XRAY raised the bar in the 1/10 buggy class with the XB4, bringing a new high-quality, high-performance player into the field for all others to measure themselves against. Now with a more adaptive platform, XRAY’s 1/10 buggy, the new XB4’15, is even more the beast to beat.

We present the new 2-in-1 concept in the 2015-spec XB4, giving the ability to change or reposition components on the car to use a short LiPo battery pack -or- saddle packs. Everything has been considered, adapted, and included: repositionable bulkheads, slipper clutch, and motor mount; different upper decks and center CVD drive shafts; even a repositionable radio trays and servo mounts. This is an incredible leap forward to make the XB4 platform ultra-diverse to satisfy the needs, wants, and desires of racers around the world.

The new XB4 is artistically crafted in our in-house XRAY factory by design & production specialists, and then extensively tested and refined by the world's best drivers. Designed, developed, and fully manufactured in Slovakia, Europe, with XRAY's legendary attention to the details, fine materials and extreme performance, I am excited to present you the all-new XB4.
Dipl. Eng. Juraj Hudy
XRAY XB4 designer

Development Team.

Development of the XB4 platform will continue as we move into future, fueled by our fundamental belief in precision design and a desire to bring forth only the best products and world-class support. Race results from XB4 drivers around the world – including the European Champion title and dozens of national titles worldwide – prove we are on the right track

2015 All-new Features:

XB4 Platform.

The XB4 is a typical XRAY car – a premium, professional, high competition model racing car for the most demanding racers, developed and designed with attention to the smallest details. Manufactured from premium European materials, machined using state of the art Swiss and German machines and backed by premium service & support, the XB4 is a typical XRAY, a luxury masterpiece.

2-in-1 Concept.

You now have the choice to use either a short battery pack -or- saddle packs; the new XB4 is designed to fit both perfectly! With the all-new 2-in-1 concept, you can easily transform the saddle pack configuration into a short pack battery configuration and place the motor either frontwards or rearwards… all parts for the transformation are included.

Chassis Weight Balance.

You can easily adjust the weight balance with the all-new 2-in-1 concept. You can move the motor frontwards and rearwards, but you can do this independently of the short battery pack. You can also place the electronics - including servo - on either left or right as well.


CNC-machined from high-quality Swiss 2mm 7075 T6 aluminum, the chassis is strategically machined in low-stress areas to make it as light as possible without affecting strength or rigidity.

Weight distribution, chassis width, and chassis length have a key influence on the handling of the car. All of these features were incorporated into the design of the chassis. All screw holes on the bottom of the chassis are countersunk, allowing for a very smooth chassis underside with no protruding screw heads. To increase the lifetime, the chassis is hardcoated at XRAY’s own in-house fully robotic operated coating line.

Side Guards.

Tough composite side guards perfectly fit the chassis to seal against dirt and protect from side impacts.

Chassis Braces.

The front and rear lower composite braces are mounted to the aluminum chassis, and reinforce the chassis assembly with the desired flex.

The wires between the motor and electronics are routed via a channel in the front brace to ensure they do not interfere with the drive shafts or other rotating parts.

Top Decks.

The XB4 is equipped with both front and rear top decks which not only hold the body mounts but also reinforce the chassis assembly by connecting the front and rear bulkheads with the central drive system. The length, thickness, width, and shape of the top decks are all features that have a significant influence on handling.

With the all-new 2-in-1 concept, the XB4 includes two sets of front & rear top decks, each specifically designed for use with either the short battery or saddle pack battery configuration. Depending on the configuration of the car, the appropriate top decks are installed to ensure the highest performance and best handling.
All top decks are machined from high-grade graphite. The top decks capture the central drivetrain bearings and hold them in place in their supporting bulkheads.

Central Drive Shafts.

For the new 2-in-1 concept, the XB4 includes two pairs of central drive shafts of different lengths, each specifically designed for use either with short battery or saddle pack battery configurations.

The XB4 constant velocity drives (CVDs) are manufactured from world-renowned HUDY Spring Steel™. 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 lifetime and reliability.

Safety Collars.

