  We show that sums of the SL(3,Z) long element Kloosterman sum against a
smooth weight function have cancellation due to the variation in argument of
the Kloosterman sums, when each modulus is at least the square root of the
other. Our main tool is Li's generalization of the Kuznetsov formula on
SL(3,R), which has to date been prohibitively difficult to apply. We first
obtain analytic expressions for the weight functions on the Kloosterman sum
side by converting them to Mellin-Barnes integral form. This allows us to relax
the conditions on the test function and to produce a partial inversion formula
suitable for studying sums of the long-element SL(3,Z) Kloosterman sums.
