Ride height technology reaches a new low

Jan. 1, 2020
You can't help but notice all the vehicles with modified ride heights sharing the roads with us these days. Whether it's a pickup or SUV that requires a ladder to get into, or a tuner market subcompact that's so low that it can't clear a shopping cen

Vehicle adjustments can bring in profitable business to the shop that makes itself a pro.

You can't help but notice all the vehicles with modified ride heights sharing the roads with us these days. Whether it's a pickup or SUV that requires a ladder to get into, or a tuner market subcompact that's so low that it can't clear a shopping center speed bump, it is fair to say they're multiplying and they grab your attention.

This is a hot market trend — so hot that some would say it's on fire. Just as any fire needs a constant fuel supply, in this inferno, we have consumer styling interest as well as a huge aftermarket parts and accessories industry supplying unlimited combustibles.

Whether you're part of the multibillion-dollar vehicle modification boom or simply trying to correct alignment after the fact, it helps to gain some additional insight into this phenomenon. For the sake of limited space, we will devote the focus of this discussion to the lowered vehicle and leave the topic of raised vehicles for another day. Keep in mind, however, some of the discussion herein will definitely apply to the raised vehicle, either in commonality or in inverse relationships.

Art vs. science

The "art" of altering a vehicle's ride height is practiced by many individuals — from part-time novice auto enthusiasts to professional service providers. However, it is the science at hand that is often overlooked by the artistic novice. Whether going up or down, the consequences are stated in physics and geometry. And like it or not, Newton's laws and principles of physics are always in effect.

Automotive engineering teams pay special attention to the science of suspension design and vehicle handling dynamics. Center of gravity, weight transfer, vehicle dynamics of roll, pitch and yaw, as well as tire life, adjustability and marketing strategy are among the suspension and steering design objectives. Often minor changes in ride height can have a noticeable impact on component geometry. This, in turn, can affect wheel alignment, tire wear, steering response and handling.

Engineering teams anticipate changes in ride height and typically provide some adjustability to compensate and maintain nominal base alignment angles. During normal component life, ride height settles slowly as the springs age. With springs working 24/7, predictable loss of ride height is a very common reason for periodic alignment service.

Engineers know that with expected changes in ride height, minor alignment corrections will serve to maintain their original design and handling objectives. When a vehicle's basic alignment specifications (commonly camber) can't be achieved with available adjustments, it's time to find the cause and replace the springs and/or other components at the root cause.

Of course, industry engineers also produce and subscribe to various kits and "fixes" for enhanced alignment adjustability. In some cases, OEM or aftermarket parts, kits and/or procedures provide for adjustability that the engineers were forced to leave on the drawing board for production cost savings.

In any case, the trained alignment technician knows the importance of measuring ride height as part of the pre-alignment inspection. Incorrect ride height can lead to a myriad of consequences extending well beyond the ability to achieve preferred camber settings.

Has anyone seen my camber?

It doesn't take much time in the alignment bay to recognize that changes in ride height have a direct and noticeable impact on camber. On traditional rear-wheel-drive (RWD) cars using short-long arm (SLA) upper and lower control arm suspensions, loss of altitude from factory elevations creates slight increases in camber. With strut suspensions, the tendency is just the opposite: loss of ride height tends to make camber go negative.

With the need to maintain drivetrain geometry so that constant velocity (CV) joints are properly engaged and to avoid possible torque steer, these vehicles have their available camber adjustments typically situated at the top of the knuckle or at the top of the strut. This helps to minimize changes in the delivery of power to the wheels and adverse feedback to the driver.

Unfortunately, with the higher positioning of the adjustment points, it takes longer linear travel to affect the angular change for camber. In a nutshell, there is generally less available camber adjustment on today's ride than what your grandfather's mechanic had. This is one reason that when vehicles run out of camber correction adjustment, the car is really screaming, "Somebody please pick me back up!"

To test this, suggest a simple experiment. While on the alignment rack, a camber-anemic vehicle with struts should be given a slight lift on the front bumper and the camber should be observed as it returns home. In the case of our present tuner market craze of "gettin' 'em down in the weeds," the camber is bound to head south quickly. It's not uncommon to see a loss of more than three-quarters of a degree of camber with a one-inch drop in ride height. It's possible to have more than two full degrees of camber loss with a two-inch drop on these strut suspension vehicles.

Technician awareness

Knowing that modifications in ride height can alter the pivot locations, component angles and key geometric intersection points of the steering and suspension will help techs approach the tuner's artwork with enhanced appreciation. Vehicle suspension and steering are somewhat analogous to a well-tuned orchestra. Tuning and balance are critical: get too far out of tune or balance, and the sour result is apparent.

