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Upgrading and replacing gears isn't the most glorious part of modifying Power Wheels ride-on cars but is one of the most rewarding. It makes the ride on vehicles more reliable by complementing the motor and battery upgrades. Since gearboxes come in different sizes, you must get the right one when upgrading or replacing a damaged set.
Replacing or upgrading a Power Wheels gearbox is an effective way to deal with stripped or broken gears. Stock gearboxes ship with plastic gears, which are prone to stripping and limit speed and performance. You can replace the vulnerable first gear with a stock plastic or upgrade to hardened steel.
Replacing damaged and stripped gearboxes is a standard part of Power Wheels maintenance and repair. The decision to replace or upgrade a damaged gearbox boils down to personal choice and budget. This guide lays out the exact steps to follow when you need to upgrade or replace a Power Wheels gearbox, including:
- Step-by-step Power Wheels gearbox replacement
- Step-by-step Power Wheels gearbox upgrade
- Common gear problems in Power Wheels
- A guide to Power Wheels gearboxes
- Quick facts about Power Wheels gearboxes
A Quick Guide to Power Wheels Gearboxes
Recent ride on cars from Power Wheels use a 7R gearcase, which is an upgrade from the #7 gearcases that were discontinued in 2010. Fortunately, the newer and trendier gearcases are compatible with the older models.
The 7R gearcases are remarkably different from the older #7 models because they:
- Are made of sturdy plastic material
- Accommodate different sized internal shafts
- Have a thicker fourth gear
- Are compatible with 550 and 775 motors
- Have multiple numbers printed on the casing
- Use a hole to denote the internal gear number
- Have a white output shaft instead of orange
Getting the new 7R casing is beneficial because Power Wheel continually upgrades the molds to improve performance and durability.
Each gearbox houses five gears in sequential order:
- The Pinion Gear. It is the first in line and attaches to the Power Wheels' motor.
- The First Gear. It connects with the pinion gear and is the most vulnerable to stripping and damage. It's the smallest and sits on the gearbox casing.
- The Second Gear. It's the second smallest gear wheel and sits above the first gear.
- The Third Gear. It's the second-largest gear wheel and sits between the second and the final drive gear.
- The four or Final Drive Gear. It's the biggest gear wheel and sits above the third gear on the first gear's opposite side. It attaches to the driver hub or the wheel.
Power Wheels produces four different 7R gearboxes, each of which accommodates a range of gear ratios. The size of the pinion gear determines the gear ratios.
Ride-on cars with bigger pinion gears have higher speeds but a lower power output. If the pinion is too big, it will overheat the engine and blow the fuses.
Bigger pinion gears are perfect for riding on smooth surfaces that allow incredible speeds, such as pavements.
A small pinion gear gives a ride-on car a lower speed but higher power. Riders who like off-road riding, mud bogging, and towing should use small pinions because it results in massive power output.
Step-by-Step Guide to Replacing Power Wheels Gearbox
You don't need any special tools or engineering skills to replace a Power Wheels gearbox. You only need to be handy with a screwdriver and a power drill fitted with a screwdriver, and you're good to go.
Since ride on cars are primarily made of plastic parts, they're held together by safety clips and screws. That makes it easy for anyone to take them apart, carry out repairs, and put them back together.
Getting the right model is the tricky part of replacing a gearbox, but that information is on the back of the gearbox casing.
To replace a Power Wheels gearbox, you'll need:
- A screwdriver
- The replacement gearbox
- Power drill
Here are the steps to follow:
- Turn over the Power Wheels ride-on car on a flat surface. Since the car doesn't have any fluids that can spill, you can overturn it just about anywhere.
- Identify the protective housing. While all Power Wheels gearboxes are mounted on the rear wheels, the protective housing varies between models. You need to unscrew the protective cover to access the gearbox.
- Pull the wheels off. In most models, the protective covering sits below the rear wheel axle. That means you must remove the wheels before accessing them and loosen all screws on the cover.
- Pull off the hubcaps. Insert the screwdriver along the edge where the hubcap meets the wheel and pop off the tabs to remove it.
- Remove the screw on the wheel axle. Depending on the model, removing the hubcaps exposes the screw locking the wheel on the axle. Work the screw loose with a screwdriver or a power drill until it comes off and remove the cover.
- Pull the tire off. Removing the screw works the wheel loose. Pull it right off and place it on the floor.
- Repeat the process on the other rear wheel and take it off the car. Doing so gives you access to the screws attaching the protective cover to the Power Wheels body.
