Brake judder - Disc Skimming

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 St Albans (one days march from London)
My Coupe (along with loads of the other cars I've owned) is really prone to brake judder. I stick on new discs + pads (always decent ones) and within a couple of thousand miles I have the same problem again. No track days (and I even take it easy through the eleven roundabouts at Milton Keynes these days.)

I've checked the run out (which is difficult as the discs are grooved) but I reckon I've only got about 0.06mm which doesn't seem like much. I couldn't accurately get the thicknesses. After much Googling, I'm thinking I'm now going to try a different approach and get the discs skimmed on the car (and fit new pads even though the current ones are not old). Does anyone have any experience with brake disc skimming (or perhaps curing brake judder in other ways)?
 
My Coupe (along with loads of the other cars I've owned) is really prone to brake judder.
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Don't take this the wrong way but the common denominator here is you

Is it brake judder or something else

Are you fitting the discs on all the other cars as well as your coupe

Strange it is loads of other cars you have driven

If you was nearer to Manchester I would have a look at the car and its discs for you
 
It judders when I brake and at a frequency that is related to the speed and it stops when I release the brake - not sure what else you'd call it!

Loads of cars is a bit of an exaggeration - five that I remember (all BMW or Mercedes) would be accurate! Some of the discs I've fitted but many not (main dealer or specialist). Mostly on older cars but my e46 I had from new and I did have trouble with that (admittedly that got driven hard and probably got over heated).

I'm really careful to make sure everything is cleaned and properly torqued. A couple of years ago I did a fairly extensive overhaul on the e86: calipers refurbed at BCS, new discs, pads, shocks, springs all the major bushes, alignment etc. It was fine for a couple of thousand miles then it started to judder again.

My Mercedes ML has done about 25k on discs and pads that were main dealer fitted (they are barely even lipped and no scoring that you can feel). When you brake in that, you feel it in the steering wheel - its very pronounced. That car is booked in tomorrow.

The guys at my local garage that use a Pro-Cut lathe reckon that a lot of modern cars are sensitive to it and that hitting potholes or driving up kerbs can lead to damaging the hub (leading to run-out). They say they check the run out after fitting new discs and will sometimes skim them.

The stuff written by professionals (the brake companies) largely indicates that the issue (judder) starts with run out caused by dirt/rust between disc and hub, a hub that's out of alignment or potentially a tired wheel bearing. This over time leads to a variation in the disc thickness and that causes the judder. Also mentioned is heavy braking from speed to a standstill.

If you can suggest anything else or have a view on skimming I'd be very pleased to hear it!
 
Just a thought, but my E91 was suffering from something similar recently - the steering wheel would jiggle in my hands whenever I braked with any more force than gently.

I got the front Track Control Arm bushes replaced and it's been much better since then - although it still isn't perfect!
 
Go out and give them a re bed , 70 or more down to 20 a dozen or so times very aggressively, brake as hard as you can and get them stinking hot , literally stinking and drive home the long way to let them cool down properly with gentle braking .
It's worked for me a couple of times and it's free so as long as you keep an eye on your mirrors you've nothing to lose :lol:
On hub skimming also worked once when a re bed didn't.
 
Paulwirral said:
Go out and give them a re bed , 70 or more down to 20 a dozen or so times very aggressively, brake as hard as you can and get them stinking hot , literally stinking and drive home the long way to let them cool down properly with gentle braking .
It's worked for me a couple of times and it's free so as long as you keep an eye on your mirrors you've nothing to lose :lol:
On hub skimming also worked once when a re bed didn't.
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humour me here, have you identified which wheel is causing problems by touching each wheel to see if one is hotter than the rest ?? you might have a sticking caliper. if they are all the same temperature more or less, then..
i agree, if your light on the brakes all the time you transfer the compound of the pads to the disk and you get judder, and a high speed braking ALWAYS causes juddering UNLESS you burn off the pad compound on the disks that form a film on the disks and as a result always judder., i have never EVER needed skimming on any car i have ever owned - so stand on them a few times and burn off the film and you will be amazed how good your brakes become ! although i would advise not to brake from high speed as the juddering will be disconcerting, 30/40 mph will do fine, stand on them at least 10 times until you can smell them, another way is to drive with your foot lightly on the brake pedal for a couple of miles, again you will be shocked how they quickly bed in.
 
If you’re using bargain basement discs....don’t...utter rubbish that warp very quickly. If not then as Paulwirral says use them hard, nannying brakes is not good for them.
 
road warrior said:
Paulwirral said:
Go out and give them a re bed , 70 or more down to 20 a dozen or so times very aggressively, brake as hard as you can and get them stinking hot , literally stinking and drive home the long way to let them cool down properly with gentle braking .
It's worked for me a couple of times and it's free so as long as you keep an eye on your mirrors you've nothing to lose :lol:
On hub skimming also worked once when a re bed didn't.
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humour me here, have you identified which wheel is causing problems by touching each wheel to see if one is hotter than the rest ?? you might have a sticking caliper. if they are all the same temperature more or less, then..
i agree, if your light on the brakes all the time you transfer the compound of the pads to the disk and you get judder, and a high speed braking ALWAYS causes juddering UNLESS you burn off the pad compound on the disks that form a film on the disks and as a result always judder., i have never EVER needed skimming on any car i have ever owned - so stand on them a few times and burn off the film and you will be amazed how good your brakes become ! although i would advise not to brake from high speed as the juddering will be disconcerting, 30/40 mph will do fine, stand on them at least 10 times until you can smell them, another way is to drive with your foot lightly on the brake pedal for a couple of miles, again you will be shocked how they quickly bed in.
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Personally I would hit a happy medium of both these answers, I’m afraid the common denominator in all your cases is you! No offence but try and moderate your driving style. Occasionally hit the brakes hard and get them good and warm(hot) you will do them no harm and as others have said burn off the old pad deposits that get on there when braking gently. Best of luck and hope this cures it for you.
 
