C5 Mk1 Front Brake Knocking - Loose Caliper Bracket And Brake Pads De-

[aspire_helen]

C5 mk1 2001 2.2hdi The other day during some heavy braking from 60mph, the front brakes began making an alarming knocking and banging - the harder the braking, the louder the banging. On investigation, it only happened on moderate to hard braking, apparently from the drivers side. From the violence of the knocking i antipated a broken bolt or similar. On inspection, all brake and suspension components appeared as normal, nothing loose or broken. I removed the pads and caliper and found 2 problems.

1. The friction material on both brake pads has partially de-bonded from their metal backing plates. The inner pad is worse with about 30-40mm of its length seperated. Both pads have plenty of friction material remaing, 8-10mm. The pads APEC 1283 were fitted about 60,000miles/6 years ago along with new discs by a garage. The disc is now 1.05ins thick (yes, most of my mileage is motorway). Has anyone experienced similar with APEC or other makes? Any possible cause other than poor quality? Of course, i now need to replace all front pads.

2. The bracket supporting the braking cooling air deflector was slightly loose. The deflector is attached to the hub by the same bolts securing the caliper bracket to the hub, and effectively act as washers under the bolt heads. Both bolts were securely held by the hub and very tight. However, the bracket under the lower bolt head had rusted and thinned such that the bolt no longer held the caliper bracket against the hub, resulting in about 5-10thou play.

 

After much struggling i removed both bolts. The upper bolt was pristine, no sign of rust. However, the lower bolt was well rusted into the hub and all mating surfaces were well rusted. These bolts were last removed by the garage to replace the disks. After removing all loose rust from all the brake components, i refitted the bolts with some copper grease and torqued them down satis.

 

I temporarily replaced the original pads and took it for a test drive - no more knocking. If it was the cause, the next time you're looking at the front brakes, just check that the cooling air deflecor is not a little loose, even when the hub bolts are tight.