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BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Happened twice now, suddenly braking for traffic lights that are changing to red, and the car just isn't stopping! I brake but it still tries to move, I put the handbrake on and its still trying to move. What is this? It's a BMW 320i, used, 2012 model, its an automatic. I'm worried that I'm going to have an accident or get flashed/recorded and done for going through a red light, even though I don't fully go through it I get into the junction before the car eventually stops. Also worried this could be a very serious and expensive fault. It only seems to happen when braking suddenly. Happened before at a roundabout and I nearly went into the guy in front. Brake pads both front and back are new. I tried replicating this the first time on a side road but couldn't, so I think it literally just is after braking sharply.

As a matter of interest, would I have a leg to stand on if I went through a red light but it wasn't my fault beccause something about the vehicle was defective and it would not physically stop in time?

BMW 320i F30 - Car isn't fully stopping after sharp braking - Adampr

It sounds like your gearbox is not disengaging properly under sudden braking. Maybe the clutch pack? You need to go to either a BMW specialist or an auto gearbox (your gearbox is not unique to BMW) specialist to have it checked out.

No, you wouldn't have a leg to stand on if you knew (which you do) that the car has a dangerous fault. Ideally, you should have the car towed to a garage.

BMW 320i F30 - Car isn't fully stopping after sharp braking - badbusdriver

It sounds like your gearbox is not disengaging properly under sudden braking.

Surely there is more to it than that?. As an auto in drive, at a standstill, lifting your foot off the brake pedal will result in forward motion because the gearbox won't fully disengage (while in drive). But in drive, at idling speed with no pressure on the accelerator pedal, there isn't (or shouldn't) be anywhere near enough "drive" to overcome even a modest amount of pressure on the brake pedal. That would suggest to me either a problem with the brakes (are they working properly otherwise?), or that something within the accelerator "mechanism" is not fully releasing when the foot is lifted off the pedal.

It isn't ideal, but a way to (at least temporarily) drive around it (assuming the brakes themselves are not the problem) is to slip the car into neutral at a standstill. Also, obviously, avoid baking sharply!.

But regardless of what the actual problem is, you shouldn't be driving it until it has been sorted

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

That's not the issue though, it isn't even coming to a stop.

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

I mean I know now but the first time I thought it could be an issue with me just putting the wrong foot on the pedal, as it had never happened before and hadn't happened after, when I tried recreating the issue on a side road.

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

A garage I went to about 7 weeks ago for an unrelated issue. They said there was an error code on the OBD about a transmission module. They didn't know much about it, but said that as I wasn't having issues with the gears, I shouldn't worry about it and it could be an error that hasn't been wiped.

Could a bad transmission module be related to this?

I took it to a garage today so just got to wait.

BMW 320i F30 - Car isn't fully stopping after sharp braking - Adampr

A garage I went to about 7 weeks ago for an unrelated issue. They said there was an error code on the OBD about a transmission module. They didn't know much about it, but said that as I wasn't having issues with the gears, I shouldn't worry about it and it could be an error that hasn't been wiped.

Could a bad transmission module be related to this?

I took it to a garage today so just got to wait.

Yes. Your issue is with the transmission, not the brakes.

BMW 320i F30 - Car isn't fully stopping after sharp braking - mcb100
Could it be anything as simple as catching the edge of the accelerator pedal whilst in a hurry to get off it and onto the brake?
BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
Is this a petrol or diesel engine?
BMW 320i F30 - Car isn't fully stopping after sharp braking - paul 1963

S@d worrying about going through a red light, you should be more worried about killing someone! You really need to stop using it at once, get it recovered to a garage.

BMW 320i F30 - Car isn't fully stopping after sharp braking - Xileno

We've covered the legal aspect in the (now locked) thread in the Legal forum. There's a redirect to this thread. People far more technical than me may have a view regarding what might be wrong with the car but it shouldn't be driven in its current state.

Mod

Edited by Xileno on 06/08/2024 at 09:19

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Petrol

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Definitely not. As even when I applied the handbrake it kept wanting to move

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Garage says there is nothing wrong with the brakes.

