Brake bedding in advice

[Funkyboy]

Hi All,

Just replaced set of rear discs and pads on my 14 plate e class. Looking online there's mixed messages about bedding in process. Some saying it's essential some saying just drive normally? Anyone have any experience of this?

Thanks

 

[DSK]

For standard brakes, I just use them normally but avoid aggressive braking for the first 30 or so miles. Then on a quieter stretches I will slow more aggressively a few times from higher speeds allowing them to cool suitably between applications. Never had any brake issues doing this.

However on performance brakes, the bed in is much shorter and aggressive and can vary a little depending on manufacturers parts in question.

As yours are the rear ones, which have a lot less work to do, just drive normally but avoid aggressive braking for a few miles.


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[brandwooddixon]

Rear brakes only apply about 20-30% of total braking force for most cars which is why some say bedding in isn't necessary, but I would anyway.

I've never found the "drive it carefully for the first x miles routine" to work for me.
Instead I drive to a quiet road that has good visibility, so that I can check for cars approaching from behind and let them past, and follow the following procedure:

1. Accelerate to 30mph, brake using light to medium force, down to 10mph. Repeat 6 times without pause.
2. Drive for a few minutes to allow the brakes to cool. Brake only gently in this phase, but best to avoid it if possible.
3. Accelerate to 60mph, brake using firm, not hard, pedal pressure down to 10 mph. Repeat 6 times without pause.
4. Drive for a few minutes (any speed) to allow the brakes to cool. Brake only gently in this phase, but best to avoid it if possible.
5. Accelerate to 30mph brake hard to a stop. Release the brake pedal as soon as you stop.
6. Accelerate to 60mph brake hard to a stop. Release the brake pedal as soon as you stop.
7. Drive gently to allow the brakes to cool.

Important points:
Release brake pedal pressure as soon as you stop. Use the parking brake to hold the car stationary if you need to allow other vehicles to pass you. This prevents pad material being embedded unevenly into the discs and also allows them to cool evenly.
Be aware of vehicles approaching from behind as they will be confused by your antics or stand a chance of running into you.
Take into account road conditions, especially for 5 & 6 to ensure your safety..

Explanation:
Point 1 & 2 builds up disc and pad temperature, embedding pad material evenly over the disc friction surface.
Point 3 & 4 builds up higher disc and pad temperatures, burning off new pad material volatiles and heat treats the disc.
Points 5 & 6 add a minor heat treatment to the discs but is really to ensure that everything has settled evenly.

 

[EmilysDad]

.... Use the parking brake to hold the car stationary if you need to allow other vehicles to pass you. .....

..... and what if your parking brake is electric & operates on the discs?

I've just put new discs & pads on the front of my ML ..... just driven carefully to & from work a couple of times (25ish miles each way)

 

[brandwooddixon]

..... and what if your parking brake is electric & operates on the discs?

I've just put new discs & pads on the front of my ML ..... just driven carefully to & from work a couple of times (25ish miles each way)

True, but the biggest gripe that people have is what they claim to be warped discs and typically these are the front discs as that is where most of a car's braking force is applied.

The main point is that if you sit with your foot on the brake pedal and the brakes are hot then pad material will be deposited on the discs in one location. This will produce a friction high point and over time, as more material is deposited in that location, give the feel of a warped disc. If your journeys are always short distance and low speed then you may never have an issue as the discs and pads never get hot enough to embed pad material into the disc.

For me, the drive it gently method has never worked as my driving routes are generally long distance, high speed with shorter portions of stop start traffic at either end. The discs never get hot enough during the low speed sections to evenly deposit pad material over the disc and the temperatures from high speed braking are too infrequent to adequately heat treat it. This gives rise, for me at least, to brake judder within 3000 miles, and that is even when I try to religiously not sit with my foot on the brake pedal when I come to a stop.

I have also found that following the above bedding in procedure gives better brake feel, sharper response and fade resistance particularly for high speed braking.

 

[rpaterson]

For rear brakes I wouldn't be overly concerned. I'd likely just drive along at maybe 30-40mph and press the parking brake on for 100m at a time a few times.
If it was the front brakes, then I'd be a whole lot more aggressive with the bedding in bit for the rears, given how little the contribute really, I wouldn't go mad with them and might even just assume that 'normal' usage will do the trick.

 

[Blobcat]

For rear brakes I wouldn't be overly concerned. I'd likely just drive along at maybe 30-40mph and press the parking brake on for 100m at a time a few times.
If it was the front brakes, then I'd be a whole lot more aggressive with the bedding in bit for the rears, given how little the contribute really, I wouldn't go mad with them and might even just assume that 'normal' usage will do the trick.

Hello and welcome,

The parking brake on Mercedes is normally drum brakes inside the rear disks. Using that when moving (especially if the vehicle is a few years old) is a great way to rip the shoes, springs and mechanism out of the rusted dust shield…

 

[rpaterson]

Hello and welcome,

The parking brake on Mercedes is normally drum brakes inside the rear disks. Using that when moving (especially if the vehicle is a few years old) is a great way to rip the shoes, springs and mechanism out of the rusted dust shield…

Apologies, I hadn't looked that far into the set up on ours - I should have done prior to posting this . Ta.

 

[EmilysDad]

Apologies, I hadn't looked that far into the set up on ours - I should have done prior to posting this . Ta.

Not just applicable to Mercs .... my Senators & Omega had the same 'top hat' set up at the back, as did my Dad's Kia Sedona