The Fox 38 Factory GRIP2 fork is engineered for aggressive trail and enduro riding, delivering unmatched damping performance and front-end control. Over time, regular use will demand a full rebuild to maintain peak functionality. This guide provides a detailed, technical walkthrough on how to properly rebuild the 38 Factory GRIP2 fork for optimal longevity and performance. Each section is tailored to help riders achieve precision and reliability during the rebuild process.
Tools Required
- 6mm and 10mm hex wrenches
- Torque wrench [paid link]
- 2.5mm and 5mm Allen keys [paid link]
- 26mm socket
- Suspension-specific pick set
- Isopropyl alcohol (99%)
- Clean, lint-free rags
- Suspension oil (Fox 20wt Gold and Fox 5wt Teflon)
- Float NA2 volume spacers (optional)
- High-quality suspension grease
- Soft-jawed vise and crown race setting tool
Disassembly and Initial Cleaning
Begin by removing the fork from the bike. This allows full access and eliminates external variables during service. Once the fork is removed, depressurize the air spring completely via the Schrader valve cap on the left leg. Slowly release all air to prevent internal damage.
Secure the fork in a soft-jawed vise. Remove the lower legs by loosening the foot nut bolts with a 10mm socket. Gently tap the bolts to disengage the shafts, then slide the lowers off the stanchions. Drain any remaining oil and clean the lowers thoroughly using isopropyl alcohol.
Inspect the lower leg seals and foam rings. Replace them if they show signs of wear, such as cracking, drying, or deformation.
Rebuilding the Air Spring Assembly
The left leg houses the air spring. Remove the top cap using a 26mm socket. With the air cap removed, slide out the air spring assembly by pulling gently with a suspension pick if necessary.
Disassemble the air spring components and clean each part individually. Inspect the piston seal, dynamic o-ring, and top-out bumper. Replace worn components as needed using the correct Fox service kit.
Lightly grease the seals with suspension grease before reassembly. Reinstall the air spring into the stanchion tube, ensuring all parts are seated correctly. Torque the top cap to manufacturer specifications (typically 35 Nm).
Rebuilding the GRIP2 Damper Assembly
The right fork leg contains the GRIP2 damper cartridge. Begin by removing the rebound knob at the bottom using a 2.5mm Allen key. Use a 6mm hex to remove the lower damper bolt. Once loose, remove the damper cartridge by gently pulling upward.
Drain the damper oil and disassemble the adjuster knobs and compression valving if necessary. This is a delicate process that requires attention to part orientation and sequence. Clean all internals with isopropyl alcohol and inspect the shims, bladder, and compression assembly.
Replace the bladder if it feels stiff or has micro-tears. Carefully refill the cartridge with Fox 5wt Teflon oil, bleed any air bubbles, and reinstall the damper into the stanchion. Tighten all bolts to the recommended torque values.
Reinstalling Lower Legs and Seals
Install new foam rings soaked in 20wt Gold oil into the lower legs. Replace the dust wipers using a seal driver of the correct diameter. Lightly grease the inside of the seals to ease reinstallation.
Slide the lower legs onto the stanchions slowly to avoid damaging the seals. Once fully seated, insert and torque the foot nut bolts. Reinstall the rebound knob and adjuster caps.
Refilling Bath Oil and Final Pressurization
Inject Fox 20wt Gold oil into the lower legs through the open foot nut holes using a syringe. Follow the Fox service manual for the correct volume per leg. This ensures the fork maintains proper lubrication and damping consistency.
Reinstall the foot nuts and torque to 5.1 Nm. Inflate the air spring to the desired pressure based on rider weight and preference. Cycle the fork several times to check for smoothness and full travel engagement.
Troubleshooting Post-Rebuild Issues
If the fork feels sticky or doesn’t return to full extension, recheck air spring assembly and top-out bumper installation. Low rebound damping or harsh compression may indicate improper oil levels or trapped air in the damper.
Leaking oil from foot nuts suggests improper sealing or missing crush washers. Always verify that all sealing surfaces are clean and free from debris before torqueing.
Performance Optimization Tips
Adjusting volume spacers can fine-tune the fork’s mid-stroke support and bottom-out resistance. Adding spacers increases progressivity, which benefits aggressive riding. Conversely, removing spacers provides a more linear feel suitable for flow trails.
The GRIP2 damper allows high and low-speed compression and rebound adjustments. Start with the manufacturer’s baseline settings, then fine-tune based on trail feedback. Recheck adjustments after 3-4 rides for dialing in.
Customization and Tuning
Riders seeking maximum control can match damper tuning to their riding style by modifying the shim stack in the damper. This is an advanced modification and should only be attempted with full knowledge of suspension dynamics.
You can also replace the factory dust wipers with aftermarket low-friction seals to reduce stiction. Use only trusted brands compatible with Fox 38 stanchion dimensions.
Compatibility Considerations
The 38 Factory GRIP2 fork is optimized for aggressive riding and pairs best with robust head tubes and frames with internal cable routing. It’s designed to work seamlessly with Fox X2 and DHX2 rear shocks for balanced suspension performance.
It uses a 15x110mm Boost thru-axle and is compatible with 180–230mm rotors. Ensure your frame and brakes support this range before installing.
Comparing GRIP2 with Other Fox Fork Models
Compared to the Fox 36, the 38 GRIP2 offers increased stiffness and travel for more demanding terrain. While both share damper options, the 38 is more suitable for enduro racing and heavier riders due to its burlier chassis.
The Performance Elite variant lacks Kashima coating but retains similar internals. Riders prioritizing budget over finish might consider the Elite version, while factory riders will benefit from the smoother action of the Kashima stanchions.
Maintenance Frequency and Intervals
Routine lower leg service should be performed every 30–50 riding hours, depending on terrain and conditions. A full rebuild including damper and air spring should occur every 100–125 hours.
Always check the fork for any signs of oil leakage, bushing wear, or inconsistent damping. Preventative maintenance extends fork life and maintains performance consistency.
Frequently Asked Questions
How often should I rebuild my Fox 38 GRIP2 fork?
You should perform a full rebuild every 100 to 125 hours of riding or yearly, whichever comes first. More frequent servicing is advised for harsh environments.
Can I upgrade the GRIP2 damper from an older Fox 36 or 34 fork to the 38?
No. While they share damping principles, the damper sizes and leg architectures differ between models.
What type of oil should I use for the rebuild?
Use Fox 5wt Teflon damper oil for the cartridge and 20wt Gold for the lower legs.
Can I replace just the dust wipers without a full rebuild?
Yes, but it is recommended to inspect foam rings and bath oil condition during wiper replacement.
Why is my fork not rebounding fully after the rebuild?
This may result from trapped air in the air spring or damper. Verify assembly and bleed processes were correctly followed.
Is it safe to use third-party volume spacers in the air spring?
Only use Fox-approved spacers. Off-brand options may not fit securely and could damage the air spring assembly.
Conclusion
Rebuilding your Fox 38 Factory GRIP2 fork ensures long-term reliability and precise damping performance. Following these detailed steps helps maintain optimal ride feel while minimizing wear. Regular service, correct tools, and careful assembly are crucial to preserving one of the most advanced suspension systems in mountain biking.