The Fox Float 40 Factory eMTB suspension fork is a high-performance downhill and enduro-specific component designed for electric mountain bikes. It features advanced damping systems, robust stanchions, and an air spring tuned for aggressive riding. Despite its engineering quality, users can encounter setup or performance issues that affect ride quality and durability. This guide provides detailed, technical troubleshooting information for riders and mechanics dealing with the Float 40 Factory eMTB model.

Tools Required

• Torque wrench [paid link] (Nm calibrated)
• Shock pump
• Allen key set (1.5mm–8mm)
• Suspension oil (Fox-specified weight)
• Clean rags and degreaser
• Suspension grease
• Seal driver and dust wiper tool
• Fox digital tuning guide (optional)

Initial Setup and Sag Issues

Incorrect sag setup is one of the most common issues faced with the Float 40 Factory eMTB. This fork is air-sprung, so its initial performance is highly dependent on achieving proper sag.

Sag should be between 15%–20% of total travel. On the 203mm Float 40 Factory, this equates to roughly 30mm–40mm of sag.

Problems arise when:

• Too much air pressure results in minimal sag, leading to harsh ride feel and poor small bump compliance.
• Too little air pressure causes excessive sag, bottom-outs on moderate terrain, and poor handling.

To resolve this:

• Set the rider’s body weight including gear.
• Use a shock pump to adjust air pressure incrementally.
• Cycle the fork fully after each adjustment.
• Measure sag at zero travel by using a zip tie on the stanchion.

Compression Damping Inconsistencies

The Float 40 Factory features the GRIP2 damper with High-Speed Compression (HSC) and Low-Speed Compression (LSC) adjustments. Improper compression settings can cause symptoms like brake dive, lack of support in berms, or a harsh front end.

Common issues include:

• Over-damping from too much HSC can feel locked out over high-speed hits.
• Under-damping from too little LSC results in excessive movement under cornering and pedaling forces.

A balanced starting point is 8 clicks out from fully closed on both HSC and LSC. Fine-tune based on rider weight, riding terrain, and feedback.

If changes to compression settings don’t yield performance improvements:

• Inspect oil levels and condition inside the GRIP2 cartridge.
• Check for contamination or emulsion in damping fluid.
• Consider servicing the damper or sending it to a certified Fox service center.

Rebound Misbehavior

Incorrect rebound damping can either pack down the fork over successive hits or rebound too quickly, causing instability.

Signs of rebound issues:

• Too slow rebound: fork stays compressed on repeated hits.
• Too fast rebound: fork extends too quickly and feels bouncy.

Start tuning from 10–12 clicks out (from fully closed) on rebound. Always adjust in 1-click increments, and test in real trail conditions.

Ensure the rebound adjuster knob turns smoothly. If it sticks or feels inconsistent, internal rebound circuits may be contaminated or need servicing.

Oil Leaks and Seal Failure

The Float 40 Factory uses a closed damping system and air spring sealed with low-friction SKF wipers and foam rings. Oil leaks from either leg may suggest:

• Overfilled lower leg bath oil leading to overflow.
• Damaged dust wipers letting dirt inside, which deteriorates seals.
• Incorrect installation of foam rings causing inconsistent lubrication.

Regular lower leg service every 30–50 hours prevents these issues. Use only Fox-recommended 20wt Gold or equivalent suspension oil.

Noise and Stiction

If the fork produces creaking, clicking, or exhibits stiction:

• Creaking at the crown area often indicates a press-fit issue between the stanchions and steerer. This typically requires factory repair.
• Clicking may originate from loose axle assembly or insufficiently torqued pinch bolts.
• Stiction is usually due to contaminated or dry seals. Lower leg service with fresh grease and oil resolves this.

Avoid using non-suspension-specific lubricants on stanchions, as they can degrade seals.

Travel and Spring Curve Misconfiguration

Some riders find their Float 40 lacks mid-stroke support or bottoms out too easily. These symptoms are commonly linked to improper volume spacer configuration.

Fox includes tokens that reduce air volume to make the spring curve more progressive. If bottoming out occurs too often:

• Add a volume spacer. Each token reduces air volume and increases ramp-up at the end of travel.
• Maximum allowable tokens depend on rider weight and desired travel feel, but usually ranges from 2–5.

Ensure spacers are installed correctly to prevent rattling or air chamber issues.

Brake Dive Under Load

Brake dive can be particularly problematic on eMTBs due to their added weight. Excessive fork dive under braking can reduce traction and steepen the head angle dangerously.

Solutions include:

• Increasing LSC to control compression under braking forces.
• Reducing sag slightly by increasing air pressure.
• Installing an additional volume spacer to reduce mid-stroke wallow.

Brake dive cannot be completely eliminated but can be controlled through these adjustments.

Overheating During Long Descents

The GRIP2 damper is highly resistant to fade, but extended descents can still cause performance fade due to oil expansion or cavitation.

If performance deteriorates after long downhill runs:

• Check for signs of aeration in oil during service.
• Make sure foam rings are adequately saturated and dust wipers are not dry.
• Schedule more frequent oil changes in hot climates or high-frequency descents.

Compatibility Considerations

The Float 40 Factory eMTB fork is built for DH and long-travel eMTBs with a 20mm thru-axle and 203mm rotors.

Key compatibility notes:

• Fork must be paired with 1.5″ tapered headtube frames.
• Ensure axle-to-crown and rake are compatible with frame geometry.
• Only use brake calipers rated for 203mm rotor spacing or use proper adapters.
• Works best with Fox rear shocks tuned for similar damping response to match front-end behavior.

Performance Optimization

Optimizing the Float 40 Factory for personal riding style includes:

• Matching rebound and compression tuning to terrain type.
• Using telemetry tools (optional) to record stroke usage and behavior.
• Performing regular suspension analysis to keep components fresh.

Factory tuning support from Fox or third-party tuners can refine internal shim stacks and spring curves for elite riders.

Comparison with Similar Forks

Compared to other forks in its class, like the RockShox BoXXer Ultimate or Öhlins DH38 m.1, the Fox Float 40 Factory eMTB stands out for:

• Adjustable GRIP2 damper with superior adjustability.
• Lower leg bleeders and air release valves for improved sensitivity.
• Lower friction from SKF seals and Kashima coating.

The Float 40 provides more trail feedback than the BoXXer but requires more frequent tuning for best results.

Conclusion

The Float 40 Factory eMTB is a precision component requiring proper setup and care to function optimally. Riders experiencing performance degradation or handling quirks should begin with basic checks of air pressure, damping settings, and sag before moving to advanced diagnostics. With regular maintenance and attention to tuning, the fork will deliver reliable, top-tier downhill and enduro performance on electric mountain bikes.