Electric scooter hardware: tightening torques, thread lockers, and inspections

If the screws on your electric scooter are loosening, it's almost always due to one of these reasons: they weren't tightened to the correct torque, the parts have settled after assembly, or vibrations have compromised an assembly that should have used thread locker. The solution involves three steps: tighten the screws to the torque specified by the manufacturer using a torque wrench; use the correct thread locker in the appropriate places; and check them regularly. This guide explains each of these steps. The torque values depend on each specific model and can be found in the manufacturer's manual.

Why does a screw come loose?

A tightened screw acts like a very stiff spring: when tightened, it stretches slightly, and it is this tension that holds the parts together. As long as the tension is sufficient, the friction within the threads and under the head prevents the screw from turning. It loosens when this tension decreases:

• Insufficient tightening: The initial tension is too low, and vibrations cause the screw to gradually loosen.
• Settling: After the first few kilometers, the surfaces in contact (paint, anodization, washers) compress slightly, which reduces the tension accordingly.
• Vibrations and shocks: A rigid and fast electric scooter transmits a lot of vibrations to its fasteners.
• `Temperature variations: Parts expand and contract, particularly around the brakes and motors.`

Conversely, overtightening is not a safety measure. It can stretch the screw beyond its limits, strip the threads of an aluminum part, deform a component, or crack a collar.

Tighten to the correct torque

The torque is the rotational force applied to the screw, expressed in Newton-meters (N·m). The manufacturer calculates it to achieve the correct tension without damaging the components.

• **Where to find the value:** in the scooter's manual, on the part's documentation, or sometimes engraved directly on the part itself (stem collar, caliper). We do not provide general values: they depend on the screw diameter, its material, and the assembled parts.
• What tool is needed?: A torque wrench suitable for the target torque range. A smaller wrench for small screws, and a larger one for axle nuts.
• Condition: Clean threads. Please follow the manufacturer's instructions regarding lubrication: a lubricated bolt and a dry bolt will not achieve the same torque.
• What order?: For a part held by multiple screws (disc, half-rim, collar), tighten in a criss-cross pattern, in several passes, until the final torque is reached.

The brake cable: when to use it, which one to choose, and how to install it

Threadlocker is a liquid adhesive that hardens within the threads, protected from the air, once the screw is tightened. It fills the gap between the screw and its threads, preventing the screw from loosening due to vibrations.

Manufacturers often differentiate these forces by color, but the conventions vary from brand to brand: refer to the label. To apply it correctly:

1. Clean and degrease the threads of the screw and the threaded hole
2. Apply a few drops to the threads that will be engaged, not to the entire screw
3. Tighten to the specified torque, then wait for the recommended curing time before riding.

Where to avoid it

• On screws that already have a factory-applied product, such as many brake disc screws, a thread locker is often pre-applied.
• On the screws that the manufacturer specifies should be greased.
• Within the plastic components: certain brake pads can degrade certain types of plastic.
• For hydraulic brake components and hose fittings, unless otherwise specified by the brake manufacturer.

Aluminum and titanium: two special cases

Aluminum is easy to thread, but its threads are more prone to stripping than those of steel. Always start a screw by hand for the first few turns to avoid cross-threading, and never exceed the specified torque. A stripped thread can often be repaired with a threaded insert (a helical steel insert), which requires a workshop procedure.

Titanium has a tendency to "gripe": under high pressure, two surfaces can weld together in places, and the screw can become locked. The manufacturer of the part will indicate whether a threadlocker is required and which one to use. For our titanium steering column kits, we recommend using a torque wrench, as indicated in the product sheet for the Teverun Fighter 11, for example; our guide on titanium steering columns details the assembly process.

Regularly check

• After assembly, re-check the torque after the first few kilometers: this is when the parts settle.
• Every month, check the safety screws: wheel axles, calipers and rotors, stem and handlebars, folding mechanism and column, suspension axles. These are part of our monthly maintenance checklist.
• Mark the important screws with a line of paint or a marker that crosses the head and the component. A misaligned line indicates a screw that has been turned.
• Replace a damaged, rusted, or stripped screw with a screw of the same grade and length.

A screw that constantly loosens in the same spot, even after being tightened properly, is often a symptom of a worn-out part: this is the case with the original steering column components, which can develop play, as explained in our guide on steering column play on electric scooters. Our steering components and machined parts are in the electric scooter mechanical parts category.