The CVD safety collars were reinforced to increase reliability and keep the mounting pin solidly in place. The safety collars are molded from a special composite mixture for maximum strength.

Diff Gears.

Both front & rear diff crown gears and pinion gears are made from steel which has been additionally hardened to ensure increased lifespan and reliability. The width of the crown gear teeth is narrower to allow the gear to be as light as possible. The width of the pinion gear teeth is wider to allow it to work also with optional composite and aluminum crown gears.
For clay and low-traction tracks, optional graphite diff crown gears can be used to increase traction.

Gear Differential.

The XB4 gear diff ensures increased on-power steering for nearly all types of tracks, and is ideal for both carpet and clay tracks.

The super-smooth gear diff includes a composite case and cover with exchangeable spur gear. The gear diff set includes 81T spur gear and a range of various spur gears is available as an option.

The maintenance-free diff design will benefit racers of all levels. When the diff is correctly built, there is no need for maintenance for a very long time… no need for frequent oil changes, and no leakage due to our superior sealing system.

Motor Mount.

The all-new motor mount is another smart and innovative solution from XRAY. The motor mount design allows the entire mount to be rotated from right to left to allow the motor to be mounted either frontwards or rearwards.

The motor is connected to an eccentric mounting plate, with the assembly then inserted into an integrated motor holder/drivetrain support. The design allows quick & easy motor rotation to adjust gear mesh, and yet clamp securely using only a single screw.
To ensure the motor will not loosen in a serious crash or due to insufficient tightening, the motor plate has a bayonet mounting system which prevents it from being dislodged from the motor holder. By rotating the motor mount plate to the opposite direction, the motor can be quickly removed from the motor holder.

Removing the motor or adjusting the gear mesh has never been easier or faster, with changes possible in only a few seconds.

Central Bulkhead.

The new central bulkhead was designed to support the 2-in-1 concept, to allow the slipper clutch to be oriented either frontwards or rearwards. The graphite central upper deck holds ball-bearings in the motor mount and bulkhead assembly, while the design of the upper deck allows for very easy access for slipper clutch adjustment.

Slipper Clutch.

The power from the motor is transferred to the drivetrain via an adjustable central slipper clutch for quick and easy tuning.

To accommodate the new 2-in-1 concept, the slipper clutch shaft was redesigned with a centric design to allow it to be positioned either frontwards or rearwards.

The lightweight slipper clutch plates have a machined relief which decreased the friction surface which assists with clutch slip adjustment. With this plate design, the plate pressure is on the circumference of the clutch pads, which increases the efficiency.

The slipper clutch pads are made from ultra-efficient SLS material with very high slip efficiency, thus allowing very precise slip adjustment.

The clutch spring is much stronger to improve consistency and give ultra-fine slipper clutch adjustment.

The clutch outdrives are super lightweight and manufactured from HUDY Spring Steel™ and then additionally hardened for extra life and reliability. The slipper plates are machined from premium Swiss 7075 T6 and additionally hardened then given a black final surface treatment.

Spur Gear.

Precision-molded spur gears are made from XRAY's exclusive secret blend of composite material, allowing the gear to run true yet be robust enough to handle high-performance brushless motors. The spur gears are designed to have the lowest possible weight while staying strong and light. Each gear is stamped with the tooth number for easy identification.

The XB4 is equipped with a 81T spur gear which suits the majority of tracks. For additional tuning, optional 75T, 78T, and 84T spur gears are available.

Central Differential.

A central differential is recommended for use on clay and low-traction tracks to increase traction.
Available as an option only.


Front & rear bulkheads were reinforced to withstand rigorous impacts and abusive racing conditions. The diameter of the holes for ball-bearings was refined to minimize ball-bearing play which results in increased lifetime of the gear teeth and minimized gear stripping.

Shock Towers.

The new 3.5mm graphite front shock tower was thickened for increased lifespan, and the new design features the two most frequently used roll center positions. Both front & rear shock towers are machined from premium-grade graphite, are lightweight and strong, and have multiple shock positions as well as multiple roll center adjustment positions. The rear shock tower holds the wing mount.

I.S.S. Suspension Holders.