- Remove the screws on the protective cover with a power drill. The number of screws attaching the cover to the rest of the ride-on car will vary between models. While a screwdriver will do, it's advisable to use a power drill since it's faster. Remove each screw and keep them in a safe, accessible place.
- Lift the cover from the ride-on car and place it on the floor.
- Pull the axle from the car. Since the axle is a straight rod that runs across the vehicle, it should come right off. If the axle is bent, even slightly, you need to replace it. A bent axle contributes to gear stripping, and failing to replace it will ruin the new gearbox.
- Remove the gearbox. Removing the cover exposes the gearbox. Gently lift the gearbox out of its mounting. The gearbox comes up together with the attached motor. In-stock models, the gearbox isn't connected to the Power Wheels body. Instead, it fits snugly in a custom mold and is held in place by the outer covering and rear axle.
- Detach the motor. The lifting gearbox brings up the attached motor connected to the Power Wheel by a pair of wires. The engine is attached to the gearbox by a pair of screws. Work the screws loose with the power drill or the screwdriver.
- Replace the faulty gearbox. If you picked the right replacement gearbox for the Power Wheel, the new unit should fit perfectly with the motor. Align the gearbox with the engine and drive in the two screws and ensure a tight fit.
- Insert the replacement gearbox into the housing. Gently pop the replacement gearbox into the Power Wheel.
- Repeat the process and replace the other gearbox. It's advisable to replace both gearboxes if you notice that one has stripped gears. If the gearbox on one side of a Power Wheels is damaged, the other one isn't too far behind. Replacing them at the same time saves you the hassle of repeating the process.
- Re-insert the rear axle. Once you've replaced both gearboxes and reattached them to the ride-on car, it's time to re-insert the axle. Push the axle gently into the Power Wheels through the colored wheel mount and through to the other side. Ensure a perfect fit on both sides of the ride-on car.
- Replace the outer covering. Fit the protective cover on the Power Wheel and put back all the screws. Be sure to tighten the screws tightly to eliminate play.
- Replace the tires. Ensure the axle is balanced on both sides before fitting the tires.
- Put the tire cover back. Place the cover on each tire and then screw them in place until they are tight.
- Replace the hubcaps. Pop the hubcaps at the end of each wheel and ensure they firmly lock in place.
- Take the Power Wheels ride-on car out for a spin to see how it rides.
Power Wheels Gearbox Upgrade
Upgrading a Power Wheel gearbox is the best way to eliminate some of the common gearbox problems. The process entails replacing the stock plastic first gear that's prone to stripping with durable hardened steel first gear.
A hardened steel first gear is coupled with hardened steel ball bearings to eliminate heat and increase the lifespan.
Since the new model 7R gearboxes are sturdy and durable, you don't need to buy a new one when upgrading the Power Wheels vehicle. That lets you upgrade and improve its performance without breaking the bank.
Step-by-Step Guide to Upgrading a Power Wheels Gearbox
For this process, you'll need:
- Two hardened steel first gears
- A screwdriver
- Power drill
Here are the steps to follow:
- Overturn the ride-on car on a flat surface such as pavements, front yard, or garage floor. Ideally, it's best if you work in a well-lit area.
- Remove the tires. Remove the axle cover by popping it open with a screwdriver to access the axle retainer nut.
- Remove the axle retainer nut. The nut is held in place with a single screw. Loosen the screw with a power drill or the screwdriver. Pull the retainer nut from the axle.
- Pull the tire loose. Removing the retainer nut frees the tire, and you can pull it from the axle.
- Pull off the other tire. With one tire off, you can pull the remaining tire from the Power Wheels while still attached to the axle. That's a more convenient option than working both tires loose.
- Unscrew the protective covering. With the tires removed, you have free access to all the screws holding the cover in place. Work each of them loose with the screwdriver or the power drill. The number of screws varies between Power Wheels models but will be at least eight of them.
- Remove the protective covering. With the screws removed, lift off the cover, and place it on the floor. Be sure to put it in a safe place as it is made of fragile plastic.
- Remove the gearboxes. With the cover and axle removed, the gearboxes are visible and accessible. You can lift them from their mounting and disconnect them from the motor.
- Disconnect the motor. Each motor is joined to the gearbox by a pair of screws. Work them loose with the screwdriver or the power drill and repeat on the other gearbox.
