[Simon89]

Update 10/09

Car is booked in for an MOT in a couple of weeks. I've made the garage aware of the issue. If all looks well with the MOT then they've agreed to do a test drive to see if they can narrow down any potential issues. Unfortunately they are that busy they don't have time to investigate it prior to the MOT.

Annoyingly with the car being XDrive they can't put it on their brake testing equipment to check if the disks are actually warped.

[Sprucedmoose]

Had my car in the indy today to look at a similar issue. I was certain it was the trail arms. Diagnosed front pads and disks - replaced and seems to have resolved the problem, albeit I haven't driven it far since. Blue M Sport brakes so £££ but would have been similar for trail arms.

OP - hope you get your issue resolved soon too.

[Simon89]

Thanks Sprucedmoose. I’m hoping it isn’t the brakes as I only replaced them 12 months ago. If it turns out they are warped I may look into the warranty with Brembo.

[rosstin]

Hi Simon, how did this pan out? Any closer to finding the problem?

[Simon89]

rosstin The wobble is still there, although it doesn't seem as bad. I'm going to guess it is the front brakes being warped slightly.

I'm beginning to wonder if the 'Brembo' discs from AUTODOC are genuine items?

[rosstin]

Originally Posted by Simon89

rosstin The wobble is still there, although it doesn't seem as bad. I'm going to guess it is the front brakes being warped slightly.

I'm beginning to wonder if the 'Brembo' discs from AUTODOC are genuine items?

Thanks mate. Good luck.. I've got Zimmerman from AUTODOC with the same problem, but it seems to be getting worse recently.

[Simon89]

I'm reluctant to change them, I'm considering changing cars next year and I definitely won't get the money back in replacing them again.

Who'd have thought you could warp 370mm discs by driving gently to work and back

[Eddamoo]

Discs don't usually warp (in the vast majority of cases); typically the pad material transfers to them and makes a hot-spot. This is usually done by keeping the brakes on while stationary after a period of moderate to heavy stopping. Its also one reason why BMW and other performance cars use separate shoes/pads for the handbrake.

It can be particularly bad in an auto as you would naturally keep the brakes on to prevent creep.

Ive managed to clear the shudder by re-bedding the brakes on several cars. A series of heavy stops from 60-20 without stopping the car. I usually do it until i can feel the brakes fading slightly.

[HighlandPete]

Originally Posted by Eddamoo

Discs don't usually warp (in the vast majority of cases); typically the pad material transfers to them and makes a hot-spot. This is usually done by keeping the brakes on while stationary after a period of moderate to heavy stopping. Its also one reason why BMW and other performance cars use separate shoes/pads for the handbrake.

It can be particularly bad in an auto as you would naturally keep the brakes on to prevent creep.

Ive managed to clear the shudder by re-bedding the brakes on several cars. A series of heavy stops from 60-20 without stopping the car. I usually do it until i can feel the brakes fading slightly.

Agree, too many put brake judder down to warping, when we know not many discs actually are warped when measured. Renewing is an easy and immediate fix, but not necessarily the cause. As you say, pad transfer is often the real problem.

Strange as it may sound, a couple of nights rusting (in a humid environment) can, when brakes are worked again, reduce or eliminate judder. The burnishing off of the surface rust 'cleans' the friction surfaces.

New discs often mask suspension wear. Once the brakes get worked a bit, maybe a bit of pad transfer, the wear manifests itself again, as vibration and judder. The E39 was a car which had particular issues. Everything had to be A1 for 'shimmy' not to become manifest.

I do wonder how many discs are replaced due to "they are warped mate" comments, when no one even measures for run-out, to check if there is any warping.

[Simon89]

Originally Posted by Eddamoo

Discs don't usually warp (in the vast majority of cases); typically the pad material transfers to them and makes a hot-spot. This is usually done by keeping the brakes on while stationary after a period of moderate to heavy stopping. Its also one reason why BMW and other performance cars use separate shoes/pads for the handbrake.

It can be particularly bad in an auto as you would naturally keep the brakes on to prevent creep.

Ive managed to clear the shudder by re-bedding the brakes on several cars. A series of heavy stops from 60-20 without stopping the car. I usually do it until i can feel the brakes fading slightly.

I did this and even got to the point where the front brakes were beginning to smoke and it made absolutely no difference.

