Contact YouTube Blog Twitter facebook Turner Motorsport on Instagram
1-800-280-6966
 |   Login
  • 0
 |   Login
Shopping Cart (0) Wishlist
Contact

(0) item(s) in your Shopping Cart

Home

Categories

Specials

Gifts & Clothing

  1. Genuine BMW Accessories
  2. Genuine BMW Clothing
  3. Turner Shirts Hats and Gear
  4. Gifts under $25
  5. Gifts under $50
  6. Gifts under $100
  7. Gifts over $100
  8. Gift Certificates
  9. Stocking Stuffers
  10. Gift Packages

Brakes

  1. Brake Overhaul Packages
  2. Brake Pads
  3. Brake Pad Sensors
  4. Brake Rotors
  5. StopTech Big Brake Kits
  6. Brembo Big Brake Kits
  7. Stainless Steel Brake Lines
  8. Brake Fluid
  9. Brake Calipers
  10. Caliper Rebuild Kits
  11. Parking Brake Parts
  12. Brake Master Cylinders
  13. ABS/DSC System Parts
  14. Brake Cooling Ducts & Backing Plates
  15. Brake Pads - Brembo GT BBK Calipers
  16. Brake Pads - StopTech BBK Calipers

Car Care & Accessories

  1. Car Covers
  2. Wheel & Tire Cleaning
  3. Wax, Polish and Cleaning Supplies
  4. Detailing Gear
  5. Leather & Plastic Care
  6. Car Cleaning Supplies
  7. Chassis Paint, Coatings, Sealants, and Rust Conversion

Drivetrain

  1. Differential and Gearing Upgrades
  2. Differential Mounts and Upgrades
  3. OEM Clutch Kits & Clutch Parts
  4. Performance Clutch Kits & Parts
  5. Lightweight Aluminum Flywheel Upgrades
  6. Stock OEM Dual Mass Flywheels
  7. Stainless Steel Clutch Lines
  8. Clutch Parts
  9. UUC Short Shift Kits
  10. Axle Shafts
  11. Driveshafts
  12. B&M Short Shifters
  13. Performance Short Shift Kits
  14. UUC DSSR - Double Sheer Selector Rod
  15. Drivershaft Center Support Bearings
  16. Flex Discs & Guibos
  17. Transmission Mounts
  18. Transmission Parts

Engine Chips

  1. Performance Chips, 1986-1995 Models
  2. Shark Injector Performance Software, 1996-2005 Models
  3. Performance Flash Software, 2005+ Models
  4. Sprint Booster Drive-by-Wire Module
  5. Stand-Alone Engine Management

Engine Parts

  1. Engine Performance Packages
  2. Cam Sprockets & Gears
  3. Water Pumps
  4. Thermostats
  5. Radiators & Cooling System Overhaul Kits
  6. Oil Pan Baffles
  7. Radiator Hoses, Cooling Hoses, & Hose Sets
  8. Engine Fans & Fan Clutches
  9. Underdrive Power Pulleys
  10. Camshafts
  11. Schrick Peformance Camshafts
  12. E30 M3 S14 Engine Parts
  13. External Engine Parts
  14. Drive Belts & V-Belts
  15. Gaskets, Gasket Sets, Seals, & O-Rings
  16. Crankcase Vent, PCV, and Oil Separator Systems
  17. Motor Mounts
  18. Electrical Sensors, Switches, & Relays
  19. Ignition Parts
  20. Alternator & Alternator Parts
  21. Starter Motors & Starter Parts
  22. Fuel System Parts
  23. Internal Engine Parts
  24. Cylinder Head Parts & Head Bolts
  25. VANOS Units & Parts
  26. Rod Bearing Kits
  27. Oil Coolers & Oil Cooler Parts

Exhaust

  1. Supersprint Performance Exhaust Systems
  2. Performance Headers & Downpipes
  3. Turner Motorsport Performance Exhaust
  4. Akrapovic Performance Exhaust Systems
  5. Borla Performance Exhaust Systems
  6. Corsa Performance Exhaust Systems
  7. Performance Exhaust Systems
  8. OEM Replacement Mufflers and Exhaust Systems
  9. Exhaust System Upgrades
  10. Exhaust Muffler Tips
  11. Catalytic Converters
  12. Oxygen Sensor - O2 Sensors
  13. Exhaust Gaskets Hangers and Parts

