Brake pads - bedding procedure

Adelaidedb

Hi All,
Going to replace the front discs and pads on A4, Was wondering how/what technique to use to bed the new pads in, Any advice welcome.

See the following procedure online, Will try this if no advice given:


•Perform 3-4 medium stops from 45mph. Slightly more aggressive than normal braking. You don't need to come to a complete stop for each pass. This brings the brake rotors up to temperature so they are not exposed to sudden thermal shock.
• Make 10-20 aggressive stops from 45mph down to 5mph. For this set of semi-stops, you want to be firm and aggressive, but not to the point where ABS activates and the wheels lock up. It's important to note that you don't come to a complete stop but rather a semi-stop (~15mph). Accelerate back up to 60mph as soon as you slowed down to your semi-stop.
•The brake pads and brake rotors are extremely hot at this point and sitting on one point will imprint the pad material onto the surface unevenly. This can cause vibration and uneven braking.
• You may notice that your brakes will start fading, and sometimes smoke, after the 6th or 7th pass. This fade will stabilize and will gradually recess once your brakes have cooled down to normal operating temperatures. Drive carefully as your brakes may feel softer for the next few minutes.
•Try not to come to a complete stop and find a stretch of road where you can coast for 5-10 minutes, preferably without using your brakes.


Thanks

Alanstrainor

That advice is not correct. Sounds completely bonkers. Do you imagine every mechanic follows that regimen when they install new discs and pads? Absolutely not. I don't know who wrote that, some head the ball. I'd recommend taking it easy on the brakes initially, just do gentle stops from the get go. To remove the protective coating on the discs first, and then to bed the pads. The first few times braking will feel strange through the pedal, but it should quickly return to normal. Then just ease it in, slow down gradually on the brakes for a 100km or so. Then drive on.

Toyotafanboi

Head the ball is tight. Fit the parts, take a cautious test drive, if the pedal feels ok, then just drive as normal. No excessive bedding in process is needed.

porsche boy

This is why Google is NOT your friend. That is the most mental write up I have read in a while.

Allow a greater distance from the cars you are behind and brake as normal until you are comfortable with the vehicle stopping. While the pedal will initially feel soft it will quickly return to normal.
The write up you posted would, in my opinion, potentially lead to warping the discs.

zilog_jones

I also saw many similar instructions when I first changed pads, it all seems a bit mad. Also, the OP's quote does say "rotors" so maybe it's a yank thing? The home of 3,000 mile oil changes...

Pops_20

I'm going to disagree with the majority of opinions here and say that this is the correct procedure. The reason why it's not recommended in general is because you can't trust the average motorist to perform such a "complex" procedure after changing pad and/or discs. There is too much risk - e.g. braking hard causing an accident.

I've done a lot of research into this recently due to other brake problems I've had. Bedding in the pads properly like this leads to better brake pedal feel and braking performance. It effectively leaves a layer of brake pad material on the disc which give a better "bite" than just the pad to brake disc contact.

https://www.youtube.com/watch?v=gl6TV_nQy3o

https://www.youtube.com/watch?v=pdPX6rzuINc&t=233s

Discs don't warp either. The temperatures required to warp discs are far beyond what is usually achieved by braking. The feeling of pedal pulsation that is generally called "warp" is due to Disc Thickness Variation which is caused by excessive wheel bearing run-out / seized caliper slider pin etc, which develops over time on new discs.

Sure the brakes are fine without following any bedding in procedure, but there's a much better feel when you do follow the procedure.

Adelaidedb

Thanks guys for all your advice. I wasn't to sure on this I replaced pads (only) before on the same car and was cautious with the soft pedal feeling I had for a short time afterwards.

I asked a mechanic he just said that the new pads will bed themselves in as you drive. When I looked it up on google was curious was there many people bedding them in with the steps mentioned earlier.

pea be

The first time i changed brake pads years ago, i just pumped the pedal to get the pistons pushed out. When i was leaving for work next morning (in a rush) i found out about unbedded brake padsat the emd of thr lane when i hit the brakes to slow down and not much happened!
Next time i changed pads, i did not fall into the same trap... and drove about 3 miles with my left foot on heavily the brake. When i pulled back into the yard ... the paint on one rim was on fire!!
Since then, i've bedded in pads by taking a 0.5ish mile dive to .... first using some gentle left foot braking for the first couple of hundred yards them a couple of gentle stops. This works a lot better than my first 2 methods 🀣

Adelaidedb

Thanks Pea be for your advice. Hope to change them shortly. so will probably try your method as mentioned. Cheers

Kenny Logins

Drive.

Cee-Jay-Cee

Drive normally without sudden or dragging the brakes for long periods.

Cars are driven out of showrooms everyday of the week and people are nor given instruction or advised to 'break' or 'bed' in brakes before leaving. Its pure nonsense and is only applicable to high performance pads/discs and even then is not entirely necessary.

pea be wrote: »

The first time i changed brake pads years ago, i just pumped the pedal to get the pistons pushed out. When i was leaving for work next morning (in a rush) i found out about unbedded brake padsat the emd of thr lane when i hit the brakes to slow down and not much happened!
Next time i changed pads, i did not fall into the same trap... and drove about 3 miles with my left foot on heavily the brake. When i pulled back into the yard ... the paint on one rim was on fire!!
Since then, i've bedded in pads by taking a 0.5ish mile dive to .... first using some gentle left foot braking for the first couple of hundred yards them a couple of gentle stops. This works a lot better than my first 2 methods ��

You clearly haven't a clue and none of the above methods are helpful or necessary. Why on earth or who on earth advised you to drive and keep your foot on the pedal at the same time???? Even the final method which you now use is nonsense and unnecessary and obviously just made up by yourself seeing as your other two earlier methods were such disasters!

Fit the new pads, switch on the engine and pump the pedal till it goes hard and then drive as normal. If the pedal is still soft then you need to bleed your brakes not drive around with your foot on the brake pedal. :rolleyes:

pea be

Cee-Jay-Cee
Lol ... first attempts were from long ago ...way before the wonderful resource of the internet was even invented ... and only a tatty old second hand Haynes manual covered in oil was available.

We'll agree to differ on whether pads need bedded in and how, but over the intervening 40 years I still think it you would be poor practice to not gently bed them in after pads/discs were changed. But then again, I'm a keen DIYer over the years building up my knowledge and skills rather than a trained motor technician!

Your example of cars leaving the showroom is misleading, as those cars will have been driven at different times... from the production line to storage, during transportation/delivery and at the dealership prior to customer pickup. So the brakes will be well bedded in, long before the customer drives out the door.