• Tired of adverts on RWI? - Subscribe by clicking HERE and PMing Trailboss for instructions and they will magically go away!

Swap your CHS movement to ICHS - Is it possible?

KJ2020

Time Traveler
Supporter
12/3/18
32,372
56,759
113
This project started out as another attempted investigation into whether or not the rep Rolex GMT CHS movement could be repaired once the hour jumping spring has broken. That investigation is still on-going but as a corollary to it, I was also interested in seeing if the rep CHS cases would take either of the common ICHS movements, the 2836 ICHS or the DG2813/3804 ICHS movements (hereafter simply referred to as ‘3804’). For those interested in following the repair efforts, please see this thread:

https://forum.replica-watch.info/for...-failing/page7

Surely someone has discovered this before, but it was news to me and I haven’t seen it posted elsewhere so guess what? BOTH the 2836 and the 3804 GMT ICHS movements fit and function properly in the CHS case I had to work with. No mods to the case, rotor or caseback are needed.

At this point I’d like to thank OldNavitimer whose posts I had seen indicating multiple CHS movement issues. I contacted him and he generously sent me three watches, a 2824 CHS, a 2386 ICHS and a DG2813 ICHS. Without his pieces to work on, I could not have made these tests and conclusions. Thanks bro!

Both the ETA watches were BP factory, but I think it’s safe to assume we can apply the same results to other factory watches. Please post back with your own findings on other factory watches!

I started off by taking some key measurements and doing some visual comparisons of the ETA ICHS vs CHS. Here is what I found. All measurements are in mm
_
2836 ICHS2824 CHS
Max dial diameter28.028.2
Rehaut aperture26.826.8
Distance from bottom of rehaut to center tube3.93.95
Distance from bottom of rehaut to underside of crystal2.82.8
Movement holder outside diameter28.229.2
Movement stem height2.251.8
Dial thickness0.50.5
Dial spacer1.01.5
Datewheel tooth ring height0.750.9
Hands H/M/S (GMT)1.5/1.0/.25 (2.0)2.0/1.0/.25 (1.5)
`
I did not see a need to measure everything about the 3804 case, but it’s stem height is 2.5mm and its dial spacer was .67mm, dial thickness 0.5mm

So you can see the important elements of the two ETA cases are similar enough to be negligible, and adding up the stem height of the movement, dial, and dial spacers we get:

2824 CHS: 3.80mm
2836 ICHS: 3.75mm
3804 ICHS: 3.67mm

After reviewing the measurements and examining the cases, it’s apparent that BP just used a 2836 case to house the 2824 CHS movement. They used a thicker dial spacer to make up the height difference, and raised up the datewheel to help offset overmagnified dates. The extra space created by the thicker dial spacer on the 2824 CHS allows room for the modified intermediate date wheel, which we will see a photo of later. This modified intermediate wheel is considerably taller than its 2836 counterpart, and would have made using a 2836 as a base impractical.

Here are some shots of the cases, crowns, dials, datewheels and dial spacers.

EWyW.jpg



7MGK.jpg


7dVL.jpg


74p8.jpg


Datewheels and dial spacers

7waR.jpg


As ingenious as the design of the 2824 CHS is, I am struck by how cheap the parts are. It is a real shame that the time and money spent on pretty decorations and engravings for the backside bridges wasn’t better allocated to the movement parts that matter. The CHS movement looks marvelous when you open the back. Take the dial off and it’s a different story altogether.

Here’s a shot of the two movements together. You can see in this pic that the CHS date corrector is missing. The hole for it to fit into the CHS movement is not a slot like a normal 2824, meaning it can’t move to the right with the crown in position 2. This disables the quickset date feature usually provided by this gear.

EKCY.jpg


Here you can see an additional intermediate wheel was added to the CHS to allow the date corrector gear to interact with the GMT wheel. This is where the hour jumping spring comes into play, supposedly freezing the GMT wheel while jumping the hour wheel (in gold color).

EZYE.jpg


In the next few pics you can see the intermediate date wheels and how much taller the modified CHS one is. The gears are reversed vertically to drive the reversed wheels on the CHS, all necessary to have the GMT and hour hand positions swapped. The third tiny gear on these wheels is to power the datewheel driving wheel to change the date.

