N55 xDrive Front Differential Removal

Before you touch a bolt

Tools

Substitutes are what owners and parts stores report, not BMW's.

Order of work

Torque card

Group A only. Other groups: see the group table. "+ 90°" means a further 90° turn after the Nm figure.

Car prep, step by step

1. Raise and support the car. Shop rule of thumb, not BMW's: level ground, rear wheels chocked.
2. Ignition off, hood to the service position, acoustic cover (engine cover) off. The hood is a two-person job. BMW says unclip the cover one clip at a time, only above 20 °C (68 °F).
3. Skip the F30 text's 4-cylinder extras (engine-compartment covers, rear hood seal, control unit holder) unless in the way.
4. Battery negative off. Work the clamp off, don't lever it. No charger on the jump-start post.
5. Both front wheels off.
6. Underbody protection off, front then rear.
7. Bracing plate off. BMW says don't drive without it. If your car has bracing struts, take those off too.
8. Drain the front diff into a tray. Plugs are M22, 14 mm hex. Parts-store tips: the fill plug is behind the driver's side axle; break it loose first. If it won't open, don't drain: you couldn't refill. Then pull the drain plug.
9. Hold the engine from above (next section) before anything below comes loose.

Hold the engine from above (step 9)

BMW's method, from its text for the F30 to F36 family. Two people:

1. Unclip the hood release cable (F33 convertible: front-end struts off too).
2. Set the support on its contact points, on the frame rails, never the fenders (owners). BMW's cross-member needs every strut and foot lined up and every nut and screw tightened.
3. Check the lifting lug or tow hook for cracks (the eye the chain hooks to; your engine decides which you have), then hook the chain on.

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4. Release the mounts (one each side): right mount bolt out, left mount nut loosened, vacuum hose unclipped from the left mount.

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5. Raise the engine about 10 mm. Never move it forward, back or sideways.

Shafts out, step by step

Do both sides.

1. Cover cap off if fitted, hub locked so it can't turn (Tools: Hub lock).
2. Loosen the collar bolt, the M16 bolt holding the shaft to the hub. Shop rule of thumb, not BMW's: penetrating oil the day before. No BMW allowance for heat here, so skip the torch.
3. Track rod end (tie rod end) off. Undo the nut while holding the stud with a Torx bit, then separate it from the swivel bearing (the knuckle). BMW says no striking tools on ball joints.
4. Left side, if it's in the way: ride-height sensor rod off the wishbone.
5. Wishbone off the axle support, not the knuckle end. Loosen the nut, hold the screw, pull it out toward the front.
6. Collar bolt out, knuckle swung aside, shaft out of the wheel bearing. Note which way the bolt's spring faces.
7. Press the shaft out (Tools: Shaft press-off). Left comes out of the diff, right out of the bearing support on the pan. No impact tools.

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8. Look at what came out. Circlip on the shaft end? Splines and groove undamaged?

The 4 diff bolts: which hole gets which

Four M12 outside-Torx bolts, 140 Nm, in two lengths: M12x105 (long) and M12x55 (short). Your car's mix:

We can't show which hole takes which, so make your own map: a sticker numbered 1 to 4 beside each hole before a bolt comes out, a photo, and each bolt laid on a board in sticker order. If what comes out doesn't match the mix above, trust the car and send us your VIN. BMW doesn't list these bolts as replace-every-time, so check heads and threads.

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Diff out, step by step

1. Front prop shaft out. Four screws at each end. Hold it still while you loosen (owners put a screwdriver through the U-joint) and support the free end. BMW says don't drive without it.

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2. Anti-roll bar (sway bar) link nut loose at the bar. Hold the stud with a Torx bit.
3. Release the steering shaft where it meets the steering gear (the rack). Wheels straight, paint mark across shaft and rack (shop practice, not BMW's). The M8 clamp bolt is replaced and the thread recut. Skipping this damages the steering shaft bearing at the firewall (BMW's lowering texts).
4. Unplug the steering gear and release its cable holders and channel on the axle support, and free the left ride-height sensor cable (BMW's lowering texts).
5. Check what else is tied to the support before it drops. BMW's lowering texts release a coolant pipe, the fan cowl and the oil cooler screws, and unbolt the steering rack and tie it up. F30 and X3 owners only disconnect the shaft and wiring; F10 owners unbolt the rack. Shop rule of thumb, not BMW's: let the engine cool first.

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6. Jack under the axle support, undo its six bolts (2 front, 2 center, 2 rear), then lower it. Sandbags on the strut domes (BMW), center of gravity over the jack. Lower in small steps, 100 mm (10 cm) at most (BMW's lowering texts; some forum posts go much further, don't), watching hoses, lines and cables. The steering gear mustn't hit the firewall.

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7. Mark the four holes with stickers and photos (see above).
8. Loosen all four bolts, and hold the diff firmly while the last one comes out. BMW's older texts for this job warn it falls. About 13 kg (29 lb). Lower it onto a blanket or board and lay the bolts out in sticker order.

