Tamiya's TB EVO.8 Chassis Kit is a 1/10 four-wheel-drive, shaft-driven race touring car kit, sold without body, motor or tires.
Its gearbox and axle stage after the spur is 2.50:1, so the spur and pinion you fit decide the final drive. It is 383 mm long on a 257 mm wheelbase. Enter your spur and pinion in the gearing tool to check the ratio.
The kind of vehicle the maker sells it as. It sets what the car is built to do and which cars it is fair to compare it with.
Touring cars are 4WD on-road cars for asphalt and carpet tracks, often raced in classes with fixed motor and battery rules.
Drive
All four wheels are driven, which puts power down more evenly and keeps the car steadier accelerating out of corners.
The cost is more parts to maintain.
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.
This one is 383 mm long.
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.
Class
Touring
Drive
4WD
Build
Kit
Scale
1/10
Part number
42383
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 this car one tooth changes the gearing by about 4.3%.
Racers change the pinion to suit the track and the class's motor rules, and often compare setups by rollout rather than tooth count.
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.
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.
Among 1/10 touring and pan cars in the catalog, the middle half run between 6.5:1 and 8.3:1 on stock gearing; this one is 7.2:1.
On-road racers often compare gearing by rollout instead, because tire sizes differ between cars.
Pinion
23TStock
Stock
Spur
66TStock
Stock
Transmission & axle
2.50:1Stock
Stock
Final drive
7.17:1Stock
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.
Race tires wear down over a day, and a smaller tire gears the car shorter.
Tire diameter
Not applicable
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.
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
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
Size & weight
Length
Overall length as the maker states it, usually with the body fitted.
Useful for comparing real size, since scale labels are loose.
Width
Overall width as the maker states it, usually with the body fitted.
A wider car is more stable in corners and harder to roll over.
Wheelbase
The distance between the front and rear axle centers. A longer wheelbase is steadier at speed and over bumps; a shorter one turns more tightly.
Length
383 mm15.1 inStock
Stock
Width
186 mm7.3 inStock
Stock
Wheelbase
257 mm10.1 inStock
Stock
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.
Shaft-driven 4WD race chassis kit with carbon decks, a front direct coupling with double cardan shafts and a rear gear differential.
Tamiya prints no gear ratio for the kit itself; its 2026 All-Japan Championship rules list the TB EVO.8 on a 66T spur with a 23T pinion at 7.17:1, which gives the ratio after the spur: 7.17 x 23/66 = 2.499.
The 2024 rules print the same 66T/23T at 7.17:1 for the TB EVO.8, and 66T/22T at 7.50:1 for the TB EVO.7 (2.500).
The manual's gear table (PDF p. 26) prints 'Spur gear teeth (66T) / Pinion gear teeth x 2.5', which gives the kit spur and the ratio after it.
The final drive is from the kit pinion: the 23T pinion is in the kit's equipment list, and the table prints 23T at 7.17:1.
Tires, motor and speed controller are sold separately.
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.
