightening all nuts, bolts and screws.

If this does not stop rattles and vibration, there's something else, maybe the chain recovery system.

Vibration implies something out of balance, such as a fan counterweight; or excess dust, also causing low drag, so easily identified.

[gvcormac]

The flywheel has balance weights. It is possible that one became loose. If you remove the cover you should be able to see the weights, and if one is loose or missing, you might be able to figure out from the dirt pattern where it is supposed to be.

[lhirsch]

Dear all,

great thanks for these fast replies.

The chain is freshly lubed, the flywheel is cleaned and all counterweights seem to be in their original place.
Sadly no effect of the above.

But I haven't tightened any screws and bolts, yet. Any recommendations on what to tighten?

Thanks in advance.

Cheers,
Lutz

[Tsnor]

Not a mechanic, but have swapped parts. There is a difference.

- When running freely after an effort, at two specific flywheel speeds, I either hear a humming sound or feel a vibration through the seat.

Suggest removing the flywheel cage (instructions here https://www.concept2.nl/files/pdf/us/in ... cement.pdf Video here: https://www.youtube.com/watch?v=bxuIKL0b_uk ) That will remove anything that might have lodged in the cage. See if you can find what is vibrating by spinning the flywheel by hand at first, then if that doesn't work have a helper pull the handle. Safety third, but use common sense - the flywheel exposed at speed is a weapon. Things can get caught behind the flywheel. Maybe remove the flywheel and oil the flywheel clutch bearing while you are here and see if that fixes the vibration ???.

If the noise is in one of the flywheel bearings there are many post on how to replace just the bearing or you can buy the bearing and have a machine shop swap it in. If I ever hit the problem I'll get a complete new fan assembly from concept2 (call them, $100-$150) and just bolt it in rather than replacing bearings. If you removed the flywheel above to inspect then you can replace flywheel.

- In the first third of the catch I hear a new "ratteling noise" coming from somewhere around the sprocket, the axel or chain idler.

Sometimes things in the flywheel make noise at low speed, but stop making noise when speed gets high enough to push them to the outer edge. Like a loose car wheel lug nut in a hub cap. Check for this with the flywheel cover off. If you don't see anything then I'd remove the flywheel itself. Clean and inspect.

If every thing is perfect with the flywheel side then maybe the chain side is the issue. The plastic cover on the bottom of the erg can get pushed in and touch the chain. But it didn't sound like you describe.

If the noise is coming from the sprocket area this video near the middle shows how to access axle, sprocket etc. Clean and inspect. There are some parts in there that might be loose and vibrating (end plate?) maybe. I'd look here last. https://youtu.be/PVn3VgKatXM?si=ozeOYauX1WKSzxtE&t=1228

[lhirsch]

Dear all,

thanks for all the detailed recommendations.

In the meantime I opened the flywheel cage again and took off the flywheel. All was clean and empty behind it.

When I put the Flywheel back on I realized that there is little play in the horizontal (along the axel direction)
although the nuts are tight. Is that OK, or maybe the reason for the vibrations?

Also I replaced both chain idlers having access to them as the flywheel was off.
That seems to have reduced or solved the the "rattling noise" issue.

Cheers,
Lutz

[c2jonw]

Try tightening the two screws that hold the generator cover on. If these have loosened up then the generator assembly can move and vibrate as it interacts with the flywheel magnet.