Two-Wheel vs. Four-Wheel Alignments
![](/images/crn/1665.jpg)
Wheel alignments are a common requirement on many collision damaged vehicles. Although the methods for measuring the alignment of the wheels can vary, the results should always be the same. The wheels should be aligned within OEM specifications.
Many vehicles on the road today have independent rear suspension with adjustments for toe, camber, and sometimes caster. Other vehicles have a solid rear axle with no adjustments for the rear wheels. This may leave one asking, "If there are no rear wheel adjustments, do I only perform a two-wheel alignment?"
A two-wheel alignment is simply aligning the camber, toe, and caster (if adjustable). This is typically the front wheels. This would have the wheels at the correct angles with respect to each other and would usually produce a centered steering wheel.
However, we do not live in a perfect world. There are numerous variables that can cause the misalignment of the rear wheels. If the front wheels are aligned without taking this variance into consideration, the steering wheel will now be off center when driven, and the vehicle may seem to pull to one side. This is due to the front wheels not being aligned to the thrust angle of the rear wheels.
On an independent rear suspension equipped vehicle, thrust angle is a product of individual toe and can often be corrected during the four-wheel alignment process if the structure and suspension parts are not damaged. This ensures that the front and rear wheels are within specifications.
With solid rear axles, simple adjustments are not an option on most vehicles. There may be procedures to slightly shim to compensate for OEM tolerances, but other than that, adjustment is often limited or nonexistent.
With a solid axle, it is important that both rear wheels are tracking correctly; ideally parallel to the centerline of the vehicle. So even though the rear wheels do not have any toe or camber adjustments, it is important to make sure the front and rear wheels are within specifications. Also, if the rear wheels are out of specification, it may be an indication of bent suspension parts or structural damage that has not been repaired.
It is impossible to determine if the rear wheels are out of specification with a two-wheel alignment and makes performing a four-wheel alignment necessary. In the case of solid rear axle vehicles, since the thrust angle cannot be corrected, the front wheels are aligned not only to each other but to the thrust angle as well, putting all four wheels within specifications.
Failure to correct the thrust angle or to align to it (in the case of a solid axle vehicle) may result in increased tire wear, off center steering wheel, a pull to one side, and can even cause handling issues or affect advanced driver assistance systems (ADAS) features. This means that no matter what the rear suspension type or axle configuration, all four wheels and the steering wheel should be considered during the alignment process.
A thrust angle alignment (solid rear axle) references all four wheels and aligns the front wheels so they are in correct relationship to the thrust angle presented by the rear wheels where slight OEM tolerances do not position them perfectly parallel to the vehicle centerline. If the thrust angle is out of specification, it should be corrected before completing the alignment.
In conclusion, this is why all four wheels should be checked. Modern alignment equipment requires that sensor heads be attached/reference all four wheels and the steering wheel position verified.
Additional I-CAR Collision Repair News you may find helpful:
- Common Mistakes: Performing Wheel Alignments When Damage Still Exists
- SEMA 2020: I-CAR How ADAS, Calibration, Structure, And Wheel Alignments Are Connected Presentation
- The Effects Of Wheel Alignment On ADAS
Related I-CAR Courses
-
Toyota/Lexus/Scion Position Statement: Pre- and Post-Repair System Scanning
Thursday, 28 July 2016
As the industry continues to ask if pre- and post-repair system scanning is necessary, Toyota/Lexus/Scion provides their answer.
-
Pre- and Post-Repair System Scanning Statements
Wednesday, 9 January 2019
Are you wondering if a particular OEM or organization has a published statement on pre-repair and post-repair scanning? We have compiled a list of most of the statements on the subject, so you can...
-
ADAS, Calibration, And Scanning Article Hotspot
Monday, 14 January 2019
Since advanced driver assistance systems (ADAS), scanning, and calibration first started becoming relevant, members of the collision repair industry have required as much knowledge as possible on...
-
Honda/Acura Position Statement: Pre- and Post-Repair System Scanning - UPDATE
Wednesday, 22 May 2019
Honda /Acura has updated their position statement on pre- and post-repair scanning to give more clarification on what is expected for scanning.
-
Restraints Wiring Repairs
Monday, 23 May 2016
Over the past few months, we've been sharing OEM position statements on restraints wiring repairs. Now we're bringing them all together in one place for easy reference.
-
General Motors Position Statement: Pre- and Post-Repair System Scanning
Friday, 21 October 2016
As the industry continues to ask, are pre- and post-repair scans necessary, General Motors provides their answer.
-
Quickly Identifying Outer Quarter Panels w/Rolled Hem Flanges
Monday, 5 March 2018
The I-CAR best practice article, Recycled Outer Quarter Panels w/Rolled Hem Flanges has gotten a lot of interest from the collision repair industry. It’s important to know which vehicles are...
-
Typical Calibration Requirements For Blind Spot Sensors
Wednesday, 19 October 2016
Technicians should be aware of what’s required to keep advanced driver assistance systems (ADAS) running safely after a collision. Whether that be aiming a camera, which can cause a system to not...
-
Typical Calibration Requirements For Forward Radar Sensors
Wednesday, 12 October 2016
Technicians should be aware of what’s required to keep advanced driver assistance systems (ADAS) running safely after a collision. Whether that be aiming a camera, which can cause a system to not...
-
FCA/Stellantis Position Statement: Pre- and Post-Repair System Scanning
Thursday, 9 June 2016
FCA/Stellantis has released a position statement related to pre- and post-repair system scanning.
-
I-CAR Repairers Realm: Air Conditioning Repair Considerations - Now Available
Friday, 30 August 2024
I-CAR had a discussion on air conditioning repair considerations.
