How to Bed In New Brake Pads and Rotors: Step by Step, No Judder

The best way to bed in new brake pads and rotors is a set of moderate, back-to-back stops from about 35 to 60 mph down to a crawl, never coming to a full stop with the pedal held, followed by a few miles of easy driving with no braking so everything cools. That’s the core of every procedure the brake makers publish, from Hawk and StopTech to PowerStop and Brembo. The details change with the pad, and some modern pads barely need it at all, but get the basic pattern right and your new brakes will stop smooth, quiet and straight instead of shuddering a month from now.

What bedding in brakes actually does

Bedding in, also called breaking in or burnishing, does two jobs at once: it lays down a transfer film on the rotor and it cures the surface of the pad.

The first is laying down a transfer layer. As the pad and rotor heat up together, a thin, even film of pad material gets deposited onto the rotor face. Once it’s there, the pad is mostly rubbing against its own material rather than bare iron. Hawk calls this the transfer film and says it’s what raises stopping performance and cuts both pad and rotor wear. Tire Rack describes the same layer as a buffer that gives smooth, even friction.

The second job is curing the pad. The first time a new pad sees real heat it can fade a little and give off a hot smell as the surface volatiles burn off. EBC calls this green fade, and it means the pad is still green, not that something is broken. Finish the set.

The whole trick is to do both jobs evenly. Heat the brakes in steps, don’t let any one spot on the rotor get hotter than the rest, and never let a hot pad sit clamped in one place. That’s the part most people get wrong.

Brake pedal pulsing after new pads and rotors: why it happens

When people say “warped rotors,” most of the time the rotor isn’t bent at all. What they’re feeling is uneven pad deposits on the rotor face. Tire Rack explains that if the transfer film builds up unevenly, the pad loses and regains friction as those spots pass under it, and you feel that as a vibration through the pedal and the steering wheel. Brake people call it judder.

The fastest way to create uneven deposits is to stop the car after a hard brake and hold the pedal down. PowerStop’s instructions put it plainly: the rotors are very hot, and holding the pedal allows the pad to leave an imprint on the rotor, which is where judder can start. Hawk says the same thing about printing a deposit ring right where the pad rested.

The other big cause is lateral runout, meaning the rotor wobbles as it spins. Even a small wobble lets the pad kiss one spot of the rotor on every revolution, and over a few thousand miles that wears or deposits the rotor unevenly. Tire Rack’s guideline is that a rotor with more than 0.004 inch (0.10 mm) of runout should be replaced, and that the hub face must be cleaned of rust and scale before a new rotor goes on. A crusty hub flange is the most common reason a brand-new rotor shows runout.

So if you’ve got a pulsing pedal after a brake job, check in this order:

1. Did the car sit at a stop with the brakes held hard right after a hot test drive? If so, you likely have pad imprints.
2. Were the hub faces cleaned to bare metal before the rotors went on?
3. Were the lug nuts torqued to spec in a star pattern with a torque wrench, not zipped on with an impact gun? Uneven clamping can distort how the rotor sits on the hub.
4. Is there runout? A dial indicator on the rotor face will tell you in five minutes.
5. Are the caliper slides free? A caliper that sticks keeps one pad dragging, overheats the rotor and lays material down in odd patterns. Hawk’s article ends on this exact point: check calipers for free movement and lubricate as needed.

Mild deposit judder caught early can sometimes be cleaned up by repeating a proper bed-in, which redistributes the film. If it’s been going on for months, or if there’s real runout, the rotor needs resurfacing or replacement and the cause needs fixing first.

How to bed in new brake pads and rotors, step by step

Here’s a procedure that falls inside what Hawk, StopTech and PowerStop publish for street pads, and that works on just about any car or truck. If your pad maker gives specific numbers on the box, use theirs.

Before you start, find a quiet stretch of road with no traffic behind you, good visibility and room to make repeated stops. Do it in daylight on dry pavement. Remember the brakes won’t be at full strength until they’re bedded, so leave extra space.

1. Drive a mile or two normally. Make a few light stops to confirm the pedal is firm and the car stops straight. If anything feels wrong, stop and fix it before going further.
2. Make 6 to 10 moderate stops from about 35 mph down to about 5 mph. Brake firmly but not hard, about what you’d use for a yellow light you decided not to run. At the bottom of each stop, release the pedal and accelerate right back up. Don’t stop completely. These come back to back so heat builds steadily.
3. Make 2 or 3 harder stops from about 45 mph down to about 5 to 10 mph. These should be firm enough to feel the car’s weight shift forward, but well short of ABS or lockup. Again, don’t come to a full stop.
4. Expect a smell and possibly a bit of fade. That’s the resins curing. Don’t stop and don’t panic. Finish the set.
5. Cool down by driving. Drive 5 minutes or more at a steady moderate speed using the brakes as little as possible. PowerStop calls for about 5 minutes at moderate speed; Brembo’s Gran Turismo procedure calls for at least 5 minutes with little or no braking.
6. Park without the parking brake, then let them cool fully. Hawk calls for a 15-minute cooling period, and Tire Rack’s version of Hawk’s instructions says not to set the parking brake until the brakes have cooled. On a car with rear discs and an integrated parking brake, setting it on hot rotors can imprint the rear pads. Park on level ground in gear or in Park.
7. Look at the rotors. Once they’re cool, you should see an even, light gray or bluish tint across the full width of the pad track. Blotches or a distinct pad-shaped mark mean something went wrong.

