[fl1by]

Originally Posted by Ximian

Take that wheel off and look around the brake caliper and the brake lines. I've only seen it as clear fluid, but could even be a leaking strut. For a leaking caliper, that fluid would end up on the wheel.

If there is no evidence of a leak, it's not brake fluid. The routing of the har brake lines and that they're metal makes it unlikely that it's a leak from them without some sort of damage.

If you want to test it for a leak, park the car, leave the engine on and idling, then repeatedly press down hard on the brake pedal and hold it each time for several seconds. After several minutes of that, the pressure on the brake fluid would let it find any small holes to leak out of and you should see brake fluid on the wheel(s) or ground if there is a place to leak. Look under the car first for fluid before moving it so you can exactly figure out what part of the car the fluid is over.

If it is near the wheel or caliper then fluid would be collecting on the barrel od the wheel / rim...?

[Ximian]

Originally Posted by fl1by

If it is near the wheel or caliper then fluid would be collecting on the barrel od the wheel / rim...?

Any leaks from the caliper bleeder valves and the brake line connection would end up on the inside of the wheel. If enough leaked that it would end up on the floor. The brake fluid would have also left quite a stain on the wheel mixed with brake dust so it would be easily visible.

I had a rear caliper seal fail and I found it by the brake fluid that leaked off the wheel and onto the floor.

[mihaiilea]

Misha had a similar problem on the ring with a bmw m4. So it is very clear something is going on when the car is on a late brake going downhill…

[bresty]

Originally Posted by mihaiilea

Misha had a similar problem on the ring with a bmw m4. So it is very clear something is going on when the car is on a late brake going downhill…

Hey mihaiilea! Have you figured out what happened in your accident?

Unfortunately I think I had experienced the same issue as you did, while braking on dry straight road downhill the car suddenly didn't brake as expected and I hit a guardrail. This was on a public road, not a race track! Super scary situation. Car is working fine and suddenly no matter how hard I pressed the brake pedal the car was just not slowing down as hard as it should.

And what makes the matter even worse is that this is not the first time it happened to me, already had similar encounter in Oct last year when this exact thing happened but at that time I had the car only for few weeks and I thought maybe I did something wrong and at that time I've managed to miss guardrail by half a meter so pretty shaken up I've slowed down and given up on the drive. Well I wasn't so lucky the second time.

Can share more details from the accident, just curious if your investigation lead to anything constructive.

[SwankPeRFection]

If you guys are truly experiencing issues like this, you need to report them to BMW corporate and to NHTSA so they can investigate. It very well could be due to the electronic booster this cars runs for the brakes since it’s not vacuum driven anymore, I don’t believe. Between that and the computer controller brake pedal feel, something could be off, but only in certain conditions, which may not have been duplicated until rear world occurrences happened.

[dport]

You have one these so there should be no questions.
Page 16 in the manual.


Event Data Recorder (EDR)

This vehicle is equipped with an event data recorder (EDR). The main purpose of an EDR is to record, in certain crash or near crash-like situations such as an air bag deployment or hitting a road obstacle, data that will assist in understanding how a vehicle’s systems performed. The EDR is designed to record data related to the driving dynamics and safety systems for a short time: max. 30 seconds, typically less.

The EDR in this vehicle is designed to record
the following data, for example:

▷ How various systems in the vehicle were
operating.

▷ Whether or not the driver and passenger
seat belts were fastened.

▷ How far, if at all, the driver was depressing
the accelerator and/or brake pedal.

▷ How fast the vehicle was traveling.

This data can help provide a better understanding of the circumstances in which crashes and injuries occur.
EDR data is recorded by the vehicle only if a nontrivial crash situation occurs; no data is recorded by the EDR under normal driving conditions and no personal data, for instance name, gender, age, and crash location, are recorded.
However, other parties such as law enforcement could combine the EDR data with the type of personally identifying data routinely acquired during a crash investigation.

To read data recorded by an EDR, special equipment is required, and access to the vehicle or the EDR is needed. In addition to the vehicle manufacturer, other parties such as law enforcement that have the special equipment
can read the information if they have access to the vehicle or the EDR.

