Case 921C front differential inoperative .

[Cotterpin]

Here's a dandy problem ! Have a ZF differential causing me to have a fit . Any ideas appreciated . 921C Case loader ser. no. 125027. Operator was loading out of sandpile ,when he hears and feels a pop . Loader will no longer power front wheels .... driveshafts all intact . Can see ring and pinion are turning thru oil fill hole . Drained differential oil and did not find any metal frags . Drained transmission and found no metal frags . Removed differential and dissasembled . found no broken parts or debris . Reassembled and still no movement when turning pinion shaft yoke . Dissasembled a second time , checked planetarys and all axle shafts & splines , spiders and clutch plates . Reassembled and still able to hold wheel hubs stationary while turning pinion yoke .......

Took differential and delivered to local Case dealer They susequently found some brake discs broken and replaced those along with the clutch packs in the carrier spider assys .Upon recieving differential from dealer , I installed in machine and took to rock yard to try out . Machine still will not power front wheels . Brought machine into shop and disconnected front driveshaft . With front wheels on ground , I can turn front driveshaft with little resistance . Common sense tells me I should not be able to turn the front driveshaft at all . Jacked machine completely off ground . In forward rear wheels & front driveshaft turn , but front wheels do not ....

Sorry for lengthy story , but am open to any and all suggestions . Differential is ZF MT 3105/LK 528
stucklisten nbr 4474 054 011 23.34 sp diff
MIL-L 21050
LS/sae 90
Kunden nbr 2984 45A1

Thanks , Terry (shop mechanic)
.

 

[Jim D]

Did you check the internal splines that the axle shafts fit into?

 

[lantraxco]

Not to use to worn a phrase, but this ain't rocket science, somewhere there's a broken part.

Pop the covers off the planets and visually confirm that the axle shafts are not turning at the outboard end. If that's true pull the shafts, pull the differential again, with the diff on the floor or sturdy work surface stuff the axle shafts in and turn the yoke. Couple pipe wrenches on the axle shafts if you need to, to give some resistance. If the ring gear and housing are turning and the axle shafts are not, take it back to the dealer.

The thing that's a clue, if the dealer put all the limited slip stuff together right, even if one side had a broken axle or spline or gear, you should get some drive on the other side. Pretty much gotte be internal in the diff.

 

[Delmer]

Maybe rent a scope to look at it while it's assembled? Ring gear slipping on the differential carrier with the rivets (?) still in their holes? Both sides of the rivets are supposed to line up right? I just can't think of anything else that would break without leaving evidence.

 

[Cotterpin]

Thanks you'all for replies and good tips . Yes Jim D , checked that all at first disassembly . Delmer , I checked torque on ring gear mounting bolts at first disassembly . Dealer insisted that we bring machine in to their shop so they can try it out whenever they think they have found and fixed the problem . lantraxco's suggestion is one I didn't try , though I did block the wheel hubs and was able to turn pinion with little effort . I totally agree it's not rocket science , good phrase I use a lot too ! I will post at later date what dealer remedy was . It left headed there on a lowboy today .

Cotterpin

 

[Cotterpin]

Well , can finally put this thread to rest . Dealer was finally able to figure out that the gear in the wheel hub ( one that 4 planetary gears drive ) had come loose from the hub . Factory said it was a 100 ton press fit and was rare for one to turn in the housing . This ZF model is one that the brake/planetary assy bolts onto the end of the axle hsg . Dealer service was able to verify failure with use of a bore-scope , although I don't know where they went in with that . Thanks for helpful tips and I'll write this one down in my book of weird equipment failures !

 

[lantraxco]

Wow....

:Banghead