- Open the gearbox casing. Most gear casings come with four screws. Work each of them loose and place them in a safe place. Depress the safety clips around the edge of the case, then remove the cover to reveal the gears.
- Remove the gears. Inside the gearbox, the gear wheels are stacked in sequence, and each gear wheel is attached to a steel shaft. The final drive or the fourth gear is the largest and sits atop the rest. The third gear or the secondary drive gear is second in line and is also the second-largest. The second gear comes third and sits on top of the first gear. The first gear lies on the gearbox casing and is the smallest of the bunch.
- Clean the gearbox. Wipe clean the gearbox to remove any grime and plastic shavings from stripped gears to ensure the gears' seamless operation.
- Replace the first gear. Replace the stock first gear with the hardened steel gear. If you made a careful choice of replacement gear, it should fit snugly on the existing pin.
- Replace the rest of the gears. Place the second, third, and final drive gear in that order on their respective shafts.
- Grease the gears. Apply a layer of grease on each of the gear wheels to reduce friction and ensure smooth rotations.
- Test the gears. Rotate the final drive gear all the way to make sure that the gears rotate freely without sticky points.
- Reassemble the gearbox. Place the cover back on and snap the safety clips closed. Attach each of the screws and ensure the gearbox is well-tightened.
- Repeat the process with the other gearbox and replace the stock first gear with a hardened steel one.
- Reattach the gearbox to the motor. Once the gearbox is safely locked, it's time to reattach the motor. Align the two pieces and run each of the two screws through them and screw it tight.
- Fix the upgraded gearbox into its housing. Drop the gearbox into its mounting and ensure the motor returns to its position as well. Repeat the process with the other gearbox.
- Fix the protective cover. Replace the protective bottom cover and screw it in place. Be sure to tighten the screws properly to avoid them coming loose when the Power Wheel ride-on car is in motion.
- Reattach the tire with the axle. Fix the tire still attached to the axle by pushing the axle through the gearbox mount. Attach the retainer nut, fix the screw tightly in place, and put the axle cover.
- Fix the remaining tire. Attach the remaining tire to the axle and lock it in place with the retainer nut, then attach the axle cap.
- Test drive the upgraded ride-on vehicle. Flip back the car upright and take it out for a spin.
Common Gearbox Problems in Power Wheels
The biggest tell-tale sign that a ride-on car has a gear problem is the noise. Power Wheels cars emit a grinding sound indicates a problem with the gears.
Remove the tire on the side that's emitting the grinding noise and inspect the gearbox for stripped gear wheels.
If you have one gearbox with stripped gears, chances are even the other one isn't too far behind. Inspect each of them both and replace any broken gear wheels.
External influence is almost always the leading cause of gearboxes failure. If you merely replace the broken gears but don't fix the problem, you'll reencounter the same issue later.
Here are some of the common ways that gearboxes sustain damage:
Melted Gearbox Casing Behind the Final Drive Gear
Having a melted gearbox casing behind the final drive gear occurs if excess pressure or uneven pressure is pushing against the fourth gear. There are three major causes of this type of damage – bent axle, damaged axle mount frames, and modified tires.
Melted Gearbox Casing Behind the First Drive Gear
When the first gear's spinning action heats the shaft, the hot pin burns through the plastic casing. The beam heats up because of old grease, debris buildup, and lack of lubricant in the gearbox. Replacing the stock plastic first gear with a steel gear with ball bearings eliminates the heat buildup.
Stripped First Gear
The first gear is the weakest link in a Power Wheels gearbox. It's the first to go when you modify a ride-on can by adding more power. If each tooth is stripped in half, the pinion gear isn't center-aligned with the first gear. If the teeth are stripped at an angle, the motor wasn't evenly placed and bolted to the gearbox. When only a few of the teeth are affected, the gearbox experienced a sudden jolt.
If all the gear's teeth are stripped, the Power Wheels ride-on could be having all the problems mentioned above.
Replacing the stock plastic first gear with a hardened steel variety coupled with hardened steel pinions solves the problem and prevents a recurrence. Installing a brake reduction module reduces the wear and tear of the gears.
Broken Teeth on Gears 2, 3, and 4
Damage to these three gear wheels results when the gearbox is subjected to a sudden jolt when the vehicle is in motion. Typically, this happens when a ride changes the Power Wheels' direction without coming to a complete stop.
It also happens when the rid-on car rams into an immovable object. With proper care and handling, Power Wheels' gears can handle 775 motors coupled with 24 volts.