Exterior / Body

  1. Black Grills
  2. Chrome Grills & Trim
  3. Emblems & Decals for Hood, Trunk, and Wheels
  4. Painted Reflectors
  5. Front Spoilers, Bumper Covers, & Air Dams
  6. Rear Spoilers, Rear Wings, & Aprons
  7. Body Trim Parts & Accessories
  8. Carbon Fiber Trunk Lids
  9. Hood & Trunk Shocks, Struts
  10. License Plate Brackets & License Plate Frames
  11. Mirror Kits & Mirror Parts
  12. Window Regulators & Motors
  13. Wiper Blades, Wiper Pumps, & Wiper Motor Parts
  14. Hood Pins and AeroCatch Latches
  15. Racing Tow Hooks and Tow Straps

Intake

  1. aFe Cold-Air Intake Kits
  2. Turbos & Active Autowerke Superchargers
  3. Gruppe M Cold-Air Intake Kits
  4. Performance Intake Kits
  5. aFe Performance Air Filters
  6. K&N Performance Air Filters
  7. Replacement Cone Air Filters (for Cold Air Intakes)
  8. Intake Cleaning & Recharging Kits
  9. Intake Manifold Upgrades
  10. Intake Manifold Components (DISA, Vacuum, CCV, Etc)
  11. BOV, Chargepipe, and Intercooler Upgrade Kits
  12. Mass Air Sensor & Air Flow Meters
  13. Intake Boots & Hoses
  14. Throttle Body Parts

Interior

  1. Floor Mats
  2. Gauge Kits and Data Acquisition
  3. Auxiliary Input Adaptors for BMW
  4. Pedal Sets
  5. Escort Radar Detectors
  6. Factory Steering Wheels
  7. MOMO Steering Wheels
  8. Shift Knobs, Shift Boots, & Shift Handles
  9. Seats & Seat Accessories
  10. Seat Belts and Racing Harnesses
  11. Cup Holders and Storage
  12. Carbon Fiber Interior Parts
  13. Door Sill Strips
  14. Heating & Air Conditioning
  15. Interior Switches and Switchgear
  16. Sunshades & Windscreens
  17. Interior Trim & Accessories

Lighting

  1. Euro Clear Turn Signals, Parking Lights, & Tail Lights
  2. Turn Signals / Parking Lights
  3. Angel Eye Headlight Conversions
  4. PIAA Driving Lamp Kits
  5. Bulbs for Headlights, Turn Signals and Tail Lights
  6. Headlights, Headlight Lenses, & Headlight Parts
  7. Fog Lights, Fog Light Lenses, & Fog Light Parts
  8. Tail Lights
  9. Stealth Bulbs

Maintenance

  1. Routine Maintenance & Tune-Up Packages
  2. Oil Filters & Oil Filter Kits
  3. Air Filters
  4. Fuel Filters
  5. Cabin Air Filters, Heppa Filters, & Microfilters
  6. Transmission Filter Kits & Transmission Service Parts
  7. Distributor Caps & Rotors
  8. Ignition Coils
  9. Ignition Wires / Spark Plug Wires
  10. Spark Plugs
  11. Bentley Repair / Service Manuals
  12. Service Reset Tools & Fault Code Readers
  13. Anti-Freeze and Coolant
  14. Engine Oils - Genuine BMW and OEM
  15. Power Steering and Hydraulic Fluids
  16. Transmission and Gear Oil - Genuine BMW and OEM
  17. MOTUL Engine Oil and Gear Lubricants
  18. Red Line Oil & Fluids

Suspension

  1. Shocks & Struts
  2. H&R Performance Springs
  3. H&R Cup Kit Shock & Spring Packages
  4. Spring & Shock Packages
  5. Turner / H&R Height Adjustable Spring Sets
  6. Bilstein PSS PSS9 PSS10 Coil Over Suspensions
  7. H&R Coil Over Suspensions
  8. KW Coil Over Suspensions
  9. Moton Coil Overs & Race Shocks
  10. ST Suspension Coilover Kits
  11. Turner Motorsport TrackSport Coil-Over Suspension Kits
  12. Turner Motorsport Racing Suspension Kits
  13. Chassis Reinforcement Kits & Parts
  14. Sway Bar Kits
  15. Sway Bar Links & Sway Bar Parts
  16. Camber / Caster Kits
  17. Strut Braces & Stress Bars
  18. Control Arm Replacements & Upgrades
  19. Suspension Bushings & Mounts
  20. Wheel Bearings & Hub Assemblies
  21. Steering Racks & Power Steering Pumps
  22. Tie Rods & Steering Parts
  23. Coil Over Spring Hardware

