The Fox Float 40 Factory eMTB fork is a high-performance suspension fork tailored for electric mountain bikes. It offers exceptional damping control, fine-tuned adjustability, and rugged performance characteristics suited for aggressive downhill and enduro riding. However, to get the best from this fork, understanding its setup, maintenance, and customization potential is crucial. This guide provides a detailed walkthrough on how to install, adjust, maintain, and optimize the Float 40 Factory for superior ride quality and reliability.
Tools Required
- Torque wrench [paid link] with hex bit set (3mm, 4mm, 5mm, 6mm)
- Shock pump (with PSI gauge)
- Suspension sag measurement tool or ruler
- Suspension oil (Fox 20wt Gold or specified fluid)
- Allen key set
- Suspension grease (Fox Float Fluid or Slick Honey)
- Workstand or bike holder
- Clean rags and isopropyl alcohol
- Lower leg service kit (if servicing lowers)
Installation Overview
Before installation, ensure your frame is compatible with a dual crown fork. The Float 40 Factory requires a 1.5″ tapered head tube and a suitable axle-to-crown clearance for 29″ wheels.
Steerer Tube Preparation
The steerer tube must be cut precisely to match the bike’s head tube stack height and stem clamping area. Use a guide and pipe cutter for accuracy. Install a star nut using a designated star nut setter.
Crown and Stanchion Alignment
Mount the fork ensuring both crowns are torqued evenly and aligned perpendicular to the wheel axle. Use a torque wrench [paid link] to tighten the crown pinch bolts to Fox’s specified torque values (usually 5-6 Nm).
Brake and Axle Setup
Install the brake caliper using the correct adapter for your rotor size. Ensure proper caliper alignment to avoid rotor rub. Mount the front wheel, inserting the 20mm axle and securing it with Fox’s pinch bolt and axle system. Torque all hardware to spec.
Suspension Adjustment for Rider Weight and Style
The Float 40 Factory includes air spring adjustment, compression, and rebound tuning for a personalized setup.
Setting Sag (Air Spring Pressure)
Adjust air pressure based on rider weight and riding style:
- Begin by inflating the EVOL air spring using a shock pump.
- With full gear, mount the bike and compress the fork to settle into sag.
- Measure sag; target 15–20% of total travel (approximately 30–40mm of 203mm).
- Adjust pressure in 5 PSI increments as needed to achieve the target sag range.
High-Speed and Low-Speed Compression Tuning
The GRIP2 damper provides separate high-speed and low-speed compression adjusters:
- Low-Speed Compression (LSC): Controls motion during pedaling and slow compression. Turn clockwise to increase firmness.
- High-Speed Compression (HSC): Handles sharp impacts and fast compressions. Adjust based on terrain roughness.
Rebound Damping
Adjust rebound via the red dial at the bottom of the right leg:
- Start with the factory base setting.
- Slow the rebound for more control (turn clockwise) or speed it up (counter-clockwise) for responsiveness.
- Fine-tune based on terrain feedback and personal preference.
Routine Maintenance and Lower Leg Service
Maintaining the Float 40 Factory eMTB fork extends its performance and lifespan.
Regular Cleaning
Wipe the stanchions after every ride using a clean cloth and alcohol. Inspect for dirt buildup, which can degrade seals and cause wear.
Lubrication Intervals
Add suspension-specific lubricating fluid to the wiper seals regularly. Fox recommends a lower leg service every 30 riding hours.
Lower Leg Service Steps
- Remove the front wheel and release air pressure.
- Remove the lower bolts using a 10mm socket.
- Drain and clean old oil and debris.
- Install new foam rings and seals if worn.
- Add 20wt Gold oil to each leg per Fox specifications (approx. 30cc).
- Reassemble, torque bolts, and re-inflate the air spring.
Troubleshooting Common Issues
Excessive Fork Dive
- Increase air pressure slightly.
- Add volume spacers to reduce air spring progression.
Harsh Ride on Repeated Bumps
- Reduce high-speed compression damping.
- Ensure adequate lubrication in lower legs.
Inconsistent Rebound Feel
- Check for rebound adjuster damage.
- Bleed damper if symptoms persist after external tuning.
Fork Not Returning to Full Travel
- Check for negative air spring imbalance.
- Reset the air chamber by fully deflating and reinflating.
Customization for Performance Optimization
The Float 40 Factory can be customized extensively for performance tuning:
Air Volume Spacers
Adding or removing spacers changes the fork’s progression rate:
- More spacers = More progression (firmer end-stroke)
- Fewer spacers = More linear (plusher feel)
Grip2 Damper Tuning
Advanced riders can revalve or internally tune the GRIP2 damper for specific damping curves, though this requires expertise.
Coil Spring Conversion
Fox offers a coil conversion kit for riders preferring the small bump sensitivity and consistency of a coil spring over air.
Compatibility with Other Drivetrain and Frame Components
The Fox Float 40 Factory eMTB is designed for electric mountain bikes and may not be compatible with non-eMTB frames due to:
- Dual crown configuration requiring larger head tubes
- Specific rotor size clearances (up to 223mm)
- Wide stance potentially interfering with some frame designs
Ensure your headset, stem, and frame accommodate this fork’s dimensions and travel. Verify axle compatibility and rotor size with your braking system.
Model Comparison: Float 40 Factory vs. Fox 38 Factory
| Feature | Float 40 Factory eMTB | Fox 38 Factory |
|---|---|---|
| Travel | 203mm | 160–180mm |
| Intended Use | Downhill / eMTB | Enduro / Trail |
| Stanchion Diameter | 40mm | 38mm |
| Axle | 20mm bolt-on | 15mm thru-axle |
| Adjustability | Advanced (GRIP2) | Advanced (GRIP2) |
| Weight | Heavier (dual crown) | Lighter (single crown) |
Riders seeking pure downhill capability and eMTB strength should prioritize the Float 40. The Fox 38, however, suits aggressive trail riders who value weight savings and versatility.
FAQs
1. How often should I service the Float 40 Factory fork?
Basic cleaning should be done after every ride. Lower leg service is recommended every 30 hours of riding, while a full damper service is ideal every 100–125 hours.
2. Can I use the Float 40 on a non-electric mountain bike?
Technically yes, but it’s overbuilt for non-eMTB use. Its weight and stiffness are optimized for the demands of electric downhill riding.
3. What pressure should I use for the air spring?
Start with Fox’s weight-based PSI chart, then adjust to reach 15–20% sag with full gear. Fine-tune based on terrain and personal preference.
4. What tools are needed for basic adjustments?
You’ll need a shock pump, Allen keys [paid link], and a torque wrench. Suspension-specific grease and oils are essential for service tasks.
5. How do I know if the fork has the right rebound setting?
If the fork feels pogo-like, it’s too fast. If it packs down on repeated hits, it’s too slow. Adjust rebound gradually based on feedback.
6. Is the Float 40 compatible with all brake systems?
It supports most 7” and 8” disc brake rotors with the proper adapter. Always verify caliper and rotor clearance before riding.
Conclusion
Tuning and maintaining your Fox Float 40 Factory eMTB fork is essential for unlocking its full potential. Whether you’re racing downhill tracks or tackling rugged eMTB trails, proper setup and care will ensure optimal performance and durability. From sag and rebound adjustments to full-service intervals, this guide gives you all the knowledge needed to ride with confidence.