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
Very much doubt it’s a gearbox fault. I would consider looking at the brake servo vacuum system. When the fault occurs, does it feel as if the pedal has gone hard?
BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Honestly couldn't say. In those situations , my only focus is to try and stop the car. It's not like it's out of control and won't brake at all and is going fast but it's still a danger.

It does feel like the right half of the brake pedal is significantly firmer than the left, if I put my foot down on the left side its like an emergency stop, the right side is just very gradual.

It's going to a BMW specialist diagnostic centre tommorow.

BMW 320i F30 - Car isn't fully stopping after sharp braking - RT

It does feel like the right half of the brake pedal is significantly firmer than the left, if I put my foot down on the left side its like an emergency stop, the right side is just very gradual.

That's because your left foot isn't accustomed to braking - unless you're saying the brake pedal is loose?

BMW 320i F30 - Car isn't fully stopping after sharp braking - FiestaOwner

Happened twice now, suddenly braking for traffic lights that are changing to red, and the car just isn't stopping! I brake but it still tries to move, I put the handbrake on and its still trying to move. What is this? It's a BMW 320i, used, 2012 model, its an automatic. I'm worried that I'm going to have an accident or get flashed/recorded and done for going through a red light, even though I don't fully go through it I get into the junction before the car eventually stops. Also worried this could be a very serious and expensive fault. It only seems to happen when braking suddenly. Happened before at a roundabout and I nearly went into the guy in front. Brake pads both front and back are new. I tried replicating this the first time on a side road but couldn't, so I think it literally just is after braking sharply.

I had a similar issue with a works diesel Peugeot Boxer van in the mid 1990's. Usually the brakes were excellent, but the odd time they were terrible.

I finally figured out that if I was pressing the brake pedal on 3 or 4 occasions when approaching a junction, that would use up all the vacuum, so on the next press nothing happened apart from getting a very firm brake pedal. It wasn't building up vacuum quickly enough, unless you put your foot on the clutch and revved it!

In my case, it was a faulty brake vacuum pump. Garage fitted a new pump and that solved the issue. Once I was able to work out when the brakes were failing, it was easy for the garage to fix it.

So, I wonder if it's a lack of vacuum/ or servo issue.

BMW 320i F30 - Car isn't fully stopping after sharp braking - blindspot

i experience that situation in a bad dream a couple of times, car keeps moving really slow towards the car in fronts bumper wakes me up . b***** awful

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Alright everyone so apparently the brake fluid levels are too high , and of low quality, and the rear left caliper is getting stuck intermittently. This would coincide with the fact the rear brakepads were recently replaced , and the issues only started after that

BMW 320i F30 - Car isn't fully stopping after sharp braking - 72 dudes

Alright everyone so apparently the brake fluid levels are too high , and of low quality, and the rear left caliper is getting stuck intermittently. This would coincide with the fact the rear brakepads were recently replaced , and the issues only started after that

I'm not sure how that would cause the car to keep running forward after you've brought it to a stop though.

BMW 320i F30 - Car isn't fully stopping after sharp braking - galileo

Alright everyone so apparently the brake fluid levels are too high , and of low quality, and the rear left caliper is getting stuck intermittently. This would coincide with the fact the rear brake pads were recently replaced , and the issues only started after that

I don't understand how 'brake fluid levels are too high'. They can't be higher than up to the top of the fluid reservoir, this can't stop the brakes working. If the fluid is low quality, go back to whoever replaced pads and fine out if they added fluid, why and with what.

A stuck rear caliper will not prevent the brakes stopping the car either.

BMW 320i F30 - Car isn't fully stopping after sharp braking - Bromptonaut

A stuck rear caliper will not prevent the brakes stopping the car either.

Had my share of stuck calipers and the consequence is smoke, noise and a ruined disc.

If, when this phenomenon occurs, you knock the gears into neutral is there still a problem?

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

I haven't tried that but its not even stopping, to clarify the car is not just coming to a stop and then still moving, it is not stopping at all. It gets down to like 1-2mph. Would putting it in neutral stop the car then?

