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JHM Helical Rear LSD for B7-RS4 (HNR) - Pre-Built Core


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JH Motorsports is excited to now offer the JHM Rear LSD Pre-Built Rear Differential Core Program. Installing a rear LSD can be simple work, if you have experience and the variety of tools required to properly install an LSD into a rear differential. However, a majority of people do not have that luxury which is why we now offer the JHM LSD Pre-Built Rear Differential Core.

What is a Pre-Built Rear Differential Core? A pre-built core is an OEM Rear Differential that we have pre-installed our JHM Helical Rear LSD into here at JH Motorsports, meaning the customer does not need to perform any specialty work to have our JHM Helical Rear LSD installed in their car. All the customer will need to do is a simple swap of rear differentials and they are ready to hit the road with their new found grip.

Since this is a core program, you will be receiving a Good Used OEM Rear Differential in exchange for yours. We inspect all differential cores when they come in to make sure they are in good working order before they are rebuilt (Some cores may look different than your original differential due to different locations and weather climates). During the installation of the JHM Helical Rear LSD we will also refresh the differential with all new Ringer Gear Bolts, Seals, and O-rings! ALL JHM Rear LSD Pre-Built Rear Differential Cores will come with a 12 Month Limited Warranty as well as a Limited Lifetime Warranty on the LSD itself.

NOTE: ALL rear differentials will NEED to be shipped DRY to JH Motorsports. ALL rear differentials shipped FROM JH Motorsports will be DRY. You will need to fill the rear differential with gear oil before driving the car.

NOTE: Rear Differential Cores will NEED to be packaged very carefully when shipping to JH Motorsports. Any damages to the rear differential from shipping will automatically cause the rear differential to NOT be accepted as a core.


After years of research and development, we are proud to release our JHM Helical Rear Limited Slip Differential LSD for the B7-RS4.

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B7 RS4 Rear Limited Slip Differential by JH Motorsports

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B7 RS4 Rear Limited Slip Differential by JH Motorsports

Click to enlarge picture
B7 RS4 Rear Limited Slip Differential by JH Motorsports

Check out our similar Rear Helical LSD for the B6-B7 A4-S4 in action in our shop's Stage 2 Supercharged, Built Motor B6-S4:

In the stock Audi rear differential, the torque from the motor that's sent to the driveline is evenly divided between the two rear axles. In most driving situations this is normally fine. However, in cases where traction is lost at one wheel (i.e. under hard acceleration out of a corner or launching from a stop) power is only being sent to the spinning wheel. In these situations, a gear-based limited slip differential will take the torque from the wheel that's starting to spin and send it back to the wheel with that's not - the one with better traction. This means that both rear tires will spin together - with or without traction.

Features and Benefits of the JHM B7-RS4 Helical LSD:
- Helical gears respond to changes in traction conditions very quickly
- Improves traction and predictability of vehicle behavior: both rear wheels will spin at the same rate. Under hard acceleration out of corners or launching from a stop the car will either "hook up" and go or both rear tires will spin. Some "track focused" drivers say that this allows you to steer the car better with the throttle.
- Prevents "one-legging" (spinning one rear tire only) and therefore eliminates losses in acceleration under load out of corners and heavy acceleration from a stop (launching).
- Maintenance free! There are no clutch packs to replace as they wear out.
- No special gear oil or additives necessary. Again, since there are no clutches, you can run the same gear oil as recommended by Audi in our LSD.
- Our JHM B7-RS4 Helical Rear LSD comes with a Limited Lifetime Warranty against manufacturer defects.

While we recommend our B7-RS4 LSD for anyone looking to improve the traction and predictability of their B7-RS4, the more horsepower your car has or the harder you drive, the more our JHM B7-RS4 LSD will make a difference in your car.

Installation Note: When replacing the differential, the factory repair manual states that you must check ring gear backlash and bearing pre-load. Our JHM B7-RS4 LSD is built to factory tolerances and all the differentials we have swapped at our service facility haven't required "re-shimming". However, due to variances in factory tolerances, it is best to make sure that these measurements are checked and confirmed. Additionally, if you do not have the right "bearing splitters" to remove your original bearings with a press, install them on the JHM differential, and correctly inspect for wear or issues you may need to replace the differential bearings. If you have concerns about your tools or your ability to properly inspect and/or disassemble and re-assemble your differential please do not hesitate to contact us. We can perform all of this work for you if you send us your differential housing.

FITMENT: 2006-2008 B7 RS4 4.2L FSI V8 ALL

**Don't forget to add axle seals and gear oil to your order before you check out!**

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This product fits the following vehicles:
Make Model Chassis Engine
Audi RS4 B7 (2006-2009) 4.2l V8 32v FSI
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Off-road Use

By Purchasing any Off-Road use ONLY products from JH Motorsports, Inc. I acknowledge and understand the following disclosure. (This notice is located at the bottom of the page description of affected products on our website.)

Vehicle Code § 27156:
(b) No person shall operate or leave standing upon a highway a motor vehicle that is required to be equipped with a motor vehicle pollution control device under Part 5 (commencing with Section 43000) of Division 26 of the Health and Safety Code or any other certified motor vehicle pollution control device required by any other state law or any rule or regulation adopted pursuant to that law, or required to be equipped with a motor vehicle pollution control device pursuant to the National Emission Standards Act (42 U.S.C. Secs. 7521 to 7550, inclusive) and the standards and regulations adopted pursuant to that federal act, unless the motor vehicle is equipped with the required motor vehicle pollution control device that is correctly installed and in operating condition. No person shall disconnect, modify, or alter any such required device.
(c) No person shall install, sell, offer for sale, or advertise any device, apparatus, or mechanism intended for use with, or as a part of, a required motor vehicle pollution control device or system that alters or modifies the original design or performance of the motor vehicle pollution control device or system.

Health and Safety Code § 43000:
43001. The provisions of this part shall not apply to:
(a) Racing vehicles.

As the aforementioned code sections outline, it is against the law to operate or use a vehicle on public streets or highways with modified, altered, or disconnected motor vehicle pollution control devices. This may include but is not limited to, Evaporative Fuel Controls, Catalysts, DPF, PTOX, PCV Systems, Exhaust Gas Recirculation Systems, Oxygen Sensors, Thermostatic Air Cleaners, Air Intake Systems, Fuel Injectors, Regulators, Adjustable Cam Gears, ECU Programming, Mapping, or other Computer Modifications. Air Pumps, Air Injection, Timing, and any other Emission System Modification(s).

Purchaser acknowledges and certifies to JH Motorsports Inc., that Purchasers vehicle will only be used for racing applications or off road vehicle use only. Purchaser requests these modifications for the purpose of enhancing the vehicle for competitive Racing Applications and will not use this vehicle on public streets or highways. Purchaser agrees to indemnify JH Motorsports Inc., all employees, officers, owners, and subsidiaries for any civil or criminal liability arising out of use of Purchasers vehicle on public streets or highways as Purchaser has been duly notified of the laws and regulations regarding disconnecting, alteration, or modification of a vehicle’s pollution control devices. Purchaser understands and has been advised the driving of a vehicle on public streets or highways could result in criminal or civil penalties.

Prop 65

Warning: This product may contain a chemical known to the State of California to cause cancer, birth defects, or other reproductive harm.

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