How Do You Know When to Rebuild Your Shocks?
How Do You Know When to Rebuild Your Shocks?
A Performance Enthusiast’s Guide to Understanding Shock Service Basics
An Overlooked Key to Performance
Your shocks are the partially unsprung heroes of your suspension system. Unfortunately, a large portion of racers miss these as critical aspects of the maintenance schedule. When dampers get overlooked that affects performance outright and cost of use goes up sometimes considerably. Your dampers manage wheel control, chassis stability, and ultimately determine how your car feels through every corner, braking zone, bump and curb. Knowing when to rebuild them isn't just about maintenance; it's about preserving the performance and driving experience you invested in.
Mileage and Usage Considerations
Street Performance Cars Racing oriented dampers on the street typically need rebuilding every 15-25k miles under mixed street/spirited driving conditions. Street oriented performance shocks like the Ohlins R&T can often go to 40k miles if not abused in the right environment. Shock covers like the ones we offer also help mitigate the environmental factors. However, mileage alone doesn't tell the whole story, the environment and conditions play a large factor (see below).
Track-Focused Applications Track use can accelerate wear. Depending on intensity and frequency, track-only setups may need rebuilding every 4-8k miles/50-100hrs or after about 25-30 track weekends start looking for a convenient opportunity.
Dual Purpose Cars These land in between road and track oriented obviously. You can only know if you keep close track of your track and road miles individually. Otherwise you would just count the track weekends the miles then augment. A meaningful reduction in service miles per track weekend (assuming 2-3hr on track per weekend) would be about 500mi per event.
On-Road Trucks It is common for systems like King or ICON etc to run between 30-80k. These are in reasonable conditions and shock covers like we provide help ensure the high end of that without shaft damage. Environment plays a huge factor here (see below). Also we find rock ships and shaft scratches to be the leading cause of shock leaks and early servicing (sub 50k miles).
Offroad Trucks If you go to any offroad parks or mudding or any form of activities that get sufficient debris, mud etc on the suspension or submerge them in water I would expect dramatically accelerated service intervals. Two things that can alleviate some of that stress is cleaning the suspension after the event and running a shock cover like we provide during it.
Environmental Factors Salt exposure, extreme temperatures (racing), and contaminated environments (offroading, submerging, caliche roads, sand, even heavy construction dust) can accelerate seal/surface deterioration and require more frequent service intervals. The exact amount cannot be predicted, so don’t expect us to know, but you can guarantee it reduces service life. If you subject your suspension to heavy doses of these factors consider ⅔ the normal mileage to be about as far as you should go at best.
Time This is a bit tricky as there is no exact time period a shock will go “bad”. Typically time goes hand in hand with usage, but when it doesn’t we tend to see shaft wiper seals (these keep dirt out of the shock) go bad and oil seals sometimes “creep” taking a new shape even if under unchanging pressure or not being exercised. I would expect a performance setup that needs to be in top shape shouldn't go more than 5-6yrs even if low use without getting dyno checked or just serviced to ensure the Nitrogen isn’t in the oil or that when exercised the seals don’t start to seep if it has sat.
The Cost of Waiting
Performance Degradation You want to go fast, right? Worn dampers create a cascade of handling problems. Poor wheel control leads to reduced grip, which drivers often try to compensate for with setup changes that mask the real issue. You end up chasing handling problems instead of addressing the root cause.
Accelerated Component Wear Waiting to service increases wear on shafts, guide bearings, internal cylinder walls, shims, valving surfaces etc. The cost of moderately delayed damper service often extends just to components like guides, shafts and cylinders, which can still become a very costly repair compared to servicing on time.
Lost Value If you pay good money for a setup it is a waste to let it underperform. Often the degradation occurs slowly and you get used to it as it happens, but there is no denying that it is occurring. Just because your engine still runs smooth and gets the same mileage doesn’t mean it's ok to keep driving on the same oil until it clatters and smokes. In many cases the dampers can cost more than a replacement engine.
What About Dampers Wears Out
Think of a damper as a finely tuned oil pump, working under high pressures and varying loads. Every compression and rebound movement forces oil through precisely engineered valving. Over time:
Seals and seal grooves wear allowing oil and/or nitrogen gas to escape and sometimes mix internally.
Oil breaks down losing viscosity and lubricity characteristics which impact wear and damping consistency.
Parts and surfaces degrade reducing the damper’s ability to control oil flow and causes leaks.
Dirt ingress through the seals and from parts breakdown causes particles to float in the oil causing unseen wear and interference with the valving.
