As you may have noticed...
The new cargo boost kits provide up to 1" of lift and use adjustable coilover style systems. This system uses a spring seat that sits on a threaded sleeve which can be adjusted up and down by leftward or rightward rotation of the lower spring seat around the sleeve. The total configuration can achieve the same height as the OE spring and can produce an extra 1" of lift by using the adjustable spring seat to further compress the spring 0.5" (a .5" increase in spring height will cause 1" of lift due to the suspension geometry). Lowering down to -2" can also be achieved in some cases. The percentage increases for the rear springs are expressed relative to the OE spring rates. Generally we offer two rates for the back, you can expect to see about the same amount of drop with 400 pounds of cargo that you used to see with 200 pounds with the first REAR option. With the higher REAR option you can expect to see about the same amount of drop with 600 pounds that you used to see with 200 pounds. In some cases a FRONT option will also be available and is intended primarily for those seeking an all around +1" lift and/ or those looking to increase the vehicle's resistance to dipping in corners and bottoming out off road. In any case these products will use your existing shock absorbers, which will be addressed momentarily as well as differential spring rates between front and rear axles.
The coilover kits (the Rallyover) can provide up to 2" of lift using a similar coilover style system. This kit uses special hardware to extend the dampening range of the shock absorbers in order to match the extended range of the suspension. Essentially what is achieved with the Rallyover lift kit is that the functional travel of the suspension is increased instead of simply increasing the ride height. In addition to extending the suspension travel the spring rates are also increased slightly to provide the best balance of cargo carrying capacity and on/ off road handling. This rate increase is vehicle specific to provide the best balance for that specific vehicle.
These kits are available fully assembled or as parts only. The parts only style will use your existing shock absorbers, upper spring seats, and strut rod isolation hardware to achieve the Rallyover configuration. If these components are badly worn (more than 120,000) you may find the best value in the fully assembled version as new shock absorbers, spring seats, and strut rod isolation hardware will all be included since each suspension arm will be fully assembled and ready to install. We do have various technical support files available on our website but generally suggest professional installation and will shortly state that there are good reasons why suspension work is expensive.
As far as avoiding wear on your CV joints it will ultimately depend on the primary ride height, usage, and equipment dead weight. The main concern is wheel camber which will need to be corrected if using a nominal lift above 1". Camber kits that will make this correction are available for purchase on our website. If your car has 250k or more and you have not replaced the front CV drive shafts you should seriously consider doing so. At that point the grease in the joint has probably disintegrated and any new stresses may be the last. They are about 65 dollars each at your local auto parts store after core charges and take about 3 hours for a professional mechanic to install. A guide for CV drive shafts can also be found in our technical literature. For heavy off-road usage try to select a greaseable joint, if possible, with a grease port so you can add new grease with a grease gun and force out any contaminants. With 1" or less nominal lift you may not need to install a camber kit unless you notice uneven tire wear, however increasing tire diameters will add to existing strains on the CV and may be a reason to replace with new equipment.
Returning to spring rates for the 1" kits they are largely cross-compatible with OE equipment. For example the new CRV uses 250# springs in front and whopping 500# springs in the back. Generally large increases in the rear spring rate will not adversely affect the handling of the vehicle regardless of the front spring rate unless the vehicle is primarily rear wheel drive, such as a camaro. Even with the AWD the majority of power on any CUV remains portioned on the front axle so the car mainly behaves like a front wheel drive vehicle. Large increases in the front suspension's spring rate will adversely affect the handling, however as you notice we do not typically exceed more than 50% of the front OE rate. The spring rate increases we do offer for the front again are primarily for added high-speed banking ability and to reduce the tendency of the front suspension to bottom out.
As you might conclude by this point the Rallyover system is more intended for the enthusiast whereas for simple towing and highway comfort you will very likely be happy with the rear 1" cargo boost kit. Can't decide? The 2" block lift kit is probably best for you.
Just one more thing, since we had mentioned shock absorbers it is important to match the shock, spring, and application. For example, in a situation where large impacts are quickly repeated, such as off road driving, it is important for the shock to rebound quickly or it will begin to loose its dampening capacity over repeated impacts. We intentionally use shocks with a lower gas charge in the Rallyover kits because this allows the shock to rebound more quickly, however it may not provide adequate dampening if heavily loaded on a highway. If towing or hauling on highways will be your main application, your best option will be to use a heavily charged shock (which may be advertised as "heavy-duty" or "slow strut rod extension"). Keep in mind that you will need to use higher spring rates to match the heavy charged shock because otherwise the shock may overly resist the action of the spring and reduce the spring's ability to absorb impacts. Select the stronger version of the rear cargo boost kits if using heavy charged rear shocks. Premium shocks such as Blisten, KYB, and MOOG tend to be relatively close to an OE charge density. These are your best options for OE springs or slight increases, so if you are intending on using the 2" block lift kit or the lighter 1" cargo boost kits then these will be the best choice.
Thank you again for your interest in our products and for considering Colorado Mountain Rally as your provider of quality aftermarket lift solutions for your CUV.