The Fox Float 40 Factory eMTB suspension fork is engineered for aggressive enduro and downhill e-mountain bike riding. Its high-performance damping system and adjustability make it a top-tier choice among experienced riders. Regular maintenance, especially oil changes, is crucial to keeping this fork operating smoothly and to prevent premature wear of internal components. This guide provides step-by-step instructions for performing an oil change on the Float 40 Factory eMTB fork, along with detailed tips on troubleshooting, performance optimization, and compatibility considerations.
Tools Required
- 10 mm socket wrench
- Torque wrench [paid link] (with Nm setting)
- Flat-blade screwdriver
- Drain pan
- Isopropyl alcohol (for cleaning)
- FOX 20wt Gold suspension fluid
- Syringe or oil volume tool
- Clean lint-free rags
- Soft mallet
- Pick tool
- Safety gloves and goggles
Understanding the Float 40 Factory eMTB Fork
The Float 40 Factory is an air-sprung, dual-crown fork designed for aggressive terrain. It features a GRIP2 damper, high/low-speed compression and rebound adjustments, and Kashima-coated stanchions for smooth travel. The fork’s design supports the additional load and braking forces of eMTBs, making it stiffer and more robust than traditional mountain bike forks.
When and Why to Change the Suspension Oil
Fox recommends changing the oil every 30–50 hours of riding for optimal damping and lubrication performance. Over time, oil can become contaminated with dirt and metal particles, reducing the fork’s responsiveness and increasing internal friction. Regular oil changes restore the fork’s smooth feel, maintain damper consistency, and extend component life.
Preparing the Fork for Oil Change
Before starting, remove the fork from the bike and clean the exterior thoroughly to avoid contamination. Work in a clean, well-lit environment. Position the fork vertically in a repair stand with the lowers pointing down.
Disconnect the front brake caliper and remove the front wheel. Remove the thru-axle and slide the wheel out carefully to avoid damaging the fork dropouts.
Draining the Old Suspension Oil
To access the damper and air spring:
- Remove the rebound adjuster knob using a 2 mm hex key if present.
- Use a 10 mm socket to remove the lower leg bolts.
- Gently tap the bolt ends with a soft mallet to disengage the internal shafts.
- Drain the oil from both legs into a pan by sliding the lowers off the stanchions.
Inspect the removed oil for metal shavings or unusual discoloration, which could indicate internal wear or seal damage.
Cleaning Internal Components
Clean the inside of the lowers and stanchions using isopropyl alcohol and a lint-free rag. Ensure no residue or debris remains. Use a pick tool to inspect and clean around the oil seals carefully. Do not use sharp tools near the Kashima-coated stanchions.
Replace the foam rings and oil seals if they show signs of wear or contamination. This ensures a better seal and optimal lubrication retention.
Refilling With Fresh Suspension Oil
Reinstall the lowers partway onto the stanchions. Using a syringe, inject FOX 20wt Gold fluid:
- 40 ml into the air spring side
- 50 ml into the damper side
Slide the lowers completely into position, ensuring a tight and even seal. Reinstall the lower bolts and torque them to 5.1 Nm. Replace the rebound knob if applicable.
Cycle the fork through its travel a few times to distribute the oil evenly and eliminate air pockets.
Reassembly and Final Check
Wipe down any excess oil. Reinstall the fork onto the bike, ensuring all bolts are torqued to the manufacturer’s specifications. Reinstall the brake caliper, thru-axle, and front wheel. Compress the fork several times to ensure smooth movement and proper damping.
Test the fork on a short ride, checking for leaks, irregular compression, or knocking noises. Adjust rebound and compression settings as needed based on rider weight and terrain.
Common Troubleshooting After Oil Change
If the fork feels harsh or doesn’t fully compress:
- Ensure correct oil volume was added.
- Recheck lower bolt torque.
- Inspect for trapped air in the lowers and re-bleed if necessary.
If you notice oil leaking from the seals:
- Confirm seal condition and seating.
- Check for damage to the stanchions that may affect sealing.
Unusual rebound speed or spongy feel may indicate incorrect damper reassembly or contamination.
Customization and Performance Optimization
To fine-tune performance after an oil change:
- Adjust high/low-speed rebound and compression dials according to rider preference.
- Add or remove air volume spacers (tokens) to tune progression.
- Use a digital shock pump to precisely set sag based on rider weight and style.
Regular tuning alongside oil changes ensures optimal performance tailored to the specific trail demands and eMTB load.
Compatibility with Other Components
The Float 40 Factory eMTB is compatible with Boost front hubs (110mm) and 29” wheelsets. It pairs well with modern 12-speed drivetrains and is fully compatible with integrated front fenders and electronic suspension systems, such as Fox Live Valve.
Ensure any aftermarket parts, such as crown race adapters or axle upgrades, are verified for dual-crown 40mm stanchion forks.
Comparison With Similar Fork Models
Compared to the Fox 38 Factory, the Float 40 offers:
- Increased stiffness due to dual-crown construction
- Higher oil volume capacity for longer descents
- Superior damping control under heavy braking
However, the 38 is more suited to enduro riders seeking a lighter, more maneuverable option. The RockShox BoXXer Ultimate is a comparable alternative, but the Float 40 excels in tunability and Kashima-coated performance.
FAQs
1. How often should I change the oil in my Float 40 Factory eMTB fork?
Every 30 to 50 riding hours for consistent damping and longevity.
2. Can I use any suspension oil for this fork?
No. Only FOX 20wt Gold oil is recommended for proper lubrication and seal compatibility.
3. What happens if I overfill the fork oil?
Overfilling can restrict travel and cause pressure buildup, affecting performance and potentially damaging seals.
4. Is it necessary to replace seals during every oil change?
Not always, but inspect seals for wear. Replace them if they show signs of damage or leaking.
5. Can I perform an oil change without removing the fork from the bike?
It is strongly recommended to remove the fork to ensure cleanliness and proper reassembly.
6. What tools are essential for a DIY fork oil change?
A torque wrench [paid link], 10 mm socket, syringe, and the correct suspension oil are crucial.