I've just had a quick look at that adjuster and it's screwed in very tight, I haven't moved it but if it was there to stop the crown wheel moving when under load I would expect it to be just in far enough to touch the back of the gear, it appears it may be over tightened.

In the service manual it only shows the screw and locknut which runs in a grove on the back of the crown gear, there doesn't appear to be anything attached to that screw on the inside of the cover, or no part listed in the parts list anyway.

The manual doesn't give any info on the screw other than the torque of the lock nut

I'm thinking about undoing it and screwing it back in until it just touch's the crown wheel, any thoughts ?

[2015 Z Force 800 53/Trail EPS]

I've just had a quick look at that adjuster and it's screwed in very tight, I haven't moved it but if it was there to stop the crown wheel moving when under load I would expect it to be just in far enough to touch the back of the gear, it appears it may be over tightened.

In the service manual it only shows the screw and locknut which runs in a grove on the back of the crown gear, there doesn't appear to be anything attached to that screw on the inside of the cover, or no part listed in the parts list anyway.

The manual doesn't give any info on the screw other than the torque of the lock nut

I'm thinking about undoing it and screwing it back in until it just touch's the crown wheel, any thoughts ?

It talks about some precise measurements after a set. I don't think you want to touch it unless you are it apart and on the bench. Looks like a relationship between the ring gear and the distance between the case..

Although to me somewhat vague on description, this is what it says:

Looks to me like a mounting point for the dial indicator. It refers to the shims I mentioned as an adjustment method if required after assembly. Which unfortunately requires disassembly again. Not too bad, just like a car.

I've just printed off the manual all 296 pages which make it easier to read It's probably the thread lock that's holding the bolt tight.
Thinking about it I'm going to order the different size shims and then remove the diff, strip and inspect.
I don't want to take it out and find I need the shims and then have to wait weeks for them to turn up.

I've just printed off the manual all 296 pages which make it easier to read It's probably the thread lock that's holding the bolt tight.
Thinking about it I'm going to order the different size shims and then remove the diff, strip and inspect.
I don't want to take it out and find I need the shims and then have to wait weeks for them to turn up.

Be sure and post pics of the repair along the way, part numbers, measurements yours showed before and after etc.....This brand needs this kinda knowledge publicized.

I will update as soon as I can, shims are ordered

In my opinion it shouldn't be that loud. I would prefer if it was quieter. The adjuster can be seen in the picture

The manual screen shot you posted does mention an Item #29 that seems to be directly related to gear backlash although its is not shown on the manual screen shot pic. Here is a screen shot of the rear diff. It is in fact a gear lash adjuster, my opinion of CF Moto and their engineers just went up a few points.  It would definitely be worth it to loosen that lock nut, and loosen the preload screw a quarter turn or so. Gear backlash doesnt take much to be noisy so a little goes a long way.

I've just had a quick look at that adjuster and it's screwed in very tight, I haven't moved it but if it was there to stop the crown wheel moving when under load I would expect it to be just in far enough to touch the back of the gear, it appears it may be over tightened.

In the service manual it only shows the screw and locknut which runs in a grove on the back of the crown gear, there doesn't appear to be anything attached to that screw on the inside of the cover, or no part listed in the parts list anyway.

The manual doesn't give any info on the screw other than the torque of the lock nut

I'm thinking about undoing it and screwing it back in until it just touch's the crown wheel, any thoughts ?

http://www.alpha-sports.com/cfmoto/2016/2016%20ZFORCE%20800EX/31.gif

In this link, the rear differential is shown. Part number 4,5,and 6 are definitely a ring gear preload bolt. My opinion, is I would definitely mark the center adjuster screws location, loosen the lock nut, and loosen the adjuster screw 1/4 turn and test.

This is a great design! Locknut tq specs are not critical here, just snug is fine. 6-8 ft lbs would be sufficient

Update, my new shims for the rear "diff" are on their way, so project quiet diff should be under way in a week or so

I definitely want to know how this works since mine is really noisy as well. 

Has anyone else adjusted the screw and find that helped?

The new shims are on their way so I'll be starting strip down very soon, as soon as I have some more info I will post it here.

I'm going to check rear wheel bearings as well while she's being looked at.

I tried to loosen the adjuster screw but it's locked in place with some very good thread lock so I didn't force it, once the diff is apart I will have a closer look.

[2015 Z Force 800 53/Trail EPS]

I almost want try it. Mine.. to the contrary.. has excessive play or backlash. I can turn the wheels almost 3" before the ring gear contacts the pinion and moves it. That's just too much IMO.

I almost want try it. Mine.. to the contrary.. has excessive play or backlash. I can turn the wheels almost 3" before the ring gear contacts the pinion and moves it. That's just too much IMO.

OMG, I have so little movement in mine it's hard to tell if it has any play/clearance at all, she's certainly quieter when cold, which would be consistent with it being to tight/not enough clearance.
Two or three hours in mine is about all I can take with the noise from the axle, I'm hoping it will be obvious what the problem is when she's striped.
I want to get some plasti gauge to check the clearance of the crown wheel and pinion.   

I definitely want to know how this works since mine is really noisy as well. 

Has anyone else adjusted the screw and find that helped?

After looking at the parts explosion, this would be the first thing I would do.