Hello friends
I have one Zforce 800 EX that i realy like.
For several times when running in H position and always slowing down , never with throttle open , i heard a lound noise at the back , like gears engaging . Instinctively I brake and stop. After that, even without changing the gear ,i restart and usually i can ride 100km or more without any problem  and any noise.
This noise is completely unpredictable.
I had contacted with my mechanic and other people and nobothy give me one aswer.
I will apreciate any help that one of the menbers can give me , befor i broke the diferential or gerabox !!!
Thanks in advance

[2015 Z Force 800 53/Trail EPS]

The first two things I would check are the motor mount bolts, then the gear shifter linkage for proper alignment. If nothing is found I would want to know if the rubber parts of the engine mounts are still OK so I would have someone in the cab holding the brake and shifting it from reverse to forward with a little gas when in gear while I watched the engine closely for any movement. If that seemed OK, I would inspect the front drive line and all it's parts for excessive movement from a bad carrier bearing, u-joint or spline. If that was OK then I would be back at the engine inspecting the clutches and that cover bearing. After that ...well, that leaves the rear drive parts and gear case to inspect. Might have a bad CV joint some where too so put those on your list.

Thank you so much for the advises !
I have well sycronised the shift lever with the engine . For the other aspects i will check and after write a post.
To be more precise , that happens ALWAYS when slowing down and never with open throtlle . 3 times at very low speed.
Regards

You might be hearing the engine brake engaging. It should do it in low as well, if not more frequently. It freaked me out my first few times riding until I realized when I heard the noise was when the engine braking was engaging, sounds like a damn box of rocks until it fully engages.  Then again maybe mine isn't normal either, but I haven't had a problem yet other than once in a while It Won't engage, gotta tap throttle sometimes to get her to engage

Thank you for your opinion !
It is not the engine brake engaging. It is a mettalic sound like gears getting in contact in the gearbox or rear diferential.

After a brainstorm with the mechanical , we have understood that probably the H gear drive inside the gearbox (14) don´t engage correctly or is wear out -see attached file .
I don´t want desassemble all the engine to change the H gear drive once is expensive and time consuming, so i go to wait and see what happens.

Hello guys ,The time has past but the grinding noise is gowing on ! Inside the gearbox i think evrything is fine once the noise don´t appear when i open the trothle hardly or in hard breaking.Usually appears at low speed in impreditable moments. I have changed the belt and inside the CVT evrything seems fine. I notice the midle bearing that supports the front transmission axles has an important looseness . I remeber that NMKawierider had advised to check  this item . Can be there the probleam ? Any othe sugestion ? Thank you

[2015 Z Force 800 53/Trail EPS]

Hello guys ,The time has past but the grinding noise is gowing on ! Inside the gearbox i think evrything is fine once the noise don´t appear when i open the trothle hardly or in hard breaking.Usually appears at low speed in impreditable moments. I have changed the belt and inside the CVT evrything seems fine. I notice the midle bearing that supports the front transmission axles has an important looseness . I remeber that NMKawierider had advised to check  this item . Can be there the probleam ? Any othe sugestion ? Thank you

Does it do this both in and out of 4WD? Have you confirmed the shifter is adjusted correctly? I will say that if by chance it is an alignment problem or a bent fork in the transmission, it won't be corrected now by any adjustments. Parts will have to be replaced.

NMKawierider Thanks for your replay.
I never driver in 4 wd but i supose it will make that grinding noise..The shifter is well sincronysed .Any shifter issue engaging in any position .
What you means about "alignement probleam" ? Engine not aligned with the transmission ?
The first thought is that the H gear disenganges due to the bend fork or wear and make that noise...Anyway from one year ago i have made 2.000 km and that grinding noise never happens with full throtlle or when the gearbox is under stress...
I have noticed has i told , that the bearing that supports the front transmission axle has same clearence and eventually  can create same vibrations in the engine.
Also i saw when i have changed the belt that the primary clutch was blocked and did not open , once the weigths inside had turned around, i don´t know why and how ..
Sameone told me that noise could be from the "one way bearing" that is inside the belt where the clutch engages...
I wonder how is possible nobothy had this issue...I have checked so many foruns..
I remember is a Zforce 800 -2015

[2015 Z Force 800 53/Trail EPS]

