At this stage we have all seen the in depth video presentation from Xray on the design and production of their new for 2021 XB4 4wd buggy. Now that we know what went into making the car, we finally get to see the final results of all that work. The XB4 is an evolution of their World Championship winning buggy platform and for the first time the car will be available in either carpet or dirt editions. The main focus seems to have been around the front and rear horizontal split design bulkheads, which allow for the adjustment of the differential height in the car. The ability to make this adjustment, necessary for the switch between dirt and carpet, has meant changes needed to be able to be made to the central drivetrain angle and height. Longer front and rear central drive shafts and shortened pinion gears offer up improved drivetrain efficiency and both shafts are connected by an all-new multi-adjustable slipper clutch with independently adjustable front/rear slippage. new shock bodies, shock towers, a tweak free quick battery holder and body shells complete the main areas of focus.
2021 All-new Features:
– Next generation of the multi-time World Champion XB4 platform
– Available in Carpet and Dirt Editions ready for high or low track conditions
– All-new front & rear bulkheads with Horizontal Split Design (HS)
– All-new front and rear diff height adjustment
– All-new central drivetrain angle and height adjustment
– Longer front and rear central drive shafts and shortened pinion gears for improved drivetrain efficiency
– All-new Multi-Adjustable Slipper Clutch with independently adjustable front/rear slippage
– New 2mm chassis redesigned to accommodate all the new components
– All-new front & rear suspension holders with extra wide range of set-up adjustments
– Revised front & rear shock towers with closer shock positions for finer adjustment
– Updated front shock absorber bodies and shafts shortened by 2mm for increased stability and corner speed
– All-new tweak-free Quick Battery Holder featuring smart height adjustment
– New rear body mount with a more frontward position to accommodate the new bodies
– All-new servo saver stands to accommodate the new front Horizontal Split Bulkhead (HS)
– Two new Gamma body styles designed to enhance the handling characteristics of the Carpet and Dirt Edition kits
The chassis is updated to accommodate all the new features including the new front and rear bulkheads, the new suspension holders and the tweak-free Quick Battery Holders. The chassis is an important component that contributes to the XB4’s handling characteristics. The chassis dimensions and flex characteristics are selected for the best blend of stability, traction and steering. The chassis is machined for extra clearance under the bulkheads to accommodate the new diff height adjustment feature. CNC-machined from high-quality Swiss 2mm 7075 T6 aluminium, the chassis is strategically machined in low-stress areas to make it as light as possible without affecting strength or rigidity; and it is additionally black-coated for increased lifespan.
All-new front & rear bulkheads feature a horizontal split design (HS) to retain easy diff access while adding the valuable new diff height adjustment. The unique design of the bulkheads uses an inline bushing to alter the alignment and height of the bevel drive gear. In addition to accommodating the new diff height adjustments, it also allows the front central driveshaft to operate with a reduced angle for less friction and wear on the CV joint components and improved driveline efficiency. The XB4 bulkheads allow fast and easy differential access for setup changes or servicing by removing only 4 screws from the upper gear box cover while the lower section remains mounted to the chassis. This super-fast diff access is featured on both front and rear gearboxes. The super-strong, narrow bulkheads provide the needed clearance for the redesigned suspension holders with increased set-up range possibilities.
Diff Height Adjustment
All-new front & rear HS bulkheads allow for a new diff height adjustment using eccentric bushings. In the front gearbox, the diff height has 3 different settings. The rear differential can be adjusted through a 5mm range. The diff height adjustment is a vital set-up capability that allows quick set-up adaption for either Carpet or Dirt tracks. Carpet edition uses a lower ride height and the upper differential position to keep the drive shafts level. Dirt edition typically uses a taller ride height and a lower differential position to keep the drive shafts level.
Central Drive Train
The new design of the HS bulkhead with the inline bushing for the bevel drive gear creates a more linear orientation for the front centre drive shaft to reduce the CV joint angle for increased driveline efficiency and decreased friction and wear. The height and angle of the rear centre drive shaft is also adjustable depending on the height adjustment of the differential. Front – there are 3 different angle configurations for adjustment of the front drive train. Rear – there are 6 different height configurations for adjustment of the rear drive train.
The new pinion gear is shorter to allow the drive shafts to move the CV joint closer to the differential to improve drive train efficiency. Both crown gear and pinion gear are CNC-machined from HUDY Spring Steel and are ultra-hardened making them very strong and reliable with a longer life span. The split crown gear allows for a simpler exchange to optional gears without requiring a rebuild of the internal diff assembly and results in significantly lower rotating mass and improves the serviceability. To improve the gear engagement both crown gear and pinion gear have more teeth and geometry that results in smoother engagement and increased efficiency.
All-new longer front and rear central driveshafts integrate with the new gearbox dimensions and move the CV joint closer to the differential to improve drive train efficiency. XB4 constant velocity drive shafts are manufactured from world-renowned HUDY Spring Steel™ and feature 2.5mm drive pins for maximum drivetrain efficiency. The drive shafts are some of the world‘s thinnest yet most durable drive shafts used in electric off-road cars. Hardened with a proprietary hardening process, the drive shafts provide unbeatable lifespan and reliability.
