GM TH400 transmissions set front endplay with selective thrust washers between the pump and forward drum. In heavy-duty and racing applications, a common durability upgrade is to replace the washer with a thrust bearing, but there has never been a proper-fitting bearing available for this location. Sonnax pump thrust bearing kit 34211-01K includes the ideal .126" thick thrust bearing and a selection of shims that allow setting endplay in .005" increments.

In most instances, pump machining is required. The bearing can be used without shims if measurements are taken and then just enough material is machined from the pump to allow the Sonnax bearing to fit and have endplay set. Alternatively, .062" can be pre-machined from the pump and the selective shims will allow an adjustment range equivalent to the six most common selective washers.

• Custom thrust bearing easily sets proper front endplay between pump and forward drum
• Optional shims refine endplay in .005" increments
• Thrust bearing improves transmission durability in performance vehicles