300c front brakes woe

[jonnyjeep]

After my last posting a few months ago that concerned clunking brakes that were all but sorted, I have a new woe !

Back in December '23 I fitted a pair of new front brake calipers on my 2007 300C CRD as the old ones were seizing up when hot.

........and thats when the rattling started !

Since then I have tried a couple of different makes of pads, new slider pins & new pad carrier clips.....but only on uneven roads at below 20 mph, I have this rattling noise coming from the brake area.

I have narrowed it down to the inner brake pads & have concluded that the twin pot floating brake caliper design on the front of this vehicle is not really fit for purpose. There is nothing to hold the inner brake pad to the caliper piston...hence it rattles at low speed.

Previous vehicles that I've owned have only had single pot floating front calipers & the inner brake pads always came with a backing clip that pushed into the caliper piston to stop it moving up & down.

The workshop manual states that the pads are interchangeable inside to outside. Is there a reason for this ?

Until they produce front inner brake pads for the 300C with clips that fit into the caliper pistons (to stop the pads moving), then there will always be a rattle problem with the inner front pads on the 300C

[jonnyjeep]

Problem now sorted hopefully...

Before I go into details, I would like to quote the old saying 'buy cheap, buy twice, buy thrice' as all brake pads are not equal & all brake pads do not fit as properly as OEM pads....especially if they are produced in China for the EU.

My problem was brake knock/rattle over bumpy roads at low speed & it was indeed the pads. It wasn't the height of the pads that was the problem (183.4 mm), it was the width of the pad ears. The pad ears on cheap pads are not wide enough, hence they rock back & forth, which causes a clunk/rattle on rough ground which goes away when you apply the brakes.

I bought some NAPA 'proformer' pads & they have ears that are (and I've measured them with a micrometer) 0.9mm wider, which pushes into the caliper clips alot tighter, thus stopping them rocking back & forth and preventing the brake pad from rattling....at last I'm a happy 300C driver