This 2013 Vauxhall Insignia came in with grinding brakes. On inspection the front discs had a severe lip on the outer edge — a classic sign of long-term wear. One of the inner pads had worn completely through to metal-on-metal contact, and critically, one of the pad slider shims was missing from the caliper carrier, which had caused the pads to wear unevenly and prematurely.
This guide covers full front brake disc and pad replacement including caliper carrier cleaning, slider shim replacement and correct piston retraction technique.
Symptoms That Brought This Car In
- Loud grinding noise when braking
- Severe disc lip visible on the outer edge of the disc
- One pad worn completely to metal — metal-on-metal contact
- Scored and thinned disc surface from prolonged wear
- Missing slider shim causing uneven pad wear
Tools & Parts You'll Need
Step-by-Step Guide
Remove the Wheel & Initial Inspection
Loosen the wheel nuts with a 22mm socket before raising the car, then lift and support it safely. Remove the wheel. With the disc exposed, inspect the disc face and edges — on this Insignia a massive lip was visible on the disc edge and the inner brake pad had worn completely through. Note the condition before removing anything as it tells the full story of what's happened.
Push the Caliper Piston Back & Remove Caliper
Before removing the caliper, push the piston back while it's still in position — place a flat screwdriver on the edge of the disc and lever it to push the piston inward, then press the piston all the way home. This checks it moves freely and isn't seized. Remove the two caliper bolts (14mm bolt, held with a 17mm spanner on the slider pin behind). Lift the caliper off and hang it safely — never let it hang on the brake hose.
Remove Caliper Carrier & Inspect Slider Shims
Remove the two large 21mm caliper carrier bolts and pull the carrier free. Take it to the bench. On this Insignia one of the four pad slider shims was completely missing — three were present, one was absent. Missing shims cause the pad to sit unevenly and wear at an angle. Always check all four shim positions carefully and replace any that are missing, bent or corroded. New shims were ordered from Euro Car Parts.
Remove the Old Disc
Remove the T30 Torx retaining screw from the disc face. The disc will likely be seized to the hub — use a hammer to tap it firmly from behind to break the rust bond. Once freed, the old disc slides off. Side-by-side comparison with the new disc clearly shows how much material had been lost to wear.
Clean All Mating Surfaces & Caliper Carrier
Use a wire brush to clean the hub face where the disc sits, removing all rust and corrosion. Clean the caliper carrier thoroughly — all four pad sliding channels need to be rust-free and smooth. Use a Dremel with a wire wheel attachment on stubborn areas. Run your finger across the surfaces — they should feel flat with no lumpy corrosion. Apply a thin smear of copper slip to the hub face before fitting the new disc.
Fit New Disc, Slider Shims & Pads
Slide the new disc onto the hub and refit the T30 Torx retaining screw. Clip the new slider shims into all four positions on the clean caliper carrier — they should click firmly into place. Refit the caliper carrier with the 21mm bolts torqued to spec. Fit the new brake pads — note the wear indicator position on the inner pad (usually faces inward at the top). The pad locates against the slider shim which prevents vibration and squealing.
Wind Back the Piston & Refit Caliper
With the new thicker pads, the caliper piston must be fully retracted to allow the caliper to fit over the disc. Use a large pair of grips or a piston wind-back tool to push the piston all the way back until it stops. Slide the caliper over the new pads and disc, refit the two caliper bolts with a 14mm socket and 17mm spanner, and tighten securely.
Refit Wheel, Torque & Bed In the Brakes
Refit the wheel and tighten the wheel nuts to the correct torque (typically 110Nm on the Insignia). Repeat the full procedure on the other front wheel. With both sides complete, pump the pedal firmly several times before moving the car. Road test with a series of moderate stops from 30mph to bed in the new pads and discs — avoid any hard emergency stops for the first 200 miles.
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