The unique Multi-Adjustable Slipper Clutch – MSC, with independently adjustable front and/or rear slippage via different slipper pads and clutch plates of different diameter, ensures more efficient and more consistent clutch operation to generate faster acceleration and less wheel spin. For improved performance there are two different pad materials; yellow SLS pads with higher slippage and black medium hardness with less slippage. The slippage ratio between front and rear tires can be adjusted independently depending on the type of track, tires and racing style. The Multi-Adjustable Slipper Clutch is included in Carpet Edition.
Central Gear Differential
The central differential is now included in the Dirt Edition. The gear diff shares the same universal diff case and internal parts found in the front/rear differentials. The maintenance-free, super-smooth gear diff has greater internal oil volume to increase consistency of the diff action and includes a composite case and cover with internal satellite gears that are precision-moulded from special Xray-developed graphite composite material, ensuring a long lifespan and super-smooth, efficient operation. The differential outdrives are designed for use with 2.5mm driveshaft pins. The gear diff set includes an 81T spur gear and a 78T spur gear is available as an option. The central differential is recommended for use on clay, bumpy Astro and low-traction tracks to increase traction.
I.S.S. Suspension Holders
All-new front & rear suspension holders are redesigned along with the new HS bulkheads for an expanded range of set-up adjustments. The rear suspension holders can be installed in upward or downward orientations, resulting in additional roll centre locations for the inner hinge pins. The downward orientation of the suspension holder is used primarily for Dirt tracks. The upward orientation of the suspension holder is used primarily for Carpet tracks. The suspension holders allow use of both the long or standard suspension arm configurations. Machined from premium Swiss 7075 T6 aluminium and black coated.
Carpet and Dirt editions include different suspension arms selected for their expected track conditions. The Carpet edition uses the short suspension arms, while the Dirt edition includes the long suspension arms. Rear suspension arms accommodate the multi-adjustable uprights. The outer pivot of each arm uses small screws to secure the hinge pins and prevent separation in a crash. This floating hinge pin reduces suspension bind. The suspension arm itself is rigid enough to provide a responsive feel, yet soft enough for extreme durability. The exclusive composite mixtures used for the suspension arms offer a perfect balance between reliability & performance. There are two different suspension arms available: hard and graphite, each suitable for particular track conditions.
All-new front & rear shock towers are redesigned to accommodate the Horizontal Split Bulkheads (HS) and feature denser upper shock mount positions for more precise set-up adjustments. The rear shock tower features extra roll centre positions for precise set-up adjustment and extra wing mounting positions. Both front & rear shock towers are machined from premium-grade graphite and are lightweight & strong, with multiple shock positions and roll centre adjustment positions.
The front shock absorber bodies and shock shafts are shorter by 2mm. Combined with the new shock towers and suspension geometry, these changes increase stability and improve cornering speeds. The big-bore shocks are membrane free, but still allow for easy, consistent building and rebound control using a bleed-screw shock cap design. The aluminium body and lower cap are all machined from premium Swiss 7075 T6 aluminium. The shock shafts are machined from special steel material, precision hand-ground for maximum smooth operation, and additionally hardened for increased lifespan.
All-new tweak-free Quick Battery Holder allows for easy retainer height adjustment for more convenient battery mounting. The entire system is intended to reduce the effects of the battery and holder on chassis flex, making the XB4 more predictable and easier to drive. The battery holder is universal for both Dirt and Carpet edition.
Side guards are redesigned to accommodate the all-new Quick Battery Holder. The side guards allow the servo mount to be connected to avoid any unwanted negative flex coming from the servo in very high traction conditions. Tough composite side guards perfectly fit the chassis to seal against dirt and protect from side impacts. Moulded from a hard composite material, the side guards are an important part of the chassis flex adjustment for the majority of track conditions. For very-low-traction tracks, optional medium stiffness side guards are available. To improve protection against dust, Velcro® double-sided tape is included to ensure a perfect seal of the body to the side guards, and to reduce the noise level of the running car.
The dual arm steering system is simple yet effective, and features an easily adjustable integrated servo saver. Ackermann is easily adjusted by quickly changing the steering link mounting positions on the steering plate. Bump steer is adjusted for more aggression by inserting a shim between the steering block and steering linkage.
High Traction Body
The XB4’21 Carpet and Dirt Editions each feature new specifically designed Xray Gamma bodies with super-smooth airflow and revised downforce characteristics fine-tuned for their intended conditions. The Carpet edition of the all-new Gamma body is designed especially for high traction conditions and improves the stability in the fast corners, chicanes and improves rotation in tight corners. The Gamma Carpet body is also available in lightweight version.
Low Traction Body
The Dirt edition of the all-new Xray XB4 Gamma body is designed for low traction conditions. The all-new design improves the stability and increases traction. The Gamma Dirt body is also available in lightweight version.
The Carpet and Dirt Editions of the XB4 each feature and individually paired wing to work with their particular body. Made from strong Lexan material, the wing is supported on the wing mounts by extra flat shims to better support and extend the life of the wing. Various wing designs in different thickness are available separately. The thicker wing gives higher traction and stability but gives reduced steering.