The factory center differential uses only 2 spider gears, making it one of the weakest links on the AWD transmission. The best way to eliminate  breakage is to upgrade it with a 4 spider center differential, effectively doubling the load bearing teeth and strength.

This upgrade requires the center differential housing to be machined out to make room for the additional spider gears and the 4 posts cross shaft. There are many ways to machine the housing, we use a CNC mill. This gives the best accuracy so that the spider gears are perfectly square to the side gears and the finish is better than from the factory. TRE machines the housing to leave as much material in the corners of the housing as possible in order to maintain strength. Oil passageways are enlarged to provide additional lubrication to the extra spider gears and the outer gear on the housing is shot peened to increase the strength and to improve oil retention which promotes longer life of the intermediate shaft primary reduction gear.

Our 4 spider center differential uses a case hardened 4 post cross shaft.  It's the cross shaft that we've been using for the past 9 years without any failures. Our cross shaft features 4 equal length posts that all make contact with the center differential housing. This doubles the loading surface and will eliminate the problem of the center diff housing getting all beat up and the spider gears to binding on the cross shaft. The cross shaft starts out as a forging that is machined, ground, heat treated and finally shot peened for superior strength. Simply the best. The spider gearset is also shot peened and afterwards to eliminate any chance of breakage or galling. 

Afterwards, the parts are assembled with all new shims, hardened & chromed spider gear washers and shimmed with a Torrington bearing. Simply the best 4 spider you can buy.


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