What is the difference between coilovers vs lowering springs and which is the better choice for your everyday car?
Obviously coilover suspension kits are adjustable, depending on the kit, for height and damping
Lowering springs are not adjustable.
The spring used in a coilover kit are usually linear rate springs. ie regardless of the travel/compression of the spring, the spring rate, their hardness is the same.
Lowering springs usually use progressive springs. Progressive springs on small compression have a lower spring rate and the spring rate gradually stiffens as compression increases.
Good points of lowering springs
The height is set for you. You do not need to figure out what is the best ride height, the engineers of the spring manufacturer have done that for you. Coilovers on the other hand give you freedom to use your own ride height so you have to do the R&D to find the optimum ride height. Short of the racing circuit, it is probably better to have engineers do the work for you so lowering springs are the best choice.
Performance. Roads are not smooth. Unlike racetracks. For maximum grip and traction you want the wheels to follow the contours of the ground, lowering springs with their progressiveness and their use of the orginal dampers do a much better job than coilovers. In short, lowering springs give better performance more of the time compared to coilovers.
Coilovers fundamentally are designed for the track and the demands of the track are not the same as the road.
Comfort. Dips and bumps in the road are dealt with in a kinder fashion if you have some progression in the suspension. The springs on a coilover immediately give full resistance. Lowering springs as I mentioned and progressive. Lowering springs give a better ride over dips and bumps.
Coilovers vs Lowering Springs – Is it fair to compare the two?
Coilovers were originally designed for the track so immediately they are at a disadvantage to lowering springs and dampers which are designed for the road. The demands of the road ie compliance to maintain contact with bumpy surfaces and the the track where the surface is smooth and comfort is not on the priority list means coilovers are at a fundamental disadvantage in all but the most extreme speeds.
So why are coilover used on a road car?
Looks. If you don’t mind compromising performance, you can make the car look really fast by making the car very low.
Comfort. Some cars, from the factory, have unnecessarily harsh suspension, in this case, a set of coilovers have the potential to improve the ride over the standard dampers and lowering springs. (Focus RS, Matt Farah for example)
Coilovers vs Lowering Springs – What do coilovers do better?
Fast direction changes. Not necessarily single direction changes but rapid direction changes, coilovers will have the edge of progressive lowering springs. The progressiveness of the springs allows slightly more body movement than linear rate springs and this allows more momentum to build up in the movement of the car’s body. Coilovers generally will have more control. For the road, 99% of the time this is what makes their performance worse than progressive lowering springs but when you are at maximum attack and you need total control of the cars body above all else, coilovers are what you need.
Coilovers vs Lowering Springs – Summary
For that maximum performance for 1% of the time you need coilovers but for the rest of the time, you will probably be going faster and in more comfort with lowering springs.
For the perfect corner with the perfect road surface, coilovers are the best but the rest of time, consciously or not, you will be driving faster with progressive springs (on the road).