The 4x pro is the evolution of the famous innovative Project 4x series. More flexibility and improved performance on any surface.

New rear suspension.

Race proofed with multiple ETS A final results and Podium at the IFMAR World Championship

RRS rear end with new geometry

Fixed-toe rear with special geometry for stock racing with maximum rear stability and precision

New horizontal topdeck for more steering on high grip surfaces. Keyed topdeck for reduced risk of chassis tweak

Additional holes

in the chassis plate for more flex options

Separate roll

and heave motion in the car to make set-up easier and more precise
Small and light roll dampers front and rear that need only small amounts of oil, with through rod piston systems so no membrane is needed

Large heave damper

with more oil and bigger springs and easy-bleeding system for precise rebound setting. All dampers include machined pistons for best possible consistency

Good selection of heave and roll springs

  • Anti-roll bar function integrated in roll damper/springs
  • Easy and fast to change / replace the whole damper units (2 screws each)
  • Pivot ball suspension with small balls for simplicity and free movement
  • Easy diff and spool removal
  • Extremely low center of gravity
  • Reversed steering system for better Ackermann geometry
  • Motor holder with carefully designed, optimised flex options
  • Re-Active rear steering RRS system and fixed-toe rear are included
  • Molded pull rod activated system with rockers to activate the dampers
  • Same heave damper front and rear which is mounted below the diff/spool just above the chassis for lowest possible center of gravity
  • Durable and smooth gear differential
  • Battery mounting system allows reposition the battery more front or rear and is prepared for shorty lipos
  • One screw ride-height adjustment from chassis side
  • Lightweight front aluminium spool with hardened steel outdrives, bladeless
  • Carbon fibre chassis in 2mm as standard

DJC system

in the front made out of spring-steel prevent wheel chatter and rear regular CVDs made out of 7075 T6 aluminium save weight

One short and one longer

Kevlar reinforced drive belt and 38T pulleys on diff and front spool, 19T midshaft pulleys made out of hard anodized aluminium for maximum durability
Concept and design by Serpent Designer David Ehrbar from Germany

Roll damper

The roll damper unit consist of an oil body for dampening with a through shaft and has a small spring on each side. This unit controls the roll of the chassis; it works as an anti-roll bar. Different oils and springs can be used for setup work. The whole unit comes out after releasing just 2 screws. One can have complete roll damper assemblies ready to change settings in seconds.

Gear differential

The nicely shaped gear differential features molded internal gears which makes it super smooth. The compact and light unit holds a good amount of oil to deliver consistent performance throughout the run. It is fast and easy to take out and re-mount the differential.

Front spool

The coated aluminium front spool with lightened spring steel outdrives is a bladeless type which ensures superb handling and durability throughout the race. It is fast and easy to take out and re-mount the spool

Battery mounts

Battery mounts made in aluminium and carbon fibre allow positioning the battery more to the front or backing and securing it well in place. Shorty lipos can be placed centered, in front or rearward position.

Floating servo mount

The servo mount is a combination of a carbon brace and aluminium posts. The carbon brace is holds the left side of the servo while maintaining the lowest possible cg. It is bolted to the central brace and does not touch the chassis to prevent any flex influence.

Steering system

The ball raced aluminium steering system consists of an inversed lever system for maximum front grip. The angle difference between the inside and outside wheel is a lot more linear than in conventional designs.

Front Steering blocks / uprights

In the front the steeringblocks from the 4x evo are carried over. The pivot ball system allows for easy and quick set-up changes and works very smoothly. In the front there are 3 Ackermann positions and shimming below the steering rod can be used for fine tuning of the bump steer characteristics.

Rear uprights

The rear suspension geometry has been redesigned completely. By giving up the same parts front and rear concept, it was possible to use a dedicated rear suspension geometry which creates more rotation on asphalt without sacrificing stability.
For best versatility all parts for RRS and non RRS suspension are included in the kit, with the RRS version having a geometry with shorter arms for more optimised for asphalt and modified racing (more balance shift on thottle/braking transitions) and the fixed rear and having a geometry with longer arms, best suited for stock racing (maximum stability and precision).

Wishbones / pull rods / rockers

The lower arm mounts of 2 short pivot pins and the mounts allow to play with wheelbase by using clips. The lower arms also feature down stop screws.
The upper wishbones allow quick caster changes with clips and run on an easily removable long pivot pin.

Rocker and pull rods system

The pull rods connect to the upper arms and operate the ball raced aluminium rocker system which activates the dampening systems for heave and roll action. The pull rods have a fixed length for easy setup and 5 lengths are included: 19, 19.5, 20, 20,5 and 21. Each step is roughtly 1mm of ride height. The fine tuning is done on the excentric ride height adjuster.