Do check that you don't have a sticking caliper. I had the same, kept getting judder, eventually I replaced the calipers and never happened again.
 
do they only judder when you're braking or during normal driving?

I believe a sticking caliper will judder during normal driving too (not under braking). Otherwise check all your suspension bushes & components.
 
had mine skimmed after suffering judder under high speed braking,(below 60 not noticeable at all) whilst it reduced it pretty well it didnt quite 100% cure it, theres still very light vibes there but a big improvement on what it was...new discs and pads next time though
 
Got the fronts done on the ML on Thursday and that is much better. I've just taken all the wheel weights off and cleaned the wheels and will get them rebalanced this week as they are not quite right. We'll see how that is in a couple of thousand miles...

I'm fairly reluctant to believe my driving style has a lot to do with it. I drive considerably harder than most but an awful lot better than the average person that BMW design their cars for. I do a lot of motorway driving (which admittedly doesn't require a lot of braking). I'm not in the habit of screeching to a dead halt so I don't really see pad material building up on the discs unevenly that way and the car does get to brake hard when the opportunity presents.
 
I'm not questioning or judging your driving before I post , I'm trying to help as others have helped me .
A couple of months before going to the ring earlier this year I put a new set of yellow pads in the front of my car , along with fresh fluid and a set of yoko ad08 tyres just so you know I take it seriously . I gave them a very aggressive bed in procedure as I described earlier but then due to a slight change of plan the car ended up being driven around at normal speeds for longer than I thought by myself and my wife .
Eventually got to the ring and for the first half of the first lap I had brake judder , improving with every hard application of the brakes , it is the ring after all , after half a lap of aggressive braking they were fine , I did 6 laps straight off the bat only letting them cool off from the last corner and once to the fuel station, never had any more judder and didn't suffer any fade either .
As I said earlier, it's free and it normally works and I'm trying to save you money in the future, not trying to be an Internet smart arse .
 
The other thing to bear in mind is to never hold the brakes on with the pedal after any 'spirited' driving, like at a junction or lights etc. You can get deposits from the pad sticking to the discs.
 
ph001 said:
The other thing to bear in mind is to never hold the brakes on with the pedal after any 'spirited' driving, like at a junction or lights etc. You can get deposits from the pad sticking to the discs.
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^^^^ As PH says.

Holding the pad on the disc when hot also promotes warping.
 
Just to add a bit more colour to this, my local BMW specialist took it for a spin today and came back saying he couldn't detect any judder. After this I took him out and drove with my foot on the brake until we got to a clear road to get some heat in to the discs. I then accelerated to high speed and braked pretty hard six or seven times. The juddering got more and more pronounced - he was in no doubt. Later with discs cold again I went up to the shops no juddering.

This really has nothing to do with me coming to a halt with the brake on and leaving pad material on the discs - the discs are running out (warping) when they get hot and returning to tolerance when they cool.

I have emailed MTEC discs and they want me to measure run out with cold and then hot discs (that'll be a nice job :cry: ).

For the agro I think I might as well just stick some new discs on and get on with my life. I really can't see that the problem could be anything else.
 
"I have emailed MTEC discs and they want me to measure run out with cold and then hot discs (that'll be a nice job :cry: ).

For the agro I think I might as well just stick some new discs on and get on with my life. I really can't see that the problem could be anything else"

I know a lot of people on here swear by MTEC discs but I have had 2 sets warp (grooved, not drilled) on my Z4 and a set on my bike-engined kit car also. The first set on my Z4 I had skimmed on the car and they warped again ! Thought it was maybe me not prepping the hub face well enough etc whilst fitting so like an idiot I ordered another set. The hub face was scrupulously cleaned and lightly coated in Copaslip and the runout was well within tolerances along with new pads fitted all round....they warped too !
Lesson learnt I fitted Brembo discs & pads in exactly the same manner and they have been perfect :thumbsup:
 
Are MTEC disks the common denominator on all your cars with this problem?

I've not suffered with warped discs...ever...but I've only ever used OE or better-than-OE discs & pads (Pagid/ATE/AP/Alcon).
 
Actually this is the first time I've ventured from OE (based on good reviews on here).
 
I guess it's all about eliminating the possibles. This article mentions everything that has been suggested for hot disc judder, plus a couple I've not heard of before. One being the hub fixing screw being over tightened which interferes with the even expansion of the disc when very hot, or the hub being slightly distorted. MTEC's own 'warping' page goes over the same ground.
https://mycarneedsa.com/blog/causes-of-brake-judder-and-how-to-fix-it
https://www.mtecbrakes.com/brake_disc_fitting_bedding_in

Let us know how you get on with the fix, there is nothing more annoying than an intermittent fault! :thumbsup:
 
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