Are you an automotive enthusiast who loves motorsports? Do you want to take your car’s handling to the next level? If so, you need to align your car’s geometry with simple string and rulers! Proper alignment is crucial for optimal handling, and it’s not as difficult as you might think. In this article, we’ll show you how to align your car’s geometry with string and rulers for motorsport. Buckle up and get ready to learn!
- Understanding the Basics of Car Geometry
- Why Proper Alignment Is Important for Motorsport
- Aligning Your Car’s Geometry with String and Rulers
- Tips for Optimal Alignment
Understanding the Basics of Car Geometry
Before we dive into the specifics of aligning your car’s geometry, let’s take a moment to understand the basics. There are three main components of car geometry that affect handling: camber, caster, and toe.
Camber refers to the angle of the wheels relative to vertical when viewed from the front or rear of the vehicle. If the top of the wheel leans towards the centre of the car, it’s called negative camber. If the top of the wheel leans away from the centre of the car, it’s called positive camber.
Caster refers to the angle of the steering axis when viewed from the side of the vehicle. A positive caster angle means the steering axis tilts towards the rear of the car, while a negative caster angle means the steering axis tilts towards the front of the car.
Toe refers to the angle of the wheels relative to the longitudinal axis of the car. If the wheels point towards each other, it’s called toe-in. If the wheels point away from each other, it’s called toe-out.
If you want more info on these check out our article on how each affects driving in motorsport!
Why Proper Alignment Is Important for Motorsport
Proper alignment is crucial for optimal handling in motorsport. When your car’s geometry is correctly aligned, you’ll experience better steering response, improved cornering grip, and increased stability at high speeds. Improper alignment, on the other hand, can lead to uneven tire wear, poor handling, and decreased performance.
Aligning Your Car’s Geometry with String and Rulers
Now that you understand the basics of car geometry and why proper alignment is important, let’s get into the nitty-gritty of how to align your car’s geometry with string and rulers.
It may sound primitive but using a string alignment system is a highly cost-effective method of achieving precise wheel alignment. This involves running a string or nylon parallel to the car’s centerline on each side of the vehicle and taking accurate measurements from the front and rear of each rim to the string to calculate the toe.
While some people may view this technique as unsophisticated compared to using professional alignment machines with laser beams or cameras, even professional motorsport teams use it for alignment. The method is powerful, portable, and affordable, and there are professional string wheel alignment rigs available from various manufacturers.
However, all you need are four jack stands, some nylon or string, and a steel ruler to do the job. Adding a pair of alloy bars to attach the strings is advantageous, as we can cut slots into them at the same distance apart and support them on our jack stands at the front and rear of the vehicle, ensuring that the strings are parallel to each other.
Using the string alignment system allows us to measure toe on each corner of the car independently, ensuring equal toe side to side and avoiding situations where the steering wheel is not straight or where the car crabs down the racetrack. While the string alignment system cannot be used to check and adjust camber or caster, we will cover the necessary equipment for those jobs later on.
Here’s what you’ll need:
- Axle Stands
- 2 pieces of pipe or wood wider than the vehicle
- A level surface
- A friend to help
Step 1: Set Up Your Alignment Equipment
- Before setting up the equipment, we need to find a flat and smooth concrete pad that provides enough space to work. Ideal locations include racetracks or any area free from other people working. Any bump to the string equipment can affect the results and waste time.
- Mark out the location on the workshop floor where each wheel of the car is going to sit. This will allow you to check and ensure that the floor is level. Use blue low tack tape to mark each corner.
- Roll the car out of location and check the setup patch for levelness. Ideally use a pair of 17 millimetre sockets as packers and a rectangular aluminium extrusion to check if the surface is level but if these are not available do your best to substitute for something equivalent!
- Roll the car back into location and align it with the marks made on the ground.
- Fit the string wheel alignment equipment. Start with the front of the car and fit the frame into the engine bay. Adjust the frame to approximately 320 millimetres, the centre height of the wheel. Then fit the bar to the frame and align it to the centreline of the car.
(Alternatively if you do not have a frame, set up four axle stands around the car, lay your pipe across the top of the axle stands. )
- Groove the metal pipe slightly wider than the total track width of the car, so you have a slot for the string to sit in and are able to measure the distance to the wheels.
- Repeat step 5 for the rear of the car.
- Fit the strings down each side of the car. Initially, roughly locate the strings making sure that you are in the same groove at the front and rear of the car.
- Fine-tune the strings to approximately 30 millimeters off the edge of the rim for more accurate measurements.