[bresty]

Originally Posted by SwankPeRFection

If you guys are truly experiencing issues like this, you need to report them to BMW corporate and to NHTSA so they can investigate. It very well could be due to the electronic booster this cars runs for the brakes since it’s not vacuum driven anymore, I don’t believe. Between that and the computer controller brake pedal feel, something could be off, but only in certain conditions, which may not have been duplicated until rear world occurrences happened.

I'm planning to go to importer this week and potentially talking with Münich even as I have some connections there. I need to know what happened as in my case it was public road, I wasn't doing any crazy speed and was braking for like 6-7 seconds, way before the curve and the car just wasn't slowing down. I even have the recording from the car cameras (driver recorder).

There's seems to be several things ongoing regarding the brake issue including the recalls but my VIN wasn't included in that one. Anyway what happened to mihaiilea seems very similar to what happened to me (minus the fluid leak) so I was just wondering if there are any more information that could help me so I revived the thread.

I'll keep you guys posted as my case progresses...

[Needsdecaf]

Originally Posted by SwankPeRFection

If you guys are truly experiencing issues like this, you need to report them to BMW corporate and to NHTSA so they can investigate. It very well could be due to the electronic booster this cars runs for the brakes since it’s not vacuum driven anymore, I don’t believe. Between that and the computer controller brake pedal feel, something could be off, but only in certain conditions, which may not have been duplicated until rear world occurrences happened.

The car uses a fully electronic brake by wire system. The stability control system is built into the unit which is on the master cylinder.

I forget the name of the unit, will post tomorrow. I have the PDF of it saved on my work computer.

[BMWRacer523]

My only comment here is that if you noticed a fluid leak under the car prior to your track event, you should not have taken it on track without a thorough inspection and making sure that was not a leak of any consequence. I understand you took it to the dealer but that is not a thorough inspection in my experience. Dealerships do not do track inspections. This could possibly have been a component failure but most manufacturers have language denying liability for component failures on tracks.

[mdoneinvt]

Originally Posted by bresty

Hey mihaiilea! Have you figured out what happened in your accident?

Unfortunately I think I had experienced the same issue as you did, while braking on dry straight road downhill the car suddenly didn't brake as expected and I hit a guardrail. This was on a public road, not a race track! Super scary situation. Car is working fine and suddenly no matter how hard I pressed the brake pedal the car was just not slowing down as hard as it should.

And what makes the matter even worse is that this is not the first time it happened to me, already had similar encounter in Oct last year when this exact thing happened but at that time I had the car only for few weeks and I thought maybe I did something wrong and at that time I've managed to miss guardrail by half a meter so pretty shaken up I've slowed down and given up on the drive. Well I wasn't so lucky the second time.

Can share more details from the accident, just curious if your investigation lead to anything constructive.

I hope everyone is ok first and foremost and so sorry this happened. I am curious to see what you find out happened as I am still awaiting my 2025 M4 and want to know what the issue is in case it is still ongoing.

[troska]

Originally Posted by bresty

I'm planning to go to importer this week and potentially talking with Münich even as I have some connections there. I need to know what happened as in my case it was public road, I wasn't doing any crazy speed and was braking for like 6-7 seconds, way before the curve and the car just wasn't slowing down. I even have the recording from the car cameras (driver recorder).

There's seems to be several things ongoing regarding the brake issue including the recalls but my VIN wasn't included in that one. Anyway what happened to mihaiilea seems very similar to what happened to me (minus the fluid leak) so I was just wondering if there are any more information that could help me so I revived the thread.

I'll keep you guys posted as my case progresses...

The safety issue of brake-by-wire has been widely discussed in China these days.Because a brand new Chinese electric car suddenly lost braking power on the track and ran off the track.
We are eager to know what safety measures the brake-by-wire system on the G82 will take when the brakes overheat and are unable to provide sufficient braking force.Will the vehicle have any warning messages? Or will it lower the strategy? Does the vehicle have reliable sensors? You shouldn't get any information from the brake feel, right?

[mihaiilea]

Hello, i don’t have an answer with what is going on. The Bmw told me if i want more answers i have to sue them. It is not very nice how they handle the sutuation. I know the car was not overheated, the accident had 11.5 g, the brake pedal was pressed with 95-98% force. For me it look like an software error more than a mechanical one. I will repair the car in 2 weeks and i will go on motorway with ista + to make some braking test. Maybe i can see something there. It is a very complicated situation. In Romania nobody cares about these kind of situation and the dealers don’t have the tools to make an investigation. The factory i am sure they have an answer but that answer is not helping them so they don’t have a reason to tell me because they would help me.

