A pump that has been resurfaced or accumulated shaft spline wear creates excessive endplay of the forward and direct drums. This reduces sealing ring, clutch, bearing, and thrust washer life. Having the ability to shim both the lower unit sun gear with Sonnax shim 34500-Z on '96 and earlier TH400, 4L80-E and 4L85-E transmissions and washer 34301-078 or 34301-094 on all units addresses these problems.

• Washer 34301-078 (.015" oversized) and 34301-094 (.030" oversized) take up the play between the forward clutch hub and the direct clutch housing, allowing front unit endplay to be reduced.
• Washers also stabilize the direct drum, reducing delayed reverse and improving 2-3 clutch circuit.
• Allows salvage of valuable hard parts.