Tamiya's F104 PRO II is a 1/10 rear-drive formula car chassis you build yourself, sold with a body and 64 mm tires but no motor.
The motor drives the 104T spur on the rear axle directly, so the ratio after the spur is 1.00:1 and the final drive is simply the spur over your pinion. The car is 440 mm long on a 270 mm wheelbase. Pick the pinion in the gearing tool first, since it is the only gear that sets the final drive.
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.
Formula cars are open-wheel on-road cars modelled on single-seat racers.
Drive
Only one axle is driven, the rear on almost every 2WD RC car.
It is lighter and simpler, and it takes more throttle control out of corners.
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 440 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
Formula
Drive
2WD
Build
Kit
Scale
1/10
Part number
58652
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.
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.
This one is worked out from the tooth counts the maker publishes.
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.
On-road racers often compare gearing by rollout instead, because tire sizes differ between cars.
Pinion
Not published
Spur
104TStock
Stock
Transmission & axle
1.00:1Derived
Derived
Final drive
Not published
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
64mmStock
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.
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.
Height
Overall height as the maker states it, usually with the body fitted.
Useful when checking it fits a shelf, a bag or a car trunk.
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
440 mm17.3 inStock
Stock
Width
180 mm7.1 inStock
Stock
Height
88 mm3.5 inStock
Stock
Wheelbase
270 mm10.6 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.
Derived is worked out from gear tooth counts the maker publishes rather than printed as a ratio; the notes below say how.
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.
Not published means it exists but no source we could find prints it.
How these numbers were settled
1/10 formula chassis with a transverse motor and rear direct drive through a ball differential, sold with a Type 2017 body.
Tamiya prints 'Gear Ratio 4.16:1 (When used with 25T Pinion and 104T Spur Gears)': 104/25 = 4.16, so there is no reduction after the spur and that ratio is 1:1, derived.
Tamiya's pages do not say whether the 25T pinion is in the box, so the pinion and final drive are left blank; with a 25T fitted the final drive is 4.16:1.
Tires are 30/64mm front and 35/64mm rear, so 64mm is shown.
Type 540 motor, ESC and radio are sold separately, so there is no motor or cell rating.
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.
