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E82 135i Manual Limited Slip and Gearing Differential Upgrade

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Changing the rear gearing on your 135i is one of the best performance upgrades you can make. The shorter gearing will help accelerate the car quicker by placing the engine in the boost sooner for any given speed. Being in that 'meatier' part of the power band means more torque is available at the wheels. Using a shorter (numerically higher) gear ratio will give you better acceleration and the limited slip effect will help get that power to the pavement. Changing the limited slip lock-up will change how the car behaves in corners - low lock-up will introduce more wheel spin; a higher lock-up will give more grip to the rear wheels.

Gearing Changes All 135i differentials have welded internal pieces that require special machining and modification. Our diff builder has perfected the process and using a shorter 3.46 ring and pinion is now no more difficult than any other car. But because of the extensive labor involved, the 3.46 upgrade is currently the only gear option offered at this time but it's perfect for keeping the N54 and N55 engines on the boost. The stock 3.08 is offered for rebuilds as well. Using a shorter gear ratio (numerically higher) will give you better acceleration but will reduce your top speed. Refer to the chart below for examples on the difference.

2009 135i, 6-speed manual, 245/35-18" rear tires
(click to expand)
Gear RatioGearSpeedRPM
40 MPH in 4th
3.084th40 MPH2,000 RPM
3.464th40 MPH2,250 RPM
70 MPH Cruise
3.086th69 MPH2,500 RPM
3.466th70 MPH2,875 RPM
5th Gear Speed @ 6,000 RPM
3.085th143 MPH6,000 RPM
3.465th128 MPH6,000 RPM
Speed in 5th gear at 6,000 RPM is for theoretical and comparison purposes only. It doesn't mean that these speeds are actually reachable.

Limited Slip Options. The 135i sadly did not come with a limited slip unit. Instead, BMW used DTC (Dynamic Traction Control) to cut engine power, apply the brake(s), or a combination of both. A limited slip operates independently from either of those systems. With the LSD installed the DTC system does not engage as often. The LSD transfers torque mechanically to the opposite wheel. It will then allow some wheelspin before the traction control kicks in. If you turn off traction control you still have the torque transfer of the LSD working and then wheel spin. So you can get traction in the corner and some wheelspin out of it to facilitate rotation without engine power being cut so soon. Our limited slip units are either 2 or 3 clutch 'factory type' units with a pre-set lock-up (usually 40-60%) or the multi-disc OS Giken 0-100% variable lock-up.

Core Charge. If we are building a diff from our own stock a refundable core charge will apply until we get your original diff back. You have a maximum of 30 days from the time you receive the diff to send it back us for a refund. Click here for more detail and explanation of the core charge.

FAQ: For a full FAQ on the custom diff process, click here.

This item fits the following BMWs:
2008-2012 E82 BMW 135i (not DCT models)

Loading Kit Configurator

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Kit Configurator

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Add REM bearing polish?

Add REM ring & pinion polish?

Core Charge

Limited Slip Options

Select your 135i model (engine):

Select your gear ratio:

Base Differential:

This Part Fits the Following BMWs

Make Model Submodel Engine
BMW E82 135i N54 3.0L
BMW E82 135i N55 3.0L
BMW E88 135i N54 3.0L
BMW E88 135i N55 3.0L
*The above product applications have been written by Turner Motorsport. All warranties, product application, fitment, and performance are the responsibility of Turner Motorsport. For additional information see the terms of use.
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