Wheels

  1. Apex Flow Formed Alloy Wheels
  2. Forgeline Custom Forged Alloy Wheels
  3. HRE FlowForm Performance Alloy Wheels
  4. Vorsteiner Wheels
  5. D Force Flow Formed Alloy Wheels
  6. Original BMW Wheels and Wheel Upgrades
  7. Turner Motorsport Wheel Spacers
  8. H&R Wheel Spacers
  9. Wheel Bolts, Wheel Studs and Nuts
  10. Wheel Emblems, Caps, and Accessories

Tools

  1. Alignment Tools
  2. Battery Chargers and Tenders
  3. Brake Tools
  4. Clutch Alignment Tools
  5. Coil Over Wrenches
  6. Cylinder Head and VANOS Tools
  7. Fan and Fan Clutch Tools
  8. Fault Code Readers and OBD Scan Tools
  9. Fuel System Tools
  10. Genuine BMW Tool Kits
  11. Oil Service Tools
  12. Sockets
  13. Spark Plug Sockets
  14. Transmission and Differential Tools
  15. Wheel Pin Tools
  16. Workshop Chemicals

Clearance/Used Parts

Choose BMW

BMW 1 Series

  1. (E82) 1-series Coupe 2008+
  2. (E88) 1-series Convertible 2008+

BMW 2 Series

  1. (F22) 2-Series Coupe 2014+
  2. (F23) 2-Series Convertible 2014+

BMW 3 Series

  1. (E21) 3-Series 1977-1983
  2. (E30) 3-series 1984-1991
  3. (E30) M3 1988-1991
  4. (E36) 3-series 1992-1999
  5. (E36) M3 1995-1999
  6. (E46) 3-Series 1999-2005
  7. (E46) M3 2001-2006
  8. (E90) 3-Series Sedan 2006-2011
  9. (E90) M3 Sedan 2008-2013
  10. (E91) 3-Series Touring 2006-2013
  11. (E92) 3-Series Coupe 2007-2013
  12. (E92) M3 Coupe 2008-2013
  13. (E93) 3-Series Convertible 2007-2013
  14. (E93) M3 Convertible 2008-2013
  15. (F30) 3-Series Sedan 2012+
  16. (F31) 3-Series Touring 2014+
  17. (F80) M3 2015+

BMW 4 Series

  1. (F32) 4-Series Coupe 2014+
  2. (F33) 4-Series Convertible 2014+
  3. (F34) 4-Series Gran Turismo 2014+
  4. (F82) M4 Coupe 2015+
  5. (F83) M4 Convertible 2015+

BMW 5 Series

  1. (E34) M5 1991-1993
  2. (E39) M5 2000-2003
  3. (E60) M5 2006-2010
  4. (E28) 5-Series 1982-1988
  5. (E34) 5-Series 1989-1995
  6. (E39) 5-Series 1996-2003
  7. (E60) 5-Series Sedan 2004-2010
  8. (E61) 5-Series Touring 2006-2010
  9. (F10) 5-Series 2011+

BMW 6 Series

  1. (E24) 6-Series 1977-1989
  2. (E63) 6-Series Coupe 2004-2010
  3. (E64) 6-Series Convertible 2004-2010
  4. (F06) 6-Series Gran Coupe 2013+
  5. (F12) 6-Series Coupe 2011+
  6. (F13) 6-Series Convertible 2011+

BMW 7 Series

  1. (E32) 7-Series 1988-1994
  2. (E38) 7-Series 1995-2001
  3. (E65) 7-Series SWB 2002-2007
  4. (E66) 7-Series LWB 2002-2007
  5. (F01) 7-Series SWB 2009+
  6. (F02) 7-Series LWB 2009+

BMW 8 Series

BMW Classics (E9, Bavaria, Isetta, etc)

