Just had new pads all round and 2x new discs on the front of the van.

Fitter told Mrs S not to brake very sharply. I trust my mechanic and his opinions so have no concerns about his advice, but out of interest:

1) how long does it take to bed in car discs?
2) his advicee implies its not the same technique as one applies to MTB disc brakes…

His advice is aimed at safety, not bedding. The bedding process is largely the same as MTB ones (in fact if you find the manufacturers site they'll tell you how to) but the advice is normally "dont brake harshly" so that you dont *rely* on being able to brake harshly.

his advicee implies its not the same technique as one applies to MTB disc brakes…

No, I don't think you would want to "roughen up" the discs on your car with mud either.

I thought I just had to drag the brakes downhill and piss on it when hot?

Usually car pads will get away without being bedded, much like bike brakes the majority of users wont notice the difference. If you do bed them properly you'll have much better brakes though.

you can overheat and warp the discs if you break hard before they're bedded in properly.

found elsewhere:

In order to maximise the benefits FERODO brake pads offer the driver, it is essential they are bedded in correctly.
1. Accelerate vehicle to 60KPH. (37MPH)
2. Apply brake using moderate pedal pressure, reduce speed to 5kph (do not stop if possible)
3. Repeat setp 1 and 2 between 8 and 10 times allowing 0.3 to 0.6 km between brake applications.
4. Avoid strong pedal pressure for the first 200km. After completing bedding in procedure, the vehicle can be driven like you stole it (or in a normal manner).
Adherence to this necessary procedure will optimize the performance of the FERODO asbestos-free disc brake pad.

And Brembo…

The answer is yes, for optimum performance, any time different friction materials or discs are introduced, a bedding procedure should be carried out.

While the vehicle is stationary, pump brakes to ensure a firm pedal. Drive the vehicle cautiously to test fit and function. The brakes should be smooth, with no vibrations, judder, etc. Drive the vehicle to a remote area and perform at least 30 brake applications of 3-second duration. Use light/medium deceleration with varying starting speeds. Leave at least ½ mile between each brake application.

The purpose of this procedure is to gradually increase the temperature in the components without inducing thermal shock, and to mate the brake pad and disc friction surfaces. After the repeated stops, drive the vehicle for several miles with little or no braking in order to adequately cool the components.

After the above process is completed, the system is ready for normal use. When the system achieves elevated brake temperatures for the first time, a slight increase in pedal travel and pedal effort may occur. After this first "fade" and proper cooling, the system will maintain its optimum performance at all temperatures.

you can overheat and warp the discs if you break hard before they're bedded in properly.

EDIT:
On a CAR?????????????????????????????????????????

Juan – not sure what your point is?

What happens if the friction material comes away from the backing?

cheers CK. useful and informative stuff.

Did they use Superstar pads ?

Yep not too difficult to warp discs on a car, my front discs have only lasted a year before warping again 🙁

Surely the correct procedure is to:

– Remove pads and file a bit off them
– Soak in vinegar overnight
– Bake in a hot oven for 2 hours
– Rub the blood of a freshly culled virgin on the disks
– Fit pads
– Pour coke on discs & pads
– Brake violently & frequently whilst spraying with water from the washer bottle

Juan – yes, easy to warp discs on a car if you dont maintain them well and treat them correctly. In fact, from experience, I'd say easier than on a bike. Bike rotors are so thin that thermally induced stresses tend to be even throughout the material rather than differential across the disc as can be the case with car ones – i.e. more material to distort.

Cheesyfeet – thats the secret racers tip, Shhhh.

Ziggy – thats usually due to one of 3 reasons:
1) not cleaned the mounting surface or over-torqued the wheel nuts.
2) Cheapo castings with internal stresses remaining.
but mostly
3) stopping with hot discs and leaving your foot on the brake or handbrake on without allowing them time to cool. This keeps different parts of the disc at different temps, causing residual stresses across the disc and then warpage.

sv- only had that happen once, on a rear disc brake. The caliper held the material in place until I came to notice a lack of power on that side.

– Soak in vinegar overnight
– Bake in a hot oven for 2 hours

I thought that was the correct procedure for producing a top class/wining (and illegal) conker ?

😕

the ferodo recommendation as above is very similar to the section of Subaru owners manual i happened to read the other day!

ound elsewhere:

In order to maximise the benefits FERODO brake pads offer the driver, it is essential they are bedded in correctly.
1. Accelerate vehicle to 60KPH. (37MPH)
2. Apply brake using moderate pedal pressure, reduce speed to 5kph (do not stop if possible)
3. Repeat setp 1 and 2 between 8 and 10 times allowing 0.3 to 0.6 km between brake applications.
4. Avoid strong pedal pressure for the first 200km. After completing bedding in procedure, the vehicle can be driven like you stole it (or in a normal manner).
Adherence to this necessary procedure will optimize the performance of the FERODO asbestos-free disc brake pad.

Thats all a bit gay, common sense is the aim of the game. Try not to drive enthusiastically for the first 10 miles as they can overheat when new (although that will only manifest itself by fading).

His advice was purely for safety due to a) pedal bite point likely being different b) braking performance likely to be poor the first couple of applications. It is extremely unlikely you will rip the material off the backing (on a road car I have never heard of this) and a warped disc is also extremely unlikely. Do do this on a road car you really need to apply maximum braking consistently for 20-30+ miles, and even then it is hard to do.

Basically driving like most people do you will be fine.

new pads and disks for me a few months back.

drove normaly, power in the brake increased over the course of a week or so as they bedded in.

unless your like "some guy i know", and come up to roundabouts looking for a gap, and then abort if there isnt one, rather than coming up carefully and waiting for the next one, youll be fine i would have thought

Most road car discs warping problems are due to unreleaved stresses in the disc when it is made. The heat then causes the disc to reshape itself (minimally). Very similar to using a used engine block for a high power rebuild.

Not sure that's still the case boobs – its a fairly simple and symmetric casting and they undergo fairly uniform heat treatment, not like the olden days where they were cast and thrown in a bin. Only the cheapest makes really suffer that from my experience (go to your motor factors and buy £10 discs and you'll probably get this).

unless your like "some guy i know", and come up to roundabouts looking for a gap, and then abort if there isnt one, rather than coming up carefully and waiting for the next one, youll be fine i would have thought

At the risk of being called a nutter that shouldnt be allowed a license etc etc…That's how you're meant to drive – that's why its a give way rather than a stop. Nothing pees me off more (ok, a few things do) than someone who stops at a roundabout with next to nothing on it! The idea is you can continue on your way unless there's traffic that you need to give way to.