Possible Rear Diff Issue

[Chiz]

Hello All,

I have a problem with my rear wheels not turning. Both the grub screws are in place and not sheared off. The dog bone turns like crazy so I assumed something inside the diff was tore up but I tore the diff apart and all is good inside it. Is this where the diff shimming comes into play? Any ideas would be greatly appreciated.

Thanks

 

[Mickey]

check the diff bearings for slop or play . if they are bad they will mess up the mesh between the bevel gears

 

[whipnet]

Sounds like you already checked the obvious, so dig into the diffs. If you have a X or XL, it's super easy to get to them.

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[AllanQ]

Just so I understand this, the dogbones are turning but the wheels are not? If this is the case, and you checked the inside of the diffs, check the pinion in back of the bulkhead, and also check to make sure the pins are installed in the wheel axels that the wheel hex goes.

 

[frddyj]

in case you need to shim your diff, here is a pic that may be helpful. This is a cen diff in an X ss bulkhead, but you get the basic idea. Shims used are HPI Part # 86598
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[/IMG]

 

[Pineapple]

I have seen broken grub screws where the head of it remains and just a bit is left to turn the dogbone when not under load. Pull grub all the way out to see if it's intact first.

 

[whipnet]

in case you need to shim your diff, here is a pic that may be helpful. This is a cen diff in an X ss bulkhead, but you get the basic idea. Shims used are HPI Part # 86598

Is that the correct part number for the shims frddy? I ask because I am getting ready to shim my CEN's and was given # Z892

There is a difference in size I think.

Thanks and sorry to hijack thread.

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[frddyj]

Is that the correct part number for the shims frddy? I ask because I am getting ready to shim my CEN's and was given # Z892

There is a difference in size I think.

Thanks and sorry to hijack thread.

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Yep, your right whips they are different size:
Z892 = 10x12x0.2mm
86598 = 13x16x0.2mm

I used Z892 to shim the pinion only. i tried a Z892 where i used the 86598 in the pic, but i didnt like how it contacted the rubber shield on the bearing which I'm thinking would eventually wear out the shield. The Hellfire shims lined up better & only contacted the outer metal race and was a good fit. also shimmed my X diffs & Hellfire diffs like this & they're smooth... rockout

 

[whipnet]

I used Z892 to shim the pinion only. i tried a Z892 where i did in the pic, but it contacted the rubber shield on the bearing only which i think would wear out the sheild. Used the Hellfire shims like in the pic & they contact the outer metal race only which is how i think you want it. also shimmed my X diffs & Hellfire diffs like this & they're smooth...

Thanks for the info frddy!!

[/hijack]

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[Chiz]

Alright Guys, thanks for all the replies. I'm fixin to dig into it again, but a quick check proves that one of my wheel hexes was completely rounded out, and the other really wasn't that bad, so I'm still confused as to why at least one wasn't turning.

I had already verified the grub screws were intact and not sheared off, and I didn't see any damage inside the diff. But I'll take it apart again and have another looksy.

What is the purpose of shimming the diffs? Could my diff, not being shimmed, result in the problem I am having?

Thanks guys.