Dana 300 Input Shaft and Bearing Retainer Damage

[dwjeep]

Does anyone know what would cause the input shaft retainer to break like this? The entire shoulder that the snap ring goes in broke off. The transfer case was rebuilt about 5,000 miles ago. I don't want to rebuild it just to have the same happen again. Thank you. 

[Moses Ludel]

dwjeep...It's clear that the bearing retainer snap ring broke loose from the retainer.  What year is your CJ and which transmission are you running with this Dana 300?  Was the snap ring loose (floating around) when you removed the transfer case?  Was the seal pushed out the front of the retainer?

I would be looking for internal components in the transfer case that are pushing the input shaft and bearing forward toward the bearing retainer.  This could be as simple as the wrong shimming of the input shaft.  Or the front bearing may not be seated fully on the input shaft.

If the input shaft sets too far forward, bolting and torquing the input and output retainers into place would load the front bearing toward the retainer and snap ring.  There should be a slight endplay in the input/output shafts if shimmed properly.  This is checked with a dial indicator when the transfer case is fully assembled and both sets of retainer bolts are torqued to specification. 

Caution:  Never force the bearing retainers into place;  if too tight, the input or output shim stacks could be the wrong stack thickness.  Eliminating a retainer gasket (i.e., substituting RTV sealant) will also affect the stack height.  When a bearing retainer calls for a gasket, install the correct gasket. Torque up the bearing retainers slowly and gradually, making sure the input and output shafts rotate freely as you tighten the bolts.  Below is a parts schematic.  Note the shim stacks #16 and #34.  These must be adjusted properly to get the right (slight) shaft endplay.

When there is too much (too thick) shimming or misaligned parts, the front bearing and input shaft could be pushing forward with enough pressure to break the snap ring lip on the retainer.  Verify shaft shim thickness/endplay, whether a gasket is needed at either retainer and whether bearings are seated on shafts.  Note whether there was originally a gasket at either retainer, which would be a part of the endplay measurement.

Check the front bearing and input shaft endplay with the retainer in place.  If there isn't any end play, or worse yet, the front bearing clearly sticks too far forward, the shims/stack height are out of adjustment.  Shims are at #16 and #34.

Moses