Off Road Racing Shock FAQHere's a list of the most frequently asked questions. If you can think of any not listed here please email me at Michael@offroad-engineering.com. |
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| What's so good about a coil over shock?Answer: A coil over shock has more easily adjustable features than standard suspension, and the reason they are so popular is that they can be finely tuned. Also, a coil spring generally has a linear spring rate which allows more consistent driving characteristics. Most people like the smooth ride a coil spring can provide. Adjustment and fine tuning are easier and more accurate with a coilover suspension than any other. |
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| How do I pick spring rates?Answer: There are a number of variables in choosing a spring rate, not to mention driver preference. We are creating a spring rate calculator in the Technical Info section on Offroad-Engineering.com. |
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| How do I install coil springs on my coil over shocks?Answer: On Fox, King, and Bilstein shocks, you remove the lower spring seat and pull the coils off from the bottom of the shocks. |
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| How do I estimate what valving to order?Answer: Based on our experience there is no “One” correct valving. Rather we prefer to offer what has worked well for similar vehicles in the past, and help you fine tune YOUR shocks to YOUR preferences. We will list the valving settings in the Technical Section as time permits. |
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| How big of a shock do I need?Answer: That can be a tricky question to ask. A rock crawler doesn’t need as big of a shock as a Desert Race Car, even when the car weighs less. Consider it safe to always go “Bigger than you need,” and for more suggestions and information on shocks check out what similar vehicles are running successfully. |
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| What length shock do I need?Answer: Choosing a shock can be more complicated than it seems. While matching your shock travel to the suspension travel is ideal, it isn’t always practical. This is why you see 10”-12” travel shocks on the front of long travel buggies with 20” of suspension travel or more. The best method for determining what shock length to use is to measure your shock mounts when fully extended and and find a length close to that measurement. If you do not have your suspension set up already, I recommend coming as close to a 1:1 motion ratio, which is explained in the glossary section under technical info. Try to match your suspension travel with the shocks travel up until 14" or more, where spring rates have fewer options, unless you plan on running a triple rate suspension. |
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| What is a dual-rate coil over, and are they better?Answer: Dual-rate literally means that you can achieve two separate spring rates. This is usually a desired feature on coil over shocks as you can have one rate to soak up the washboard chatter and a second to kick in and keep the car from bottoming out thru the rougher sections. It is advantageous on all types of suspensions because secondary suspension can provide multiple facets to performance. |
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| What is preloading?Answer: Preloading a coil over means creating or increasing tension on the coil spring(s) in addition to the load the coils are meant to carry. Preloading is used to adjust ride height. |
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| Do you have a diagram of what coil over components are called?Answer: We certainly do. Will post ASAP! |
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| How do I adjust my suspension?Answer: For more detailed information on how to adjust and tune your suspension see the Coil Over How To Guide in the Technical Info section on Offroad-Engineering.com. |
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| What size shaft do I need?Answer: A 5/8" shaft will allow the shock to dampen suspension better as there is less spring force created by the smaller volume of displacement, but a 7/8" shaft is clearly stronger. A 7/8" shaft can provide more resistance to compression by providing another easy adjustment in spring force thru increased nitrogen pressure. A 1.25" shaft shock (air shock) is just an extreme example of high pressure gas created spring force. |
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| What angle should I mount my shocks?Answer: Shock angles greatly affect performance and design characteristics. Setup is key in maximizing the potential performance of your offroad racing shocks. We recommend you set your shocks perpendicular to the angle of motion at full compression. This will provide a progressively stiffer suspension as you come closer to full compression. |
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| What do the valving numbers mean?Answer: Valving numbers vary by brand. In general Bilstein uses xxx/xx. The xxx is the compression damping and xx is the rebound damping, both in Newton Meters per Second. King uses shim thicknesses. For example, the compression stack might be all .010” Shims and the rebound stack might be .012” shim thicknesses. Fox uses percentages. For example 50/70, where 50 means 50% of the available compression damping and 70 means 70% of the available rebound damping. |
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| What does a bypass shock do?Answer: While the explanation can be more complicated we’ll keep this one simple. Bypass shocks divert oil thru passages External to the normal valving shims by running extremely stiff valving. Once the oil is forced thru the external tubes/passages it is metered by a check valve with an adjustable set screw. This allows for valving adjustments without disassembly, however, the main advantage is multi-stage damping. Why? Because when you run more than one spring rate, one damping rate will not control both rates effectively. |
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| Why are racing shocks pressurized?Answer: The main reason is due to cavitation. When shocks are extended rapidly with great force, there are extreme pressure drops. These pressure drops are microscopic implosions that can destroy the working components of any damper. Just think of cavitations as mini depth-charges inside your shocks. To reduce the affects and possibility of cavitation the engineers who designed the dampers try to maintain a more stable pressure by starting off higher. Hence high pressure shock absorbers. |
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| What length coils do I need?Answer: While there are a variety of methods to make this decision, we prefer to use the maximum length that a coil over will allow without preloading the coils. |
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| What are some differences to consider when choosing a brand of shock?Answer: There are many: Price, availability, quality, reputation, ease of replacement parts, tunability, materials, longevity, and did I mention price? |
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| What should my shocks be charged to, and can I use compressed air?Answer: Generally, off road racing shocks need to be charged to within 150-250psi with nitrogen only. Airshox are capable of being used at a range of 50-500psi. DO NOT USE compressed air as it can cause a number of problems. The oxygen and moisture in compressed air will corrode ferrous (made with iron) materials. Not only that, but nitrogen is more stable thru a greater pressure and temperature range. |
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| How Does a Dual Rate Coil Over Work |
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