Author Topic: Rear Diff/Gear Case Question  (Read 857 times)

0 Members and 1 Guest are viewing this topic.

Offline NMKawierider

  • Global Moderator
  • Guru
  • *****
  • Posts: 5437
  • 2015 ZForce 800 EPS
    • View Profile
    • Visit my YouTube Channel
  • Location: Albuquerque, NM
Rear Diff/Gear Case Question
« on: May 31, 2018, 08:06:58 PM »
Ok, my turn to ask a question. I know there have been a few of you that have had your rear diffs out and apart that may know the answer.
In the last 1200 miles I have changed my diff oil at least 4 times. Today I just did it again...any way every time there is always a small bit of metal particles on the plug's magnet..say maybe enough to cover your thumb nail..I get that. What I don't get is..the extreme (IMO) amount of aluminum particles suspended in the oil...every time...I mean I take the drain pan out in the sun and it looks like automotive metallic paint. Run a magnet through it and nothing..so it must be aluminum. So...
My question is, besides the case itself, what else in there is aluminum that can be the source for this? And if nothing, what can be grinding my case like this..a bad bearing?.. Incorrect shimming or thrusts? There is a lot of play or backlash between the ring and pinion..always has been. And always been a bit noisy. I don't see any odd movement in either axle or the pinion that would indicate a loose bearing..yet anyway. 
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | Magellan TRX7 GPS| Bandit Springs

My Videos On YouTube

Offline ctdls

  • Guru
  • *****
  • Posts: 372
    • View Profile
  • Location: Sicamous, BC
Re: Rear Diff/Gear Case Question
« Reply #1 on: May 31, 2018, 10:35:06 PM »
That oil should be clean coming out of the diff.

I've no experience with rear diff failure's or anything other than normal maintenace. If I were to see anything other than clean oil I would be concerned.

Where is that Wheels dude? He should chime in here.
ZF 800 LX Trail, stock for now.......not for long.

Offline Etchluke90

  • Senior Member
  • ****
  • Posts: 138
    • View Profile
  • Location: 62216
Re: Rear Diff/Gear Case Question
« Reply #2 on: May 31, 2018, 10:35:39 PM »
I can speak for the front and every peice in it except the ring and pinion is powdered metal so super soft metal I still have the old spider gears and carrier on my work bench and u could take a screw driver to then and take serious material away. Just poor choice of parts. I have noticed on my rear diff there is a bolt and locking nut that looks like it could possibly adjust the back lash on the ring gear can't say for sure but I can't think of what else it would be it's location is on the driver side about mid way into the middle of the diff.
Don't hesitate, accelerate
"That's what it's made for"

Offline NMKawierider

  • Global Moderator
  • Guru
  • *****
  • Posts: 5437
  • 2015 ZForce 800 EPS
    • View Profile
    • Visit my YouTube Channel
  • Location: Albuquerque, NM
Re: Rear Diff/Gear Case Question
« Reply #3 on: June 01, 2018, 08:42:38 AM »
I believe from the post of another member that adjustment is for a flex limiter. Apparently under high load situations the ring gear can be flexed or forced away from the pinion enough to be a problem. CFM's solution was to position something directly across from the pinion contact area that ring gear can come in contact with if flexed too far. I think I remember reading it was to be set at like .05. A testament to their quality of parts/materials... I can't think of any other manufacturer that uses..or needs something like this. 

Well, whatever it is, it can't keep grinding-off metal without causing an issue...someday. I guess I'll just wait and see.
If it works this time, here a vid/sound clips of the sounds it makes cold and hot. If all this is actually fron the rear diff..I think there is an issue but it's always done it.
Not a valid vimeo URL
« Last Edit: June 01, 2018, 10:29:12 AM by NMKawierider »
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | Magellan TRX7 GPS| Bandit Springs

My Videos On YouTube

Offline Willness33

  • Junior Member
  • **
  • Posts: 9
    • View Profile
  • Location: NC
Re: Rear Diff/Gear Case Question
« Reply #4 on: June 01, 2018, 10:24:46 AM »
I can speak for the front and every peice in it except the ring and pinion is powdered metal so super soft metal I still have the old spider gears and carrier on my work bench and u could take a screw driver to then and take serious material away. Just poor choice of parts. I have noticed on my rear diff there is a bolt and locking nut that looks like it could possibly adjust the back lash on the ring gear can't say for sure but I can't think of what else it would be it's location is on the driver side about mid way into the middle of the diff.
Non-hardened steel spiders??? Wow. I can't see how that would hold up.

I have no experience with the different on these but a fairly extensive jeep and crawling background. The fluid should be clean or at least not glittery. The only metal will be the fine steel slime on the plugs magnet. Some gear sets can whine louder than others even when set properly but not howl.

Offline glenlivet

  • Guru
  • *****
  • Posts: 363
    • View Profile
  • Location: Hope British Columbia
Re: Rear Diff/Gear Case Question
« Reply #5 on: June 01, 2018, 10:27:49 AM »
Hmm... Mine doesn't have that particular sound, best I can tell.
For a nation to believe it can tax itself into prosperity is like a man standing in a bucket and believing he can raise himself by pulling on the handle - Winston Churchill

Offline ctdls

  • Guru
  • *****
  • Posts: 372
    • View Profile
  • Location: Sicamous, BC
Re: Rear Diff/Gear Case Question
« Reply #6 on: June 01, 2018, 11:55:12 AM »
Are you able to confirm the noise is generated from the rear? I remember talking with the Eastern Canada service rep about a noisy gear set on the output of the transmision. They checked the gear pattern, re shimed it, the noise stayed so the gear set was replaced.

