🔧 340i - Rear Brake Pads & Rotor Replacement

You’ll be removing the rear wheels, compressing the rear caliper pistons, replacing the rear pads and rotors, then reassembling everything with the correct torque. This job matters because worn pads/rotors reduce stopping power and can damage the calipers if driven too far.

Difficulty Level: Intermediate | Estimated Time: 2-4 hours

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⚠️ Safety & Precautions

• ⚠️ Support the car with jack stands—never rely on a floor jack alone.
• ⚠️ Your 340i uses an electronic parking brake (EPB); keep it released during the job and don’t switch it on while parts are removed.
• ⚠️ Brake dust is harmful—wear a dust mask and use brake cleaner, not compressed air.
• ⚠️ Don’t let the caliper hang by the hose—use a caliper hook.
• ⚠️ Do not press the brake pedal while a caliper is off.
• 🔋 Battery disconnect is not required for this repair.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Safety glasses
• Nitrile gloves
• Dust mask
• Breaker bar 1/2"
• Torque wrench 1/2" (20-200 Nm range)
• 17mm socket
• Ratchet 3/8"
• E-Torx E18 socket
• Hex bit socket 7mm
• Torx T30 bit
• Flathead screwdriver
• Wire brush
• Brake caliper piston compression tool (specialty)
• Caliper hanger hook (specialty)
• Bungee cord
• Rubber mallet
• Micrometer or digital caliper (specialty)
• Brake cleaner spray
• Scan tool with BMW EPB service function (specialty)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Rear brake pad set - Qty: 1
• Rear brake rotors - Replace in pairs - Qty: 2
• Rear brake pad wear sensor - Qty: 1
• Brake caliper grease (silicone or synthetic) - Qty: 1
• Brake anti-seize compound - Qty: 1
• Brake parts cleaner - Qty: 1

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📋 Before You Begin

• Park on level ground, put the transmission in P, and make sure the EPB is OFF.
• Chock the front wheels with wheel chocks.
• Loosen rear wheel bolts 1/2 turn using a 17mm socket and breaker bar before lifting.
• Open the hood and loosen (do not remove) the brake fluid reservoir cap. This helps fluid return when compressing pistons.
• EPB note: Some BMWs require putting the EPB into a service mode. Use a scan tool with BMW EPB service function (specialty) to command the EPB into service position if your scan tool supports it. Safest way to avoid EPB damage.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Lift and secure the rear

• Use a floor jack (rated 3-ton minimum) to lift the rear at the approved jacking point.
• Set the car down onto jack stands (rated 3-ton minimum).
• Remove the rear wheels using a 17mm socket and ratchet 3/8".

Step 2: Put the electronic parking brake in a safe state

• Verify the EPB is released (no EPB warning applied) before touching the calipers.
• If your scan tool supports it, run the EPB service function using the scan tool with BMW EPB service function (specialty).
• Never apply EPB with calipers removed.

Step 3: Remove the caliper (leave the hose connected)

• Locate the two caliper guide bolts on the back of the caliper.
• Remove both guide bolts using a 7mm hex bit socket and ratchet 3/8".
• Lift the caliper off the bracket and support it with a caliper hanger hook (specialty) or bungee cord.
• Torque spec (reinstall later): Torque to 30 Nm (22 ft-lbs)
• If it’s stuck, wiggle—don’t pry the hose.

Step 4: Remove old pads and the wear sensor

• Slide out the inner and outer pads by hand. If tight, use a flathead screwdriver gently.
• Unclip the wear sensor from the pad and disconnect it from its harness mounts (usually clipped along the arm/liner).
• Use a flathead screwdriver to open clips carefully so you don’t break them.

Step 5: Compress the caliper piston

• Use a brake caliper piston compression tool (specialty) to slowly push the piston back into the caliper.
• Watch the brake fluid level; if it rises too high, remove a little with a suction tool (not required, but keep it from overflowing).
• Go slow to protect seals.

Step 6: Remove the caliper carrier (bracket)

• Remove the two carrier bolts using an E-Torx E18 socket, breaker bar 1/2", and ratchet.
• Set the carrier aside.
• Torque spec (reinstall later): Torque to 110 Nm (81 ft-lbs)

Step 7: Remove the rotor

• Remove the rotor retaining screw using a Torx T30 bit and ratchet 3/8".
• If the rotor is stuck, tap the rotor hat with a rubber mallet to break it loose.
• Torque spec (reinstall later): Torque to 16 Nm (12 ft-lbs)

Step 8: Clean the hub surface (prevents rotor wobble)

• Use a wire brush to clean rust off the wheel hub face.
• Spray with brake cleaner spray and wipe clean.
• Apply a very thin film of brake anti-seize compound to the hub face (avoid studs/bolt holes and rotor friction surface).
• Thin layer only—no globs.

Step 9: Install the new rotor

• Clean the new rotor with brake cleaner spray to remove packing oil.
• Place the rotor on the hub and install the retaining screw using a Torx T30 bit.
• Torque to 16 Nm (12 ft-lbs)

Step 10: Reinstall the caliper carrier

• Reinstall the carrier bolts using an E-Torx E18 socket and torque wrench 1/2".
• Torque to 110 Nm (81 ft-lbs)

Step 11: Install new pads and new wear sensor

• Apply a light coat of brake caliper grease (silicone or synthetic) to pad backing plates and pad “ears” where they slide (keep grease off friction material).
• Install the inner and outer pads into the carrier by hand.
• Install the new wear sensor onto the correct pad (it clips in) and route it exactly like the original, snapping it into the same clips.

Step 12: Reinstall the caliper

• Place the caliper over the new pads.
• Install the guide bolts using a 7mm hex bit socket.
• Torque to 30 Nm (22 ft-lbs)

Step 13: Reinstall wheels

• Reinstall the wheels and hand-thread the bolts.
• Lower the car off the jack stands using the floor jack.
• Tighten wheel bolts in a star pattern using a torque wrench 1/2".
• Torque to 140 Nm (103 ft-lbs)

Step 14: Restore brake pedal and EPB operation

• With the car still in Park, pump the brake pedal 10–15 times until it feels firm.
• If you used a scan tool EPB service function, use the scan tool to exit service mode.
• Apply and release the EPB to confirm normal operation.
• Pedal must be firm before driving.

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✅ After Repair

• Check brake fluid level and top off only if needed (do not overfill).
• Test at low speed first: confirm normal stopping, no grinding, no pulling.
• Reset brake pad service reminder (if shown) using a scan tool with BMW service reset (specialty).
• Bed-in (break-in) procedure: Make 8–10 medium stops from ~40 mph down to ~10 mph, with cool-down driving between stops. Avoid hard braking for the first 150–200 miles.

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💰 DIY vs Shop Cost

Shop Cost: $650-$1,100 (parts + labor)

DIY Cost: $220-$520 (parts only)

You Save: $430-$580 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2-3 hours.

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