What Are Reservoir Shocks?
Reservoir shocks add an external chamber that increases oil capacity and provides additional cooling. They come in two main configurations.
Types of Reservoir Shocks
Piggyback Reservoir
The reservoir is mounted directly to the shock body, connected by internal passages.
- Pros: Compact, no external hoses, easier mounting
- Cons: Less oil capacity than remote, can be harder to fit
- Common on: Fox 2.5, King 2.5, Icon
Remote Reservoir
The reservoir is separate from the shock body, connected by a hose.
- Pros: Maximum oil capacity, flexible mounting, best cooling
- Cons: More complex, requires mounting location, hose routing
- Common on: King, Fox race series, Icon Delta
Why Reservoirs Matter
More Oil = Better Cooling
Shock absorbers work by converting motion into heat. More oil means more thermal mass to absorb that heat without performance degradation.
Consistent Performance
When standard shocks overheat, damping decreases (fade). Reservoir shocks maintain consistent damping longer under heavy use.
Additional Features
Many reservoir shocks include adjustable compression settings in the reservoir, allowing fine-tuning of damping behavior.
When You Need Reservoir Shocks
- High-speed desert: Extended high-speed running generates significant heat
- Racing: Consistent performance throughout an event is critical
- Heavily loaded vehicles: More work = more heat
- Repeated hard use: Rock crawling, whoops, etc.
- Hot climates: Starting with higher ambient temps
When You Don't Need Them
- Daily driving: Normal use doesn't generate enough heat
- Light trails: Slow-speed wheeling doesn't create fade
- Budget builds: Money is better spent on quality non-reservoir shocks
- Primarily street use: Even with occasional trail time
Reservoir Shock Options
| Brand/Model | Type | Price (per shock) | Best For |
|---|---|---|---|
| Fox 2.5 Piggyback | Piggyback | $400-600 | Mixed use, trail |
| King 2.5 Piggyback | Piggyback | $700-1,000 | Serious off-road |
| Icon Delta | Remote | $600-900 | Trucks, overlanding |
| King 2.5 Remote | Remote | $900-1,400 | Racing, extreme use |
Installation Considerations
Piggyback
- Check clearance, piggyback adds width
- May require shock relocation on some vehicles
- Usually direct bolt-on with minimal modification
Remote
- Need to find/create mounting location for reservoir
- Route hoses away from heat and moving parts
- Consider reservoir orientation (usually upright)
- More complex installation overall
Performance Comparison
| Shock Type | Heat Capacity | Fade Resistance | Cost |
|---|---|---|---|
| Standard Monotube | Baseline | Good | $ |
| Piggyback | +40-60% | Very Good | $ |
| Remote Reservoir | +80-120% | Excellent | $$ |
The Bypass Option
The ultimate reservoir configuration is the bypass shock, which uses multiple tubes in the reservoir for position-sensitive damping. These are primarily for racing and extreme applications.
- Smooth ride at low speed
- Progressive damping as speed increases
- Maximum control at full speed
- Price: $1,500-3,000+ per shock
Our Recommendation
For most enthusiasts: A quality non-reservoir monotube (like Bilstein 5100 or Fox 2.0) is sufficient. Save the money for other upgrades.
For serious off-roaders: Piggyback shocks (Fox 2.5, King 2.5) provide meaningful improvement for trail and desert use.
For competition/extreme: Remote reservoir shocks are the standard. Don't compromise here.
The Bottom Line
Reservoir shocks are a legitimate performance upgrade, but only for use cases that generate significant heat. Most daily drivers and weekend warriors don't need them. If you're not fading shocks regularly, your money is better spent elsewhere.