I just had a guy with tracks exploded that gear set in the transmission.......broke the crankcases  :( I check the pattern after replacing everything & it was good......no noise.

ZF 800 LX Trail, stock for now.......not for long.

Offline NMKawierider

  • Global Moderator
  • Guru
  • *****
  • Posts: 5437
  • 2015 ZForce 800 EPS
    • View Profile
    • Visit my YouTube Channel
  • Location: Albuquerque, NM
Re: Rear Diff/Gear Case Question
« Reply #7 on: June 01, 2018, 12:12:20 PM »
Are you able to confirm the noise is generated from the rear? I remember talking with the Eastern Canada service rep about a noisy gear set on the output of the transmision. They checked the gear pattern, re shimed it, the noise stayed so the gear set was replaced.

I just had a guy with tracks exploded that gear set in the transmission.......broke the crankcases  :( I check the pattern after replacing everything & it was good......no noise.


No..that's my problem..I can't confirm weather its' the rear diff or in the transmission. Either can make that noise as I understand it but the sound really doesn't change in high or low range so..to me my brain thinks it's something that the ratios or RPMs don't change...like the diff. I need to do more testing and let you know.
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | Magellan TRX7 GPS| Bandit Springs

My Videos On YouTube

Offline Etchluke90

  • Senior Member
  • ****
  • Posts: 138
    • View Profile
  • Location: 62216
Re: Rear Diff/Gear Case Question
« Reply #8 on: June 02, 2018, 02:54:41 PM »

Video I made showing the metal in the front diffs
Don't hesitate, accelerate
"That's what it's made for"

Offline NMKawierider

  • Global Moderator
  • Guru
  • *****
  • Posts: 5437
  • 2015 ZForce 800 EPS
    • View Profile
    • Visit my YouTube Channel
  • Location: Albuquerque, NM
Re: Rear Diff/Gear Case Question
« Reply #9 on: June 02, 2018, 03:39:00 PM »
Hmm..so..will a magnet collect the fragments from this..powdered metal?
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | Magellan TRX7 GPS| Bandit Springs

My Videos On YouTube

Offline REDRIDER

  • Guru
  • *****
  • Posts: 850
    • View Profile
  • Location: Putnam CT
Re: Rear Diff/Gear Case Question
« Reply #10 on: June 02, 2018, 09:39:57 PM »
I would think so,  its still steel.  That is some really soft metal they used for the spider gear....

Offline ctdls

  • Guru
  • *****
  • Posts: 372
    • View Profile
  • Location: Sicamous, BC
Re: Rear Diff/Gear Case Question
« Reply #11 on: June 03, 2018, 07:31:08 AM »

Video I made showing the metal in the front diffs

Tx's for that, must be reason why.......
ZF 800 LX Trail, stock for now.......not for long.

Offline doug80638

  • Senior Member
  • ****
  • Posts: 211
    • View Profile
  • Location: Pelham, NH
Re: Rear Diff/Gear Case Question
« Reply #12 on: June 03, 2018, 08:21:23 AM »

You can get spider gears for automotive applications for various manufacturing methods as well. Powdered metal can offer some advantages in some applications, particularly where tight tolerances are involved, but mostly, it's a cost advantage. Spiders don't suffer the same wear impact as pinions and ring gears.

When properly fitted and lubricated, powdered metal gears should perform just fine. Having said that, I always pay the extra money for the ground/hardened types when that option is available.

If there are filings in the oil, then something is out of tolerance and parts are wearing as a result.
2017 Zforce 800 - Red
SuperATV Flip windshield
Tusk soft rear window
Twin-Air foam air filter

Offline tripplec

  • Junior Member
  • **
  • Posts: 8
    • View Profile
  • Location: Belleville, ON, Canada
Re: Rear Diff/Gear Case Question
« Reply #13 on: November 13, 2018, 12:22:02 PM »
Ouch, this certain doesn't sound good have such weak metal. no wonder the setup using Track blew it apart. A lot more load moving track than wheels for sure.

Normally the diff gear oil doesn't need to be changed for a very long time (high miles). As its steadily eroding the soft aluminum it going to fail at some point (stranding you). Better quality materials need to be used in the PowerTrain. knowone wants to break down because of poor weak parts.

I was going to look a one this weekend to see what I though but I can see the innards of the assemblies. Makes you wonder what the engine and front diff is like as well inside.

I think I am going to give these a pass and focus on other makes/models.

Offline davidpaul

  • Guru
  • *****
  • Posts: 350
    • View Profile
  • Location: UK
Re: Rear Diff/Gear Case Question
« Reply #14 on: November 13, 2018, 04:10:54 PM »
Thought I would throw in my thoughts, my rear diff was noisy from the start I had two attempts at shimming it better, the first time I had been concerned about the back lash so didn't really get the contact patch as I would have liked,  on the second attempt I concentrated on the contact patch which with the limited shims I had left me with more back lash which hasn't been a problem.

On mine the gears were bashing into each other rather than gliding together, I wonder if this is were your getting the fine powder on your drain plug
2015 Zforce 800, Dr Pulley weights and sliders, Dobeck EJK, Innovate Motorsports AFR gauge,
Custom exhaust outlet, Ramair foam air filter, Led light bars, Modified air intake, CRD a-arm guards