Straight cut drop gears are the most durable arrangement that can be fitted to a transverse A-series powerunit. These 3 gears are responsible for transferring all the Hp from the motor to the gearbox, so their longevity should be a top priority for any serious engine builder. In addition to the durability of a straight cut arrangment you get the added benefit of less Hp loss due to reduced side loadings in this critical area, which in turn minimizes the wear on the idler thrust washers. The Trannex gear sets are all built around a 30 tooth idler, which means that to change ratios, only the input gear and/or primary need to be changed to accommodate a wide variety of ratios. Idler gear is also available with a Timken bearing, order part number C-STR30/TIMKEN.
The best straight cut drop gears are those with "Timkin" roller bearings on the idler gear. You can now upgrade from the stock S/C drop gears to "Timkin" by simply replacing the idler gear. This gear fits into the gearbox and flywheel housing without the standard bearing. This does NOT fit the latest A+ type with larger idler bearings.