NMKawierider Thanks for your replay.
I never driver in 4 wd but i supose it will make that grinding noise..The shifter is well sincronysed .Any shifter issue engaging in any position .
What you means about "alignement probleam" ? Engine not aligned with the transmission ?
The first thought is that the H gear disenganges due to the bend fork or wear and make that noise...Anyway from one year ago i have made 2.000 km and that grinding noise never happens with full throtlle or when the gearbox is under stress...
I have noticed has i told , that the bearing that supports the front transmission axle has same clearence and eventually  can create same vibrations in the engine.
Also i saw when i have changed the belt that the primary clutch was blocked and did not open , once the weigths inside had turned around, i don´t know why and how ..
Sameone told me that noise could be from the "one way bearing" that is inside the belt where the clutch engages...
I wonder how is possible nobothy had this issue...I have checked so many foruns..
I remember is a Zforce 800 -2015

What I meant about alignment was that there are two shifter detents-one in the transmission for the barrow and one on the shifter handle itself. Both must be aligned together in order to fully be in any gear position. Try this: Loosen the lock nut under the shifter handle and screw it down several turns and re-lock it. That will push-down the shifter lock so it no longer engages. Now you can shift it without pushing the button. The detents you now feel are from the transmission. Take it for a ride and gently keep your hand on the shifter...remember..it's NOT locked and will move with enough pressure so be careful. See if you van make it do the grinding sound. When it starts, if you feel the shifter move a little...any at all...that means it got kicked out of gear in the transmission and it's probably that bent fork...and now some rounded-off dogs on the gears. If no movement at all is felt, then I would look elsewhere for the problem. Like a bad pinion shaft bearing. I would also fix that loose carrier bearing on the front drive line. Making that tight again can't hurt.

NMKawierider So impressed how helpfull you are ! Thanks and thanks again.
The test you have sugested about leave the shifter free ,is very clever ! I go to try do that for sure ..i must run 100 or 200 km with my hands on the shifter lever .
Sametimes i try hardly to do that the noise appears ,and don´t happens !
The only doubt i have , and once the H is engaged with a spring that moves the fork , is if the fork moves , that move is transmited to the shift drum...(please see image attached)
Also i go to test to run without the front drive axle to see what happens.

[2015 Z Force 800 53/Trail EPS]

If it moves the drum...and it should, you should feel it in the shifter.

NMKawierider - This weeck end i have done what you had advised. I have diconected the detent shifter systeam and when the noise had appears again , any movement or vibration in the shifter lever. After several tests i have succed to replicate the noise , and it cames from the rear transmission box.
Maybe the ring and pignion inside have wear .
My Zforce 800 is a 2015 model and from what i saw in the web , it seams to have two diferents models from the rear tramsimission box -one only with 1 pignion and ring and other with 2 pignions inside . Once you are an expert,have you the rigth number part for this 2015 model or one link where i can see the componets inside with the numbers ?
Once more thanks a lot for the help.

[2015 Z Force 800 53/Trail EPS]

NMKawierider - This weeck end i have done what you had advised. I have diconected the detent shifter systeam and when the noise had appears again , any movement or vibration in the shifter lever. After several tests i have succed to replicate the noise , and it cames from the rear transmission box.
Maybe the ring and pignion inside have wear .
My Zforce 800 is a 2015 model and from what i saw in the web , it seams to have two diferents models from the rear tramsimission box -one only with 1 pignion and ring and other with 2 pignions inside . Once you are an expert,have you the rigth number part for this 2015 model or one link where i can see the componets inside with the numbers ?
Once more thanks a lot for the help.

Well, I do know that all the ZForce 800s, both the EX and the trail all use one rear gear case or Diff. They all have only one ring and pinion gear. On that note, Some, mine being one of them, have an issue that causes then to grind the aluminum case. This is thought to be a bearing race problem moving in the case...maybe a pinion bearing. If it is, and that bearing gets too loose, it will mis-match against the ring gear bad enough to grind. Mine is not that far along yet but it is leaving lots of aluminum "glitter" in the oil and I change it every 100 miles or so. The thought is I will probably have to replace the case anyway so I'll let it go until it has to be replaced. Is your oil full of aluminum "glitter"? 

Hello again ! I go to take that rear diferencial out and see waht is wrong . I suppose to be a mis-contact pinion and ring. After i will tell you