I have a friend with a dial gauge and I'll investigate one day but I'm just living with it at the moment.

[martin10chk]

Originally Posted by Simon89

I did this and even got to the point where the front brakes were beginning to smoke and it made absolutely no difference.

I have a friend with a dial gauge and I'll investigate one day but I'm just living with it at the moment.

The other potential cause (much more likely than actually ‘warped’ discs) is some contamination on the mating surfaces - hub to disc interface - that wasn’t removed fully when fitting. If the vibration changes as wheel has been removed and refitted I would very much suspect that.

[Simon89]

martin10chk Surely if that was the case it would be almost like having a wheel out of balance as it wouldn't be 'true' in relation to the hub?

[martin10chk]

Originally Posted by Simon89

martin10chk Surely if that was the case it would be almost like having a wheel out of balance as it wouldn't be 'true' in relation to the hub?

Hi Simon89 -- see here

https://pmmonline.co.uk/article/why-clean-hubs-matter/

Dirt on hub causes disc runout - same effect as supposedly 'warped' disc.

[martin10chk]

Originally Posted by martin10chk

Hi Simon89 -- see here

https://pmmonline.co.uk/article/why-clean-hubs-matter/

Dirt on hub causes disc runout - same effect as supposedly 'warped' disc.

Here is a quote from that link "A common misconception is that this vibration is due to the disc being warped from overheating, but this is rarely the case. Almost all cases are caused by improper fitment – in fact, 90% of TAROX warranty claims relate to improperly fitted discs."

[M140_BCS]

I got the hubs looking brand new again with one of these wire brush attachments for the battery drill.

Took no time to take all the rust off.

[scotsman335dxDrive]

Hi Simon89,

Did you get it sorted out ? I have just had the car into BMW with braking vibration/ judder and they replaced the LCAs under warranty as they were leaking oil. They also said that my front discs on the inside were badly corroded, (the rears were not quite so bad )and they needed replacing. I have a full set of Brembo front and rear discs, pads and sensors, so I told them I would do the brakes myself. The vibration is still present but not nearly as bad. I hope doing the brakes cures it.

[Simon89]

scotsman335dxDrive I haven't yet, the judder is still present.

Someone at work said it may be the pistons in the calipers sticking slightly. not quite sure how true this would be.

I checked my LCAs earlier in the year and neither appeared to be leaking. Could you let me know how when yours are replaced if that has helped at all, preferably before replacing your brakes lol

[scotsman335dxDrive]

They were just replaced by BMW under warranty on Wednesday and the vibration / judder is reduced but it is still present to a much lesser degree. Will post when I get the front brakes done.

Edit, After a few miles and days the judder and vibration is back so replacing the worn and leaking LCA`s didn`t make no difference to the situation. As i said in will post back once i do the brakes and discs. I have a full set front and back so will replace all a the same time.

[scotsman335dxDrive]

Did the brakes front and rear done on Tuesday and although I obviously haven't braked in earnest until I get a chance to bed them in properly, they are noticeably vibration free but I did notice when I checked the old discs, the front ones that BMW had said needed replaced, were only showing a narrow band about 3cms wide where the inner pads were contacting. This might indeed be a caliper fault, so I will contact BMW and say that if the vibration does comes back after a few thousand miles I will be expectng them to reopen my warranty case again to check the calipers. Hopefully the really corroded front discs were the problem and all will be fine i hope.

[johnung]

Originally Posted by scotsman335dxDrive

They were just replaced by BMW under warranty on Wednesday and the vibration / judder is reduced but it is still present to a much lesser degree. Will post when I get the front brakes done.

Edit, After a few miles and days the judder and vibration is back so replacing the worn and leaking LCA`s didn`t make no difference to the situation. As i said in will post back once i do the brakes and discs. I have a full set front and back so will replace all a the same time.

So it was your Lower Control Arms (also called Wishbones) that were leaking and replaced? It's more common for the big fluid filled bushings on the Upper Control Arms (Thrust Arms or Tension Struts) to leak and require replacement. See photo for those unfamiliar.