The aluminum suspension holders feature Integrated Suspension Settings (I.S.S.) which allows for super-fast & easy suspension geometry setting. This XRAY concept was first introduced in the very first XB8 and now has been carried over to the 1/10 scale XB4.
Using eccentric suspension bushings – which are inserted into aluminum suspension blocks – as well as additional shims, the XB4 suspension geometry can be completely adjusted including:
A complete set of eccentric bushings is included for complete suspension geometry adjustment. The bushings are inserted into aluminum holders which are machined from premium Swiss 7075 T6.


The new uprights were reinforced for increased strength, reliability, and lifespan. The very compact rear uprights are small in size but are also very strong due to the special composite mixture used.

The lower roll center adjustment has 2 different positions on the upright, and the upper roll center adjustment has 3 different positions. The rear uprights feature 0° toe to ensure stability and prevent suspension geometry changes in hard crashes.
For maximum drivetrain reliability, larger 5x12 ball-bearings are used in the outer position for increased dynamic load. On the inner position, the smaller 5x10 ball-bearings are used to minimize unsprung weight.

The outer suspension pin on which the rear upright sits features shims which allow for additional wheelbase adjustment.

Radio Plate.

A very handy, compact radio plate allows for mounting the receiver and speed controller for quick & easy removal and assembly. The antenna mount allows the electronics to be located in one place for easy servicing.

Battery Strap.

With the all-new 2-in-1 concept, the XB4 includes two short and one long battery strap to accommodate either a short battery pack or saddle packs. The battery strap holders were updated with a new higher design, and the front holders are completely new.

Servo Mount.

New servo mounts allow the servo to be installed on either left or right side to allow for weight balance adjustment. The chassis and side guards have predrilled holes to allow the servo mounts to be mounted on either side.


The front lower bumper was redesigned for improved protection. The bumper now protrudes from the bottom of the chassis to absorb all impacts from contact between the chassis and the track surface.

Body Posts.

Beefy 6mm thick body posts are made from special composite material that provides maximum strength. The new front body post is shorter to fix the new body. The body supports are rounded to have a better fit and provide better support to the car body.


The new, aggressive XB4 body is wider to fit the new wider layout and the new 2-IN-1 concept. The high-performance low-profile aerodynamic body was designed by XRAY to perfectly fit the XB4 and to work in most track conditions. The front and rear of the body have been designed to provide downforce for maximum stability. The body sides as well as the cockpit sides are as flat as possible to direct airflow around the body for maximum stability. On the rooftop, two flow channels are incorporated for proper air flow. The body is made from high-quality premium Lexan material.


XRAY Multi-Flex Technology™ has resulted in some of the most significant milestones in RC model car development in the last decade. This innovation has proven to be a distinct competitive advantage at tracks worldwide, helping XRAY cars dominate races at local and national levels.

The XB4 is the world’s first 1/10 off-road chassis incorporating Multi-Flex™ adjustment technology, which allows tuning the chassis flex for different track conditions. Whether the track is low, medium or super-high traction, you can adjust the chassis flex to suit the track conditions in a matter of seconds, and again adjust the flex easily when the conditions change. It has never been so easy to professionally set-up flex… yet another smart innovation from XRAY.


Use soft setting for low-traction, dust tracks. The car will create a lot of traction with this setting but will have less steering and response compared to stiffer setting.


Use medium setting for medium-traction tracks. This setting offers good balance between steering responsiveness and traction.


Use stiff setting for high-traction tracks where a lot of steering and car response is required.

The more screws used, stiffer the car is and less screws used, softer the car is.
Do not remove any other screw except those shown.

Drive Train.

The XB4 is a conventional shaft-driven 4WD off-road car featuring:

The internal ratio of the drive train is 1:2.5

Drive Shafts.

XB4 constant velocity drives (CVDs) are manufactured from world-renowned HUDY Spring Steel™. 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 CVD assembly also features a composite safety collar to keep the mounting pin solidly in place.

Ball Differential.

The optional ball differential was designed and is suggested for low traction track conditions. Externally adjustable ball differential is machined from HUDY Spring Steel™ and additionally hardened for extra durability and long lifetime. High-quality carbide thrustbearing is included for smooth operation and the carbide balls ensure ultra-smooth running. The ball differential comes factory pre-assembled.