Doing the pan? Stop here: the diff stays off until the pan is on and torqued, and the bearing support comes off too. Then come back for "Diff in".

Replacing the diff itself? Check the ratio

Some 3.15 listings add a note about automatic and Sport automatic cars, and the catalog stops at 2020, so buy by VIN, not car name, and read the ratio off your old diff (photograph any tag). If a wrong-ratio diff already went in, BMW's fix is the right diff plus a shop job: transfer case oil change at operating temperature, wear value reset, calibration.

Diff in, step by step

1. New O-ring, oiled, then the diff up. Each bolt in its own hole by your stickers, then 140 Nm.
2. Jack the axle support back up, evenly, lines and cables clear. Six new bolts (shop rule of thumb: BMW's F2x and F3x table has no renew note, its X3 and X4 row does), 120 Nm.
3. Steering shaft back. Wheels straight, marks lined up, NEW clamp bolt, thread recut, 24 Nm, no retorquing. Plug the steering gear in and refit what you released (torques on the F30: send us your VIN). Then turn the wheel lock to lock: the airbag lamp stays off (BMW).
4. Anti-roll bar link. New nut, 56 Nm, holding the stud.
5. Prop shaft. New screws, both ends, 20 Nm + 45°. Support its weight.
6. New shaft seals, one in the diff, one in the bearing support. Pry the old ones out. Wet the new seal's outer edge with diff oil and drive it in to the stop. Keep its protection ring in place, then fold it open for the shaft.
7. Shaft in, one side at a time. New circlip on the inner end. Slide in part way, tear the protection ring's tab away, then push past the circlip until it clicks (extreme force means stop: something is damaged). Pull-test it (shop rule of thumb, not BMW's): the outer end must not come out by hand. Owners say a little in and out play is normal, side to side wobble is not. Then offer the outer end to the wheel bearing.
8. Hub end. Clean and grease the spur teeth (gear teeth) on bearing and shaft (BMW's F30 text; older texts for other cars say no grease), fit them, and turn hub and shaft until the teeth are fully meshed. Clean and degrease the collar bolt thread.
9. Wishbone on from the front. New screw and nut, snug only for now. Left ride-height rod back on.
10. Track rod end. Check the rubber boot and spring circlip: a cracked or porous boot means a new part. Keep the stud's taper free of oil and grease. New nut, 175 Nm, holding the stud.
11. Collar bolt. New bolt and spring, spring the way you noted. Hub locked, 210 Nm + 90°.

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12. Diff oil. New drain plug, 60 Nm. Pump oil in to the lower edge of the fill opening (BMW's method), car level (shop rule of thumb, not BMW's). If the amount differs from the catalog's 0.6 L, the edge wins. New fill plug, 60 Nm.
13. Plate, panels, wheels. Bracing plate with new screws, 56 Nm + 60° (bracing struts too, if yours had them: send us your VIN), then underbody protection (screws: 3 Nm non-metric, 8.8 Nm M6, 2.5 Nm nut). Wheels: clean the mating faces, thin grease on the centring, check bolts for silver wear on the taper (BMW's limit: 30%), no impact tools, 140 Nm.
14. Engine down, support off, mount nuts 56 Nm.

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15. Car down on its wheels at ride height, then the wishbone nut: 100 Nm + 90°. BMW says normal stance, which we read as ride height, as owners do. Never with the suspension hanging.
16. Battery negative on, covers, hood down. Every connector must click.
17. Check the engine oil level (BMW's 4-cylinder text ends with it). Shop rule of thumb, not BMW's: look for weeping at the diff joint and seals after a short drive. Then book the alignment.

Alignment: plan on it

Either end, plan on an alignment: the whole axle support goes down and back up. Owners split on whether a lowered subframe needs one.

Where people mess it up

• No engine support, or the wrong one. Fix: a proper support on the rails, right eye, chain tight, lift about 10 mm, recheck half way down.
• Shaft not seated, wrong circlip, damaged splines. Owners report aftermarket circlips flattening and letting the shaft pop out. Fix: BMW circlip, push to the click, pull-test.
• Bolts in the wrong holes, or chewed threads. Owners report a welded nut torn out of its plate and stripped axle support threads. Fix: your sticker map, hold the welded nut still, guide pins, a Helicoil for a damaged thread.
• Reusing seals, O-rings or other one-time parts. Fix: buy the whole list first, protection ring in place, seal edge oiled, driven to the stop.
• Dropping the support too far or with things attached. Fix: steering shaft released first, lines freed, small steps, 10 cm.
• Wrong oil, too little, or a diff you can't refill. Fix: fill plug first, approved oil, fill to the edge, new plugs.
• Skipping the alignment, or tightening the wishbone nut with the suspension hanging. Fix: book it, torque at ride height.

Steps, torque values and part rules come from BMW's repair instructions for the front axle differential, output shafts, axle support lowering and engine securing, and BMW's torque tables. BMW's text for this job is for the 4-cylinder F30, and where we lean on other cars' texts we say so. Part numbers come from BMW's parts catalog up to 2020. Check yours by VIN.