EawS.jpg


7rpD.jpg


7tFk.jpg


Here you can see just how little there really is to the CHS movement.

7l6J.jpg


Here’s pics of the 2 ICHS movements installed in the CHS case

7RYI.jpg


7Sii.jpg


7fkc.jpg


7FVX.jpg


70pb.jpg


Things you will need to replace your CHS movement
_
Replacement ICHSWhat you need
2836 ICHSCHS case crown
CHS case movement holder
CHS or ICHS dial
ICHS datewheel with DWO (or CHS DWO cut off and swapped to 2836 DW)
2836 ICHS Movement
2836 ICHS dial spacer
Hour and GMT hands (or whole new set)
DG 2813/3804 ICHSCHS case crown
CHS case movement holder
CHS or ICHS dial (3804 dial must fit and have gen-spec date window position or CHS dial needs feet cut and redone)
ICHS datewheel with DWO (or CHS DWO cut off and swapped to 3804 DW)
3804 ICHS Movement
3804 ICHS dial spacer
Whole new hands set
`
This freshly serviced 2836 ICHS movement is happy in its new CHS case home.

silo.jpg


I hope this will be the first of many and we can start returning our paperweights to their former glory!

A new DG3804 movement is about $40, hands about $20. Easily found on ebay or Startime.
A new 2836 ICHS can be gotten for around $110, hands about $30. Look on ebay or ask your TD.
 
Last edited:

OldNavitimer

I'm Pretty Popular
Patron
Certified
22/1/19
1,331
1,693
113
KJ2020 Wow! Amazing write up that should be a sticky. I’m grateful to KJ2020 for doing this for all of us, and particularly for bringing my favourite Batman back to life! Thank you!!
 

KJ2020

Time Traveler
Supporter
12/3/18
32,372
56,759
113
KJ2020 Wow! Amazing write up that should be a sticky. I’m grateful to KJ2020 for doing this for all of us, and particularly for bringing my favourite Batman back to life! Thank you!!

You're welcome bro. Thank you for the parts to work on, and the willingness to help us all benefit from some workaround. Now on to Part Deux - Can the CHS movement be resurrected from the dead and made to work in a not too diminished capacity? We shall see...
 
Last edited:
  • Like
Reactions: Surftime

Tione12

Active Member
11/6/19
447
139
43
Thank you for the detailed explanation! The photo work is wonderful :)
 

Vvvlllooo

I'm Pretty Popular
13/6/15
2,412
1,770
113
Wow bro, nice write up. Very good explanation. Your work amazes me. I saw tickleshoes do a quick write up on how to fix it too. Is there a fix to the correct hand stack movements per say to make it more reliable?
 
Last edited:
  • Like
Reactions: KJ2020

MrBeasy

Put Some Respect On My Name
8/2/16
3,068
874
113
Thanks for posting mate. appreciate you sharing the info!
 
  • Like
Reactions: KJ2020

KJ2020

Time Traveler
Supporter
12/3/18
32,372
56,759
113
Wow bro, nice write up. Very good explanation. Your work amazes me. I saw tickleshoes do a quick write up on how to fix it too. Is there a fix to the correct hand stack movements per say to make it more reliable?

Thanks bro. There is an outside chance the hour jumping spring could be made slightly thicker or stronger. Perhaps just bolstered at the weak points as merlix has attempted. This would restore full normal functionality. Photo credits to merlix.

N2oc.jpg


NATX.jpg


Failing that, I believe there could be a another fix. It would necessitate adhering the upper and lower halves of the GMT wheel together which Tickleshoes did and it worked for a while then quit. This approach needs further investigation. It would lock the GMT and hour hands together but a GMT offset can be achieved if desired by manually setting the hands with the offset.

Also in this second scenario I believe there is a possibilty of restoring the quickset date feature. Once the hands are locked, there is no longer a need for either of the two intermediate wheels linking the date corrector to the GMT wheel. After their removal, the date corrector is free to resume its normal function. As I noted above, the date corrector gear does not sit in a slotted hole in the movement like it does on a normal 2824, so the movement plate would have to be filed to create the slot. This could be easily done, child's play compared to what Micasol did to his skeleton Daytona.

I'm hopeful I can do this, I just wish I had more parts. If anyone has a dead CHS movement they can contribute to this cause, please PM me!
 