Diff Outdrives.

To reduce rotating weight, the super-lightweight diff outdrives are machined from HUDY Spring Steel™ material which allows additional material to be removed on the outer part of the outdrives, further reducing the weight without effecting durability. The inner part of the outdrives is additionally hand-ground for perfect fitment into the diff case.
The outdrives are hardened using XRAY’s own special hardening process to provide extended lifespan and reliability.

Suspension Concept.

The correct suspension geometry is one of the most important features of any RC model car, while at the same time being one of the most difficult and challenging features for a designer.

The suspension is always a mixture of:
From the suspension arms, through the suspension blocks, to the light yet robust steering blocks, every suspension part has been specially designed for the 1/10 off-road racing platform to provide responsive racing characteristics in all conditions.

Over the years, XRAY has successfully gained and utilized extensive knowledge of suspension geometry and stiffness, which has been applied while designing suspension parts. The ultra-lightweight suspension parts are molded from a special composite material to make the parts very light yet very durable to withstand the rigors of high-performance racing.

The XB4 platform features suspension parts inspired by the big brother XB9, while having been re-engineered for the smaller 1/10 platform. The front and rear arms feature double shock mounting positions and integrated anti-roll bar mounts.

Suspension Arms.

Suspension arms are one of the most important parts of any RC model car, as they directly influence the handling characteristics of the car. The XB4 suspension arms are the result of long-term tests of different designs and layouts. Length, thickness, flexibility, geometry of suspension points, and materials used… these are all the concepts and details that had to be thoroughly reviewed to create optimum suspension arms.
The exclusive composite mixture used for suspension arms is a perfect balance between reliability and performance. The suspension arm itself is rigid enough to provide a responsive feel, yet soft enough to provide extreme durability.

SFA Arm Stiffeners.

Innovative and unique SFA™ graphite stiffeners allow for super-quick suspension flex adjustment to easily adjust the traction of the car in various track conditions.

Whether you drive in low- or high-traction conditions, with the smart graphite stiffeners you can very quickly and easily adjust your car to suit current conditions. At the beginning of a race event when traction is low, the arms are used without the SFA™ graphite stiffeners. As traction increases, the suspension can easily be made stiffer by mounting the SFA™ graphite stiffeners for more stability and easier driving characteristics. The graphite stiffeners give the car maximum stability in chicanes and allow for easier and smoother steering.
Made from 1.6mm thick high-quality CNC-machined graphite material, the stiffeners can be easily mounted or removed by only a few screws.

The stiffeners are available only as an optional part.

Wheelbase Adjustment.

All-new suspension arms are narrower which allows for quick and easy wheelbase adjustment. Using included 2mm shims, both front and rear suspension arms can be moved either forward or rearward to adjust weight balance depending on track conditions. By moving the arms to the front, the balance and weight of the car are transferred more to the rear; this is recommended for medium– and high-traction conditions. By moving the arms to the rear, the balance and weight of the car are transferred more to the front; this is recommended for medium- and low-traction conditions.

The wheelbase shims allow not only to move the suspension forward/rearward, but also allows the wheelbase to be adjusted shorter or longer for fine set-up tuning under various track conditions.

Caster Blocks.

The 1-piece caster blocks are very lightweight, yet the construction of the caster blocks makes them very stiff and rigid. The non-adjustable caster angle is preset for 9°. The roll center position can be easily and quickly adjusted by inserting different thickness of shims on the top of the caster block between the block and the vertical ball stud.

The caster blocks feature large openings for quick & easy assembly/disassembly of the CVDs. The entire CVD assembly can be easily inserted/removed through the C-hub without the need for disassembly. The large openings also prevent collision of the CVD with the C-hub in serious crashes.

The front of the chassis is pre-angled with an integrated 8° caster angle, however the position of the adjustable eccentric bushings in the I.S.S. suspension holders influence the caster as well. (For example, if the eccentric bushings have the roll center in middle position, the caster angle is 9° and with the 9° in caster block the overall caster angle is 18° of caster. The total adjustable caster range in the kit is 16-20°.)
Optional caster blocks with 6° and 12° caster angles are available for further suspension geometry adjustment.