  1. 2500
  2. 2800
  3. 3.0Si
  4. Bavaria
  5. 2800CS
  6. 3.0CS
  7. 2002
  8. 2002tii
  9. (E12) 528i 1977-1981
  10. (E12) 530i 1975-1978

BMW X Series (SAV)

  1. (E84) X1 Series 2013+
  2. (E83) X3 2004-2010
  3. (F25) X3 2011+
  4. (F26) X4 2015+
  5. (E53) X5 2000-2006
  6. (E70) X5 2007-2013
  7. (F15) X5 2014+
  8. (F85) X5 M 2015+
  9. (E71) X6 2008+
  10. (F16) X6 2015+
  11. (F86) X6 M 2015+

BMW Z Series

  1. (E36/7) Z3 1997-2002
  2. (E85) Z4 M Roadster
  3. (E85/E86/E89) Z4 2003+
  4. (E86) Z4 M Coupe
  5. (E52) Z8 2000-2003

BMW 1600-2002 / tii

BMW i Series

  1. (I01) BMW i3 2014+
  2. (I12) BMW i8 2014+

MINI Cooper and Cooper S

Racing

Racing Home

Racing News

Racing Schedule

Racing Photo Gallery

Gallery

Photo Gallery

Wallpaper

Project Cars

  1. Project i8
  2. Project F80 M3
  3. Turner F82 M4
  4. Turner X5 M
  5. Turner F22 2 Series
  6. Turner F13 M6
  7. Turner F10 M5
  8. Turner F30 335i
  9. Turner E9X M3
  10. Turner E92 335i
  11. Turner E82 1 Series
  12. Turner ActiveE (100% Electric)
  13. Turner E46 M3
  14. Turner E46 330i ZHP
  15. Turner E36 M3
  16. Turner E30 M3
  17. Turner MINI Cooper S
  18. McLaren F1
  19. Turner E92 M3 Lime Rock
  20. Turner F80 M3 Silverstone

Video Gallery

Projects

Turner i8

Turner F80 M3

Turner F82 M4

Turner X5 M

Turner F22 2 Series

Turner F13 M6

Turner F10 M5

Turner F30 335i

Turner E9X M3

Turner E92 335i

Turner E82 1 Series

Turner ActiveE (100% Electric)

Turner E46 M3

Turner E46 330i ZHP

Turner E36 M3

Turner E30 M3

Turner MINI Cooper S

McLaren F1

Turner E92 M3 Lime Rock

Turner F80 M3 Silverstone

About Us

About Turner Motorsport

Customer Feedback

The Turner Team

Employment Opportunities

Returns Policy

Shipping Info

Contact Us

Privacy Policy

Security Policy

FAQs

Custom Differential FAQ

Looking into having your diff upgraded? Here you will find all of the answers to your questions. Still have a question, drop us an e-mail or give us a call.

What is the process for buying a diff?
It's easy! Differentials are built from the specs you choose on the order. Each diff is custom-built by a diff specialist. You choose the gear ratio, limited slip upgrade, and any other options and submit your order.

What's the core charge?
If we build a diff from our stock a core charge will apply. If a core charge applies, it may be refunded after you send in your original diff and it is inspected. Cores must be received back within 30 days of when you receive the diff. If you send in your original diff first, the core charge may not apply (depending on the condition of the diff you send in). See below for complete information on cores.

Ring & Pinion / Gear Ratio Options.
BMW diff rebuilds All of our diffs are built with a final drive gear of your choice. For better acceleration select a shorter gear set (higher number = shorter gear). Most manual transmission cars have a tall gear. And most automatic transmission cars use a shorter gear set to offset the transmission ratios and heavier weight. The shorter the gear the higher the revs will be for any given speed. You don't want to go too short because it will leave you with higher revs on the highway, shifting more often, an extra shift in quarter-mile and acceleration runs, etc. This can also impact your fuel efficiency and also engine and road noise. Consider your gear choice carefully and remember we can always give you advice via phone or e-mail. We offer all of the factory gear ratios as well as some BMW Motorsport designed gear sets for certain models. We can also have the ring and pinion set polished to reduce friction and lower temperatures.


