Everything you need to know about lowering your car's suspension

02 August 2021 - 13:05 By brenwin naidu
Lowering your car's suspension might look cool but there are many things to consider before taking the plunge.
Lowering your car's suspension might look cool but there are many things to consider before taking the plunge.
Image: Supplied

It’s always been a thing, especially in the ‘hood I grew up in. The phenomenon of ground-hugging cars isn’t new, but lately, I feel like the trend is more popular than it ever was.

Humble hatchbacks and mainstream sedans (even the odd bakkie!) sitting so low, their drivers have to negotiate minor road imperfections at an extreme angle. Their Waze maps are always set to the route with the least speedbumps.

And when you see some of these cars bobbing on the road like water in a jug being carried by a child, you have to wonder: is that safe? Or completely roadworthy? On one hand, you have apologists of the lowered brigade chanting that stance is not a crime.

This is literally a movement, with actual online petitions and demonstrations in convoy. On the other hand, you have law enforcement bodies countering with certain sections of the Road Traffic Act, giving the impetus to clamp down on cars that are ... not so stock.

Let me state for the record that we at this publication advocate responsible, safe and legal motoring. It is undeniable that properly-executed modifications can enhance a car. Better brakes will help you stop quicker. An uprated cooling system will do wonders for the longevity of your engine. An enhanced suspension setup has a number of benefits too.

Though, as with most things in life, there are some provisos. We must now go back to basics and remind ourselves what exactly an effective suspension system is supposed to do. We reached out to the engineering department at Volkswagen SA, who served up a concise, but detailed working definition.

Memorise this for those fireside discussions: “The suspension system allows the maximum contact between the tyres and the road surface, providing steering stability and good handling, evenly supporting the weight of the vehicle and ensuring the comfort of passengers by absorbing and dampening shock.”

Keen on air suspension? Expect to pay upwards of R20k for a setup on an average hatchback. More sophisticated systems can cost north of R100k.
Keen on air suspension? Expect to pay upwards of R20k for a setup on an average hatchback. More sophisticated systems can cost north of R100k.
Image: Supplied

Absolute poetry. So, how does lowering influence the handling characteristics of a motor vehicle?

“We understand that lowering a car’s ride height will give the vehicle a more aggressive look and will also lower its centre of gravity, in some instances it may improve handling.” But before you dash out the door to your nearest fitment centre, note that there can be unintended consequences: “If the drop is too low, steering geometry can be negatively affected and interference issues may arise with the tyres, chassis or body parts.”

“Stability may be compromised,” it said, adding that a harmonious setup means a correctly-tuned system of shocks, springs and stabiliser bars. If you were thinking of taking a shortcut to your tarmac-smooching endgame by cutting the springs, hang on...

“Springs generally have a temper in them, to improve strength, heat would remove this when cut with a blowtorch or bandsaw. The result of adding heat while cutting a coil is that basically the spring ends up with reduced spring constant stiffness.

“Cut it in the incorrect place and you end up with an inconsistent spring height which would cause the vehicle to pull to one side.

“When lowering the coil spring, either through aftermarket replacement or cutting, you are changing the stroke of the shock or strut. So, the piston is further inside the body, it will not work as intended.

“The shock shaft, as originally supplied, now becomes too long when lowering your vehicle in this way. The risk here is that you would repeatedly reach the end-of-stroke condition, commonly known as a ‘bump stop’.”

Generally speaking, a lowered suspension requires a stiffer shock to compensate for a shorter stroke.
Generally speaking, a lowered suspension requires a stiffer shock to compensate for a shorter stroke.
Image: Supplied

Look, you can go low – just do it properly...

“In summary, if you are going to lower your vehicle’s height through coil spring changes, one would need a shock or strut designed to work in combination with the shorter spring. Generally, a lowered suspension requires a stiffer shock because of shorter stroke.”

We also reached out to specialist Jonathan Rudman of RAPID Fabrication and Performance. He said his firm receives varied requests from customers.

What looks good for one person will not look good for another. Some clients just want the car to sit a tad lower, so the wheels can fill the arches, and others want the car as low as possible.”

Asked what an average setup would be, for balance between performance and practicality, Rudman said it depended on the type of vehicle.

“Some vehicles sit a lot higher than others, a 20mm drop will look good on some vehicles and on others, will look like you hardly did anything to it from stock.”

The practice of retrofitted pneumatic suspension is an increasing trend, he confirmed.

“To simplify the workings of the system, it is basically rubber bags that replace the suspension springs on your vehicle, then you can inflate or deflate them, depending on the ride height your desire.

“The air pressure is supplied from a pressure vessel – air tank – that is usually installed in the boot as it takes up quite a bit of space. It is also accompanied with either one or two electric air compressors to replenish the air that is used to lift the vehicle.”

An inordinate amount of R&D time and money go into engineering your car's suspension – modify it with caution.
An inordinate amount of R&D time and money go into engineering your car's suspension – modify it with caution.
Image: Supplied

Expect to pay upwards of R20,000 for a setup on an average hatchback. More sophisticated systems that continuously analyse ride height and make adjustments on the go can cost north of R100,000.

Rudman agrees with the sentiment that air-bagging is the safest way to achieve that extreme-stance look, since it offers the flexibility to revert to a “normal” ride height. And he cautions keen modifiers to do their homework.

“Understand that buying a second-hand or a cheap, knock-off air ride system, or having someone that has no experience with what to look for, or how to install the system, can be very dangerous.

“Please be informed and have it done the right way. It is not only your life at stake, but other drivers and passengers on the roads.”


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