That’s the whole job. On a typical street car it takes about 15 minutes of driving plus the cool-down.

Bed-in procedures by brand

Brake makers don’t all agree, and the differences tell you a lot about their pads. Some build heat fast with a handful of hard stops. Others want a long, gentle break-in because their pads are designed to mate slowly. Here are the published numbers.

Brand / pad type	Published bed-in procedure
StopTech street-performance pads	10 partial stops from 60 to 10 mph at about 80 to 90% of lockup deceleration, back to back, as one bed-in set
Hawk street pads	6 to 10 moderate stops from 30 to 35 mph, then 2 or 3 hard stops from 40 to 45 mph; 15 minutes cooling; never hold the pedal while stationary
PowerStop (drilled and slotted rotor kits)	5 moderate to aggressive stops from 40 to 10 mph, then 5 moderate stops from 35 to 5 mph, in rapid succession; about 5 minutes of moderate driving to cool
Brembo Gran Turismo	At least 20 stops at about 60% of maximum from 60 to 20 mph, 20 to 30 seconds between; at least 5 minutes of driving with little or no braking
Brembo OE	At least 30 light to medium applications of about 3 seconds from varying speeds, at least 1/2 mile apart; then several miles of little or no braking
Brembo (brembo.com, new pads and discs)	Avoid hard braking for the first 200 to 300 km (125 to 185 miles), then about 10 moderate stops from 80 to 30 km/h with cooling between
EBC Ultimax, Greenstuff, Yellowstuff, Redstuff	Break-in coating; pads self-seat over about the first 100 miles of normal driving
Akebono and Bosch	Pre-burnished or no set procedure; 400 to 500 miles of moderate driving, avoid heavy braking

The pattern is easy to see. Performance and enthusiast brands (StopTech, Hawk, PowerStop) use short, deliberate heat cycles. Brands focused on daily drivers and OE replacement (Akebono, Bosch, Brembo’s OE line) lean toward a long, gentle break-in over hundreds of miles. EBC’s mainstream street pads come with a break-in coating that does most of the work for you over about the first 100 miles. Neither approach is wrong; they’re matched to the pad.

If your pads are a daily-driver ceramic from a parts store and the box says nothing, the step-by-step above is a safe middle ground. If your box says “pre-burnished” or “no bed-in required,” you can skip the hard stops, but still avoid panic stops for the first couple hundred miles and still don’t sit on a hot rotor.

Bedding in brakes on a classic car or a drum-to-disc conversion

Classic owners need to pay a little extra attention here. Plenty of older cars run solid front rotors, single-piston sliding calipers and brake fluid that’s been in there since a previous owner. All of that affects how bedding goes.

First, if you’ve just done a drum-to-disc conversion, those new pads and rotors need a proper bed-in just like on a modern car, and probably more so because the caliper slides and bracket are all new. Check the brake bias before you start. A converted car with the wrong proportioning valve can lock the rears or the fronts early during the harder stops. Start with the gentler 30 to 35 mph stops and only move to the harder set if the car stays straight and stable.

Second, the rear brakes on most classics are still drums, and drums need their own break-in. New shoes have to wear into the drum’s curve, and until they do, the contact patch is small and the shoes need adjusting. After a rear shoe job, our drum shoe replacement guide for GM A-bodies walks through setting the adjusters. On GM-style self-adjusting drums the adjusters work when you brake in reverse, so a few firm stops backing up, after the bed-in, help take up the slack.

Third, look at the fluid. A bed-in is a deliberately hot run, and old, wet DOT 3 fluid boils at a lower temperature than fresh fluid. If the pedal goes soft halfway through the set, stop the hard stops right away, let everything cool and look at the fluid and the system. Our post on diagnosing a soft, spongy brake pedal on a classic muscle car covers what to check. EBC suggests changing fluid every two years for normal street use, which is a fine rule for a classic that sees mostly weekend miles.

Finally, older cars often lack ABS, so it’s easier to lock a wheel than you think. Keep the hard stops firm but well short of lockup. If you feel a wheel start to skid, back off.

