XRAY's GTXE'27 is an electric 1/8 GT car kit, built by you and sold without motor, electronics, wheels or tires.
A 45T spur feeds a 3.54:1 reduction in the transmission, so the pinion you fit sets the final drive. It runs 17 mm wheel hexes. The front diff is filled with 500K oil and the rear with 50K, and all four shocks use 800 cSt. Choose a pinion that suits your motor and pack, then check the motor temperature after the first runs before going any larger.
Sold without a motor, so you choose the motor, ESC and battery yourself.
Rows that depend on the motor say so.
Build
A kit you build yourself from parts.
Most kits come without motor, ESC, servo, radio and battery, and many without tires or a painted body.
The manual lists what to add.
Scale
The maker's nominal size compared with a full-size vehicle. It works more as a class label than a measurement.
A 1/10 monster truck is far bigger than a 1/10 touring car, so compare length and weight for real size.
Part number
The maker's product number for this exact version.
A V2, a new color, or a kit instead of an RTR usually has a different number, and parts can differ between them.
Check it against your box or receipt before ordering parts.
Power
Motor not included
Build
Kit
Scale
1/8
Part number
350606
Drivetrain
Pinion
The small gear on the motor shaft. Fewer teeth gear the car shorter: quicker acceleration, lower top speed and a cooler motor. More teeth do the opposite.
On a chassis sold as kits, each kit brings its own.
Spur
The large gear the pinion drives. A bigger spur with the same pinion gears the car shorter.
Pinion and spur must have the same pitch, or tooth size, to mesh.
The Gearing parts table below shows this car's pitch and part numbers.
Transmission & axle
Every reduction after the spur, multiplied together: transmission, differentials and axle gears.
It is fixed by the design; the gearing you change is the pinion and spur.
Final drive
How many times the motor turns for one turn of the wheels. A higher number is shorter gearing: more acceleration and pulling power, less top speed.
Diff oil, front
Silicone oil sealed inside the differential. A diff lets the wheels on one axle turn at different speeds in a corner; thicker oil makes it act more like a solid axle.
At the front, thicker oil keeps both front wheels pulling out of a corner but makes the car turn in less willingly; thinner oil steers more easily.
It is graded in cSt (centistokes), a measure of thickness that means the same across brands. K means thousands, so 500K is 500,000 cSt.
Diff oil, rear
The rear diff mostly shapes drive out of corners.
Thicker oil there puts power down more evenly on loose or slippery ground; thinner oil lets the car rotate more easily through a corner.
This car runs thicker oil in the front diff (500K) than the rear (50K): steadier on turn-in, with a rear that lets the car rotate.
Pinion
Not applicable
Spur
45TStock
Stock
Transmission & axle
3.54:1Stock
Stock
Final drive
Not applicable
Diff oil, front
500KStock
Stock
Diff oil, rear
50KStock
Stock
Wheels & tires
Tire diameter
The outside diameter of the mounted tire, tread to tread. A taller tire covers more ground each turn, which gears the car taller.
At high speed tires can balloon and grow, so the real gearing gets taller as the car goes faster.
Wheel hex
The hex on the axle that the wheel locks onto and is driven by. A wheel must match the hex size to fit.
17 mm is the standard size on 1/8 cars.
The wheel nut is a separate size, so check its thread too before buying nuts.
Tire diameter
Not applicable
Wheel hex
17 mmStock
Stock
Suspension
Shock oil, front
The oil in the shocks slows how fast the suspension moves. Thicker oil settles the car more slowly and resists bottoming out; thinner oil lets the wheels follow bumps.
At the front it mostly shapes the steering: thicker oil makes the car turn in more calmly and dive less under braking; thinner oil turns in sharper and keeps the front tires on the ground over bumps.
Bashers and monster trucks often go thicker to take big landings without bottoming out.
It is graded in cSt (centistokes), a measure of thickness that is the same across brands.
Shock oil, rear
The rear shocks mostly shape grip under power and how the car lands.
Thicker oil at the rear holds the back up on landings and keeps it steadier on the throttle; thinner oil lets it squat and follow rough or loose ground for more grip.
Front and rear run the same oil here (800 cSt), so both ends respond alike. Changing one end at a time is the usual way to shift the balance.
Shock oil, front
800 cStStock
Stock
Shock oil, rear
800 cStStock
Stock
Power
Motor
Motor KV is the RPM a motor turns per volt with no load.
This vehicle comes without a motor, so there is no stock KV; it depends on the one you fit.
Motor shaft
The diameter of the motor's output shaft, which a pinion's bore must match.
This vehicle comes without a motor, so it depends on the one you fit.
Battery
The highest LiPo cell count the maker rates the electronics for.
This vehicle comes without electronics, so it depends on the ESC and motor you fit.
Motor
Not applicable
Motor shaft
Not applicable
Battery
Not applicable
Performance
Theoretical top speed
It needs a motor KV, and this vehicle comes without a motor. Fit one and the calculator works it out from the motor's KV and the gearing.
Theoretical top speed
Not applicable
How to read these figures
Stock is as the vehicle ships.
Calculated is worked from the stock figures on this page rather than stored beside them, so the two cannot drift apart.
Not applicable means the vehicle does not come with it, like the motor on a roller or the tires on a race kit, or does not have one, like a KV rating on a brushed motor.
Pinion and spur parts for the XRAY GTXE'27: fitted, and optional gearing supplied in the box
Component
Teeth
Pitch
Bore
Part number
Fitted at the factory
Spur
45T
Not published
Not applicable
345545
About teeth, pitch and bore
Tooth counts are the ones in the specifications above.
Pitch is given as metric module (Mod 1, Mod 0.8) or diametral pitch (32P, 48P). They are different standards and are not interchangeable, even where the numbers look close.
Bore is the pinion’s hole, listed separately from the motor shaft.
The manual's gearing formula reads 45 : X x 3.54 = FDR, with the 45T composite spur (#345545) marked as included and 46T and 47T spurs as options.
The 3.54 constant is the 46T diff crown gear against the 13T pinion, sold as a matched set (#355006), the same pair XRAY's features page describes.
Motor, speed controller, pinion (19T to 24T options listed), wheels and tires are on the list of items to buy, so there is no stock pinion or total ratio and the tire size is left blank.
XRAY's product page gives the kit number 350606.
Sources
Every figure on this page traces to one of these; where they disagreed, the note above says which was used and why. Links open in a new tab.
