Traxxas's TRX-4MT Ford F-150 Monster Truck is a 1/18 four-wheel-drive monster truck, sold ready to run with a Titan 180 brushed motor and an ECM 2.5 control module.
An 11T pinion feeds an 11.38:1 reduction, which makes the final drive 16.6:1. It runs a 2S pack, weighs 0.58 kg and rolls on 76.2 mm tires with 7 mm hexes. The shocks hold 20 wt oil. The pinion is 64P, so a larger one is an inexpensive way to speed up trail runs, while the factory 11T gives the finest control.
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.
Monster trucks have tall tires and long suspension travel, built for jumping and rough ground rather than a race track.
Drive
All four wheels are driven. That gives more grip under power, especially on loose ground.
The cost is more parts to maintain.
Power
A brushed motor carries current through carbon brushes that rub on the commutator.
It is cheaper and smooth at low speed.
The brushes wear and the motor loses power over time.
Build
Ready to run: built at the factory with the electronics installed.
Some come without a battery or charger; the maker's box contents say which.
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 276 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
Monster truck
Drive
4WD
Power
Brushed
Build
Ready to run
Scale
1/18
Part number
98044-1
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 9.1%.
A bigger pinion loads the motor and ESC harder, so check the maker's gearing chart and feel the motor temperature after a run.
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.
Differentials
The type of each differential, as the maker states it.
A gear or ball diff lets the wheels on one axle turn at different speeds in a corner; a spool or locked diff turns them together for straight-line drive and climbing, at the cost of steering.
Pinion
11TStock
Stock
Spur
Not published
Transmission & axle
11.38:1Stock
Stock
Final drive
16.60:1Stock
Stock
Differentials
Spoolfront and rearStock
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.
Rollout
How far the car moves for one turn of the motor: tire circumference divided by final drive.
It lets you compare gearing across different tire sizes; more rollout is taller gearing.
Here it is 14.4 mm.
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.
A small hex like this is used on mini and micro cars.
The wheel nut is a separate size, so check its thread too before buying nuts.
Tire diameter
76.2mmStock
Stock
Rollout
14.4mm per motor turnCalculated
Calculated
Wheel hex
7 mmStock
Stock
Suspension
Shock oil
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.
Front and rear run the same oil on this car, so both ends respond alike. Changing one end at a time is the usual way to shift the balance.
It is graded in wt here. A wt number is the oil maker's own grade and differs between brands, so match the brand, or use the oil maker's chart to convert.
Shock oil
20 wtfront and rearStock
Stock
Power
Motor
Brushed motors are rated by can size and turns rather than KV, so there is no KV to show.
Battery
The highest LiPo cell count the maker rates the electronics for. Each cell is 3.7 V nominal and 4.2 V fully charged.
2S is 7.4 V nominal and 8.4 V off the charger.
Running more cells than this risks the ESC and motor.
Many cars also run on fewer cells, only slower.
Stock motor
The motor fitted at the factory, as the maker names it.
Brushed motors are often named by can size, such as 540 or 550, and by turns: fewer turns is faster.
Stock ESC
The electronic speed control. It feeds power from the battery to the motor as you work the throttle, and usually powers the receiver and servo too.
An amp figure in its name is normally the maker's continuous rating.
A brushed ESC cannot run a brushless motor.
Set its low-voltage cutoff for LiPo, so a pack is not run flat.
Battery space
The biggest pack that fits the tray, as the maker states it: length and width, and height where given.
Compare it with the pack's case size, not its capacity.
Allow room for the leads.
Water resistance
What the maker says about water, in its own words.
Waterproof electronics survive splashes, puddles and wet grass; they are not meant to be submerged.
After a wet run, dry the car and check the bearings, which rust.
Motor
Not applicable
Battery
2SLiPoStock
Stock
Stock motor
Titan 180Stock
Stock
Stock ESC
ECM 2.5Stock
Stock
Battery space
51 × 31 mmmax pack, length × widthStock
Stock
Water resistance
Fully waterproof for all-weather funStock
Stock
Steering & radio
Steering servo
The stock servo that steers the car.
Steering servo
2065RStock
Stock
Performance
Theoretical top speed
A brushed motor has no KV rating, so no theoretical top speed is worked out. Compare gearing by rollout instead.
Theoretical top speed
Not applicable
Size & weight
Weight
The vehicle's weight as the maker states it.
The maker does not say whether it includes a battery.
More weight takes more power to accelerate and lands harder on the parts; it changes top speed very little.
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.
Weight
0.58 kg (1.3 lb)Stock
Stock
Length
276 mm10.9 inStock
Stock
Width
166 mm6.5 inStock
Stock
Height
170 mm6.7 inStock
Stock
Wheelbase
164 mm6.5 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.
Not published means it exists but no source we could find prints it.
Pinion and spur dimensions for the Traxxas TRX-4MT Ford F-150 Monster Truck: fitted, and optional gearing supplied in the box
Component
Teeth
Pitch
Bore
Fitted at the factory
Pinion
11T
64P
Not published
Spur
Not published
Not recorded
Not applicable
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 parts list sets the high-range (trail) transmission gear set, part 9776, in regular type and describes it as a 16.6:1 reduction ratio with an 11-tooth pinion, so 16.6:1 is the final drive.
The product page prints 'Gear Ratio (Internal): 11.38', which is the ratio after the spur, and 16.6 x 11 / 11.38 works out to about 16 teeth on the first transmission gear.
Traxxas prints no spur tooth count, so the spur is left blank.
The transmission is single-speed direct drive, and the low-range (crawl) and speed gear sets in the parts list are optional.
The tire is the Terra Groove 3.0x1.0 in (9867) on 1.2 in wheels, so the tire is 76.2 mm.
The ECM 2.5 control module is used with the included 2-cell LiPo battery (manual p. 4), so the maximum is 2 cells.
The motor is a brushed Titan 180, so there is no KV rating.
The page prints a battery compartment of 51 x 31 mm with no height.
The shocks are filled with 20 wt oil.
The drivetrain matches the TRX-4M Defender (97054-1), which runs smaller 55.9 mm tires.
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.