Last edited:

Vvvlllooo

I'm Pretty Popular
13/6/15
2,412
1,770
113
Thanks bro. There is an outside chance the hour jumping spring could be made slightly thicker or stronger. Perhaps just bolstered at the weak points as merlix has attempted. This would retain full normal functionality. Photo credits to merlix.

N2oc.jpg


NATX.jpg


Failing that, I believe there could be a another fix. It would necessitate adhering the upper and lower halves of the GMT wheel together which Tickleshoes did and it worked for a while then quit. This approach needs further investigation. It would lock the GMT and hour hands together but a GMT offset can be achieved if desired by manually setting the hands with the offset.

Also I believe there is a possibilty of restoring the quickset date feature. Once the hands are locked, there is no longer a need for either of the two intermediate wheels linking the date corrector to the GMT wheel. After their removal, the date corrector is free to resume its normal function. As I noted above, the date corrector gear does not sit in a slotted hole in the movement like it does on a normal 2824, so the movement plate would have to be filed to create the slot. This could be easily done, child's play compared to what Micasol did to his skeleton Daytona.

I'm hopeful I can do this, I just wish I had more parts. If anyone has a dead CHS movement they can contribute to this cause, please PM me!

wow very nice brother. wish i had a CHS lying around for you!!! Please share for anyone who would like to donate for this cause!!!
 
  • Like
Reactions: KJ2020

grandphuba

Active Member
8/4/18
255
41
0
With this CHS movement being out for so many years already one thinks why they haven't fixed the problem yet. Seems like they only need to reinforce or rework the part so it's not as fragile. Then again I'm just a pedestrian naive enough to trivialize such matters
 

Rubberman

Forever young
Patron
Certified
9/12/17
1,091
388
83
Will this swap applicable to the new Noob Pepsi which is CHS?
 

Interesting

Renowned Member
Supporter
Certified
19/8/19
964
3,805
93
You should sign up as a tech consultant to Noob and ARF and get them pay you .... just saying
 

Jammydodger79

Active Member
15/10/18
307
102
43
So am I correct in thinking I can get my Noob Explorer 2 back up and running with a A2836 and an ICHS handset?
 
Last edited:
  • Like
Reactions: KJ2020

Lutaito

Active Member
Supporter
Certified
2/8/19
451
63
28
Things you will need to replace your CHS movement
_
Replacement ICHSWhat you need
2836 ICHSCHS case crown
CHS case movement holder
CHS or ICHS dial
ICHS datewheel with DWO (or CHS DWO cut off and swapped to 2836 DW)
2836 ICHS Movement
2836 ICHS dial spacer
Hour and GMT hands (or whole new set)
DG 2813/3804 ICHSCHS case crown
CHS case movement holder
CHS or ICHS dial (3804 dial must fit and have gen-spec date window position or CHS dial needs feet cut and redone)
ICHS datewheel with DWO (or CHS DWO cut off and swapped to 3804 DW)
3804 ICHS Movement
3804 ICHS dial spacer
Whole new hands set


A new DG3804 movement is about $40, hands about $20. Easily found on ebay or Startime.
A new 2836 ICHS can be gotten for around $110, hands about $30. Look on ebay or ask your TD.



Hey KJ, i got the Batman noob v7 with rolex movment, idk if its clone or just cosmetic rolex movement. The movement is working looks like the wheels and balance is working. Also i have ordered DG 3804 from ebay and Hongzhou 6460 gmt movement that you suggested. The hongzhou is still on the way. Dg3804 is here. Im thinking to work it with 3804. Would the noob case and dial/hands and stem on the 3804 as is or it will be a waste?
Thanks
 

KJ2020

Time Traveler
Supporter
12/3/18
32,372
56,759
113
Hey KJ, i got the Batman noob v7 with rolex movment, idk if its clone or just cosmetic rolex movement. The movement is working looks like the wheels and balance is working. Also i have ordered DG 3804 from ebay and Hongzhou 6460 gmt movement that you suggested. The hongzhou is still on the way. Dg3804 is here. Im thinking to work it with 3804. Would the noob case and dial/hands and stem on the 3804 as is or it will be a waste?
Thanks

Your answers can be found in the table I posted. ETA and DG dials and hands are not compatible. The HZ6460 is an ETA clone.