Hard driving and heat accelerate this process to different degrees. As mentioned above, racing dampers that perform acceptably for 15–25k miles in normal road use may require service by 50–100 hours or ~4–8k miles on track! Waiting can accelerate wear into damage. Rough roads and dirt can accelerate wear dramatically, while highway driving runs the damper piston in one spot buzzing at one area of the bore. This can cause its own wear patterns especially in aluminum body shocks.
The Performance Impact A worn damper doesn't just ride poorly—it fundamentally changes your car's behavior. You lose precise wheel control, load transfer can become less consistent, lowers responsiveness, can cause adjustment confusion and lowers overall limit performance. What starts as a slight drop in responsiveness can become a car that has limited potential often slowly over time making it hard to identify. The worst case is when you can’t feel the difference until damage is done.
Visual and Physical Inspection Signs
External Leakage Even without advanced tools, many signs of shock absorber wear can be caught by careful observation and attention to noises in the suspension. The most obvious warning sign is fluid escaping from the shock at hose junctions or near the shaft. Light oil “weeping” can sometimes be tolerated, but it may indicate seal or seal groove wear and a possible loss of internal gas pressure. Persistent leakage or visible dripping means the seals or the sealing surface on the shaft are worn, gas pressure may also be lost, and it is time for service. Driving on a damper in this condition risks further damage.
Physical Damage Assessment This may be pretty obvious, but I’ll mention it anyway. Inspect for rust spots on rods, damaged mounting hardware, or impact damage to the body. Road debris, excessive dirt or buildup around the shaft, track excursions, or aggressive driving can cause structural damage that compromises internal operation even without visible leaks. If nothing else, wash the shocks off if the opportunity presents itself.
Shaft Play and Mounting Point Wear Unintended movement within the suspension should always be investigated. McPherson struts, for example, require minimal shaft play under side load. Check by pushing and pulling at the top of the wheel when in the air. Any excess movement can lead to noise, friction, and poor alignment control under load. Check end eye bushings, spherical bearings, and mounting eyes for excessive play. Worn spherical bearings can clunk or screech.
Performance-Based Warning Signs
Inconsistent handling where the car behaves differently in similar corners or conditions than it once did. You may find tire temperature irregularities indicating poor contact patch control. Braking instability with symptoms like nose dive or general instability under heavy braking. Traction problems under power can also arise that are not explained by tire condition or differential settings.
Advanced Diagnostic Techniques
Professional Damper Testing Specialized shops like Inertia Lab can perform damper dyno testing to measure actual force curves. This objective data eliminates guesswork and provides baseline measurements for future comparison. This is also done post service to ensure the job was completed correctly and to check for obvious faults before returning to the customer.
Data Logging Analysis If you run data acquisition you can look for changes in suspension travel patterns in histograms. If something is very wrong it will stand out and may transcend needing data in the first place, but a sudden change in data can be an indicator of impending issues.
Working with Professional Shops
What to Expect from a Quality Rebuild A proper rebuild includes disassembly, cleaning, seal replacement, oil change, and valving maintenance. Inertia Lab goes as far as resurfacing specific areas like the shaft surface and certain seal grooves which are very common areas to have caused leakage or seal damage in the first place. Quality shops perform final dyno inspection to validate the rebuild success. There are varying bars for determining that success and at Inertia Lab we perform at least two 10 speed tests of full soft and full stiff and make sure at each test speed axle pairs match. On more complicated valving we run enough tests to analyze check valve function and adjuster preload ranges etc.
Communicating Your Needs Describing your driving environment, typical use cases, performance issues and any damage, problems or concerns up front in reasonable detail is needed. A good suspension shop can let you know if you need to revalve or respring etc based on the provided information, but you need to ask for the analysis.
Timeline and Planning This is hugely shop dependent and at Inertia lab it ranges between 1-day and 2-weeks in 98% of circumstances. Consider having spare dampers for cars and trucks that MUST have low/no down time. 30% additional is charged to any emergency or rushed work that disrupts or displaces already scheduled work in our case.
Finishing remarks
Recognizing when your dampers need rebuilding is part mechanical knowledge, part feel, and part preventive thinking. Performance enthusiasts who stay ahead of damper service maintain consistent, predictable handling while avoiding the frustration of random leaks and service delays due to parts damage.
The investment in developing a service schedule pays dividends in driving enjoyment, predictable down time and long-term suspension system health. Your future self, and your lap times, will thank you for staying proactive about this critical maintenance item.
Remember: Your suspension is a system, and dampers are its most dynamic and complex component. Keep them fresh, and your driving experience will always be better.