What is REM Polishing?
REM(tm) is a process where high spots and imperfections are removed from the surface. We offer polishing for the ring and pinion and the bearings. These imperfections are a normal byproduct of the manufacturing process and BMW does perform a basic finish to ensure there are no major defects. For a regular street car with regular service intervals the BMW-finished part works just fine. But there is always a little more that can be done, especially with precision machining, and this is where REM(tm) polishing comes in. Under extreme conditions these imperfections can create stress risers and localized hot spots and deformation of the material, which will accelerate wear and create more residual heat throughout the diff. REM(tm) polishing removes these high spots and imperfections and leaving a mirror smooth finish behind. The parts are given a chemical treatment and then ground with a very fine ceramic media. The grinding is gentle and designed only to take off high points on the surface and not to dig into the material itself. It's a 'micro polishing' multi-step procedure with proven results.

Benefits of REM(tm) finishing:
  • reduced friction, vibration, and noise
  • improved engagement
  • longer life and less stress and fatigue
  • lower temperatures

How To Check Your Current Gear Ratio
Not sure of your current diff ratio or think it was changed in the past? There are several ways to tell which ratio is currently installed -
Mark the input shaft and the diff housing together (paint marker, scribe, etc). Similarly mark an output shaft flange and housing. Spin the input shaft, which will turn the output flanges, and count the number of revolutions on the output flange until the markings on the output flange line up again. If the input flange spins 3.25 turns around then the ratio is 3.25:1. If it takes 4 turns then it's likely 4.00 or 4.10. You'll have guess to a certain degree (for instance it's hard to distinguish between 3.38 and 3.46) but you should be able to get an accurate range of what ratio is installed in your car. You can also spin it 10 times the normal number to get a more accurate gear ratio (41 turns = 4.10; 38 turns = 3.80; etc). The original ratio may be cast into the diff housing but that's no guarantee that someone didn't already change it.

Limited Slip Options.
Limited Slip units fall into two general categories: street-only use, mixed street-track, and full race use. The street LSD units are similar to most OE BMW LSDs - a 2 or 3 disc clutch-type with limited lock-up (up to 60%). These work great for regular street and daily driver use as they are simple, effective, reliable, and priced accordingly. The small number of clutch packs means heat can be a factor on grip and wear so high horsepower cars may want something stronger (OS Giken, Quaife, or helical). The performance of a factory-type LSD is simple, long-lasting, quiet, and predictable and you can expect it to perform just like it would have come from the BMW factory. Variable-lock diffs generally work best on the street but are not the ideal setup for track use.

Street/Track-type diffs are more complex with multiple clutch plates or with helical-style gears (no clutch plates). Because of their complexity they require special care and maintenance with more frequent oil changes with special fluid and periodic rebuilds. There may also be noise considerations depending on the type you choose. Track setups are dictated mainly by the track you're running on with gearing, ramp angles, and lock-up the major determining factors. It may be beneficial to have more than one diff for use at different tracks (as long as rules allow). A variable lock diff may be the best answer unless wheel spin is part of your handling setup. However, variable diffs can also alter the handling behavior of the car from one corner to another, making the handling unpredictable. If you have found the stock M Variable diff to be problematic on the track then we would suggest you switch to a more traditional 2 or 3-disc limited slip which will be more reliable. We can also build limited slip diffs with ramp angles that match your driving style and the track. Our race team used the OS Giken LSD in our E46 M3 and E92 M3 racecars.
OS Giken LSD

Limited Slip Ramp Angles.
The ramps are machined sections of the limited slip housing that the spider gear pin rides on. The pin slides up and down the ramps to engage or disengage the clutch packs. The angle of the ramp determines how much and how quickly the LSD locks up. The higher the ramp angle (degrees) the more resistance there is and the less likely the diff will lock. A shallower angle will get the diff to lock quicker. There are ramps for acceleration and deceleration. Typically the decel ramp is very mild unless it's a full race setup. The factory LSD units are set at a 45* angle for accel and decel. We can vary the ramp angle depending on the car, useage, and driving style. We can even have an "adjustable" ramp angle design with multiple ramp angle options.
typical factory BMW 45/45 ramp angles custom 30/60 ramp angles
(not actual design, used for illustrative purposes only)

One of the big advantages of a traditional clutch-type or helical LSD over the M Variable diff is there is no wasted motion in the LSD. When slip is detected the mechanical diff will instantly transfer load to the other wheel. In the M Variable viscous diff there is a delay as wheel spin happens first and then the diff begins to lock up.

