DRT Primary Driven Gear/Pinion: fine ratio tuning via the crankshaft gear - fast, effective and ideal for straight-toothed primary ratios.

Replacing the Primary Driven Gear on the Crankshaft is a simple and effective way of changing the transmission ratio. The prerequisite is a straight-toothed primary gear ratio. Thanks to the fine gradation of the small Primary Driven Gears, the transmission ratio can be precisely matched to the respective tuning level.

DRT Gear Cogs are high-quality processed, tempered and made of special steel. They are CNC-milled and some have recesses to reduce weight.

• Fine-tune the transmission ratio by replacing the crankshaft sprocket
• CNC-milled, hardened and tempered, made from special steel
• Intermediate sizes for precise gradation per setup
• Partially with weight reduction through cut-outs

The 24/72 (3.00) covers a range from 75-102 cc. DRT Gear Cogs with Z 21, 22, 23 are welcome intermediate sizes here and also harmonize very well with 75-85 cc Cylinders. For the 27/69 (2.55) there are special Drive Sprockets for the SURFLEX primary. The Z 24/25/26/28 are often used in round and sprint races, where they are combined with DRT Input Shafts such as MATRIX/SINCRO and their gear recommendations. The Z 26 also works very well with ROAD-tuned 125-130 cc setups. The 27/69 with its variations is the most commonly used primary gear ratio in 130-155 cc tuning.

The 29/68, which is normally only suitable for high-end Engines, can also be used for weaker engines with Z 26/27/68 Drive Sprockets - allowing this long ratio to be gradually opened up. High-speed fans can even extend to 2.27 with Z 30. Ratio recommendations for different Cylinders are compiled under Downloads. The TOB line also includes ready-made DRT Primary Driven Gears and Gearboxes especially for the M-200 cc QUATTRINI Smallframe Cylinders.

Conclusion: Once a primary gear ratio has been installed, it can be fine-tuned quickly and easily using DRT Gear Cogs.