FAQs

Q4. Do I need a core charge?
A: No core exchange—keep your original diff.

Q5. Service interval?
A: Check plate wear every 80 000 km of street use or every second drift season.

4. Billet Differential Covers

Q1. Why upgrade to a billet diff cover?
A: CNC-milled 7075-T6 aluminum triples rigidity, adds oil capacity and finned cooling, and eliminates porous OEM casting failures.

Q2. Will it crack like the stock E30 cover?
A: No—7075 billet has 2× the yield strength of the factory casting, so mounting ears don’t snap during clutch kicks. Even under more extreme loads, like crashes. 

Q3. Does it lower oil temperature?
A: Yes. Internal baffling + 30 % extra volume drop diff temps by ~12 °C in testing.

Q4. What bushings come pre-installed?
A: Genuine Powerflex poly inserts rated 80 ShA for track and street comfort.

Q5. Do I need a secondary mount?
A: For E30 drift builds, we strongly recommend the optional dual-mount bracket; it bolts straight to factory ears.

5. LSD Block Discs (100 % Lock)

Q1. What are block discs?
A: Solid steel plates that replace factory clutches and dog ear plates, giving your LSD a fixed 100 % lock—ideal for drag launches or drift application (who prefers welded diff over limited slip).

Q2. Street-drivable?
A: Only if you don’t mind tire scrub; we suggest them for competition cars.

Q3. Reversible?
A: Yes—swap clutch stack back in and you're back to stock setup.

Q4. Which BMW M models are supported?
A: E46 M3, E92 M3, E60/63 M, Z4 M, plus E39 M5.

6. Ready-to-Mount BMW LSD Units

Q1. What’s included in a “ready‑to‑mount” diff?
A: Every unit is built to order and ships with a brand‑new, fully adjustable All‑Solution LSD core already installed—no used or welded internals. The package also contains:

• New SKF/Timken carrier bearings and OEM oil‑seals
• A sand‑blasted, painted housing (model‑correct)
• Optional laser‑engraved rear cover (select at checkout)
• Ships dry to avoid haz‑mat fees—simply add 75 W‑140 and drive; we recommend a 100 km gentle break‑in

That core list applies to every SKU, while extras like custom gear ratios or billet finned covers vary by model. Lead‑time is about two weeks because each diff is assembled after you place the order

Q2. Do I have to send my old diff?
A: No diff exchange. Keep, sell or wall-mount your original.

Q3. Can I tweak lock after purchase?
A: Yes—the internal pack is user-adjustable from 25 % to 100 %.

Q4. What ratio options are available?
A: Depends on a model. For most of the models we have OEM range of gear ratios available, from 2.65 to 4.45.

Q5. Warranty?
A: 12 months when used with 75W-140 GL-5 oil.

7. Bearing & Oil-Seal Service Kits

Q1. How do I know my differential bearings are worn out?
A: A tired pinion or carrier bearing creates a humming or growling noise under both acceleration and engine‑braking. Do an “S‑turn” test: weave left‑right as if you’re warming tires; if the noise changes, it’s a wheel bearing—if it stays constant, the differential bearings are the culprits.

Q2. What’s the difference between a Repair kit and an Overhaul kit?

Q3. Which models are covered, and how do I pick the right set?
A: The collection includes size‑indexed kits for MM (E30/E36/E34), K (E46/E39/E38/E53), L/LW (E87/E90/E60/E70), Motorsport “215 K/L”, front‑diff kits, plus multi‑brand packs for Audi/Porsche/VW and others. Select the kit whose type matches your carrier casting (MM, K, L…)—or just drop your VIN in the chat and we’ll identify it for you in < 24 h

Q4. Do I need special tools or a press?
A: Yes. Pinion and carrier bearings are interference‑fit; you’ll need a 10‑ton press (or at least a bearing puller/installer set), an torque wrench for pinion preload. Most DIY enthusiasts can do the job in a weekend, but a driveline shop will have all the fixtures if you’d rather outsource.

Q5. Will I have to reset backlash or gear pattern after the swap?
A: Not with RacingDiffs kits. Our SKF/Timken bearings are ground to OEM thickness tolerances (±0.01 mm), so pinion depth and carrier preload stay exactly where the factory set them. Simply reinstall the original shims/crush sleeve, torque to spec, and you’re done—no extra backlash or gear‑pattern adjustments required. A quick paint check is fine for peace of mind but almost never needs correction.

8. BMW LSD & Gear-Ratio Swap Tools

Q1. What’s the breakout torque adapter for?
A: It lets you measure breakaway torque at the flange—no axle removal.

Q2. Which puller fits E30/E36 carrier bearings?
A: Our three-arm 62–88 mm puller clears the flange lip without grinding.

9. Differential Tuning Parts

Q1. What counts as a “tuning part” in this collection?
A: Everything that lets you fine‑tune or upgrade an existing BMW LSD without buying a whole new diff—multi‑angle ramp/pressure‑plate sets, preload shims, spider‑gear thrust washers, crown‑gear spacers, backlash C‑clips, output‑flange upgrades and the special tools to install them.

Q2. Why choose RacingDiffs tuning parts over used OEM bits?
A: We machine brand‑new, heavy‑duty spares that BMW stopped supplying—cross‑pins, gears, caps and ramps forged or billet‑cut to handle well over factory torque loads. You replace only the worn item instead of buying an entire LSD, saving money and keeping the original housing.

Q3. Do the multi‑variant ramp/pressure‑plate sets really change lock?
A: Yes. One kit gives you three ramp pairs—30°/30°, 30°/60°, 50°/65°—so you can dial lock from ~25 % to 100 % in either 1.5‑way or 2‑way form. Swap plates with basic hand tools; no extra machining required.

Q4. Are these parts compatible with the All‑Solution LSD core?
A: Absolutely. The ramp/pressure‑plate sets, preload shims and spider‑gear washers are the same components we install in the All‑Solution core, so they drop straight in. Just match the part number to your carrier size (168 mm, 188 mm, 210 mm or 215 L).

Q5. Will I need to reset backlash or gear pattern after installing tuning parts?
A: Usually no. Most items (ramps, shims, gears, spacers) sit inside the carrier and don’t disturb ring‑and‑pinion alignment. As long as you keep the original carrier bearings and shims in place, backlash stays within factory spec—so it’s a true plug‑and‑play performance tweak.

Terms & Conditions – Quick‑Answer FAQ

Q1. Do you ship worldwide and how long does delivery take?
A: Yes. We offer DHL Express (2‑3 days EU, 3‑5 days North America, 3‑7 days RoW) and Standard International Post for select countries (7‑21 days). Both options include end‑to‑end tracking.

Q2. Will I have to pay import duties or taxes?
A: Orders ship from Serbia (non‑EU). Most destinations have a duty‑free value threshold; below it you pay nothing, above it local customs may charge import tax. For U S customers, goods from Serbia are duty‑free up to $800.

Q3. Which payment methods and currencies do you accept?
A: We accept PayPal and all major cards. Card payments are processed in Serbian dinars (RSD) via Banca Intesa; your bank then converts to your local currency using its daily FX rate, so minor variances versus the EUR price are possible.

Q4. What is your return window and refund policy?
A: If you’re not 100 % satisfied, return the product within 45 days for a full refund (minus outbound shipping/customs). Contact support@racingdiffs.com first and ship via regular post in the original packaging.

Q5. Is my card data secure when ordering?
A: Absolutely. Card details travel over SSL encryption and are handled entirely by Banca Intesa’s PCI‑compliant gateway—RacingDiffs never sees or stores your card number.