Squeaking noise from brakes whilst reversing

[NewOwner]

My local garage recently fitted new brake discs and pads to the front of my C180 (W202) and new pads to the rear. They advised they needed doing following the MOT.

After picking up the car from the garage, it made an unpleasant squeaking noise when braking whilst going forward and reversing. I took the car back to the garage and they tried to rectify the problem by replacing the pads with new ones from a different manufacturer. This seems to have cured the squeakying whilst going forward, but when applying the brakes in reverse, I still get a very high pitch squeal.

Any ideas? Is this normal with new pads? Can the brakes be greased? Could the garage have screwed something up?

 

[bolide]

On a W124 the squeaking in reverse appears when using cheap (Textar) brake pads and disappears when you use MB pads

Nick Froome
www.w124.co.uk

 

[Brian WH]

Any ideas? Is this normal with new pads? Can the brakes be greased? Could the garage have screwed something up?

Don't grease the brake pads whatever you do.

It can be cured by fitted MB OEM pads only. However it might get better as the pads break in.

 

[television]

The brakes fitted to you car are standard ATE calipers, and pads by TMD friction (Textar)

Squeaking is caused through resonance, set up by vibrations of the pads against the disc.

With the greasing done correctly this is minimized, but in all fairness the car should be taken out and given a few hard braking runs, to bed the surface of the pads to that of the disc. When the pads are fitted by MB the cars are taken out on a run to do this.

In all fairness if they have been greased correctly you should give car a chance to bed them in, then the noise will go away.

 

[NewOwner]

Thanks for the quick responses. It sounds like there's nothing to worry about! I'll just give the pads a few weeks to bed in and put up with the noise.

 

[television]

My SL took about 400 miles to be silent at all times

 

[Bobby Dazzler]

As a garage did the work I'm assuming that they applied anti-squeal paste - in the right place - especially given the first set squealed.

Some pads also squeal when cold due to the compound, but given this doesn't happen going forwards, it's unlikely to be this.

I agree with television - it's likely that not all of the pad is in complete contact with the disc just yet - this will only happen after the pads have bedded in, ie the pads wear to match the surface of the disc.

Until then only part of the pad will be in contact, and so the remainder is able to vibrate - or resonate - at high frequency.

To be honest though the odd squeak when reversing is fairly normal. Pads wear into a slight wedge shape, as the vast majority of wear takes place when the vehicle is travelling forwards.

The momentum/inertia of the car and rotation of the disk place a slightly greater load on the front edge of the pad, wearing it very slightly more than the rear edge.

When revering the opposite is true, and the sharp edge of the wedge comes into contact first, and hence high frequency vibration.

PS I found that lot out as it often affects MLs so I did lots of very reliable Internet research.

 

[rf065]

To be honest though the odd squeak when reversing is fairly normal.

I'll second that, mine sometimes does it reversing out of the driveway.

Russ

 

[NewOwner]

Thanks Bobby Dazzler for the great info. This makes a lot of sense.