A great upgrade for drivers looking for added acceleration and grip for their E82 1M!
A differential upgrade/rebuild for your 1M delivers performance far above the original factory spec. Diffsonline has 20 years of expertise in BMW differential upgrades and rebuilding. The factory M Variable viscous differential is good for about 60,000 miles before it's worn out. What good is a worn-out limited slip diff in an M car? Diffsonline specializes in BMW differentials and makes it easy to replace and upgrade your diff.
When planning a diff upgrade in your 1M there are two factors to consider: limited slip type and gearing choice. For a turbo M car like the 1M, limited slip choice is more important than gearing.1M Limited Slip Options
There are a number of limited-slip carrier upgrades for the 1M Coupe but they fall into two groups - clutch and helical. For purely street use we would recommend a helical such as Wavetrac or the in-house Diffsonline carrier. Helical diffs offer advantages in wear resistance and performance over traditional clutches. Torque transfer happens instantly and it doesn't need to sense a spinning wheel first. Lock-up is quicker and smoother and it's less affected by heat than a clutch. The only downside is potentially higher gear whine (but not in all cases). Some street 2 and 3-disc street clutch options have been discontinued due to the dwindling supply of original BMW cores.
Our clutch options are designed around serious track or race use since they can be easily customized around car setup and driving style. These diffs feature multiple clutch and spring discs - more clutches equal greater capacity for torque and heat management. Custom ramp angles are machined into the carrier to dictate lockup behavior under acceleration and deceleration (coast). Lower values equal a more aggressive lock-up. Our clutch options are generally not for street use except in highly-modified cars that need the extra traction.
The BMW M Variable viscous diff uses plates and heavy fluid to transfer torque between axles. When new and fresh the system works quite well for street use. However, it is out-performed by traditional clutch differentials on the track and loses performance and refinement within 60,000 miles.
Full Race LSD carrier - This carrier is a wish list come true for differential features. Up to 10 clutch discs are used with preload set by coil springs instead of spring plates that are affected by wear. As with any racing part, weight is the enemy and Diffsonline reduces mass by over 25%. Engagement is set by single-driven ramps - aggressive engagement on acceleration but none or very little on deceleration. This is known as a 1-way limited slip and the zero lockup under braking and mid-corner coasting means very little lock-up is pushing you into understeer. The Race carrier option is designed only for race and track use - it will be noisy and unrefined for street use and no warranty is offered.
The OS Giken is a multi-clutch design that is recommended only for track use and no warranty is provided.1M Gearing Options
Gearing selection for a turbo car can be tricky. The factory specified a gear that was optimal for acceleration, smoothness, and fuel economy. All of those are affected by using a new gear ratio. On turbo cars, a shorter (numerically higher) gear ratio will get you into the boost sooner but at the expense of smoothness and traction. Some lag in a turbo system is desirable so that the car doesn't feel like an off/on switch. For street driving a stock or mildly upgraded gear is advised (3.15-3.23). Any ratio over 3.45 will be great for acceleration but will be difficult to modulate on the street. Also keep in mind the shorter gears will mean extra shifts during 1/4 and acceleration runs. The true advantage in buying a 1M differential upgrade comes from a better limited slip and getting power down. Contact our sales staff if you have any questions.
|Max Speed at 7,000 RPM (click for larger)||RPM at Cruising Speeds (click for larger)|
REM Polishing - REM is a light surface polish treatment of the gears and/or bearings that removes small imperfections on the surface. This reduces internal temps and friction, improving performance and efficiency. It also makes the ring & pinion smoother and quieter. REM polishing is done on a as-ordered basis and may result in additional build time. REM is a registered trademark of REM Chemicals, Inc.Core Charge
There is a $1,500 core charge for your usable original diff. This charge will be in addition to the advertised price. Core exchanges help keep the overall cost low and wait times to a minimum. Therefore we require that your return your original diff to Diffsonline within 14 days. You can even re-use the shipping container and packing material. The core refund is at the discretion of the diff builder - only rebuildable cores will be accepted. Click here
for the core policy and instructions. You can avoid the core charge by sending in your existing diff for the rebuild.Selecting the best differential type for your application can be a difficult task considering the amount of ratios and limited slip carriers. Please feel free to contact your BimmerWorld sales representative to discuss the best differential for your application.
BMW Fitments:1 Series
E82 (11-12) > 1M Coupe