The Float 36 Rhythm eMTB fork from Fox is a robust and responsive suspension solution designed specifically for electric mountain bikes. Over time, like all high-performance components, it requires a full rebuild to maintain its precision and functionality. This guide offers a thorough, technical walk-through of the rebuild process, including preparation, disassembly, replacement, reassembly, and troubleshooting. Whether you’re an experienced mechanic or an advanced DIY rider, following this structured guide ensures optimal performance from your Fox Float 36 Rhythm.
Tools Required
- 10mm, 26mm sockets
- Torque wrench [paid link] (in Nm range)
- Seal driver kit for 36mm stanchions
- Pick tool and flat-blade screwdriver
- Allen keys [paid link] (4mm, 5mm)
- Clean lint-free cloths
- Suspension-specific grease (e.g., Slickoleum)
- Isopropyl alcohol (minimum 90%)
- Suspension oil (Fox 20wt Gold and Float Fluid)
- Oil measuring syringe or graduated cylinder
- Rubber mallet
- Work stand (optional but recommended)
Preparing the Fork for Rebuild
Before any service, clean the fork thoroughly. Remove the front wheel, disc brake caliper, and brake hose if it interferes with access. Ensure the work area is well-lit and free from contaminants. Position the fork upright in a secure stand to facilitate a safe rebuild.
Release all air pressure from the fork using the Schrader valve under the top cap on the left leg. This is a critical safety step to avoid injury during disassembly. Then remove the rebound knob on the lower right leg using a 2mm hex wrench.
Disassembling the Fork
Start by removing the lowers. Using the 10mm socket, loosen the foot nuts on the bottom of both legs but do not fully remove them yet. Use a rubber mallet to gently tap the nuts to break the inner seal and free the lowers from the damper and air spring shafts.
Once the seal has broken, remove the foot nuts completely and carefully slide the lowers off. Be prepared for some oil drainage, so have a waste oil pan ready.
Next, remove the air spring assembly. Using a 26mm socket, unscrew the top cap on the left leg. With a 5mm hex, remove the bolt at the bottom of the leg to extract the air shaft. Inspect all internal components for wear, particularly the shaft seals and piston rings.
On the right leg, the damper side, remove the top cap using a 26mm socket as well. If performing a full service, the damper cartridge must be removed and bled, which requires advanced tooling. Otherwise, you can focus on cleaning and inspecting the damper rod area and replenishing bath oil.
Replacing Seals and Lubricating Internals
Remove the old wiper seals and foam rings from the fork lowers using a seal pick. Clean the inside thoroughly with isopropyl alcohol and inspect for scratches or damage.
Soak new foam rings in Fox 20wt Gold oil and install them into the lowers. Use a seal driver designed for 36mm stanchions to press in the new wiper seals. Apply a light coating of suspension-specific grease to both the seals and the stanchion surfaces.
Grease the air shaft and apply Float Fluid around the air piston. Insert the air spring back into the left leg and torque the lower bolt to manufacturer spec (usually around 5.7 Nm). Then reinstall the air top cap and torque to 21.7 Nm.
Reassembling the Fork
Slide the lowers carefully over the stanchions, aligning the shafts with their respective holes. Pause just before full insertion to add the correct volume of bath oil into each leg—typically 20cc of Fox 20wt Gold per side.
Push the lowers on fully and reinstall the foot nuts, torquing them to 5.7 Nm. Replace the rebound knob, ensuring proper indexing. Reinflate the fork to your baseline pressure and check for leaks or abnormal stiction.
Post-Rebuild Testing and Setup
After reassembly, compress the fork fully several times to ensure smooth travel and even oil distribution. Reinstall the fork on the bike, reconnect the brake caliper, and reattach any removed components.
Check air pressure, sag, and rebound settings. The Float 36 Rhythm typically runs higher pressures on eMTBs due to the added weight. Dial in compression and rebound according to rider weight and terrain preference.
Troubleshooting Common Issues
- Persistent oil leaks: This often indicates improper seal seating or overfilling with bath oil. Recheck seal installation and oil volume.
- Harsh top-out: Insufficient Float Fluid or trapped air in the negative chamber can cause a harsh rebound at full extension.
- Sticky travel: Most likely due to dry seals or inadequate grease. Ensure seals and foam rings are well-lubricated.
- Excessive play or creaking: This may stem from worn bushings within the lowers or insufficient torque on the foot nuts.
Customization and Performance Optimization
For riders seeking enhanced performance, consider upgrading internal parts such as the air spring assembly to Fox’s GRIP2 damper for more adjustability. Volume spacers can also be inserted into the air chamber to alter the fork’s spring curve, making it more progressive for aggressive descending.
In addition, installing low-friction aftermarket seals and tuning oil weights for different rebound characteristics can yield a more responsive fork.
Compatibility with Other Drivetrain Components
The Float 36 Rhythm eMTB fork is primarily concerned with front-end performance but interacts indirectly with drivetrain elements. Ensure the axle spacing and rotor size match your hub and brake system. Additionally, consider drivetrain chain line and drop when making suspension adjustments that significantly alter front-end height.
It is not compatible with Fox’s older 36mm air shafts from prior generations without modification. Always verify part numbers when ordering rebuild kits or replacement dampers.
Comparing the Float 36 Rhythm to Similar Models
Compared to the Fox 36 Performance and Factory series, the Rhythm version uses a simpler GRIP damper instead of the more adjustable GRIP2. The stanchions are also anodized black rather than Kashima-coated, resulting in a marginal difference in friction resistance.
However, the Rhythm is tailored for eMTB use, with a chassis that balances stiffness and weight well. Riders who prioritize simplicity and cost-efficiency will find it ideal, while those seeking high-end adjustability may prefer the Performance Elite or Factory versions.
FAQs
Q1: How often should I rebuild the Float 36 Rhythm eMTB fork?
Fox recommends a full rebuild every 125 hours of riding or annually, whichever comes first.
Q2: Can I use any suspension oil for the rebuild?
Only use Fox 20wt Gold and Float Fluid. Other oils may affect performance and damage seals.
Q3: What torque settings are required for reassembly?
Top caps: 21.7 Nm; foot nuts: 5.7 Nm. Always use a calibrated torque wrench [paid link].
Q4: Is the Float 36 Rhythm compatible with coil conversions?
No, the chassis is not designed for coil spring kits and may void the warranty.
Q5: Can I replace the GRIP damper with GRIP2?
Yes, but it requires purchasing the correct GRIP2 cartridge and potentially modifying the damper side.
Q6: My fork feels harsh after service. Why?
Check air pressure, bath oil volume, and ensure no air is trapped in the negative chamber.