Seized Calipers

EBC Automotive Brake Tech – brake calipers

Brake calipers are a vital part of your brake system. The brake caliper is what brings the disc brake pad into contact against your brake rotor and generates the stopping power of the vehicle. Seized calipers or seized sliding parts of the brake caliper will cause many problems including brake drag, brake overheat and hot spots on brake rotors, cracks in brake rotors and very commonly rotor ribbing or rotor galling which shows up as record style grooves or ribs on the rotor in a general pattern.

Whilst it is not within the ability of most mechanics to strip and refurbish a brake caliper, certain service work can be carried on by competent technicians or by your dealer. Do NOT please attempt to rebuild brake calipers as this is a SAFETY ISSUE if you are not totally qualified to do this. Our following notes guide people in the basics of making sure your caliper is working properly.

There are several types of automotive brake caliper.

Most cars use a single piston sliding caliper which has a single large piston, on the inboard side of the caliper into which the hydraulic fluid enters. Through a slider mechanism the opposing half of the caliper is pulled towards the piston clamping the brake pads on to the brake rotor. These sliding calipers as they are know are prone to seizure due to corrosion in two areas.

The bores need to be gently honed clean, the slider pins wire brushed and emery paper cleaned, greased and re assembled.Shown below are the slider pins that are part of the carrier and fit inside blind holes in the caliper body.

It is essential that these slider pins and the holes into which they fit are free of all dirt rust and scale and are fully lubricated with a high temperature lithium soap base grease and that the bellows seals which enclose these pins fit snugly and are not split or perished whereby they might allow moisture into the slider bores.

Shown below are the slider pins that are part of the carrier and fit inside blind holes in the caliper body

If the pads cannot slide freely on the slide rails because of this rust or scale, the outboard pad will not release staying in contact with the brake rotor after the brake is released , will cause overheating of the brake rotor, hot spots on the brake rotor, brake vibration and eventually brake pad surface scoring on that side of the brake pad and rotor.

If your brake rotor looks like this in the picture below, it has to be turned or replaced and new pads fitted. The matching faces on the brake pad will show rib marks.It is most common in European cars that these slide rails become rusty and the free movement of pads cannot take place. On every brake pad change, clean these slide rails with a wire brush and apply a VERY THIN coating amount of high temperature grease on them, take care not to contact the brake pads with ANY greases or lubricant which can ruin the brake pads and can CAUSE TOTAL LOSS OF BRAKE in driving.

Again EBC Brakes wants to draw customer’s attention to the numerous advantages of slotted rotors or drilled and slotted rotors such as our GD series or USR series sport rotors which eliminate rotor ribbing, eliminate rotor scoring and rotor damage, help brake pads last longer and run cooler.