Steering Blocks.

The tiny yet tough steering blocks are molded from a special composite mixture for maximum strength.

Composite steering block inserts allow for very quick & easy lower roll center adjustment. With additional shims and extra inserts, fine tuning the roll center is easily achieved.

For maximum drivetrain reliability, larger 5x12 ball-bearings are used in the outer position with increased dynamic load. On the inner position, the smaller 5x10 ball-bearings are used for minimized unsprung weight.
When the longer bushin is used at the top, the roll-center is in lower position. Recommended for rough track to gain stability.
When the longer bushin is used at the bottom, the roll center is in higher position. Recommended for smooth track to gain more steering.

Hex Hubs.

Ultra-lightweight 14mm wheel hex drive hubs are CNC-machined from Swiss 7075 T6 black-coated aluminum. These ultra-true hex hubs have a clamping design which ensures ultra- solid mounting of the wheel on the hub.

The alu hex hubs are specially machined to reduce rotating weight while guaranteeing wobble-free wheel mounting.

To adjust the track-width, optional offsets are available: -0.75mm and +0.75mm.

Dual Arm Steering System.

The dual arm steering system is very simple yet effective and features an integrated easily adjustable servo saver. Ackermann is easily adjusted by quickly & easily changing the steering link mounting positions on the steering plate.

Bump steer is easily adjusted for more aggression by inserting a shim between the steering block and steering linkage.

HUDY Spring Steel Turnbuckles.

To guarantee maximum reliability, all turnbuckles are manufactured from special HUDY Spring Steel material for turnbuckles which features a tougher core. These turnbuckles are used for front & rear upright linkages, steering system, and also for the servo saver.

Big-bore Shocks.

Well-built, reliable shock absorbers are extremely important for super-smooth suspension action on every type of track. The shocks on the XB4 have been specifically designed to be built easily, perform consistently, and last reliably. Attention was paid to all the smallest details during the design process, as well as during the long-term testing in various conditions and track types.
The big-bore shocks are membrane free,
but still allow for easy, consistent building and
rebound setting using the bleed-screw shock cap design.
The up-stop travel of shock rod is adjusted via rubber O-rings, while the
downstop is adjusted using composite shims under the pistons.
The aluminum body, lower nut, and bleeder shock caps are all machined from premium Swiss 7075 T6 and then black hardcoated for maximum strength and durability.

The pistons are made from Delrin® and are molded using super-precise moulds. There are several types of pistons included with different holes and diameters for precise shock adjustments. For custom adjustment, a set of blank non-drilled pistons are also included.

The shock rods are machined from special steel material, precision hand-ground for maximum smooth operation and additionally hardened for increased lifespan.

Shock Springs.

The XB4 springs have been specifically designed to complement the big-bore shocks.

The XB4 springs, like all other XRAY springs, are manually measured, selected, and matched into pairs to guarantee precisely equal length and damping characteristics.
the spring rate is constant during the entire spring compression. There are springs with different spring rates available as optional tuning parts.
The main advantage and benefit of progressive springs is that as the car initially enters the corner they work like a softer spring to provide maximum traction. As the chassis begins to roll in the middle of the corner, the spring rate progressively increases until it works like a stiffer spring which allows the car to maintain maximum cornering speed.

Variable Shock Mounting.

The new design of the rear suspension arm allows very practical variable position of the rear shock absorbers. Depending on track conditions, the rear shock absorbers can be installed either in front or behind the shock tower.

Silicone Oils.

XRAY Premium Silicone Oils are manufactured in Europe by a specialized premium silicone oil manufacturer; these new oils were exclusively created for XRAY. Each batch of premium oil is laboratory tested and calibrated to ensure the highest possible consistency and quality from one batch to the next. Based on the industry-standard cSt rating, the new line of oils will be easy to identify, adjust, and feel.
When following any set-up sheets by XRAY or XRAY team drivers, you can be sure that the oils you get for your car will be exactly same oil as used by the factory racing team, thus ensuring very reproducible set-ups and handling.

