These kits feature a non-SAC mechanism pressure plate, which , deviating from the original design, provides a lighter rotating assembly, higher rpm capability and greater clamp load levels. Required for the install is a billet rebuildable flywheel that features a lightweight, low MOI design and infinite rebuildability. The billet aluminum flywheel weighs 14lbs, and billet steel 22 lbs.
Tuning your N54/N55 with all of the bolt-on upgrades? Don't allow your clutch or flywheel let you down! The stock clutch is fine for a stock car or just a simple software upgrade. But anything more and it quickly becomes the weak link (especially with drag races or hard launches). The 135i/335i/535i/Z4 35i SPEC Stage 2+ clutch kit is perfect for owners who want a performance clutch that works great with simple bolt-on modifications and will have a minimum of downsides or trade-offs. SPEC has spent considerable time and effort on the 335i models to produce a performance clutch and flywheel package that holds up to track and drag strip demands but is also easy to live with for daily driving. This clutch kit is meant to be used only with a SPEC flywheel.
What was most important to them was offering a kit that has stock-like clutch pedal effort but will grab and hold when the car has been mildly tuned. Full bolt-on upgrades like software, intake, FMIC, E85 mix, or methanol demand a better clutch. The Stage 2+ has a peak torque rating of 545ft-lbs but note that the stock dual-mass flywheel will be a limiting factor to how much torque you can use. There have been cases of high mileage or abused flywheels coming apart with high torque tuned engines. We recommend using a new factory flywheel or jumping to the SPEC single-mass flywheel. The clutch in this Stage 2+ kit is self-adjusting, like the factory design, and the engagement point can be adjusted. The clutch disc is a rigid hub (not spring loaded) so it's best used with the stock dual mass flywheel.
We recommend using the Stage 2+ clutch kit if you don't plan on doing tuning beyon bolt-on upgrades. If you plan on going beyond bolt-ons, such as upgrading turbos or single turbo, we strongly recommended using the Stage 3+ clutch. The Stage 2+ offers the best drivability for 90% of the tuned 335s out there but when going beyond bolt-on upgrades it would be best to go to a more advanced clutch stage.
SPEC Clutch is one of the premier clutch and flywheel suppliers to the tuner market. They are often found on the most highly tuned import and domestic vehicles. They are recent players in the German car community with a special focus on the newer turbo BMW models with high torque output. SPEC has been proven time after time to provide superior performance, drivability, and longevity to the most hardcore enthusiasts around the globe.
- Limitations of the stock flywheel are eliminated
- Self-adjusting, like the factory design, and the engagement point can be adjusted
- Sprung hub clutch to be used with the single-mass flywheel with near-stock levels of noise, vibration, and refinement
Stage 1: 430ft/lbs
Stage 2: 485ft/lbs
Stage 2+: 545ft/lbs
Stage 3: 580ft/lbs
Stage 3+: 671ft/lbs
Stage 4: 580ft/lbs
Stage 5: 820ft/lbs