Hot Racing Steel Helical Diff Ring/Pinion Overdrive (12/33T) TRX4 [TRXF9312]

Steel Helical Diff Ring/Pinion Overdrive (12/33T) TRX4


Hot Racing 



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Hot Racing steel helical spiral overdrive 33T/12T gear set for 1/10 Traxxas TRX-4


  • Precision machined helical spiral cut gears offer inherently greater strength and smooth operation than the factory Straight cut bevel gears
  • High carbon steel construction
  • Less vibration, less noise, less wear then stock straight cut bevel gears
  • 33T/12T provides 9% overdrive (vs stock 34T/11T) increases the wheel speed and is commonly used in the front end for digs
  • Works on front or rear. Use cases are typically front and rear at the same time, or front only to increase front digs

In the Package:

  • One (1) 33 tooth spiral cut ring gear
  • One (1) 12 tooth spiral cut pinion gear


  • Installation following kit manual
  • Medium threadlock (e.g. blue Loctite) if screws are threaded into metal
  • Hot Racing SPL10G05 high temp grease recommended


  • Replaces Traxxas 8287
  • Option - overdrive the front axle, and underdrive the rear axle
  • Combinations One. TRXF9312 in the front and TRXF9411 in the rear
  • Combinstion Two. TRXF9411 in the front and TRXF9510 in the rear
  • Combinstion Three TRXF9312 in the front and TRXF9510 in the rear
  • Straight Bevel Gear
  • Spiral Bevel Gear
  • Teeth of this type of gear are straight and are cut along the axis on a cone
  • Here the teeth are spiral and are cut in the form of spiral curve on the pitch cone
  • Two teeth of the mating gears comes in sudden contact. The contact is always a line of length equals to face width of teeth
  • Teeth of two mating gears gradually comes in contact. Engagement starts with a point and gradually becomes a line
  • Due to sudden contact, teeth are also subjected to impact or shock loading
  • Here teeth are subjected to gradual loading
  • Sudden contact also causes noise
  • Its operation is quite
  • Shock loading induces vibration and thus its operation is not smooth
  • Due to gradual building up of load, it produces less vibration and thus the operation is smooth
  • Designing and manufacturing of straight teeth bevel gear are easier and thus these are cheaper
  • Complicated design and manufacturing leads to higher cost for this type of gear
  • It exerts less thrust force on the bearings that hold the shafts
  • It exerts more thrust force on bearings

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