Anti-roll Bars.

Anti-roll bars are manufactured from special spring steel material and are included to stabilize the front & rear ends of the car. The roll bars are easily mounted to the diff cases and can be adjusted with the linkages.

Both front & rear anti-roll bars are interchangeable since they have same design and shape. The thickness of each anti-roll bar is laser-engraved for easy identification. Anti-roll bar wires of different thickness are optionally available for fine-tuning.


A full set of 22 high-speed, blue-sealed ball-bearings are used throughout the drivetrain to ensure maximum efficiency. All of the bearings are degreased and oiled with Aero Shell® Fluid 12 for maximum smoothness and long life.

Rear Wing.

Stylish and effective rear wing was designed to work perfectly with the XRAY XB4 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.

Optional thicker 1.5mm (#363511) and 2.0mm (#363512) rear wings are highly reliable with less chance of breakage, while at the same time influencing the performance of the car as well. The thicker wing gives higher traction and stability, but gives reduced steering.


The specially-designed XB4 wheels included in the kit are perfect for high-competition racing. The wheels are made from a very flexible material, while still being durable to withstand impacts. The side of the wheel is aerodynamic for maximum performance.

The special features of the wheel are visible from the inside – the reinforcement ribs are designed to make the wheels as stable as possible and to eliminate deformation.

The front wheels feature +1mm offset which makes the front of the car wider and as such more stable.

The wheel design features a 14mm internal hex.

Chassis Balance.

The chassis design focuses on balanced weight distribution and weight transfer. The chassis features pre-drilled holes for additional weights for optimum car balancing. Centerline holes are pre-drilled for easy balancing with the HUDY Chassis Balancing Tool #107880.

Adjustment Possibilities.

The extensive and impressive range of adjustment possibilities includes: caster, camber, toe, kick-up, anti-squat, ride height, downstops, track-width, lower roll center, upper roll center, roll center positions, bump steer, wheelbase, Ackermann, adjustable shocks, adjustable front and rear diff and adjustable XRAY Multi-Flex™.

Graphite Grease.

The XB4 includes premium HUDY Graphite Grease which is a high-performance, advanced-technology semi-fluid lubricant which incorporates both extreme pressure additives and finely-dispersed graphite for load carrying. It is intended primarily for the lubrication of rotating parts and loaded gears. In addition to providing outstanding load carrying, it is formulated to have excellent adhesion and resistance to "fling-off" under extreme conditions. The grease reduces wear and increases parts life.

Set-up Book.

The XB4 is one of the most adjustable electric off-road car in the world. Whether you are a hardcore racing fanatic or a club-level sportsman, you can very easily adjust the XB4 to suit your racing style, race track type, and all track conditions. To fully understand the set-up possibilities we recommend the legendary HUDY Set-up Book, loaded with over 50 pages of high-quality pictures and easy-to-understand RC car set-up explanations. Whether you are a novice driver or experienced racer, you can easily learn many set-up tips & tricks and improve your set-up skills, ultimately translating into improved racing performance with your XB4. The HUDY Set-up Book is available for download exclusively at www.hudy.net

XRAY Instruction Manual.

XRAY Instruction Manuals have become the industry standard, being simply the best manuals you will ever get with an RC model car. Whether you are a first-time builder or an experienced racer, all the instructions are straight-forward and easy to understand. The full-color instruction manual contains large 3D illustrations that show all assembly details in the clearest possible way.

XRAY VIP Customer Treatment.

Owning an XRAY model racing car is an experience on its own. Not only will you own the most premium luxury model racing car in the world, but you will also become a member of the prestigious family of XRAY owners with direct support and service from the XRAY factory. XRAY brings you the most up-to-date RC Web site on the Internet, with daily racing news and latest product developments. If you have any questions, problems or comments, you can ask the XRAY Support Team or any XRAY Factory Team Driver on the XRAY Support Forum. You can even upload your own set-up sheets or download from the thousands of different set-up sheets available from all around the world at the exclusive XRAY Virtual Set-up Sheet Database, the world’s largest set-up sheet database. And that is only the start of the VIP treatment you get by joining Team XRAY.