FAQ - Clutch Plate: Distortion (Warpage)

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WHY DOES A CLUTCH FRICTION PLATE WARP?

 A clutch friction plate may undergo distortion for various reasons, typically associated with incorrect installation, mishandling, or exposure to excessive heat. Clutch friction plates are inherently torsionally strong but vulnerable to distortion in other directions, affecting both the main plate and the clutch hub.

As part of the installation preparation, it is essential to conduct checks on the clutch components before assembly, as outlined in the provided instructions with each clutch kit. The pertinent instruction reads:

"Inspect (the clutch friction plate) spline diameter, spline teeth, (clutch) cover mounting and alignment holes and cover height. Placing the clutch plate on the (clean) transmission input shaft, ensure free slide movement (on the splines) and spin the plate on the shaft to check for distortion. A test fit is required before torquing down any item."

Common reasons for distortion include:

ROUGH HANDLING: 

 Clutch friction plates are susceptible to damage from rough handling,  such as knocks or drops, during storage or shipping. Although uncommon,  distortion from mishandling can occur, emphasizing the importance of  spinning the plate on the gearbox input shaft to check for distortion  before installation to avoid voiding the product warranty. 

INCORECT INSTALLATION PROCEDURE: 

Improper installation of the clutch plate can result in distortion, warpage, and an imbalance that weakens its structural integrity. Installation errors, particularly mishandling the transmission and input shaft, can lead to various issues, including:

• Insufficient Front Gearbox Support: Lack of proper support for the gearbox's front may force the input shaft to bear weight on the clutch plate.
• Rear Gearbox Misalignment: If the gearbox's rear is angled away from the clutch's center line, it can contribute to installation issues.
• Excessive Force During Input Shaft Installation: This can occur due to misalignment of spline teeth or shaft, or inadequate lubrication during the installation process.
• Incorrect Clutch Cover Fixing: Problems may arise if the clutch experiences an improper method of cover fixing. This includes failure to follow fixing bolt progressive tightening and opposing bolt pattern steps, applying uneven/incorrect torquing of bolts, or using powered tools (conventional or impact).
• Issues with Dowels or Dowel Holes: Worn dowels or dowel holes between the engine and transmission, damaged transmission support, or improper driveline angles can contribute to complications during installation.

Ensuring meticulous attention to detail and adherence to recommended procedures during installation is crucial to avoiding these issues and preserving the integrity of the clutch system.

 To prevent warranty voiding, adherence to correct installation procedures specified by the vehicle manufacturer is crucial.   

 Conduct a thorough inspection of transmission supports, mounts, engine and transmission dowels, and dowel holes for any signs of wear or elongation. To aid in proper alignment during installation, it is highly advisable to utilize an alignment tool. Choose the correct workshop tool, readily available commercially, or if included, use the single-use tool provided within the kit.

Ensure precise alignment of the clutch cover with all dowels (where dowels are applicable), and progressively tighten the clutch cover fixing bolts in an opposing bolt pattern. Avoid tightening any cover fixing bolt to completion until all fixing bolts are within one rotation of completion, maintaining a flat and even position of the cover throughout the process. 

Do not use powered (pneumatic or battery) tools or any type of impact drivers for any aspect of the clutch installation.

For compliance with manufacturer specifications, employ a calibrated torque wrench. 

Exercise caution when aligning the transmission to the engine to prevent any flexing or bending of the clutch plate. The insertion of the transmission input into the clutch plate splines should occur with minimal resistance. Never force insertion or compromise proper alignment during this crucial phase of the installation process.

EXCESSIVE HEAT: 

Engagement friction between the clutch plate and the clutch cover and  flywheel generates heat. Excessive heat can lead to warping. Several  common causes of excessive heat include: 

• Incorrect Application: Selecting a clutch kit that is not suitable for its intended use can result in excessive stress and heat. If your intended usage involves demands beyond standard conditions, it is advisable to seek professional guidance for clutch selection. Modified torque requirements, beyond typical use, can arise from factors such as increased engine torque output, elevated drive loads like consistently high or excessive vehicle mass, frequent towing of heavy loads, drive ratio alterations involving transmissions, differentials, wheel diameter changes, and sustained or excessively challenging driving conditions and environments, among other examples.  When making your purchasing decision, carefully consider your intended use to ensure the chosen clutch kit aligns with the specific demands of your driving conditions.

• Slipping Clutch: A clutch that slips frequently generates more heat than typical operation. This excess heat has the potential to modify the hardness and strength of the materials within the clutch plate, leading to a change in its shape. Localized overheating within the plate significantly increases the likelihood of distortion. The varied rates of cooling and contraction across different areas of the clutch plate, due to differences in thermal expansion among its components, contribute to the retention of the distorted shape. 

     Common reasons for clutch slippage include:

1. Clutch Hydraulic System Issues: Problems in the clutch hydraulic system can hinder proper engagement and disengagement.
2. Excessive Friction Plate Wear: When the friction material wears down excessively, it loses its ability to grip the flywheel and pressure plate.
3. Friction Plate Contamination: Contamination, such as oil leaks from the engine or gearbox, can make the friction plate slippery and compromise its ability to grip on contact surfaces.
4. Irregular Flywheel Surface: If the flywheel is not ground smooth, or the correct profile is not restored, high and low spots can develop. Without proper restoration, the contact of the friction plate is significantly reduced, leading to incorrect clutch and flywheel clearances.
5. Excessive Engine Torque: When the engine torque exceeds the operating limit of the clutch, it can result in slippage.
6. Excessive Friction Temperature: Extreme heat can cause the friction material to out-gas. This creates an air gap, reducing grip and inducing further slippage, akin to an air hockey table.

This is not intended to be an extensive nor exhaustive list of causes of clutch slippage.

• Incorrect or Rough Driving Habits: Prolonged clutch engagement due to improper clutch control or holding a vehicle stationary on an incline with the clutch causes high friction slippage. Additionally, vigorous or aggressive driving practices, such as abruptly engaging the clutch at high RPMs (commonly known as dropping the clutch), results in high friction slippage. 

• Demanding Driving Conditions: Excessive heat can occur in challenging driving environments characterized by frequent stop-and-go traffic, heavily loaded vehicles, towing substantial loads, and negotiating steep inclines in hilly or mountainous areas.

This is not intended to be an extensive nor exhaustive list of damage causes of excessive temperatures.

CONCLUSION 

Regrettably, many individuals only become aware of clutch plate distortion through first-hand experience. To minimize the likelihood of encountering this issue, it is crucial for vehicle owners to carefully select a clutch that aligns with their intended use and driving habits.

Equally important is the choice of a skilled and knowledgeable clutch installer. Opt for a professional who adheres closely to both the vehicle’s and parts manufacturer’s guidelines, taking meticulous steps to avoid errors that could potentially harm the clutch friction plate during installation.

While not impossible, instances of clutch friction plate distortion due to manufacturing defects are rare. If you suspect that none of the previously mentioned factors contributed to the part failure, we encourage you to reach out to your store. They are well-equipped to provide prompt resolution and expert assistance tailored to your specific situation.