[mihaiilea]

[QUOTE=BMWRacer523;31255523]The car had a leak 1 month prior, the car was going fine on street at very high speeds. The dealership was telling me the car dosen’t have any problem. So i take the car to the track. Also i had 3 perfect laps, one of them is the best lap for the Bmw M3 on that track.

The accident was happening after 30 minutes staying in the pit lanes, right after thw warm up lap!
So i don’t feel i have any fault. I did my best, and all my cars are in perfect shape. Just because a car has a hidden problem it dosen’t mean it is your fault.

[/ / / M3]

Originally Posted by mihaiilea

For me it look like an software error more than a mechanical one.

That seems unlikely. Brake-by-wire systems have built-in redundancies to ensure that the brakes remain functional in case of electronic failure. There is still a mechanical connection between the pedal and the brakes.

[mihaiilea]

It happen to 4-5 cases that i know until now, it will apear more cases in time. The problem is there, just it is very hard to find because it is intermitent. Also could be the abs setup going to ice mode.The car dosen’t see their is a problem because it is a bug somewhere( the car is braking at 60% procent) I would not be very relief to drive a bmw m3/m4. It could happen at any time to any driver. Just because it dosen’t happen until now to some of the owners i won’t be very sure it could not appear in the future. Also 95% don’t use the car at maximum so the probability is smaller to appear for them. Something is wrong there when the car is in some given situation. Also brake by wire is very stupid and it dosen’t have any +. Any sport car should have a normal braking system. It is much more confident inspering and it has feeling. M3 braking has 0 feeling, the steering has 0 feeling also. Just because we have the car it dosn’t mean it is perfect. Also it will be more constructive to find the problem not to say is nothing. Nothing is perfect and all products can be improved.

[NYG]

This is making me concerned about my incoming car that I plan to track.

[SwankPeRFection]

Originally Posted by mihaiilea

It happen to 4-5 cases that i know until now, it will apear more cases in time. The problem is there, just it is very hard to find because it is intermitent. Also could be the abs setup going to ice mode.The car dosen’t see their is a problem because it is a bug somewhere( the car is braking at 60% procent) I would not be very relief to drive a bmw m3/m4. It could happen at any time to any driver. Just because it dosen’t happen until now to some of the owners i won’t be very sure it could not appear in the future. Also 95% don’t use the car at maximum so the probability is smaller to appear for them. Something is wrong there when the car is in some given situation. Also brake by wire is very stupid and it dosen’t have any +. Any sport car should have a normal braking system. It is much more confident inspering and it has feeling. M3 braking has 0 feeling, the steering has 0 feeling also. Just because we have the car it dosn’t mean it is perfect. Also it will be more constructive to find the problem not to say is nothing. Nothing is perfect and all products can be improved.

I mean if you’re unloading the suspension or the sensors see a condition where if allowing more brake force, it could cause an instability condition, it could keep the brakes from applying too much force. Not a good thing, but who knows… I’d have to experience it to know what else could be going on to say what’s up.

[bresty]

Hi guys, small update from me.

- I'll be having meeting with importer (BMW Slovakia) on Monday morning and reporting the issue, and requesting investigation for the sake of all customers - will raise the issues mentioned in this thread as well
- Today I've visited BMW service where the car is located, insurance fix is approved but I requested diagnostics for the brakes failure prior to any work under insurance being done. They'll do the checks and let me know...
- Also I've used some 3rd party OBD diagnostics tool on my own and pulled data from car, no apparent brake related issues were seen, all the errors car reported were due to the impact - temperature and parking sensors not working, hood opened etc. So basically car is not reporting any issues related to the cause of the incidents, just the aftermath of me hitting the guardrail.

