🔧 340i - Front Brake Pad Replacement

You’ll remove the front wheels, unbolt the front brake calipers, swap in new pads (and the wear sensor), then reset the brake service reminder. This restores safe stopping and prevents metal-to-metal rotor damage once pads get thin.

Difficulty Level: Intermediate | Estimated Time: 1.5-3 hours

Assumption: standard single-piston front calipers (typical 340i).

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⚠️ Safety & Precautions

• ⚠️ Work on level ground and support the car with jack stands before removing any wheel.
• ⚠️ Brake dust is harmful—avoid blowing it; use brake cleaner instead.
• ⚠️ Don’t press the brake pedal with the caliper removed (the piston can pop out).
• ⚠️ Keep grease off pad friction surfaces and rotors.
• 🔋 Battery disconnect is not required for front pads, but keep the key away from the car to prevent wake-ups while working.

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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
• 17mm socket
• Breaker bar
• Torque wrench (20–200 Nm range)
• Flathead screwdriver
• Pick tool
• 7mm hex bit socket
• 16mm socket
• Bungee cord
• Brake caliper piston compressor tool (specialty)
• Wire brush
• Brake cleaner spray
• Nitrile gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Front brake pad set - Qty: 1
• Front brake pad wear sensor - Qty: 1
• Brake caliper grease - Qty: 1
• Anti-squeal compound - Qty: 1
• Brake cleaner - Qty: 1
• Front brake rotors - Qty: 2 Optional if worn or damaged

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📋 Before You Begin

• Park on level ground, steering straight, and set the parking brake.
• Chock the rear wheels with wheel chocks.
• Loosen the front wheel bolts slightly using a 17mm socket and breaker bar before lifting.
• Open the hood and locate the brake fluid reservoir; do not remove the cap yet, but check the fluid level (it can rise when you compress pistons).
• Plan your reset afterward using iDrive: Menu > Vehicle Info > Vehicle Status > Service Requirements (wording can vary).

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Lift the front and remove the wheels

• Lift the front of the car using a floor jack (rated 3-ton minimum) at the proper front jack point.
• Set the car down onto jack stands (rated 3-ton minimum) before working.
• Remove the wheel bolts using a 17mm socket and take off both front wheels.
• When reinstalling later: Torque wheel bolts to 140 Nm (103 ft-lbs).

Step 2: Remove the caliper spring clip

• On the front of the caliper, remove the anti-rattle spring using a flathead screwdriver.
• Tip: Cover the screwdriver tip to avoid scratches.

Step 3: Unplug and remove the front pad wear sensor (left front)

• Locate the wear sensor wire on the left front brake (it clips into the pad).
• Open the small sensor connector box using a flathead screwdriver and release the connector with a pick tool.
• Unclip the wire from its holders, then pull the sensor out of the pad.
• Tip: Replace the sensor whenever it has triggered.

Step 4: Remove the caliper guide pin bolts

• On the back of the caliper, pop off the two plastic caps using a pick tool.
• Remove both guide pin bolts using a 7mm hex bit socket.
• Support the caliper as the bolts come out so it doesn’t hang on the brake hose.
• Torque guide pin bolts to 30 Nm (22 ft-lbs) during reassembly.
• Guide pins are the sliding bolts the caliper rides on.

Step 5: Hang the caliper safely

• Lift the caliper off the bracket and hang it from the strut spring using a bungee cord.
• Do not let the caliper dangle by the rubber brake hose.

Step 6: Remove old pads and prep the contact points

• Remove the inner and outer pads by hand.
• Clean the pad contact areas on the bracket using a wire brush and brake cleaner spray.
• If your new pads include new stainless clips/hardware, swap them in now.

Step 7: Compress the caliper piston

• Position the old inner pad against the piston face, then compress the piston slowly using a brake caliper piston compressor tool (specialty).
• Check the brake fluid reservoir as you compress; remove a little fluid if it’s about to overflow.
• Tip: Slow compression helps protect seals.

Step 8: Install new pads and apply correct grease

• Apply a thin film of brake caliper grease to the pad “ears” (the metal ends that slide in the bracket).
• Apply anti-squeal compound to the pad backing plates if your pad manufacturer calls for it.
• Install the new inner and outer pads into the bracket.
• Keep all grease off the pad friction material and the rotor face.

Step 9: Reinstall the caliper and spring clip

• Slide the caliper back over the new pads.
• Install and tighten the guide pin bolts using a 7mm hex bit socket.
• Torque guide pin bolts to 30 Nm (22 ft-lbs).
• Reinstall the anti-rattle spring using a flathead screwdriver.
• Reinstall the plastic caps over the guide pin bolt heads by hand.

Step 10: Install the new wear sensor (left front)

• Press the new sensor into the correct pad slot until fully seated.
• Route the wire exactly like the original and clip it into all holders.
• Reconnect the plug and close the connector box using a flathead screwdriver.

Step 11: Reinstall wheels and lower the car

• Reinstall wheels and hand-thread all bolts first.
• Lower the car off the jack stands (rated 3-ton minimum).
• Torque wheel bolts in a star pattern using a torque wrench: Torque to 140 Nm (103 ft-lbs).

Step 12: Pump the brake pedal and check fluid

• Before driving, pump the brake pedal 10–15 times until it feels firm.
• Check the brake fluid level and top off only if needed.
• Look around each caliper for anything loose or leaking.

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✅ After Repair

• With the car safely parked, do a slow test: move a few feet and brake gently to confirm normal feel.
• Reset the brake service reminder using iDrive: Menu > Vehicle Info > Vehicle Status > Service Requirements > Front Brakes > Reset (wording varies by iDrive version).
• Brake bedding (break-in): do 6–10 moderate stops from ~40 to ~10 mph with cool-down between stops; avoid hard stops for the first 150–200 miles unless necessary.
• If the steering wheel shakes when braking, the rotors may be worn/warped and should be replaced.

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💰 DIY vs Shop Cost

Shop Cost: $350-$700 (parts + labor)

DIY Cost: $120-$300 (parts only)

You Save: $230-$400 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

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🎯 Ready to get started?

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