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
How do you drive the car , one or two feet ?
BMW 320i F30 - Car isn't fully stopping after sharp braking - mcb100
If it’s only 1.2mph, is this not just transmission creep?
A Grandland I had last year would shut the engine down on the approach to a stop, but if you then applied the parking brake it would fire up again and pull against the parking brake, the car sitting down on its rear springs and wanting to go. If you then put it in neutral, the engine would shut down again. Very odd and less than convenient.
As above, put the selector into neutral and note the results.
BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Yeah so update for you all, took it to a garage today which i trust and have always used quickly identified the fact that the front brakes had copper grease rather than aluminum, meaning when the car brakes get hot, they basically seize up and won't stop, so new brake fluid new front brakes and new front brake discs needed, need to see if the warranty will pay as the car place i bought it from replaced the front brakes so its their fault.

BMW 320i F30 - Car isn't fully stopping after sharp braking - bathtub tom

identified the fact that the front brakes had copper grease rather than aluminum, meaning when the car brakes get hot, they basically seize up and won't stop, so new brake fluid new front brakes and new front brake discs needed

I've used a thin smear of copper grease for years (decades) on my disc sliders and back of pads, without any problems. Do I need to update?

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

The guy at the garage told me that whilst that was accepted in the past, with modern cars its generally not the case

BMW 320i F30 - Car isn't fully stopping after sharp braking - Orb>>

Yeah so update for you all, took it to a garage today which i trust and have always used quickly identified the fact that the front brakes had copper grease rather than aluminum, meaning when the car brakes get hot, they basically seize up and won't stop, so new brake fluid new front brakes and new front brake discs needed, need to see if the warranty will pay as the car place i bought it from replaced the front brakes so its their fault.

Sorry, but you have to get the selling garage to agree first to pay those costs. They might or might not have done the work for you anyway.

You should have got it diagnosed and then asked them before repairing.

BMW 320i F30 - Car isn't fully stopping after sharp braking - RT

Yeah so update for you all, took it to a garage today which i trust and have always used quickly identified the fact that the front brakes had copper grease rather than aluminum, meaning when the car brakes get hot, they basically seize up and won't stop, so new brake fluid new front brakes and new front brake discs needed, need to see if the warranty will pay as the car place i bought it from replaced the front brakes so its their fault.

Sorry, but you have to get the selling garage to agree first to pay those costs. They might or might not have done the work for you anyway.

You should have got it diagnosed and then asked them before repairing.

By using a third party garage for the repair, the OP may well need to use the small claims court against the supplying dealer - not straightforward.

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Under the CRA 2015, the dealer should repair the car because the issue has occured within 6 months of purchase. He is not offering to repair only to supply me the parts.

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

The garage found issues with the front brakepads. Something about using copper rather than aluminium grease, they say the front brakepads, brake discs and brake fluid all need changing

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
Good business for your garage , but not going to fix your problem.
BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

What are you suggesting I do then?

There is obviously something going wrong.

It is not driver error.

It is not a case of transmission roll

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
Are you using both feet to drive ? When the fault occurs, does the brake pedal go hard ?

Edited by elekie&a/c doctor on 09/08/2024 at 20:29

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

I couldn't tell you about using both feet, it's subconscious.

Yes it feels hard, but it's always been stiff. The pedal is stuffed on the right hand side whereas on the left hand side it's much quicker in braking

BMW 320i F30 - Car isn't fully stopping after sharp braking - Adampr

I still don't really understand. Yes, copper grease will be less effective when it heats up, and it can also interfere with things like ABS and stability control, but I think some of us are not getting what happens.

You are saying that the car wants to keep moving. I took that as meaning that it felt like it still had drive i.e. it was pushing forward whilst you were braking. Are you actually saying that it's just that your brakes don't work very well and it's momentum that's pushing you forward?

I don't understand how a brake pedal can have sides. It's a single lever with a pad on it. Are you saying that the braking effectiveness depends on which side of the pad you push on? If so, the most likely explanation is that the apd is loose and needs to be refixed or replaced. Or is the lever itself bent??

