APR Clutch Packs - DQ250 DSG / S Tronic
The APR DQ250 Clutch Packs replace the factory transmissions friction disc and steel plates with an advanced and proprietary design that allows for greater performance. The system goes beyond the norm of simply increasing the disc and plate count, and takes a multi-step approach that not only greatly improves the overall friction engagement area, but does so without sacrificing the total heat-sink material mass of the steel plate. With 40-50% more friction discs, tighter tolerances, carefully specified materials, surface finishes, a proprietary top plate design and more, the clutches hold more torque, prevent premature failure, and provide quick shudder-free high-performance engagement!
The APR Difference
A balance between increasing friction material surface area and overall steel plate thickness is critical when designing a dual clutch transmission (DCT) clutch pack. To increase torque capacity, transmission manufacturers typically specify larger transmission designs with either more room for more discs, discs with wider surface areas, or a combination of both. However, this is not an option for those simply looking to upgrade their existing transmission.
All too often, steel plate thickness is shrunk in an effort to cram in more frictions discs and plates, but in doing so, the steel plates can become unable to dissipate heat, resulting in premature wear, hot spotting and ultimately failure. However, APR’s design increases the friction disc count by 40-50%, but does so while maintaining proper steel plate thickness and total mass. This is thanks to a proprietary top plate design. By replacing the factory stamped-steel top plate spacers with functional top plates, with integrated mounting surface surfaces, the clutch packs are left with substantially more room to increase the number of discs and plates without sacrificing thickness.
A three-step approach was taken to increase friction material surface, or engagement area:
- The number of discs are increased 40-50%, resulting in 13 discs with 26 friction surfaces.
- The outer diameter of the friction disc is increased and the interior diameter is decreased, leaving a wider engagement swath.
- The friction material’s surface design is optimized, increasing the physical friction material surface area within the engagement area.
The result is obvious: a larger engagement area designed to hold more torque! Furthermore, less clamping pressure is required to hold higher torque levels, reducing the temperature of the clutch fluid. Heat is a major contributor to clutch failure, making this extremely desirable, especially for higher output vehicles, and vehicles under brutal racing conditions.
Keeping it Smooth
To ensure the clutches engage smoothly and quickly, careful attention was paid to the discs and plates to ensure they resist premature wear, warping, dragging and hot spotting. The discs and clutches remain thick, despite adding more, thanks to the proprietary top plate design. The steel plates undergo a heat flattening process with stringent flatness requirements, and the hardness of the steel was increased, over the factory design, to assist in rigidity. The plates are processed with an aggressive finish, but this finish is appropriately matched to the friction disc material to prevent wear. Likewise, the friction discs use a carefully selected material for optimal shudder-free high-performance engagement, and include tighter flatness specifications, further assisting in their smooth operation.
APR Recommendations and Requirements
APR provides a detailed install manual with each set of clutch packs that covers the installation process. New shims are not included with the clutches and can be purchased separately if needed. The factory shim can be reused if not compromised during removal. Also, APR dealers will have shim kits available if they are performing the install. After install, the transmission MUST undergo a factory TCU clutch adaptation before it’s driven. Failure to do this properly can cause irreparable damage to both the friction and steel plates. This adaption can be accomplished using VCDS (BETA 16.6.0 or higher), ErWin, or the VW Factory Scan Tool.
The transmission uses a micro-slip routine with hard factory torque limits. APR’s standard TCU upgrade is a MUST to ensure proper operation.
The transmission fluid is drained during the installation process so new, factory fluid, is required along with a new filter.