-
Body Construction And Material Repair Guidelines: Rolls-Royce
Wednesday, 28 August 2024
What is the MPa of the front lower rail? What is the outer uniside made of: steel, aluminum, or composite? Can heat be used to straighten or is it cold straightening only? What are the repair...
-
Back-To-Basics: Tire Damage
Tuesday, 27 August 2024
Sometimes going back-to-basics can make the difference between a quality repair and a failed repair. When performing damage analysis do not overlook tire damage.
-
Honda Blind Spot Indicator (BSI) Dummy Sensor
Friday, 23 August 2024
We’ve had technical inquiries that asked about Honda vehicles being equipped with dummy blind spot sensors.
-
Locating OEM-Approved HV Tools: Rivian
Wednesday, 21 August 2024
When researching procedures for disabling a high-voltage (HV) vehicle, you may notice that many of the procedures require the use of specific tools. Some of them are OEM-specific tools or scan...
-
Paint Maker ADAS Radar Optimized Color Resources: PPG
Tuesday, 20 August 2024
Changes in advanced driver assistance systems (ADAS) radar technology are introducing new refinishing considerations. We know that paint film thickness can affect the performance of ADAS radars, but...
-
I-CAR Just In Time: Using A Scuff Wheel To Remove Plastic Fuzz
Thursday, 15 August 2024
Sometimes seeing is understanding, that’s why I-CAR's technical team created the Just in Time video series to guide you through a variety of collision repair topics from ADAS and EVs to repair tips...
-
Nissan Altima Laser-Welded Roof Replacement
Wednesday, 14 August 2024
How do I replace a factory laser-welded roof on a Nissan Altima is a common question. Nissan released a procedure that explains their process, let’s take a look.
-
I-CAR Just In Time: Protecting UHSS Panels When Removing Spot Welds
Friday, 9 August 2024
Sometimes seeing is understanding, that’s why I-CAR's technical team created the Just in Time video series to guide you through a variety of collision repair topics from ADAS and EVs to repair tips...
-
OEM ADAS Radar Optimized Color Resources: Genesis
Thursday, 8 August 2024
Changes in advanced driver assistance systems (ADAS) radar technology are introducing new refinishing considerations. We know that paint film thickness can affect the performance of ADAS radars, but...
- 2024
- August 2024 (12)
- July 2024 (12)
- June 2024 (10)
- May 2024 (13)
- April 2024 (12)
- March 2024 (12)
- February 2024 (12)
- January 2024 (10)
- 2023
- December 2023 (8)
- November 2023 (12)
- October 2023 (11)
- September 2023 (11)
- August 2023 (12)
- July 2023 (9)
- June 2023 (11)
- May 2023 (12)
- April 2023 (11)
- March 2023 (12)
- February 2023 (10)
- January 2023 (11)
- 2022
- December 2022 (11)
- November 2022 (12)
- October 2022 (11)
- September 2022 (13)
- August 2022 (11)
- July 2022 (10)
- June 2022 (13)
- May 2022 (11)
- April 2022 (12)
- March 2022 (10)
- February 2022 (11)
- January 2022 (13)
- 2021
- December 2021 (13)
- November 2021 (11)
- October 2021 (13)
- September 2021 (14)
- August 2021 (12)
- July 2021 (15)
- June 2021 (17)
- May 2021 (14)
- April 2021 (14)
- March 2021 (21)
- February 2021 (15)
- January 2021 (14)
- 2020
- December 2020 (13)
- November 2020 (17)
- October 2020 (12)
- September 2020 (14)
- August 2020 (11)
- July 2020 (18)
- June 2020 (16)
- May 2020 (14)
- April 2020 (20)
- March 2020 (12)
- February 2020 (14)
- January 2020 (14)
- 2019
- December 2019 (13)
- November 2019 (19)
- October 2019 (25)
- September 2019 (20)
- August 2019 (22)
- July 2019 (23)
- June 2019 (20)
- May 2019 (19)
- April 2019 (20)
- March 2019 (21)
- February 2019 (20)
- January 2019 (18)
- 2018
- December 2018 (19)
- November 2018 (19)
- October 2018 (17)
- September 2018 (16)
- August 2018 (21)
- July 2018 (20)
- June 2018 (21)
- May 2018 (17)
- April 2018 (19)
- March 2018 (22)
- February 2018 (16)
- January 2018 (20)
- 2017
- December 2017 (13)
- November 2017 (15)
- October 2017 (19)
- September 2017 (20)
- August 2017 (20)
- July 2017 (18)
- June 2017 (20)
- May 2017 (19)
- April 2017 (13)
- March 2017 (18)
- February 2017 (11)
- January 2017 (13)
- 2016
- December 2016 (9)
- November 2016 (14)
- October 2016 (21)
- September 2016 (10)
- August 2016 (11)
- July 2016 (8)
- June 2016 (10)
- May 2016 (7)
- April 2016 (11)
- March 2016 (12)
- February 2016 (11)
- January 2016 (8)
- 2015
- December 2015 (9)
- November 2015 (7)
- October 2015 (9)
- September 2015 (7)
- August 2015 (11)
- July 2015 (7)
- June 2015 (5)
- May 2015 (7)
- April 2015 (9)
- March 2015 (8)
- February 2015 (9)
- January 2015 (10)
- 2014
- December 2014 (12)
- November 2014 (7)
- October 2014 (11)
- September 2014 (10)
- August 2014 (9)
- July 2014 (12)
- June 2014 (9)
- May 2014 (13)
- April 2014 (9)
- March 2014 (6)
- February 2014 (1)
- January 2014 (27)