Mistakes that ruin a brake job in the first ten miles

Here are the ones I see most often, roughly in order of how much trouble they cause:

• Holding the pedal at a stop after the hard stops. The number one cause of judder from a fresh brake job. If you have to stop, use light pressure, leave a gap and let the car creep a little, as PowerStop suggests, or shift to neutral and hold it lightly.
• Skipping hub cleaning. Rust and scale on the hub face lead to runout, and runout leads to pulsation a few thousand miles later.
• Impact-gunning the lug nuts. Torque them to spec with a torque wrench in a star pattern.
• Not cleaning new rotors. Many rotors ship with a protective oil or coating. Unless the box says it’s a coating meant to stay on, clean the faces with brake cleaner before install.
• Getting grease or brake fluid on the pads. Contaminated pads won’t bed properly and often squeal. Replace them rather than trying to clean them.
• Ignoring the calipers. A seized slide pin makes one pad drag. You’ll smell it, the wheel will be hotter than the others and the pad will wear unevenly.
• Doing the bed-in in traffic. You can’t do back-to-back stops safely with someone behind you. Find an empty road or wait.

FAQ

Do you need to bed in new pads on old rotors?

Yes, and arguably it matters more. An old rotor already has a transfer layer on it from the old pads, and that layer may be from a different compound. Hawk says that old film baked onto a used rotor will interfere with the new pad’s bed-in and give inconsistent performance from the start.

Hawk’s procedure for reusing rotors goes like this:

1. Measure rotor thickness and confirm it’s above the minimum (the discard thickness is usually cast or stamped on the rotor).
2. Look for deep grooves, scoring, heat cracks or a lip at the outer edge. Resurface or replace as needed.
3. If the rotors are good enough to reuse without machining, scuff the faces with 130-grit sandpaper using moderate pressure to break up the old film.
4. Wash them with soap and water to get rid of grit, oil, grease and brake fluid. Rinse and dry.
5. Install the new pads and bed them in as above.

Tire Rack goes further and says new pads should always go on new rotors, or the old ones should be resurfaced. I’d say it depends on the rotor. A smooth, thick rotor with no runout can take a fresh set of pads after a scuff and a wash. A rotor with a lip, grooves or a pulsation history should be machined or replaced. Rotors are cheap compared with doing the job twice.

Brembo makes one more point worth repeating in the other direction: don’t put old pads on new rotors. A used pad has an irregular profile that touches a new disc in only a few spots and can scratch it, so braking stays poor until a long new bed-in is done.

How long do new brake pads take to bed in?

There are two answers. The active bed-in procedure, the set of stops and the cool-down, takes 15 to 20 minutes of driving. Full mating of pad and rotor takes much longer. Tire Rack says most pad compounds take up to 300 to 400 miles to fully develop an even transfer film. Brembo advises avoiding hard and sudden braking for the first 200 to 300 km, about 125 to 185 miles, before doing its thermal cycling. EBC says its street pads seat themselves over roughly the first 100 miles, and that spirited drivers should not expect the final high-temperature cure until after at least 300 miles of use.

In practice: do the bed-in the day you finish the job, then drive normally and skip the panic stops, heavy towing and mountain descents for the next few hundred miles if you can. If you’ve got to tow or haul right after a brake job, do the bed-in first, without the load.

What happens if you don’t bed in new brakes?

Most of the time, on a plain daily driver, the brakes will eventually bed in on their own through normal driving. That’s why so many people skip it and nothing bad happens. The risk is in the meantime. Without an even transfer layer, the first time the brakes get properly hot (a long downhill, a panic stop, a trailer) the pad can lay down material unevenly and you get judder. Hawk also warns that bringing a fresh pad up to temperature too fast can glaze it, leaving a glassy surface with much less grip. The only fix for a glazed pad, Hawk says, is to sand off the glaze and bed it in again.

The other cost is performance. A green pad won’t stop as hard as a bedded one, and the first green fade can catch you off guard if it happens in traffic rather than on an empty road where you planned for it. That alone is reason enough to spend 15 minutes on it.

If you’re in the middle of other maintenance before winter, have a look at our guide to the best tires for driving on ice. New brakes don’t help much if the tires can’t grip.

Sources

• Hawk Performance: Bedding In Brake Pads Is Not Optional
• PowerStop: What is the Break-In Procedure?
• Brembo: brake guide (break-in and thermal cycling)
• EBC Brakes: How To Bed-In Your EBC Brakes For Street Or Track Use
• Tire Rack: How Do I Bed-In New Brake Pads And Rotors? (Akebono, Bosch, Brembo OE and GT, Hawk, StopTech procedures)

Photo credits (Wikimedia Commons): disc brake behind a wheel by Envy fstop, CC BY-SA 4.0. Front disc brake with wheel removed by Irvin calicut, CC BY-SA 3.0. New brake pads by William J Sisti, CC BY-SA 2.0. Worn and new brake discs by Gordonjcp, CC BY 2.5. Images resized by CarNutChronicles.

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