Noisey Rotor

[GaG]

I think I know the answer to this but I want to check before going back to the dealer.

My Alt1C-Cr on my wrist makes a squeaking/grinding noise and on removing it from my wrist and looking at the movement, when the watch is lightly shaken the rotor spins fully round and is out of balance and is obviously the source of the noise. I take it this is not normal and my three week old watch is faulty?

[calsoertj]

Hi GaG,

You can never be too careful and take it back to your AD for a check up. But the Alt1-C/CR has an updated Valjoux 7750 which will have squeaky noise and it tends to spin more than it should. Personally I find the squeaky sound part of the charm as it feels more mechanical.

Hope this helps

[jwalker9]

Agree, the chronographs have a little bit of "wobble" as you wear them and you can hear it if you listen closely. The word "grind" does sound a bit concerning. You could download the Tapatalk app, find the forum, go to this thread and create, then post a short video demonstrating what you are hearing/seeing!?

[GaG]

Thanks for the reassurance. I don't think it was making any noise until today or if it was I never noticed it but I'll do as you say and take it back to the AD just to make sure.

[calsoertj]

I think you will be fine, Bremont's chronometers have gone through intensive quality control before it gets to your wrist. I did not notice the wobble and squeaky sound until a few days later on my first Valjoux 7750 time piece.

Unless you are Hulk, you do not have to worry to much ;)
If there is a problem, I am sure the AD or Bremont (legendary customer service) will sort you out.

[GaG]

Hopefully you are all correct and there is nothing wrong. I'll get it checked out in the morning and post back what the AD has to say about it. Thanks again.

[GaG]

I went to the AD and we checked it out against one in stock and they were both the same. Looks like I over reacted. No problems so I can breath again.

[calsoertj]

Glad to hear everything is fine!

Enjoy your mechanical watch! It will wobble but that's part of the charm ;)


Sent from my iPhone using Tapatalk

[MarkH]

The Chronograph Valjoux 7750 has a much larger, heavier rotor and a different clutch mechanism to the smaller ETA 2836 type movements found in the non chrono Bremont watches. The 7750 rotor is a free spinning type so you will notice a distinct "wobble" as it spins, and due to the velocity at which it can spin the rotor bearings will be slightly noisy in operation. The 2836 movements have a much smaller and lighter rotor and are not free spinning, so you'll not feel them wobble and will not hear any noise from them at all.

[chunkythebulldog]

Is the rotor unidirectional or bi-directional on Bremonts?

[RedsBluesGreens]

Is the rotor unidirectional or bi-directional on Bremonts?

It depends on the movement. The 2836 in all of the non-chrono watches, including the the 2893-2 found in the MBIII are bidirectional. The Valijoux 7750 series found in the non in-house chronographs are unidirectional.

J.

[MarkH]

To be more precise the 7750 rotor will spin bidirectionally, but the mechanism that transfers that into charging the mainspring is unidirectional. What's really amazing about the 7750 movement is that the original movement on which it's based was a manual winding chronograph known as the Venus Calibre 188 and dates from 1948.

[chunkythebulldog]

To be more precise the 7750 rotor will spin bidirectionally, but the mechanism that transfers that into charging the mainspring is unidirectional. What's really amazing about the 7750 movement is that the original movement on which it's based was a manual winding chronograph known as the Venus Calibre 188 and dates from 1948.

Unidirectional mechanisms tend to spin at higher RPMs than bidirectional ones because if energy is imparted in the non-winding direction it faces almost no resistance. This then leads to Rotor Wobble on the wrist, where you can actually feel the rotor spinning as it's an inherently unbalanced motion. I take it that this is then the grinding noise that the OP refers to?

[MarkH]

It's also that the 7750 rotor has considerably more mass than the rotor in the 2836 type movements, and will spin more easily in either direction, however you're right that it's easier in the non winding direction and the wobble is the result. The 2836 also has 2 reversing wheels in the automatic bridge, which engage with the geared teeth of the rotor, and these are both clutch wheels so damp the rotation of the rotor. The 7750 only has a single reversing wheel/clutch so has far less resistance to the greater mass of it's rotor! If anyone is interested you can download the parts lists and servicing diagrams from ETA here by selecting either Mecaline or Mecaline Specialities and then clicking the calibre number in the next drop down box.

https://secure.eta.ch/CSP/DefaultDesktop.aspx?tabindex=1&tabid=28

[kaufen]

Agree, the chronographs have a little bit of "wobble" as you wear them and you can hear it if you listen closely.