More details about my accidents:
- M4 Comp xDr produced in nov 2021, CCB, everything in sport+, ESP and all assistance systems were ON
- happened here: https://maps.app.goo.gl/d82bVDWcUQ3FaDCeA?g_st=iw
- prior to that I drove the car around 40 min up and down the village to get fuel
- drive was around half an hour
- no prior brake fade or any issues during that day
- dry surface, around 12 degrees temp
- I overtook car on the straight part, got back to my lane and pressed brake, kept braking for 6-7 seconds, car was not slowing down as usual and I've hit guardrail at the end of the staight
- it wasn't any dramatic situation, wasn't going crazy fast, started braking long before the curve
- no braking marks on the road, no hazard lights activated during emergency braking when I pressed the pedal with full force, I haven't felt any ABS working
- based on the google maps I was braking for around 120m



Will keep you posted about any updates

[SwankPeRFection]

Did you try getting off the brake and back on it or did you just press once and kept pressing harder and harder and nothing? Do you remember pumping the brakes to try and get a response from them?

There is a recall that was done a while back affecting some 2021 cars where basically the brake booster would fail due to a software condition and it would leave you with no brake assistance during braking, so you would essentially be on your own to apply the needed hydraulic pressure to clamp down. If you’re not strong enough to do that, then you could have an issue and it could still happen regardless of strength if you’re not expecting it.

Sounds like this could be a continuation of that same issue or something else along those same lines which happens in rare instances.

[bresty]

Originally Posted by SwankPeRFection

Did you try getting off the brake and back on it or did you just press once and kept pressing harder and harder and nothing? Do you remember pumping the brakes to try and get a response from them?

There is a recall that was done a while back affecting some 2021 cars where basically the brake booster would fail due to a software condition and it would leave you with no brake assistance during braking, so you would essentially be on your own to apply the needed hydraulic pressure to clamp down. If you’re not strong enough to do that, then you could have an issue and it could still happen regardless of strength if you’re not expecting it.

Sounds like this could be a continuation of that same issue or something else along those same lines which happens in rare instances.

Unfortunately I didn't pump the brakes, I have never been in such situation and never even heard about such procedure before the accident so it didn't come to my mind. Also I'm not sure if it would help in this case of brake-by-wire system.

What I did is as you wrote, I kept pressing the brake harder and harder till I was pressing the pedal with full force and just saw I'm still moving too fast and there is no chance to avoid the guardrail which was pretty terrifying. Obviously after the incident it came to my mind I could have downshifted manually and brake by engine or even pull the e-handbrake, but that's not really something you come up with in the heat of the moment if you are not prepared for it or haven't experienced it before

I've heard of the recall for the brake booster, I have asked in BMW service about it but when they checked my VIN wasn't recognised for that recall. Anyway they said it still doesn't mean it couldn't be this issue even when I'm not eligible for the recall.

So based on the info in this thread and elsewhere I would say in my case it was either the brake booster or the ABS "ice mode", because I have somewhat slowed down but not with the usual brake performance which resulted in the accident.

Thankfully no one was injured and the car is mostly harmed on bumpers, fenders etc so it's mostly cosmetic damage (plus broken headlight and 2 rims) so it could be repaired. What is pending question is the front suspension, they haven't checked yet if it's ok or would need to be replaced. Anyway what is critical for me is to figure out what exactly happened, hopefully with the EDR data, to confirm my impressions of the speed, brake distance etc. and potentially discover and help solve this issue for other drivers so there is at least something positive coming out of this negative experience. On the other hand if they will say there was nothing wrong I will get rid of the card and potentially purse legal action as this is very serious issue which could have deadly consequences and I would not be risking it by driving the car anymore.

[bresty]

Quick update again, I spoke with BMW Slovakia yesterday and I reported the issue, basically they told me the BMW service where the car is located need to make initial investigation for any issue, then they can open tech support ticket and request help from Munich directly. So I guess I have to just wait now and see where it goes.

In the meantime I'm looking for 3rd party EDR data retrieval to confirm my suspicion and course of events. I didn't get clear answer if the BMW service can do this or it would have the be someone from Munich...

Will keep you posted once there is any progress...

[Ximian]

Originally Posted by bresty

Quick update again, I spoke with BMW Slovakia yesterday and I reported the issue, basically they told me the BMW service where the car is located need to make initial investigation for any issue, then they can open tech support ticket and request help from Munich directly. So I guess I have to just wait now and see where it goes.

In the meantime I'm looking for 3rd party EDR data retrieval to confirm my suspicion and course of events. I didn't get clear answer if the BMW service can do this or it would have the be someone from Munich...

Will keep you posted once there is any progress...

https://boschcdrtool.com/

Ask around to see if someone already has this tool.