Fact Check: Are hq and commodore stud pattern the same?

Are HQ and Commodore Stud Patterns the Same?

Introduction

The claim that the stud patterns of HQ and Commodore vehicles are the same has been a topic of discussion among automotive enthusiasts, particularly those involved in modifying or restoring classic Holden vehicles. This claim suggests that wheels designed for one model can be interchanged with the other without issue. However, the nuances of stud patterns, including measurements and compatibility, warrant a closer examination.

What We Know

1. Stud Pattern Measurements: The HQ stud pattern is described as having 5 studs on a 4.75-inch (approximately 120.65 mm) circle, while the Commodore stud pattern features 5 studs on a 120 mm circle. This indicates a slight difference in the diameter of the circle formed by the studs, with the HQ pattern being about 0.65 mm larger than the Commodore pattern 49.

2. Compatibility Issues: Several sources indicate that using HQ wheels on a Commodore or vice versa can lead to problems. For instance, one source notes that the taper on the seating face of the rim and nut taper will not seat correctly, potentially leading to vibration issues, rim cracking, and fatigue on the wheel studs 1. Another source emphasizes that the difference, although seemingly minor, can result in stud failure at high speeds 6.

3. Community Consensus: Discussions in automotive forums reveal a general consensus that while the two stud patterns are close, they are not interchangeable without risking safety and performance 234.

4. Potential Modifications: Some enthusiasts suggest that modifications can be made, such as using different discs or spacers, to accommodate the differences in stud patterns 8. However, these modifications may introduce their own set of complications.

Analysis

The reliability of the sources cited varies, but many come from automotive enthusiast forums and communities where individuals share personal experiences and technical knowledge. While these sources can provide valuable insights, they may also reflect anecdotal evidence rather than rigorous testing or scientific analysis.

• Source Credibility:

  • Forums: Many of the sources are from automotive forums (e.g., Just Commodores, Ozrodders) where users discuss their experiences and technical advice. While these can be informative, they often lack formal verification and may be influenced by personal biases or anecdotal experiences 246.
  • Technical Specifications: Some sources provide specific measurements and technical details, which can be more reliable. For example, the distinction between imperial and metric measurements is a factual basis that can be verified against industry standards 9.

• Potential Conflicts of Interest: Some contributors may have a vested interest in promoting specific modifications or products, which could influence their perspectives. For instance, discussions about using spacers or modifications may be driven by personal experiences rather than universally applicable advice.

• Methodological Concerns: The evidence presented in these discussions often lacks formal testing or peer-reviewed studies. While the anecdotal evidence can be compelling, it does not substitute for systematic investigation into the safety and performance implications of using incompatible stud patterns.

Conclusion

Verdict: False

The claim that the stud patterns of HQ and Commodore vehicles are the same is false. Key evidence supporting this conclusion includes the distinct measurements of the stud patterns, with the HQ pattern being approximately 0.65 mm larger than that of the Commodore. This difference, while seemingly minor, can lead to significant compatibility issues, including improper seating of wheel nuts, which may result in vibrations and potential safety hazards.

It is important to note that while some enthusiasts suggest modifications to accommodate these differences, such alterations can introduce additional risks and complications. The consensus within automotive communities indicates that interchanging wheels between these two models is not advisable without addressing these safety concerns.

However, the evidence primarily comes from anecdotal sources and automotive forums, which may not always provide rigorous testing or verification. Therefore, while the conclusion is based on the available information, it is essential to recognize the limitations of this evidence and the potential for variability in individual experiences.

Readers are encouraged to critically evaluate information and consult multiple sources when considering modifications or repairs to their vehicles.