Last sunday, I raced my (quite heavily! 😀) modified HNR H9804 FoxHound at the Czech National RC Rally Championship event, RC Rally Zálesí in Humpolec. The car handled beautifully, allowing me to take 7th place overall in a highly competitive field.

To share some insight, here is the breakdown of the EmbieRacing (ER) and other custom modifications that made this result possible:

Chassis & Layout

• Lower Chassis:
  • ER PROTOTYPE glass-fibre shortened chassis. This allowed me to straighten the rear driveshafts compared to the original setup, which is too long and features forward-facing rear suspension arms.
• Central Driveshaft:
  • ER PROTOTYPE glass-fibre shortened rear central driveshaft. Originally just a test piece, its performance has been excellent, resulting in significantly less wear on the outdrives.
• Chassis Brace:
  • ER PROTOTYPE 3D-printed rear chassis brace.

Suspension Modification

• Front:
  • Front suspension arms from the ER HNR KIT – UPGRADE SUSPENSION ARMS SET.
• Rear:
  • ER PROTOTYPE 3D-printed rear suspension arms designed to fit the shortened chassis. The dampers are now front-mounted. Fitting them this way was quite a challenge due to limited space—requiring modifications to the original cover and battery holder—but the handling improvement is definitely worth it.
• Anti-Roll Bar:
  • ER PROTOTYPE 3D-printed anti-roll bar holder.

Steering & Drivetrain

• Steering Hardware:
  • ER HNR KIT – STEERING HARDWARE (part of the ER HNR KIT – FULL) with a 16 mm wide steering arm, paired with a 3 mm spacer at the steering knuckles to reduce bump steer.
• Top Deck:
  • Stiffening Top Deck (included in the steering hardware set).
• Driveshafts:
  • YeahRacing (XR-T4-027) driveshafts paired with Xray 3.5 mm plastic drive shaft caps (XR-305241). Using plastic caps drastically reduces outdrive wear.
    • Tip: While you can use 3.0 mm caps, I used what I had at home. This required widening the outdrive slots to 3.5 mm, but the 3.5 mm caps have better availability and last longer.

Dampers & Shocks

• Shock Towers:
  • ER HNR KIT – ADJUSTABLE SHOCK TOWERS.
• Dampers:
  • Xtra Speed Aluminum Big Bore Damper Combo Set (XS-TA29208GD), using 75 mm at the front and 90 mm at the rear.
• Top Damper Joints:
  • Modified using this Printables 3D model ( https://www.printables.com/model/1647996-rc-car-shock-damper-top-joint). Crucial step: Double-check that everything moves smoothly here.
• Inner Shock Spacers: Custom 3D-printed spacers.
  • The original spacer is about 2.4 mm high, which over-compresses the sealing X-rings and causes the piston to bind. I replaced them with 3D-printed versions (marked in red in the picture) lowered to 1.4 mm, making the dampers very smooth.

• Springs:
  • Blue springs on both axles from the Tamiya Big Bore Damper Spring Set (Aeration Type):
    • Front set (4WD): 54506
    • Rear set: 54508
• Oil: 200 cSt front / 350 cSt rear.

Pictures will be added later!

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