Un'warping' discs

[willmagrath]

I've always had problems with warping discs. Last 4 times I've fitted new discs and pads, they've all warped or given uneven pad deposits within 1000 miles.

I recently fitted new pads to my 3 series and after about 1500 miles, there's bad brake judder.

I did do a few fast stops to try and bed them in a bit and it was fine after that, but now they're bad.

Can I un warp? Could I try a few fast stops again to even up the pad wear?

Thanks

[stevieturbo]

What vehicle ? what usage ? and are you fitting cheap ste ?

[willmagrath]

stevieturbo said:

What vehicle ? what usage ? and are you fitting cheap ste ?

A 330d touring auto. Used for commuting (tiny bit of town, mostly fast country lanes) and long motorway journeys.

The latest discs are a middling euro car parts brand. Maybe pagid. I have had this issue with all brands though.

[willmagrath]

stevieturbo said:

What vehicle ? what usage ? and are you fitting cheap ste ?

It may be my driving style. I bought the car in January with used brakes and it was smooth and by March they were juddering. Driving style wise I don't really heavy brake.

I've also had this issue on multiple cars (Fiesta st, mk1 mx5, Peugeot 208, m135i). Usually I have just just driven normally as instructed and they always start juddering.

[mmm-five]

If the only common element on all the cars is your driving style, then I'd agree that it's likely that...and light braking is leaving deposits that have no opportunity to get scrubbed off.

So it's not 'warped discs', just pad deposits...which can be cleaned off by a round of heavy braking, or by a wire brush on the disk.

But remember to follow the correct/full bedding in process for whatever disc/pad combo you use...otherwise you'll just be back to square one.

[paul_c123]

I wonder if there is some issue with the hub, like there's a lot of corrosion or unevenness on it. If its happening over and over, might be worth putting a dial gauge on the disc; then on the hub; and measuring what's actually going on.

[cuprabob]

paul_c123 said:

I wonder if there is some issue with the hub, like there's a lot of corrosion or unevenness on it. If its happening over and over, might be worth putting a dial gauge on the disc; then on the hub; and measuring what's actually going on.

The OP has had the exact same issue with a number of their previous cars, which points to driving style, as someone has already said.

[OldGermanHeaps]

Suspension bush wear in bmws can give you braking judder too. Check the discs and hubs for runout with a dial gauge before spending too much money.

[BlindedByTheLights]

Lots of people on the f series forum report the same issue. The cure seems to be buy the discs from BMW.

[John D.]

mmm-five said:

If the only common element on all the cars is your driving style, then I'd agree that it's likely that...and light braking is leaving deposits that have no opportunity to get scrubbed off.

So it's not 'warped discs', just pad deposits...which can be cleaned off by a round of heavy braking, or by a wire brush on the disk.

But remember to follow the correct/full bedding in process for whatever disc/pad combo you use...otherwise you'll just be back to square one.

This is what I'd do. Had pad deposits after a track day once and bedding them in again fixed it. Ferrodo DS2500 pads.

[willmagrath]

Thanks all for the responses. Sounds like it's just deposits then. I've just been out and did 4 big stops from 70 to 20. Its definitely better but not cured yet. I am a very light brakes so maybe its just that!

[willmagrath]

OldGermanHeaps said:

Suspension bush wear in bmws can give you braking judder too. Check the discs and hubs for runout with a dial gauge before spending too much money.

Just seen a video about hub run out so worth a look some time.

[mmm-five]

willmagrath said:

Just seen a video about hub run out so worth a look some time.

But that would only affect a specific vehicle, not all of them!

[jfdi]

"warped" discs can be caused by heat soak on a patch of the disc, causing that area to become harder than the rest of the discs. As the disc wears the hard area then doesn't wear as fast, leaving a thicker patch which then causes juddering.
The heat soak is caused by high speed stops then keeping the pedal pressed down so the pads remain in contact with the disc. To correctly bed in new discs you need several incidents of high speed braking to heat up the discs but do not come to a complete stop, if you do have to stop, release the brake pedal.

[Chris32345]

willmagrath said:

I've always had problems with warping discs. Last 4 times I've fitted new discs and pads, they've all warped or given uneven pad deposits within 1000 miles.

I recently fitted new pads to my 3 series and after about 1500 miles, there's bad brake judder.

I did do a few fast stops to try and bed them in a bit and it was fine after that, but now they're bad.

Can I un warp? Could I try a few fast stops again to even up the pad wear?

Thanks

Bed them in?
Are you fitting racing pads
You don't need to do fats stop with every road pads and discs

[jfdi]

Chris32345 said:

Bed them in?
Are you fitting racing pads
You don't need to do fats stop with every road pads and discs

But it's a good idea to do so, bringing the disc up to the highest temperature it's likely to see, thus "harding" the disc evenly and preventing a single fast stop creating a hard spot as described above.

[Tony1963]

Chris32345 said:

Bed them in?
Are you fitting racing pads
You don't need to do fats stop with every road pads and discs

One misunderstanding about brakes it that the pads press against the disc. Not quite. They need to press against a layer of pad material that’s firmly attached to the surface of the disc. This layer has to be transferred by brake useage, and some heavy braking, without stopping, will do just that.
And then, try to avoid stopping, at traffic lights for example, with your foot remaining on the brake pedal… you’ll transfer pad material to just one area of each disc, causing judder.

Use the brakes more, and use them keenly every now and then.

[Pica-Pica]

I had brake judder on my F30 335d. I am a light brake user, and this occurred after a spell of little use, during and post Covid, and with the car standing and get all the winter gritter stuff, the discs got quite corroded and pitted. I tried repeated heavy braking, to no avail. I had the main dealer change the front discs and pads at 46k miles (first change). A slight improvement. I tried more heavy braking a month or so later. Eventually I had the dealer change the rears, and all was good. Being a light braker, I never bed discs in, but I do ensure that I brake on long descents to keep the discs wiped.
I gave up changing my brakes a while ago - I have never had issues with BMW dealer fitted brakes.

[MustangGT]

jfdi said:

"warped" discs can be caused by heat soak on a patch of the disc, causing that area to become harder than the rest of the discs. As the disc wears the hard area then doesn't wear as fast, leaving a thicker patch which then causes juddering.
The heat soak is caused by high speed stops then keeping the pedal pressed down so the pads remain in contact with the disc. To correctly bed in new discs you need several incidents of high speed braking to heat up the discs but do not come to a complete stop, if you do have to stop, release the brake pedal.

Never heard of that, normal road driving cannot create anywhere near high enough temperatures to do any damage at all to discs. Even by not releasing the brake pedal.

[Kawasicki]

Some cars have suspension layouts that are extremely susceptible to imperfections in the braking system causing braking judder or steering shake. BMW is one of those companies. Pay a lot of attention to detail, that’s all I will say.