The Fox Float 40 Factory eMTB fork is engineered for aggressive downhill and enduro performance, offering e-bike-specific durability, tunability, and plush travel. Maintaining this high-performance suspension fork ensures consistent handling, control, and longevity of the internal components. This guide covers installation, adjustment, routine maintenance, and common troubleshooting procedures to help riders keep their Float 40 Factory in optimal condition without a trip to the bike shop.

Tools Required

• 6 mm and 8 mm Allen wrenches [paid link]
• Torque wrench [paid link] with Nm settings
• Suspension pump
• 10 mm socket wrench
• Fox 20wt Gold oil and appropriate grease
• Clean microfiber cloths
• Isopropyl alcohol
• Pick set for seal installation
• Torque table from Fox service manual

Installation Procedure

Installing the Float 40 Factory fork requires precise alignment and careful torqueing to ensure structural integrity and performance. Start by placing the fork into the headset with a fully prepped steerer tube. The crown race must be pressed in completely, and the steerer should be cut only after confirming the desired handlebar height.

Use a torque wrench [paid link] to tighten the stem bolts in sequence, following manufacturer specs. Next, secure the brake caliper using the post mount standard. Ensure rotor alignment and caliper centering to prevent brake rub. The thru-axle must be threaded in fully and torqued to specification, as it also preloads the lowers onto the stanchions.

Ensure no lateral or vertical movement exists after installation. A test compression stroke should feel smooth and resistance-free if properly assembled.

Adjusting Suspension Settings

The Float 40 Factory includes advanced adjustments to fine-tune damping and air spring characteristics for rider weight and terrain demands. Begin with setting the sag using the suspension pump. Inflate the EVOL air spring to achieve approximately 15-20% sag while the rider is in full gear.

Low-speed compression (LSC) and high-speed compression (HSC) adjustments are available via the dials on the top right fork leg. Start with Fox’s baseline settings based on rider weight and trail type, then tune incrementally. Rebound damping, found on the bottom of the fork leg, should be adjusted so the fork returns quickly but not harshly after compression.

Volume spacers inside the air spring allow progressive spring curve tuning. Removing spacers increases linearity, while adding them increases bottom-out resistance. This setup is especially useful for heavier or aggressive riders.

Routine Maintenance and Service Intervals

Routine maintenance is critical for long-term performance. Fox recommends performing a lower leg service every 40 hours of riding. This includes draining the old bath oil, removing and cleaning the dust wipers and foam rings, and replenishing with fresh 20wt Gold oil.

Wipe the stanchions and seals after every ride to prevent dirt from migrating inside. Regular inspection for oil weeping, bushing play, or loss of travel will help catch early signs of wear. For full damper or air spring service, riders should follow Fox’s 125-hour service protocol or sooner in wet and muddy conditions.

Avoid pressure washing the fork or using strong degreasers near seals and adjusters. Always use suspension-specific lubricants and maintain proper torque values during reassembly.

Troubleshooting Common Issues

Performance issues with the Float 40 Factory fork often relate to improper setup or contamination. If the fork feels harsh or fails to return smoothly, check air pressure and rebound damping. Excessive stiction can indicate dry seals or worn bushings.

A noisy top-out clunk generally suggests inadequate rebound damping or low oil volume in the lowers. Inconsistent compression damping may result from damper degradation or air ingestion in the bladder. In these cases, a full damper service is required.

If travel feels reduced, inspect for negative air chamber issues or trapped air in the lowers. Releasing the pressure and cycling the fork slowly can reset the air equalization. Brake vibration under load may indicate loose axle preload or poorly aligned brake calipers.

Optimizing Performance for eMTB Use

The Float 40 Factory is tuned for heavier eMTB builds, but riders can further enhance its feel. Heavier riders may benefit from slightly higher air pressure and more compression damping. To reduce brake dive on steep descents, consider increasing LSC a few clicks while keeping HSC balanced to maintain small-bump sensitivity.

Dual crown stiffness can be exploited by fine-tuning cockpit height and offset to match rider preference. Consider running a slightly firmer front end to complement heavier rear-suspension loads common on eMTBs. Optimizing rebound and volume spacers ensures traction and control on loose or rocky trails.

Compatibility and Component Integration

The Float 40 Factory is compatible with both Boost 20×110 mm front hubs and standard 29-inch wheels. The fork accepts rotors up to 223 mm and is designed to integrate with Fox’s proprietary fender system.

The GRIP2 damper inside the fork pairs seamlessly with most modern eMTB drivetrain and braking systems. Ensure the front-end geometry is matched correctly when swapping to or from other fork models to maintain intended ride characteristics.

When used with Fox X2 or DHX2 rear shocks, the Float 40 ensures balanced damping front to rear. Pay attention to axle-to-crown length and rake if considering mixing brands or switching from a single crown fork.

Comparing the Float 40 Factory to Similar Forks

Against the RockShox BoXXer Ultimate, the Float 40 Factory provides more precise adjustability via the GRIP2 damper and EVOL air spring. The BoXXer may offer slightly better small-bump compliance out of the box, but the Float 40 outperforms in tunability and stiffness.

Compared to the Öhlins DH38 m.1, the Float 40 delivers a more consistent support feel, especially when pushed aggressively in high-load conditions. Riders seeking a plush feel may prefer Öhlins, but the Fox fork holds a better line under repeated hard hits.

For enduro-focused riders, the Float 38 offers a lighter, single-crown alternative, but sacrifices stiffness and brake torque resistance found in the dual crown 40 Factory.

FAQs

Q1: How often should I service my Float 40 Factory eMTB fork?
A lower leg service is recommended every 40 riding hours, and a full air/damper service every 125 hours or annually.

Q2: What is the correct sag for the Float 40 Factory fork?
Sag should be set between 15–20% of the total travel when the rider is in full gear, ideally using a suspension pump.

Q3: Can I install the Float 40 Factory on a regular mountain bike?
It is designed for eMTB and downhill use with a dual crown structure, so it is not suitable for standard trail or XC bikes due to weight and geometry constraints.

Q4: What does the GRIP2 damper offer over simpler designs?
The GRIP2 provides independent high/low speed compression and rebound adjustability for fine-tuning performance in a wide range of trail conditions.

Q5: Is it necessary to use Fox oil and grease products?
Yes, using the specified Fox suspension fluids ensures compatibility with seals and internal components for long-term reliability.

Q6: How do I fix a harsh ride feel in the Float 40 Factory?
Check for over-inflation, excessive compression damping, or dry seals. Perform a lower leg service if stiction persists.