Note that ramp angle and lock-up are two completely different things and they are expressed differently. Ramp angle is literally the angle from horizontal that the ramp follows. The lock-up is expressed as a percent. It's the percentage of torque that is distributed to the wheel with the most grip. An open (non-LSD) diff will distribute all of its torque to one wheel and that wheel will likely spin/slip under power. A LSD will transfer "XX%" of that torque to the wheel that is not spinning.

Limited Slip Lock-Up
As mentioned above the lockup is a percentage of torque transferred to the slower spinning wheel to gain better traction. The higher the percentage the more torque will be transferred during a loss of traction. The M Variable diff varies the torque based on wheel speed differences - the faster one wheel spins the more lock is given to the other wheel. Up to 100% of torque is transferred which is where the "variable" comes from. Traditional limited slip diffs have a fixed acceleration lock-up. The factory LSD is 25% lockup. We can vary the lockup based on the car and the type of driving you do. The downside to too much lock is that it pushes the car straight and will force understeer. That works great for a drag strip where you never turn but terrible when using the car on a road course where the wheels must spin at different speeds or an autocross course where some wheelspin is needed for the car to rotate.

What is replaced when my diff is rebuilt?
The first thing that is done is to clean all of the parts thoroughly. Differentials are very messy and cleaning all of the parts will make defects and wear more noticeable. We replace all of the seals, bearings, and hardware. On limited slip units the clutch discs and friction discs are heat treated and nitride coated. On M Variable diffs the viscous pump is inspected and tested. All internals are inspected and replaced if worn or damaged. Some parts get re-used as they are low or no-wear pieces. Our diff specialist also shims and aligns the diff correctly, which is absolutely crucial. This is actually the most time-consuming portion of the build becaufse it has to be just right. We take the time to build and check all of the correct clearances and tolerances to ensure the complete diff functions just as it should. The diff does not work properly if it's not built right and if you're not happy with the final result then we won't be either. You're getting back a diff that is effectively brand-new and maybe built a bit better than even a factory rebuild!

BMW diff rebuilds

How long does it take?
Each diff build is different. The typical turn-around time is less than 5 days. But for 'simple' diff builds we may be ready to ship sooner. If you select the gear polishing or other custom options it may add several days to the build time. We stock all of the common rebuild parts so parts shortages are not an issue. In rare cases, we may have to order a new part from BMW and that can take additional time. The diff build process involves significant manual labor (repeated assembly and disassembly to check clearances) and other setup. During busy times of the year we may experience some backups in the build process. In the event there is a prolonged delay, you will be notified.

How is a diff shipped?
We ship by UPS Ground. Air options are available as well but diffs are very heavy and shipping costs are high. Freight shipping is not required. We over-pack every diff in a double-core box with foam padding to ensure it makes it to your destination without damage or delay. The packaging is so robust you can usually re-use the shipping box and foam packing to send in your core. You can re-use the box and the foam packing but use new tape on the top and bottom to seal it. Every diff ships without fluid and without a cover.
BMW diff shipping

What is the break-in?
Immediately upon installing your diff, drive the car slowly to a safe and appropriate location. At no more than idle speed drive 20 figure-8 patterns (full lock-lock on the steering). Then drive in 20 full-lock turns to the left and 20 more to the right. For the next 1,200 miles do not exceed 85 MPH and drive moderately, using care not to shock or load the driveline. Perform an oil change at 1,200 miles using appropriate fluid. During the break-in period it will be normal to experience clunking and chattering from the diff. There may also be a diff whine which will diminish over time. For street cars we typically recommend a 30,000 mile oil change interval. Track cars have a very different schedule and is based mainly on use and setup. OS Giken and 3-disc diffs should have oil changes every 15-20,000 miles. Kaaz differentials have their own break-in procedures and fluid recommendations.

What fluid should I use?
We prefer the Red Line or Motul brands as that is what we have had success with over the last twenty years. We also have a selection of factory Castrol or Pentosin fluid and the special OS Giken required fluid.

