Brake Discs & Pads

Measure rather than guess. Friction material thickness is what matters, and most manufacturers set a minimum of around three millimetres over the backing plate, with many cars carrying an electrical wear sensor or a mechanical squeal tab that announces the same point. A quick visual check through the wheel spokes tells you a great deal if you know what a new pad looks like. Replace as an axle set rather than one wheel, and inspect the disc at the same time, since a disc below its minimum will need replacing anyway.

Because they are barely used. Regenerative braking handles most deceleration, so the friction surfaces rarely see the pad and never get wiped clean or heated enough to drive off moisture, and surface rust turns into pitting over time. It is a known pattern across the segment rather than a defect. Two things help: braking firmly with the friction brakes a few times a week to clean the faces, and choosing coated discs where the manufacturer offers them. A pitted disc with plenty of pad left is a legitimate replacement.

Almost certainly not warped in the literal sense. What you feel is disc thickness variation, where the friction faces have worn or corroded unevenly, so the pads are pushed apart and released as the disc turns. It builds up from uneven pad deposits, from parking hot with the brake applied, or from corrosion on a car that has stood. Machining can cure it where enough thickness remains, but on modern thin discs replacement is usually the practical answer. Fit as an axle pair.

Only if the disc calls for it, and the disc tells you. Measure the thickness against the minimum stamped on the hub face, look for a pronounced lip at the outer edge, and check the friction faces for pitting, scoring and blueing. A disc comfortably above minimum with clean faces will happily take new pads. A disc near minimum will reach it before the new pads are half worn, which means doing the job twice. Never fit new pads to a deeply scored disc and expect quiet braking.

Squeal is a vibration between the pad and the disc at audible frequency, and pad design fights it with shims, chamfers and slots. It appears when shims are missing or reused, when the backing plate contact points are dry, when the pad is glazed, or when the disc face is corroded. Fitting the correct pads with their shims and hardware, cleaning and greasing the abutment points with the right high temperature product, and bedding them in properly cures most cases. Grease belongs on the metal contact points, never on the friction face.

It matters more than most people expect. New pads and discs need a controlled series of moderate stops to lay an even transfer film of friction material onto the disc, and until that film is established the brakes feel wooden and are prone to uneven deposits. The manufacturer's procedure usually amounts to a set of progressively firmer stops from moderate speed without coming to a complete halt, then a cooling period. Skipping it is the most common cause of a judder that appears within a few hundred miles of a brake job.

Pads sit at the lower end of the category and rear pads generally cost less than front. Discs are moderate and front discs cost more than rear because they are larger and usually vented. Dust shields and retainers are inexpensive. The live minimum and maximum are shown in the band at the top of this page. Because these are axle set purchases, it is worth pricing pads and discs for both wheels together rather than a single item when planning the job.

Some references here are offered both as Original/Genuine, made for BYD under the BYD OE number, and as an Aftermarket alternative made to fit the same number, usually at a lower price. Read each listing for what is included, since kits differ in whether shims, retainers and wear sensors are supplied. Match the OE number in either case, and choose based on what the listing states rather than assuming the contents are identical.

Check the dust shield first. It is a thin steel plate behind the disc that keeps road debris off the inner face, and it is easily bent inward by a kerb, a jack placed wrongly or corrosion at its mounting. A bent shield touching the disc produces a light scraping that changes with steering angle and disappears when the wheel is straight. It is a cheap part, listed here for each side. A grinding that gets worse under braking is a different problem and means worn out pads.

Many people do, and the work is within reach with proper support, a torque wrench and a piston tool. The steps that catch people out are seized caliper guide pins, which must be cleaned and regreased or the new pads wear on one side, and rear calipers with an electric parking brake, which need the motor retracting through a scan tool before the piston will move. Torque the caliper and carrier bolts to specification, bed the brakes in, and check everything again after a short drive.

Wheel size does not settle it. Disc diameter, thickness, offset at the hat, the bolt pattern, the centre bore and the vane design all have to match, and manufacturers change disc specification between trim levels of one model with identical wheels. A disc that is fractionally thick or thin will not sit correctly in the caliper. Match the OE number from your old disc or your vehicle documents, and if the reference brings back nothing, send it through the quote form to be checked properly.

It can be ordered. Discs and pads are among the better priced references in the catalogue, so an empty field usually points at something narrower: a dust shield, a wear sensor for one particular trim, or a disc size fitted to a single variant. Send the factory number through the quote form rather than guessing from a similar model, because disc diameter and thickness follow the brake package rather than the badge. Ask for the full axle set in one message. Mixing a quoted disc with pads ordered separately is how a booked workshop slot ends up half supplied.