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
Sorry , but if you don’t know whether you’re using one or both feet , perhaps you shouldn’t be driving.
BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Alright as I suspected I had misunderstood what the garage told me.

Here is the written diagnosis from them

On inspection the vehicle has been fitted with new front brake pads at some point with an obscene amount of cooper grease on the brake pad sliders.

This has made its way on to the brake discs and contaminated them to the point when warm not being able to brake efficiently.

Copper grease should not be used on modern braking systems as copper and aluminium brake caliper carrier do not mix well and the amount used is here is very excessive.

The vehicle also has a sticking nsr brake caliper which will need to be replaced and the brake fluid in the vehicle is at 5% water content which will also need to be replaced.

So to rectify the vehicle it requires:

New front brake disc and pads

Brake fluid change

Nsr brake caliper

BMW 320i F30 - Car isn't fully stopping after sharp braking - Adampr

I couldn't tell you about using both feet, it's subconscious.

I don't get this either. If it's an auto, your left foot would normally be on a rest to the left of the brake pedal or (if you're me) occasionally tucked under the driver's seat. There is no way that you wouldn't know if you're putting it on a pedal surely?

BMW 320i F30 - Car isn't fully stopping after sharp braking - Oli rag

Something strange going on here. Especially sceptical after mention of using both feet?

BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

No I only use one foot, my right.

BMW 320i F30 - Car isn't fully stopping after sharp braking - Bromptonaut

Like all autos I've ever seen driven, with the possible exception of a 1970 Mini, I'd expect this car to have double width brake pedal. Most of us would use our right foot for normal service braking keeping the left out of the way unless perhaps during particular close quarter manoeuvres.

Using the left foot for normal service braking is controversial and has been discussed here an nauseam.

I don't understand the OP's reference to different forces on different parts of the pedal; can you clarify?

If, when the car is running on and not fully stopping you knock the gears into neutral what happens?

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
Looking at the revised garage report, it would appear that there is now some sense as to what is going on . Excessive copper slip contamination on the brake friction area will certainly be a problem and very likely to be the main issue here .
BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

Could it just be cleaned off or does it need replacing ?

I know I'm entitled to get the dealer to fix it but I don't trust them

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
The discs should clean up no problem, the pads , probably not . Have you actually seen the excess of copper slip or this another workshop upsell ?
BMW 320i F30 - Car isn't fully stopping after sharp braking - crxg

I'm due to see a picture of it , he told me in the diagnostic report it was an "obscene" amount.

BMW 320i F30 - Car isn't fully stopping after sharp braking - mickyh7

You have six pages running on Piston Heads with this issue.

You won't give all the facts, and you won't listen to knowledgeable people.

What's wrong with you?

BMW 320i F30 - Car isn't fully stopping after sharp braking - elekie&a/c doctor
Couldn’t agree more . Time to put this post to bed . I’m gradually coming to the conclusion there’s nothing wrong with this car , and it’s pilot error.

Edited by elekie&a/c doctor on 12/08/2024 at 09:42

BMW 320i F30 - Car isn't fully stopping after sharp braking - 72 dudes
Couldn’t agree more . Time to put this post to bed . I’m gradually coming to the conclusion there’s nothing wrong with this car , and it’s pilot error.

I seem to remember saying exactly this a couple of weeks ago when this was still in the legal section!

Didn't the OP run over the line through a red light?

BMW 320i F30 - Car isn't fully stopping after sharp braking - Adampr

I'm going for one last attempt at sanity.

The front brakes need degreasing. You don't need new parts but your mechanic may be suggesting it would be easier to swap them than degrease them. Whether it would be cheaper is not something they will discuss with you.

If that doesn't fix the problem, the remaining possibility is the brake vacuum pump has an issue. Take it to a BMW specialist to look at that if degreasing doesn't work.

BMW 320i F30 - Car isn't fully stopping after sharp braking - skidpan

The front brakes need degreasing. You don't need new parts but your mechanic may be suggesting it would be easier to swap them than degrease them.

If new discs are fitted they still need degreasing before use.

If the pads are contaminated they need replacing.

For your info, the old trick of poring petrol on pads and lighting it does not work.