This is the stock twin mass flywheel for the N55 engine used in the E82 135i, E9X 335, F3x 335/435, and F10 535i. It's manufactured by OEM supplier LuK. Sachs recommends a new dual mass flywheel (DMF) on every other clutch replacement. There are several indicators for replacing the flywheel: damage to the clutch contact plate (from a severely worn clutch disc), grease leaking from inside (overheating), build-up of clutch material on the contact plate (excessive slipping and overheating), and failure of the internal damping system.

The dampening system uses rubber or coil springs to absorb driveline vibrations. Through age, excessive heat, and aggressive use the rubber loses its resilience and the metal springs lose their strength and become brittle. If the clutch and flywheel have become overheated the internal grease may break down as well. A DMF failure can be massive and catastrophic, not to mention dangerous as bits of metal and rubber fling themselves through the transmission bellhousing. Heat and aggressive driving will accelerate the wear so race and track cars should have their stock flywheels replaced at regular intervals or with any new clutch. Even normal street cars should plan for a new flywheel if it has high mileage.

DMF wear can only be checked with the transmission and clutch removed. If you can rotate the outer flywheel more than 20mm in either direction then it should be replaced.

A new pilot bearing (roller bearing) is included, pre-installed in the flywheel hub.

This item fits the following BMWs with the single turbo N55 engine and manual transmission:
2011-2012 E82 BMW 135i
2011 E90 BMW 335i 335xi 335i xDrive - Sedan
2011-2013 E92 BMW 335i 335xi 335i xDrive - Coupe
2011-2013 E93 BMW 335i - Convertible
2012-2015 F30 BMW 335i 335iX - Sedan
2014-2016 F34 BMW 335iX - Gran Turismo
2014-2016 F32 BMW 435i 435iX - Coupe
2014-2016 F33 BMW 435i 435iX - Convertible
2014-2016 F36 BMW 435i 435iX - Gran Coupe
2011+ F10 BMW 535i 535i xDrive

Single piece 6061 construction, optimized cooling, provisions for temp sensor, and external cooler with removable air duct.

Built to last, made from a single piece of 6061 billet aluminum with a rugged and good-looking hard-coat anodizing the Turner diff cover can handle anything you throw at it. Not only is it an absolute masterpiece, but this billet diff cover checks all the boxes for features needed. Reinforced mounting ear for strength and stability. The mounting ear is unified with the one-piece billet cover and features added material for the highest durability possible. This diff cover is cool, literally, the entire construction was designed with optimized cooling in mind. External fins are strategically placed on the rear face, bottom, and between the mounting ears of the cover, serving as effective heat sinks for optimal heat dissipation. This ensures stable temperatures, promoting longevity for both the fluid and your differential. Additionally, the internal design ensures continuous oiling and lubrication of the ring gear, maintaining its stability and preventing fatigue by controlling heat more effectively. An internal baffle at the cover's corner helps maintain proper pressure and prevents cavitation.

All of the OEM features were retained along with the upgrades. The drain and fill plugs on the diff cover are upgraded to -6AN using the provided high-pressure fittings with replaceable o-rings. The drain and fill plugs can now be used for an external oil cooler allowing you to further expand the fluid capacity for optimized cooling and service intervals. To keep an eye on things from the driver seat is 1/8 NPT provision for temp sensors, this product from Turner has you covered at every turn.

Upgrading to our Turner Billet Differential cover gives you the strength you need to push your car to its limits without worrying about snapping a diff mount from clutch kicking or other shocks to the drivetrain. In addition to its enhanced strength, this differential cover includes numerous other upgrades and conveniences. These include improved cooling and lubrication for the ring gear, upgraded fill and drain plugs, and the option to expand an external oil cooler for extreme motorsport usage. Designed to complement both upgraded daily drivers and extensively modified track cars, it also offers a visually appealing design.

Key Benefits:

Reinforced mounting ear for strength and stability
16% Increased fluid capacity
External fins on the back side, bottom, and mounting ear on the casing for maximum cooling and consistent fluid temps
Removeable air duct to direct air across the cooling fins for even more temperature control
Optimized internal design to keep fluid consistently on the ring gear
Integrated breather to prevent cavitation by venting the appropriate amount of pressure being built up in the diff housing
-6AN ports to incorporate the use of a differential cooler - this increases capacity and lowers temps allowing for extended fluid change intervals
1/8 NPT fitting for the use of a temp sensor to monitor fluid temperature
Design:

Fits manual transmission Large Case 215mm differentials
Single piece 6061 Billet aluminum construction
T6 Black hard coat anodizing for superior corrosion resistance and aesthetics
Compatible with most differential coolers(-6AN) and temp sensors(1/8 NPT)
Designed to accommodate oversized rear sway bars
Retains OEM mounting features
Factory geometry bushing size for use with OEM and aftermarket poly bushings
Removeable air duct for easy access to sensors and drain/fill plug