The Baja Rey (LOS03008) is Losi's 1/10 four-wheel-drive desert truck, sold ready to run with a Dynamite Fuze 3800Kv brushless motor and a Fuze 130A waterproof speed control.
A 13T pinion and 3.8:1 inside the transmission give a final drive of 10.99:1, the number of motor turns for each turn of the wheels. On a 3S pack that works out to about 51 mph on 113 mm tires, against Losi's claim of 45 mph or more. The truck is 540 mm long on a 370 mm wheelbase, so check a 3S pack fits before you buy one.
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.
Desert and trophy trucks copy full-size off-road racers: long travel, and bodies that leave the rear wheels open.
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 brushless motor has no brushes to wear, so it makes more power and runs more efficiently than a brushed one.
It needs a brushless ESC.
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 540 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
Desert truck
Drive
4WD
Power
Brushless
Build
Ready to run
Scale
1/10
Part number
LOS03008
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 7.7%.
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.
Among 1/10 desert trucks in the catalog, the middle half run between 11.0:1 and 12.7:1 on stock gearing; this one is 11.0:1.
Pinion
13TStock
Stock
Spur
Not published
Transmission & axle
3.80:1Stock
Stock
Final drive
10.99:1Stock
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.
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 32.3 mm.
Tire diameter
113mmStock
Stock
Rollout
32.3mm per motor turnCalculated
Calculated
Power
Motor
RPM per volt with no load on the motor. Higher KV spins faster on the same pack; lower KV on more cells can reach the same RPM with less current.
On 3S (11.1 V nominal) this motor spins about 42,180 rpm with no load.
Under load the real RPM is lower.
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.
3S is 11.1 V nominal and 12.6 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.
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.
Set its low-voltage cutoff for LiPo, so a pack is not run flat.
Motor RPM times rollout, worked out on 3S at nominal voltage with stock gearing.
It assumes no load, no battery sag, no wheel slip and no drag, so read it as a ceiling for comparing setups.
A GPS usually reads below it; the gap is load, battery sag, tire slip and drag.
Motor speed
The motor's RPM with no load: KV times pack voltage.
Under load it drops, which is one reason real speed is lower than the theoretical figure.
Advertised top speed
The top speed the maker claims.
Makers often quote it with optional gearing, a bigger battery or a fully charged pack, so read their wording before comparing it with another car's claim or with the calculated figure.
Theoretical top speed
50.8mph on 3SCalculated
Calculated
Motor speed
42,180rpm, no loadCalculated
Calculated
Advertised top speed
45mphMaker's claim
Maker's claim
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
2.77 kg (6.1 lb)Stock
Stock
Length
540 mm21.3 inStock
Stock
Width
320 mm12.6 inStock
Stock
Height
190 mm7.5 inStock
Stock
Wheelbase
370 mm14.6 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.
Not published means it exists but no source we could find prints it.
The top speed is kinematic: an ideal no-load RPM with no slip and no loss under load, so a real car is slower.
The maker advertises 45 mph, which is their own claim on their own conditions.
Pinion and spur dimensions for the Losi Baja Rey (LOS03008): fitted, and optional gearing supplied in the box
Component
Teeth
Pitch
Bore
Fitted at the factory
Pinion
13T
Mod 1
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.
Losi's page and manual give a 13T pinion, a 3.8:1 transmission and a 10.99:1 final drive, and Big Squid RC's review repeats the 10.99:1 figure.
Those figures, with the 113 mm outer diameter in Losi's spec table and the 3800Kv motor, work out to about 51 mph on 3S, so Losi's claim of 45 mph or more sits at roughly 89% of that.
The same page prints a 43T spur, but 43T does not fit the other figures (13T on 43T at 3.8:1 would be 12.57:1), and Losi's pages for the Rey trucks print different spur counts for the same gearbox, so the spur is left blank.
The page lists 2S or 3S LiPo packs, so the cell count is 3.
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.
