As I fly to Milwaukee to conduct an Alignment Basics course for CARQUEST Technical Institute I thought it would be appropriate to take this column and write about the importance of alignments. To review any of the past year’s articles click HERE.
The winter season will be upon us all here in the Boston area, and the rest of the country, before we know it. Customers will soon be looking for snow tires and other seasonal maintenance items. When selling any customer a set of tires, or even a single replacement tire, the benefits of purchasing an alignment at the same time should be presented to the customer.
The value proposition to the customer should include things like:
- A wheel alignment increases life of expensive tires
- An alignment ensures handling performance and ride comfort
- It will decrease wear and tear on key suspension and steering components
- It is an important part of regular maintenance
For a shop owner, alignments are a source of gross profit and an easy way to increase revenues. Personally I’ve never understood the number of repair shops without an alignment machine. Since any mechanical operation that requires disassembly of the steering or suspension system requires the vehicle to be properly aligned, not having an alignment machine on the premises means introducing another repair shop into the customer experience, while you’re giving away money!
Assuming that you do have an alignment machine let’s discuss what goes into a quality alignment. Before the alignment machine is installed on the vehicle the technician must do a thorough inspection of all steering and suspension components including:
- Tire pressure
- Ball joint play
- Tie rod play
- Steering linkage – pitman arm, idler arm, steering link, etc.
- Front and rear control arms and bushings
- Sway bar and associated linkages
- Wheel bearing free play
Most of these inspection items require the use of a good quality dial indicator. Make sure your technicians have one and know how to use it. If any component shows signs of excessive wear, or is outside of state inspection guidelines (where applicable), an estimate should be written and the customer informed as to what needs to be done before the alignment can take place.
You will likely have to educate your customer as to why the alignment they came to your shop to purchase cannot be performed without further repairs. I’ll discuss the customer’s perspective on these things in another column. For now, make sure that the vehicle is in proper working order so that the alignment will be successful and will meet the customer’s expectations.
A quality alignment also includes inspection of vehicle ride height. Vehicle ride height affects such alignment angles as camber, caster, and toe.
Remember what an alignment is: you are aligning steering and suspension angles relative to one another for proper handling, ride comfort and tire wear. If anything is not where it was designed to be, the alignment will be off.
Ride height is a function of the vehicle springs. Sagging, or weak, springs will change the alignment angles relative to one another thus making the vehicle specifications irrelevant unless the suspension is put back to its original state of repair. Ride height measurements will often call attention to weak springs that need to be replaced.
Note: Any suspension changes such as lowering kits or lift kits also require a new set of alignment specifications. These will be supplied by reputable companies who supply these modification kits. I do not recommend even attempting an alignment on a modified vehicle without the proper (new) alignment specifications.
Understanding the relationship of the 3 primary alignment angles camber, castor, toe is important in performing a proper alignment. The camber and toe angles are pertinent to both front and rear suspension systems. Caster is an angle related to the front wheels only.
We define these angles as follows:
The angle formed by a line drawn through the upper and lower ball joint compared to a vertical line as viewed from the side of the vehicle.
The angle formed between a line drawn through the wheel centerline and a vertical line as viewed from the front of the vehicle.
The inward or outward tilt of the wheels as viewed from above the vehicle.
Other alignment angles technicians may utilize include:
- Thrust angle
- Steering axis inclination
- Scrub radius
Steering axis inclination, and scrub radius (although scrub radius is more of a distance measurement than an angle) are considered diagnostic angles and are generally only used when a technician is searching for a reason that continued excessive tire wear or handling concerns exist.
After the rear camber and toe are adjusted (in order), caster needs to be inspected and adjusted. Because of the difficulty in adjusting the caster angles, most technicians will only adjust caster if there is a customer complaint of pulling and the alignment report shows caster more negative by 0.5 degrees or more on one side.
Remember: Caster pulls to the more negative side.
Camber is adjusted after caster as caster is partly responsible for the camber reading. Camber must always be adjusted. Any camber reading that is more than 0.25 degrees different side to side will likely cause a pulling concern and/or tire wear. As with all angles, camber should be adjusted to its nominal value (green doesn’t necessarily mean good!).
Remember: Camber pulls toward the more positive side.
After camber, comes the toe adjustment. Toe a primary tire wearing angle. Toe will not generally result in a pulling concern, but will result in a “steering wheel off center” concern and tire wear concerns.
Note: Although you will read different versions of this, having a toe reading out by as little as 1/8th of an inch will have the effect of dragging the tire 50 feet sideways for every mile driven!
Should a technician find that adjustments need to be made to bring the vehicle into alignment, they must determine if the OE manufacturer provides for adjustments, or whether aftermarket solutions are available. The only good way to know if aftermarket solutions exist is to contact your parts distributor and ask. Just because a solution is not available this week doesn’t mean there isn’t one on the way next week. It can pay to keep asking.
Always use good quality parts when performing repairs or adjustments.
A proper alignment consists of a diligent vehicle inspection, proper installation of the alignment “heads” and alignment equipment, good diagnostics of the alignment measurements and the pride to do the job right. I am constantly dismayed when I learn of shop policies that only require technicians to set the toe and let the vehicle go. This is very unprofessional and is not providing value to the customer.
That’s it for today! Keep up the great work and never stop learning! As always, and as some of you have done, I can be reached through quadrust.com or at www.intelligentmechanic.com.