Routine maintenance of the Fox 38 Factory GRIP2 suspension fork is critical to maintaining optimal damping performance and prolonging component lifespan. One of the most essential procedures is a lower leg service, commonly referred to as an oil change. This guide walks you through the process, specifically tailored to the 38 Factory GRIP2, ensuring both precision and compatibility.
Tools Required
- 10mm and 6mm hex wrenches
- Torque wrench [paid link]
- Oil drain pan
- Plastic syringe or fork oil measuring tool
- Pick or seal puller
- Clean microfiber rags
- Isopropyl alcohol (at least 90%)
- Suspension-specific grease
- Fox 20wt. Gold oil (or manufacturer-recommended alternative)
- Retaining ring pliers (if removing the air spring assembly)
- Rubber mallet
Overview of Service Intervals
Fox recommends a lower leg oil change every 50 hours of riding. This interval keeps bushings lubricated, maintains damping consistency, and prevents internal wear from contaminant buildup. Ignoring this interval can cause premature seal degradation and increase friction within the fork.
Pre-Service Preparation
Before initiating the procedure, depressurize the fork completely using a shock pump. Remove the front wheel and brake caliper to ensure an obstruction-free work environment. Lay the fork flat on a bench with a drain pan ready beneath the lowers. Take note of the damper and spring configurations, especially if tuning settings are involved.
Removing the Lower Legs
Begin by loosening the 6mm and 10mm bolts at the bottom of the fork legs. These bolts secure the damper and air spring shafts. Lightly tap them with a rubber mallet to break them free from the internal foot nuts. Once loosened, pull off the lowers gently while catching the residual oil in the drain pan. Allow the oil to drain completely from both legs.
Be attentive to the foam rings and oil seals. If excessively dirty, remove and inspect them. Contaminated foam rings can be cleaned using isopropyl alcohol or replaced if overly worn.
Cleaning and Inspection
With the lowers removed, clean the inside surfaces using a lint-free cloth dampened in isopropyl alcohol. Inspect for scoring, bushing wear, or seal damage. Clean the foam rings thoroughly and re-saturate them with fresh Fox 20wt. Gold oil before reinstallation.
Do not use aggressive solvents that can deteriorate the elastomer components or anodized surfaces.
Adding Fresh Oil
Before reinstalling the lowers, measure the exact quantity of oil for each leg:
- Air Spring Leg (non-drive side): 20cc of Fox 20wt. Gold
- Damper Leg (drive side): 40cc of Fox 20wt. Gold
Use a syringe to accurately inject the oil directly into each leg. Coat the oil seals and wiper rings lightly with suspension grease to aid reassembly and prolong sealing life.
Reinstalling the Lower Legs
Align the lowers with the fork stanchions and carefully slide them upward. As the lowers approach the foot nuts, gently tap to seat the shafts into place. Reinstall the 6mm and 10mm bolts and torque them to manufacturer specifications:
- Air Spring Side Bolt: 7.3 Nm
- Damper Side Bolt: 7.3 Nm
Ensure that crush washers are seated correctly and not reused if they show signs of wear.
Air Pressure and Final Setup
Re-pressurize the fork air spring to your desired pressure, typically between 65-95 psi depending on rider weight and preference. Cycle the fork several times to ensure smooth travel and oil distribution.
Check the damper and rebound settings to ensure nothing was inadvertently changed during the service. Confirm that the axle is torqued to spec, and reinstall the brake caliper.
Troubleshooting Common Issues
If post-service performance feels harsh or inconsistent:
- Oil leak from seals: May indicate a damaged or misaligned oil seal. Disassemble and reseat or replace.
- Poor small bump sensitivity: Possibly caused by under-lubricated bushings or dry foam rings.
- Inconsistent rebound/compression: Check damper side oil quantity and ensure the bolt is fully torqued.
Incorrect oil amounts are a common cause of damping anomalies. Recheck your measurements if problems persist.
Customization and Optimization Tips
While the standard oil volumes serve most riders well, advanced users may fine-tune small bump sensitivity and mid-stroke support by adjusting oil height slightly. However, deviations from Fox’s recommendations should be minimal and carefully tested.
Installing SKF low-friction seals or upgrading the foam rings to higher-capacity options can yield smoother performance in aggressive terrain.
Compatibility Considerations
The 38 Factory GRIP2 fork is compatible with Fox’s proprietary air and damper cartridges. It should not be serviced using generic fluids or seals. Use only Fox-approved lubricants and parts to maintain warranty eligibility and prevent internal incompatibilities.
The GRIP2 damper, in particular, is sensitive to fluid viscosity and quantity. Using the wrong oil weight can alter the HSC/LSC behavior significantly, leading to poor ride characteristics.
Model Comparisons
Compared to the Fox 36 or RockShox ZEB, the 38 Factory GRIP2 offers superior torsional stiffness and deeper travel for aggressive enduro riders. While the lower service intervals mirror those of similar models, the GRIP2 damper’s precision tuning demands stricter adherence to maintenance protocols.
Riders choosing between the 38 GRIP2 and the Performance Elite should consider the factory Kashima coating and damper tunability—two features that justify more frequent servicing due to their complexity and performance benefits.
Conclusion
Performing a DIY oil change on the Fox 38 Factory GRIP2 is straightforward with the correct tools and attention to detail. Following this guide ensures your fork remains responsive, durable, and safe for high-performance trail and enduro use. Always adhere to Fox’s specifications for oil volume and torque, and perform this service regularly to maximize the lifespan and performance of your suspension fork.