[johnung]

Originally Posted by scotsman335dxDrive

Did the brakes front and rear done on Tuesday and although I obviously haven't braked in earnest until I get a chance to bed them in properly, they are noticeably vibration free but I did notice when I checked the old discs, the front ones that BMW had said needed replaced, were only showing a narrow band about 3cms wide where the inner pads were contacting. This might indeed be a caliper fault, so I will contact BMW and say that if the vibration does comes back after a few thousand miles I will be expectng them to reopen my warranty case again to check the calipers. Hopefully the really corroded front discs were the problem and all will be fine i hope.

Reading through your thread you've received a lot of good advice for things to look for. Thought that I would chime in with a couple.

I've been burned before chasing down suspension/brake symptoms that turned out to be rocks stuck in a tire tread or missing/dropped wheel weights that threw wheels out of balance. My tire retailer has lifetime tire warranty that provides free tire re-balancing at any time which helps to eliminate that when troubleshooting.

Check all of the suspension/brake bolts for torque. I've had something as simple as a loose bolt (that appeared okay until you put a wrench on it) cause vibration at one corner.

I would expect high quality rotors from BMW, StopTech, Zimmermann, Brembo to have great metallurgy that resists rotor warping. I would expect a higher probability of warping from cheap overseas junk with suspect metallurgy like PowerStop, R1 Concepts and others.

Over tightening wheel bolts can cause rotor warping. I trust no one when it comes to this. I carry a 1/2" drive 22" breaker bar, a torque wrench and a 17mm sleeved wheel bolt socket in my trunk. For any service likely to require wheel removal, I remove my wheel locks before I drop it off. And as soon as I pick it up I reinstall wheel locks, and loosen and retorque all wheel bolts. Only takes a few minutes because I carry the tools.

Prevents rotor warping and prevents the surprise of needing to remove a wheel only to learn that the last shop installed the bolts at the highest setting on their air gun! I had that happen. I used a 24" piece of steel pipe that I bought at Lowe's/HomeDepot for maybe $12 to slide over the handle of my breaker bar. The extra long bar creates 200+ foot pounds of torque to remove stubborn over tightened bolts.

When troubleshooting it is really important to try to isolate the corner or axle that a noise or vibration is coming from to be able to focus efforts there. I've gotten three friends to go for a ride to try to figure out where a noise is coming from. People sitting in all four corners are going to hear a noise differently than the driver. You can drive with all windows up, then down, then selectively open one window at a time. It also gives the owner a chance to let someone else drive and then sit in the corner that they begin to suspect.

Beware the shops that try to sell rotors and brake jobs based on their visual analysis of your rotors. My favorite con job is pointing to the natural wear ridge that brake pads make on the outer edge of the rotor claiming that the rotor is shot and needs to be replaced. They do the same if their are a few wear grooves. If a mechanic is any good they will take proper measurements of the rotor. It takes maybe a minute. So when you are told that rotors are shot, ask what they measured. If they can't tell you immediately then suspect a con job or a place that's not really knowledgeable.

BMW's spec is to measure the thickness of the rotor at 8 random locations on the rotor surface that the brake pad sweeps. Then take the smallest thickness number of the eight and compare it to that rotors wear limit. The wear limit on all rotors is stamped/engraved on the rotor.

For BMW F30 that wear amount is 1.6mm which is enough to last roughly 50k-70k miles. The brake pads may wear out in say 30k miles because they are purposely made softer to be sacrificed. F30 rotors are made in a few thicknesses. Fronts can be 30mm or 24mm so wear limits are 28.4mm and 22.4mm respectively. Rear rotors can be either 24mm or 20mm when new so wear limits are 22.4mm and 18.4mm respectively.

I measure my own rotors with a long reach caliper from Harbor Freight which makes it easy. 6" Longreach Digital Caliper, about $28

https://www.harborfreight.com/6-in-l...per-63714.html

Hope this helps!

[scotsman335dxDrive]

Thanks bud, yes you are correct it was the UCA,s that were replaced. When I took off tbe front discs they were corroded badly on the inside the rears were actually not too bad compared to the fronts They were not worn right down just really corroded. Mileage is 55000 miles TRW 370 discs and Brembo pads and sensors on. I know that new discs and pads can sometimes mask suspension wear hence the call to BMW about possible reopening of warranty case in about 2 or 3 thousand miles incase it might be the expensive Blue calipers also new Goodyear winter tyres just fitted at Costco. I also retorque my wheels myself. Will see if I can upload pictures from my phone. Thanks again.