Stripped Pinion Gear
Pinion gears sustain such damage if they're matched with the wrong shape or material. If installing a hardened steel first gear, you must match it with a hardened steel pinion. Using standard metal pinion is counterproductive because hardened steel is tough and will shear through softer metals.
Such considerations aren't necessary when using stock first gear since it's compatible with all pinions.
You must ensure the pinions have the correct pitch – the shape of the tooth – as it affects compatibility.
The shape of the pinion teeth matters because it affects how the two parts fit together. Similarly, shaped teeth ensure the two pieces fit perfectly and eliminate wear and tear.
With the 7R gearbox, you can change the pinion tooth count and the range of compatible tooth count if printed on the casing. Using a bigger pinion gear results in a tight mesh that strains the motor. When the mesh is too tight, the first gear melts or strips or causes the engine to fail.
What You Need To Know About Power Wheel Gearboxes
The current Power Wheels gearbox generation (7R) is superior to the previous models (#7), which are no longer in production.
You can tell two apart by the markings stamped on the gearbox casing and the output color.
The 7R has different sized internal shafts, a sturdier nylon case, thicker final output gear, multiple numbers, and a hole that denotes the internal gear number. They also have a white output shaft.
It also comes with different mounting holes for 550 and 775 motors, making for easy upgrades even though Power Wheels doesn't produce cars with 775 engines. The two motors have different sizes hence have different screw locations on the gearbox housing.
The #7 gearboxes only have one number stamped on the gear housing to show the motor pinion size. They also have an orange output shaft.
Quick Facts About Gearboxes
There are three varieties of 7R gearboxes – 15-16-17, 18-19-20, and 21-22-23.
All Power Wheels come off the assembly line with a dual-speed setting – 2.5/5 mph, but the gearboxes are different to accommodate various tire sizes. Cars such as Mustangs have larger pinions and are paired with the faster 21-22-23 gearboxes. Dune Buggy and other vehicles with larger tires have smaller pinions and are paired with the slower 15-16-17 gearboxes.
All 7R gearboxes are identical save for the position of the first gear. A hole denoting the location of the first gear is punched in the gearbox housing.
The first internal gear location variation allows the gearbox casing to accommodate the different types of pinion gears.
That ensures even the larger motor pinion gear aligns perfectly with the first gear. That allows users to swap all the four Power Wheels gears from one 7R gearbox housing to another without compromising functionality.
Since a pinion gear position is fixed, the motor pinion gear must match the gearbox casing. For instance, you must use a 22t aftermarket pinion with a 21-22-23 gearbox casing. You can't fit a slow 15-16-17 slow gearbox casing with a 22t pinion gear.
Power Wheels uses a pinion gear pitch that's not available in the aftermarket. A 15-16-17 gearbox will ship from the factory with a 15, 16, or 17 pinion gear. But when purchasing an aftermarket pinion for this gearbox, you must get the middle pinion, which in this case would be 16t.
All the gears in a Power Wheels gearbox are vulnerable to wear and tear and will often break. The smallest gear wheels are the most susceptible to breaking than the larger ones.
Avoid Breaking Power Wheels' Gears
The 7R factory Power Wheels gearboxes are the best because they are strong and durable, and the aftermarket models don't measure up to them.
Driving a Power Wheels car on uneven terrain with bumps, ruts, and sudden drops is the fastest way to break plastic gears because it causes torque spikes.
Installing rear rubber traction isn't recommended because it leads to gear failure by overheating the motors. It also increases the chances of the vehicle rolling over.
Always inspect the gearboxes to ensure the gear posts are well greased, especially on the first gear.
Since all internal gears in a 7R gearbox are identical, it's advisable to buy a spare gearbox and use it for parts when you need replacement to lower costs.
Gear failure is common when dealing with Power Wheels cars, especially those with motor and battery upgrades.
However, the frequency of gear problems depends on the level of abuse the car endures. Overvolting without ESC, overloading, off-road riding, and rear rubber tire are the most significant culprits.
Stripped gears shouldn't sound the death knell on a Power Wheels ride-on car, regardless of age. A quick gearbox replacement can have the car up and running again. The replacement process is quick and straightforward and doesn't call for special tools or engineering skills.
Coupling Power Wheels gearbox upgrades with other modifications is an excellent way to improve a ride-on car's performance. The process is simple enough, and it entails replacing the stock plastic first gear with a hardened steel gear.
Hardened steel first gears are hard wearing and aren't prone to gear stripping as the plastic variety.