- Square the strings. Choose a reference point on the centre of the front and rear wheels of the car that can be measured from. Measure the distance between the reference point on the hub and the strings. If there is a discrepancy, divide the error in half and adjust the strings between the front and rear of the car until the same measurement is obtained on each side. (i.e shuffle the pipes slightly till the strings are parallel with the car. the distance may not be the same between front and rear wheels due to track width discrepancies.)
- Check and adjust tire pressures to normal hot running pressure, for instance, 30 psi.
- With the alignment equipment fitted and set up, move on to the next step in the process.
Step 2: Measure Toe
To measure toe, measure the distance between the front and back of the rim. the difference is the amount of toe in or out you have, this should be the same for both sides of the car. (ensure your steering wheel is pointed perfectly straight)
You can now adjust the track rods to either toe in or out your wheels to gain the setting desired.
Step 3: Measure Camber
To measure camber, place a plumb line vertically until it just say touches the wheel, measure the distance between the string and the top or bottom of the wheel. if there is a gap at the top you have negative camber. If the bottom measurement is larger than the top measurement, you have positive camber. Adjust the camber by adjusting the camber plates or shims to give you the measurement you need (if using degrees use Pythagoras to determine camber angle based on wheel diameter and camber measurement.)
Step 4: Setting Castor
- Remove the strings temporarily to check the caster on the front end of the car.
- Fit the car on turn plates and zero them with the steering wheel straight ahead.
- Fit the Intercomp adapter to the wheel and magnetic camber/caster gauge onto it.
- Turn the steering wheel to the right by 20 degrees and level the camber/caster gauge. Zero the caster gauge bubble.
- Turn the steering wheel back to the left through 40 degrees total and level the gauge. Finally, read the caster.
- Check the caster on both sides of the car and make adjustments if necessary by adjusting the caster arm.
- Refit the strings and make sure they’re square to the car.
- Measure the camber on each corner of the car.
- Measure between the front and rear edges of each rim out to the string alignment equipment.
- Check the base alignment settings and make necessary adjustments.
Step 5: Check and Adjust Again
After adjusting the camber, caster, and toe, double-check your measurements and make any necessary adjustments. Repeat this process until all measurements are within spec.
The final step of our process is to perform a spanner check to ensure that all of the components we have adjusted are correctly re-tightened. We have put the car back up on the hoist and removed the wheels. We will work from the top down, starting with checking that the strut tops are correctly tightened, including the camber adjustable strut top cap screws on the front.
We will then move down the strut and check the locking screw for the lower spring platform, the two bolts that hold the MacPherson strut onto the hub, and the sway bar linkage. Moving underneath the car, we will check all suspension components and every place where a suspension component mounts to the chassis.
We will also ensure that the tie rod ends for our front steering are correctly re-tightened without inadvertently making any further adjustments. Lastly, we will check that the cap screws locking down the adjustment mechanism of the suspension arms are correctly tightened.
We will repeat this process at the rear of the car. Once everything is checked and tightened, we can put the wheels back on and move onto the final step of evaluating our changes on the racetrack.
Tips for Optimal Alignment
Here are some tips to help you achieve optimal alignment for your car:
- Use a high-quality thick coloured fishing string that won’t stretch or sag.
- Make sure your alignment equipment is level and secure.
- Use a reliable and accurate ruler or measuring tool.
- Check your car’s suspension components for wear or damage before attempting to align.
- Make small adjustments at a time and re-measure after each adjustment.
- Don’t be afraid to seek the help of a professional if you’re unsure about the alignment process.
Aligning your car’s geometry with string and rulers for motorsport may seem intimidating at first, but it’s a crucial step to achieving optimal handling and performance. By following the steps outlined in this article, you can ensure that your car’s geometry is properly aligned for your next track day or autocross event. Remember to take your time, be precise, and don’t hesitate to seek professional help if needed.
1. How often should I align my car’s geometry?
It’s recommended to align your car’s geometry at least once a year or after any significant suspension modifications.
2. Can I align my car’s geometry by myself?
While it is possible to align your car’s geometry by yourself, it’s best to seek the help of a professional to ensure accuracy and avoid causing any damage.
3. How can I tell if my car’s alignment is off?
Signs of improper alignment include uneven tire wear, pulling to one side while driving, and a crooked steering wheel when driving straight.
4. What is the ideal camber angle for motorsport?
The ideal camber angle for motorsport depends on several factors, including tire type and track conditions. It’s best to consult with a professional to determine the ideal camber angle for your specific setup.
5. Is aligning my car’s geometry with string and rulers suitable for street use?
While aligning your car’s geometry with string and rulers is commonly used in motorsport, it can also be suitable for street use to improve handling and tire wear. However, it’s essential to ensure that your alignment is within spec and won’t cause any unsafe driving conditions on public roads.