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JHM 4:1 Center Diff Upgrade (Tiptronic Trans Only) for B6-B7 S4 and B7 A4


From: $350.00

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From: $297.50

To: $797.50

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For B6-B7 S4 and B7 A4 with the 6HP19 6-speed Tiptronic transmission only. NOTE: All B6-B7 S4s and All B7 A4s with a 6-speed Tiptronic transmission are equipped with the 6HP19 by ZF and have this center differential.

The factory Torsen center differential in the S4 and A4 provides a 2:1 torque distribution between front and rear wheels. What does this mean? This enables the end of the car that still has traction (most of the time the rear) to deliver double the torque to the tires with the most traction. Our experience has proven that this closer to even distribution is best for drag racing. If you are primarily into drag racing, this modification is not for you. However for Auto-Crossers, Road Racers, and others who prefer the twisties, JHM recommends a high-bias ratio of 4:1. This is the same bias ratio that Audi has provided in the stock RS4 driveline.

So if you are tired of going through corners while using a lot of throttle and still getting "understeer" then this product is for you. It will help you get a little more "oversteer" and allow you to drive the car a little more like a rear wheel drive car but still have the superior control of Audi's legendary quattro all wheel drive system.

For B6-B7 S4 and B7 A4 with the 6HP19 6-speed Tiptronic transmission only. NOTE: All B6-B7 S4s and All B7 A4s with a 6-speed Tiptronic tramission are equipped with the 6HP19 by ZF and have this center differential.

--Here is a write up on how to perform the install on a B6/B7 S4 MT. Tiptronic cars are pretty much the same except that you MUST refill all the gear oil since it is separate from the Automatic Transmission fluid that runs the transmission. It takes just under 1 quart of 75w90 synthetic gear oil that we also sell. Make sure you purchase some before the install. Check it out --> HERE

Core Exchange
There is a core charge if we send out a JHM center differential to you (see drop box below for amount). When you exchange your center differential for a JHM unit, send your differential back to JHM and we will refund the core charge. As of 7-23-1 we currently have only a couple tiptronic cores in circulation since this is a new product and it takes time to locate them. As a result we are offering a $75 discount when sending yours in to be modified. Once we locate and stock up on cores this promotional price will end.

NOTE: If your core is damaged or worn out your core fee will not be returned or only partially returned. However if you have a damaged center differential contact us and we can discuss your options.

You may also send your differential to us for modification and not incur a core charge. We can usually modify and ship out your differential within the same day. If you will be sending yours in, select the option from the dropdown below and specify in the comments that you will be shipping it in. When shipping your differential in for modification, please include a copy of your invoice that you receive via email after you place your order. Also, put the invoice number from your order on your box when shipping it in for modification.

NOTE: It is common with this modification to notice a slight chatter when making u-turns at low speeds. This is due to the changes from the modification that make it bias differently under power and at high speeds. During normal daily driving, this chatter is not noticeable.

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This product fits the following vehicles:
Make Model Chassis Engine
Audi S4 B6 (2003-2005) 4.2l V8 40v
Audi A4 B7 (2005.5-2009) all
Audi S4 B7 (2005.5-2009) 4.2l V8 40v
Customer Reviews (2)
This is the first mod an B6 owner should do to their car. It completely transforms the car in the twisties. While it doesn't get rid of all the understeer, it's very nearly perfection.
A must for all B6ers.
Review by Michael (Posted on 2/23/2013)
bonjour je vous precise que mon audi est une audi s4 b7 de 2005 boite automatique merci de m envoyer le differentiel le plus rapidement possible merci Review by deweerdt (Posted on 12/21/2012)
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You're reviewing: JHM 4:1 Center Diff Upgrade (Tiptronic Trans Only) for B6-B7 S4 and B7 A4
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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