Progressive LSD Conversion set, you will no longer suffer from losing grip! The set is mounted on your standard differential transforming it into a clutch-type 2-way limited slip differential. No more one-wheel spin on start, and sloppy turns around corners. With this conversion set, you will gain the true performance of a proper limited slip differential. This kit does require machine work to each spider gear within the Differential, you can do this you’re self with a lathe or surface grinder, or we offer a service to carry out all machine work to your Differential for an additional cost. All parts are made in the N7 quality standard. Instructions provided with kit. Professional installation is required. Use oil for limited slip differentials ONLY once fitted. For friction shims, we use the same material as OEM LSD clutches to avoid metal shredding. Therefore, shims are perfectly safe for long term usage! Preload is provided with high rate springs, and we get a dynamic lock from 37.5° angled ramps. All of this together gives 25% progressive lock which increases with revs and vice versa. The set is made from extremely strong s6 tool steel. Parts are heat-treated and hardened to 40HRC under the protection of argon to avoid deformation. Materials used in the production are of the highest quality tool steel. We harden and nitrate the materials to achieve the highest quality surface finish possible. That gives our product the maximum durability and lifespan. 100s now fitted to many models of BMW and is now a tried, tested and reliable proven product. If you are not sure about your fitment, please send us the last 7 digits of your VIN so we can check it for you. Fitment: Progressive Limited Slip Diff conversion set / LSD for BMW 188K E60 E53 E85 E83.