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Rear diff cracked twice.

Anyone heard of this?
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Left rear diff case cracked twice?
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Offline Cfmofo

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Re: Rear diff cracked twice
« on: September 10, 2018, 11:16:07 PM »
I accidentally deleted the last post. My rear diff case has cracked twice both on the left side. It happens after going over small bumps across the trail maybe 10 inches high, the rear hits from going over this and BANG. loud bang noise and the case cracked. The original case from the factory and now the replacement has done the same. My coworker thinks when the suspension sags and the cv axle straightens out it hits the case and cracks it like maybe it's mismanufactured or something. I just felt it sitting in the garage and the the right side axle has play, and the left is solid. I'm very frustrated I have had this machine one month to the day and am now gonna have to have a 3rd diff and whatever else replaced already. Any ideas?

Offline REDRIDER

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Re: Rear diff cracked twice
« Reply #1 on: September 11, 2018, 07:08:55 AM »
Do you have it lifted?  Is this a Z1000? I haven't seen of many reports of diff's cracking in other models. When you say small bumps and reference 10 inches, a 10 inch bump is not small. Are you bottoming out on the frame? If so you would have to hit very hard to break the diff and I would recommend at least getting skid plates. If you are lifted it could contribute but if not then you shouldn't break the diff when the suspension gets unloaded.

Offline Cfmofo

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Re: Rear diff cracked twice
« Reply #2 on: September 11, 2018, 02:28:57 PM »
yes it's  a zforce 1000 Not lifted, and I don't mean like a 10 inch log, I mean like a 10 inch ramp back down to flat. Thats as big as it gets. I'm baffled and so is the dealer. The machine should easily be able to handle twice that amount with no issue. The other machines I go with all do the same thing with no issues. It's not a straight incline, I should have worded that better. It's like a 10 inch ramp to a flat landing. Nothing crazy at all. Very mild. It's got me going crazy, I just want to enjoy the machine and do some light trail riding. But at this point I do not trust this machine even 1 percent. Although everything but the rear diff has been solid other than missing or stripped bolts all over the machine. Does anyone have any idea what I can check myself before I take it to the dealer saturday.?

Offline REDRIDER

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Re: Rear diff cracked twice
« Reply #3 on: September 11, 2018, 03:00:11 PM »
That is for sure strange. not really sure what to tell you. As long as nothing is hitting the diff there should be no reason for it. possibly a bad batch of castings or something.

Offline Cfmofo

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Re: Rear diff cracked twice
« Reply #4 on: September 11, 2018, 03:10:19 PM »
I know, it's totally strange.  I sure hope theu figure it out, the best riding season is fall here in washingron where I live and sure would like to have a reliable machine very soon. Something must be shimmed wrong and the rear diff is offset possibly closer to the left side. Idk, but I sure am frustrated.

Offline doug80638

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Re: Rear diff cracked twice
« Reply #5 on: September 11, 2018, 06:51:01 PM »

Checking the parts list shows that it's the same CV axle for both sides. With that in mind, I would measure the distance from the rear axle housing to the wheel knuckle on both sides and make sure they are the same distance apart.

If they are, then I have no clue. If they are not, then I would check to see if the rear axle housing is mounted dead center, and the the knuckles are equal distance from dead center (suspension arms should be the same length).

You could remove the shocks and actuate the suspension to see if there is any binding or contact resistance.

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Offline Cfmofo

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Re: Rear diff cracked twice
« Reply #6 on: September 28, 2018, 12:42:24 AM »
Well, they couldn't figure it out so they are just giving me a new machine!I'm glad theu stepped up!