There is often more than a single route to any particular destination. For vehicle lowering, the two most prevalent methods are spring changes and wheel/tire fitments. It's not uncommon to see a combination of both approaches to achieve a desired height change and aesthetics. In earlier times, modified spindles were a common additional option seen with RWD SLA vehicles. However, with front-wheel-drive (FWD) and all-wheel-drive (AWD), altered spindles and knuckles are not common for height change options because of feasibility and cost for most strut suspensions. When equipped with front drive axles, we also have to respect axle and drivetrain geometry and symmetry that come into play.

"Stepping down" versus "stepping out" too often is overlooked. Sometimes induced height changes through component replacement can result in altered alignment dynamics from altered scrub radius. Again, this is a reminder of geometry and physics.

The scrub is determined by an analysis of two intersecting lines. A line drawn through the steering point pivots (steering axis) and a vertical line drawn through the center of the tire tread will intersect above, below or at the surface of the road where the tire tread sits. A negative scrub occurs when the intersection is above the road surface, typical for FWD vehicles. When placed in motion, the negative scrub attempts to toe the wheels in. Consequently, many negative scrub vehicles have a slight toe-out static alignment spec. It's considered positive scrub when the intersection point is below the road surface, which is commonly the case for RWD SLA vehicles. Neutral scrub occurs when the two lines intersect at the road surface and center of the tire tread.

Any changes to suspension or the centerline of the wheel/tire offset that change the original scrub radius engineered into the vehicle might have potentially serious consequences. Scrub radius is designed to create certain dynamics and handling of the vehicle. Additionally, the scrub is a huge factor in the original equipment (OE) engineers' determination of static alignment toe specifications — the tightest of all alignment angle tolerances for optimum tire life.

Scrub is a key factor in determining a vehicle's personality for handling or "feel." Obviously, mismatched scrub-to-toe specification likely will result in some often-mysterious and undesirable tire wear. (For a simple science lesson on scrub effect, see the sidebar experiment on the opposite page.)

At the end of the day, an altered scrub may require a different ideal or preferred total toe specification from what the engineers originally calculated. In other words, with altered scrub and the factory toe spec, you could have mysterious toe scuff to resolve.

So what's a tech to do?

Regardless of the reasons why or the methods how a vehicle gets lowered, it's prudent and profitable to seek out desirable wheel alignment settings. The first step is to determine the customer's objective. Typically, the driver's goal is the "in vogue" look and some anticipated improvement in handling through high-performance tires and a lowered center of gravity — and all this without severe loss of tire life.

For a few well-financed auto sport enthusiasts, the mission is all-out track performance with secondary regard for tire life. Once the customer's desire for either looks and tire life or lower track times is determined, there exists state-of-the-art alignment software and hardware to get the job done and get the profits in the cash register. Tuner alignment software is designed to guide the technician on the selected journey to either looking good with optimum tire life or establishing track setups with critical documentation. This specific software creates a custom path for the alignment technician based on the desired objective.

Whether the goal is tire life or performance, tuner alignment software also features a database of aftermarket components, specific to the vehicle, that provide additional adjustment for dialing in the needed angles and remedying bump steer. Bump steer is a condition that sometimes shows up when suspension and steering get out of designed symmetry. It's a potentially dangerous situation that causes the wheels to "steer" left or right as the vehicle experiences jounce and rebound while in motion. Tuner alignment software provides bump steer diagnostics and documentation that even the novice alignment tech can easily and quickly master.

Finally, tuner alignment software has the ability to receive and record critical tire temperature measurements and provide guidance for alignment "tuning" based on the critical data from the vehicle and tires. Securing tire temps during road tests with remote pyrometers and data storage can prove to be critical when techs need the tires' story on how they are doing under actual driving conditions.

A lucrative proposition

Lost camber can be easily and profitably retrieved with creative aftermarket components. Bump steer can be measured and remedied with available kits. This reinforces the profit to the shops willing to "get on the bus."

These are not low-cost alignments and the rewards are relative. For those striving for all-out performance tuning for the track, it comes down to doing some of the same things practiced at the OEM proving grounds and in the racing pits and garages. Engineers monitor the data, track the results with documentation and adjust designs and settings to achieve their goals.

Fortunately, tuner alignments are a strong income opportunity for shops catering to the "looking good/feeling sporty" customer. By the way, this client is the vast majority of the opportunity types: The customer who makes changes to attain that special look, then seeks a solution to accelerated tire wear and/or unexpected handling surprises.

Enhanced bottom line revenues are straightforward for alignment shops equipped with up-to-date alignment equipment and technicians with a fundamental understanding and the willingness to gain a little experience.

For the shops that go after this opportunity, tuner alignments represent an awesome niche market — a gold mine in parts, labor and accessories.