IWC caliber 89 problem

[Stian]

Hi guys, 

I'm servicing an IWC cal 89, and although I have a decent amplitude of 270, the seconds hand moves erratically, see video. Would any of you gurus have any idea as to the reason? 

--

Best regards, 

Stian

VID_20170830_215805.mp4

[Geo]

I can't view your video, but I suspect your problem will be the leaf spring that exerts pressure on the bottom of the second hand pivot is distorted slightly.  

This spring should press on the pinion slightly to damp the action of the second hand. When the pressure is too little, the backlash is transmitted to the second hand causing it to lash about.  When the spring is set correctly, there is only forward movement of the second hand.

 

The calibre 89 is one if my favourites! :-)

Edited August 30, 2017 by Geo

[wls1971]

This excellent walk through explains the tension spring and how to adjust it in the calibre 89:

http://people.timezone.com/msandler/Articles/BestYears/BestYears2.html

[Marc]

Wow!!  I don't think I have ever seen quite such an exaggerated seconds hand stutter as that.

I'm with Geo on this with the most likely cause being the leaf spring on the seconds hand pinion, which has the sole function of stopping seconds hand stutter.

Is your 270 amplitude at fully wound or a number of hours after winding? The reason I ask is that adjusting the leaf spring to apply more pressure on the seconds hand pinion (to kill the stutter) will pull down the amplitude a little as well. If you're getting 270 at full wind without the extra tension/friction in the system then you may need to revisit the servicing and maybe look at a new main spring (did you already replace this as part of the service?).

The cal.89 is a truely superb movement, and freshly serviced I would want to see amplitude over the 300 at fully wound.

 

[Stian]

Thanks a lot, guys! I will check the leaf spring and look at the walk through. 

Stian 

[oldhippy]

Just saying Geo is correct on this one. I don't need to add advice.

[clockboy]

Between Geo & Wis you should have the answer

[Stian]

On 30/08/2017 at 11:20 PM, Marc said:

Wow!!  I don't think I have ever seen quite such an exaggerated seconds hand stutter as that.

I'm with Geo on this with the most likely cause being the leaf spring on the seconds hand pinion, which has the sole function of stopping seconds hand stutter.

Is your 270 amplitude at fully wound or a number of hours after winding? The reason I ask is that adjusting the leaf spring to apply more pressure on the seconds hand pinion (to kill the stutter) will pull down the amplitude a little as well. If you're getting 270 at full wind without the extra tension/friction in the system then you may need to revisit the servicing and maybe look at a new main spring (did you already replace this as part of the service?).

The cal.89 is a truely superb movement, and freshly serviced I would want to see amplitude over the 300 at fully wound.

 

Hi Marc,

The 270 was at mid wind, I suppose. Fully wound I get 320 after tightening the tension on the seconds hand pinion.

Stian

 

[Stian]

Hi guys,

After the tip and reading the walkthrough the watch now runs as it should with a nice amplitude of 320 dial up fully wound. Thanks again for the brilliant advise and help!

Stian