Brake Pad Replacement on Smart Fortwo and Roadster
Service interval: Inspect every service; replace when pad material is below ~3mm
Tools you'll need
- Floor jack and a pair of axle stands
- Wheel-nut socket and breaker bar
- Caliper-bolt sockets or hex keys (sizes vary by year)
- Torque wrench
- C-clamp or piston retraction tool (rear pistons on some variants need a wind-back tool)
- Synthetic brake caliper grease (purple or red — NOT regular lithium)
- Brake cleaner spray
- Wire brush
Fluids & specs
| Fluid | Spec | Capacity |
|---|---|---|
| Brake fluid | DOT 4 — top-up only; full flush is a separate job | Reservoir fluid level rises as pistons retract |
What this is and why it matters
Brake pads are a wear item. The Smart Fortwo is light, so pads tend to last well — but they don't last forever, and a pad that's metal-on-rotor will chew the rotor in days. The job itself is straightforward on the Smart's sliding caliper design. The thing that turns a clean pad swap into a comeback is skipping the slide pins. A caliper with seized slides drags one pad against the rotor full-time, and you'll be back in here in two months wondering why the new pads are already gone.
This page covers pad replacement specifically. If your slide pins are dry or rusty, do the caliper inspection job at the same time — they're a natural pair.
What you'll need
Pads in OE-equivalent spec. ATE, Brembo, and Akebono all make decent aftermarket pads for Smart variants; OE pads are Mercedes/Smart-branded and a step pricier. Before you order, confirm the pad shape — front and rear differ, and there are at least two front pad shapes across the 450/451/453 generations. Match the part number to your VIN with a parts catalog.
A torque wrench matters. Caliper bolts go into aluminum carriers on some variants, and overtightening strips the threads. Look up the spec in the workshop manual on Manualslib — torque values vary by model and year.
If your Smart has front pad-wear sensors (electrical wires running into the inner pad), order new sensors with the pads. They're consumable — once the pad has worn down to the sensor, it's used.
Step by step
- Park on level ground, wheels chocked, parking brake on if you're starting on the front. Loosen the wheel nuts before jacking. Jack up the corner, axle stand under the car, wheel off.
- Inspect before disassembling. Note how the pads sit, how the spring clip locates, where any wear-sensor wire routes. Phone photos are your friend.
- Caliper bolts: some variants use one slider bolt and you pivot the caliper up; others use two bolts and the caliper comes off entirely. Both are fine — work to what your car has. Hang the caliper on a coat-hanger or zip-tie to the spring; do not let it dangle by the brake hose.
- Slide the old pads out. If they're stuck, a flat screwdriver helps. Take note of any anti-rattle clips, shims, or wear sensors so they go back in the same orientation.
- Push the piston back into the caliper to make room for the thicker new pads. Front pistons usually go straight in with a C-clamp. Rear pistons on some variants need to be wound back with a special tool because the parking brake mechanism threads them. If your rear caliper resists straight pressure, stop and check — forcing it damages the parking brake.
- While the caliper is open: pull the slide pins, wipe them clean, inspect the rubber boots, and re-grease with synthetic caliper grease. Push them back in. They should slide by hand with light resistance.
- Drop the new pads in. If your wear sensor is integrated, fit the new sensor into the new inner pad and route the wire the same way the old one ran.
- Reassemble caliper to the carrier. Torque the bolts to spec. Wheel back on, lug nuts snug; lower the car; final torque on the lug nuts.
- Before you drive — pump the brake pedal until it comes up firm. The first stroke after a pad change is usually long because the pistons are pushed all the way back. Don't skip this. A long pedal at the end of the driveway is how people back into things.
- Bed the new pads in. Manufacturer instructions vary; a typical sequence is several moderate stops from 30 mph followed by a few firmer stops from 50 mph, with cool-down time between. Don't sit at a stoplight on hot fresh pads — they'll deposit unevenly on the rotor.
Common gotchas
Skipping slide pin lubrication. Most-common reason for premature wear and uneven pad-to-rotor wear. Five minutes of work that pays back in pad life.
Wrong grease. Lithium grease swells the rubber boots over time. Use synthetic caliper grease — sold specifically for this. Tube is small and lasts years.
Overtightening caliper bolts. Aluminum threads will strip. Use the torque wrench.
Forgetting to pump the pedal before driving off. Anyone who's done this once won't forget twice, but it's easy to forget the first time.
Pad-wear sensor wire pinched on reassembly. If the new pads include a sensor, route the wire exactly where the old one ran. A pinched sensor wire reads as a pad-worn warning even on brand new pads.
When to skip DIY
If a caliper bolt is seized and rounding off, stop. Penetrating oil overnight, then revisit. If it's still stuck, a shop with an impact and the right sockets is cheaper than a snapped bolt. If your rear caliper piston won't wind back with a proper tool — meaning the parking brake mechanism is seized — that's a caliper rebuild or replacement, not a pad job. And if the rotors are scored deep, lipped, or below minimum thickness, you're doing rotors at the same time. That's still DIY-able but it's a bigger job.
Parts & typical prices
| Part | Typical price | Search |
|---|---|---|
| Front brake pads (set) | $30-90 | Search Google |
| Rear brake pads (set) | $30-80 | Search Google |
| Brake pad wear sensor (front, where fitted) | $10-25 | Search Google |
| Caliper slide pin kit + boots | $15-40 | Search Google |
| Synthetic caliper grease (small tube) | $5-12 | Search Google |
Prices are rough community-reported ranges, not quotes. Aftermarket vs. genuine Mercedes parts swing the spread.
Manual references
- Browse Smart workshop manuals on smartcarmanuals.com — model-specific reference manuals on the home page; pick your chassis code section for torque specs and detailed procedures.