All of the 2 or 3-clutch limited slip units can use a 75/90 or 75/140 diff fluid. The heavier fluid is typically only needed on track-driven or drift cars.
A factory M Variable limited slip should use the Red Line or Motul 75/140 fluid or the factory Castrol SAF XJ + FM booster.
OS Giken limited slips require their own 85W250 operating fluid.
Quaife torque biasing differentials can use a 75/90 fluid from Red Line or Motul.

Core Charge Policies
The Core Charge applies when we build a diff from our supply of differentials and parts. To ensure we have adequate diff supplies on hand we place an additional charge on your order. As an incentive to send us your original diff, all or part of that core charge may be refunded. Cores must be received back within 30 days of your receipt of the new diff. Cores returned after the 30 days will not be accepted for refund. It is important that we receive your core promptly so that we can count on having good stock on hand for our future customers. Core charges may seem like an additional upfront cost for you but it ensures we have re-useable parts. Without these re-useable parts we would have to use new parts from BMW which will make the diff builds more expensive for everyone. And shipping your core back to us quickly ensures you do not pay credit card interest on the core charge. Core diffs must be complete except for the parts required for you to re-install the new diff. In other words, you must return a diff equal in components and accessories to the one we sent you. Things like input and output flanges must be returned as these are cleaned and re-used in our diff rebuilds. Critical parts that are missing from your core diff will be deducted from your core refund.

Limited Slip Cores: The following only applies to these models: E24, E28, E30, E36, Z3
As most of our differential builds include limited slip units we need original limited slip units returned to us. Non-limited slip (open) differentials returned for cores will not receive a full refund.

Returns.
Sorry, there are no returns on custom built differentials but we stand behind our products and will work with you to resolve any and all issues. Our expertise means there is no diff issue that can't be resolved.

Turner Motorsport Custom Rebuilt BMW Differentials

click for more

E30 Custom Differentials
Upgrading or rebuilding the differential is one of the keys to the performance of the E30 325 or E30 M3. If you're stuck with a tall gear ratio you're going to be left behind on most acceleration runs. And if you have installed an M50/S50/S52 engine the gearing should be changed as well to make better use of the new torque curve...Click for more.

click for more

E36 Custom Differentials
Upgrading or rebuilding the differential is one of the keys to performance on your E36 325i/328i or E36 M3. Adding a shorter gear set will make the car accelerate quicker with almost no downside. And adding or changing the limited slip unit will improve traction and handling. The diff is crucial to getting the most out of popular engine upgrades such as an M50 manifold swap and cams where...Click for more.

click for more

E39 M5 Custom Differentials
A custom differential is one of the best, and smartest, upgrades to have done to your E39 M5. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things...Click for more.

click for more

E46, Z4, E39 Custom Differentials
One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. Using a shorter (numerically higher) gear ratio will give you better acceleration...Click for more.

click for more

E46 M3 Custom Differentials
A custom differential is one of the best upgrades to have done to your E46 M3. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit...Click for more.

click for more

Z4 M Custom Differentials
A custom differential is one of the best upgrades to have done to your Z4 M. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit...Click for more.

click for more

E90/E92 Custom Differentials
One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending....Click for more.

click for more

E9X M3 Custom Differentials
A custom differential is one of the best upgrades to have done to your E90 or E92 M3. Not only can you get more performance but you can also address the weak points in the M Variable limited slip diff. It's easy to forget about the rear axle when you're considering performance upgrades but changing the gearing is in the top 3 things to do to make the car faster. A custom diff is also a rebuilt unit with new seals, bearings, and limited slip unit...Click for more.

click for more

F30/F32 335i/435i Custom Differentials
One of the best upgrades to be made is custom building a differential. There are a lot of options to make improvements to the diff including gear sizing changes, added limited slip units, and limited slip lock-up options. It's easy to overlook the differential when planning your car's upgrades but it's one of the best areas to get return from your modification spending. 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...Click for more.

Get notified about money saving
specials & deals for your BMW
enter your email address
  • 22 years of BMW Tuning.
  • Award winning service.
  • 10,000's of parts in stock.
  • Quality BMW Parts only.
  • Hassle-free returns.

  • Find us on Facebook




    • 1-800-280-6966
      Mon-Thur 9am-6pm ET, Fri 9am-5pm ET

      • © TurnerMotorsport.com 1993-2016. All Rights Reserved.