Are my E46 brakes getting wet and losing bite??
Discussion
Hi all,
I'd appreciate a bit of knowledgeable advice from any tecchies on here.
Car is a 55/05 330Cd M Sport coupe with 80,000 miles, and new pads.
With the recent bad weather I have been doing a lot of wet motorway miles, and occasionally when I brake, there is a horrible feeling of "nothing" for a second or two, closely followed by a slight pull to the left or right, before bite is restored as normal. I am concerned that If had to do any emergency stop on a wet motorway, the car might lurch sideways or spin out completely.
My gut reaction is that the discs are getting wet, and it takes a moment for the pads to clear the discs of water, which accounts for the lack of initial bite. My concern is that I have been driving my wife's 05/05 325Ci M Sport Coupe with 50k for the last 7 years, and never, ever experienced this issue. Apart from the engine and a few other options, the cars are near enough identical.
So, with me having the diagnostic ability of a comatose baboon, what is going on please??
Cheers,
Effortless.
I'd appreciate a bit of knowledgeable advice from any tecchies on here.
Car is a 55/05 330Cd M Sport coupe with 80,000 miles, and new pads.
With the recent bad weather I have been doing a lot of wet motorway miles, and occasionally when I brake, there is a horrible feeling of "nothing" for a second or two, closely followed by a slight pull to the left or right, before bite is restored as normal. I am concerned that If had to do any emergency stop on a wet motorway, the car might lurch sideways or spin out completely.
My gut reaction is that the discs are getting wet, and it takes a moment for the pads to clear the discs of water, which accounts for the lack of initial bite. My concern is that I have been driving my wife's 05/05 325Ci M Sport Coupe with 50k for the last 7 years, and never, ever experienced this issue. Apart from the engine and a few other options, the cars are near enough identical.
So, with me having the diagnostic ability of a comatose baboon, what is going on please??
Cheers,
Effortless.
Are the wheels original? Very open design? I had the same problems during winter months on my previous E39 M5 that had a very open wheel design (style 66) which I assume would expose the discs to a lot of spray, so you would get this lack of bite for the first half second.
More modern cars have a "drying" function where they apply a bit of brake occasionally to dry the discs. But I think the wheel design is the major factor, as only the M5 gave me the problem.
More modern cars have a "drying" function where they apply a bit of brake occasionally to dry the discs. But I think the wheel design is the major factor, as only the M5 gave me the problem.
It's because of the brake ducts in the front bumper, very common E46 problem. They engineered the ducts in to keep brakes cool, which works to a certain extent. When it rains however, and you've been on the motorway without using the brakes for a while, they get soaked in spray, and hence when you first come to brake don't work.
The only solution is what I've come accustomed to do from force of habit, dab the brakes a little before you've got a big braking area coming up, junctions etc.
Bryan.
The only solution is what I've come accustomed to do from force of habit, dab the brakes a little before you've got a big braking area coming up, junctions etc.
Bryan.
_bryan_ said:
It's because of the brake ducts in the front bumper, very common E46 problem. They engineered the ducts in to keep brakes cool, which works to a certain extent. When it rains however, and you've been on the motorway without using the brakes for a while, they get soaked in spray, and hence when you first come to brake don't work.
The only solution is what I've come accustomed to do from force of habit, dab the brakes a little before you've got a big braking area coming up, junctions etc.
Bryan.
Thanks also.The only solution is what I've come accustomed to do from force of habit, dab the brakes a little before you've got a big braking area coming up, junctions etc.
Bryan.
I very rarely experience the same issue and ive now realised its when im driving in the rain.
I usually get it when im cruise controlling and some berk in a truck pulls out into my lane
kev b said:
Perhaps your wifes car had slightly stuck caliper pistons meaning the pads were dragging slightly thus clearing water from the discs.
Possibly, but remember we've had my wife's 325 since new, and it has never, ever had this problem. I've also driven it A LOT, and was the main driver of it for many years.Cheers,
Effortless.
Effortless said:
Possibly, but remember we've had my wife's 325 since new, and it has never, ever had this problem. I've also driven it A LOT, and was the main driver of it for many years.
Cheers,
Effortless.
How does it behave in the dry?Cheers,
Effortless.
If its still got a bit of a numb feeling and pulls to one side I'd get it checked out.
Effortless said:
kev b said:
Perhaps your wifes car had slightly stuck caliper pistons meaning the pads were dragging slightly thus clearing water from the discs.
Possibly, but remember we've had my wife's 325 since new, and it has never, ever had this problem. I've also driven it A LOT, and was the main driver of it for many years.Cheers,
Effortless.
Common issue with E45 Sport variants, not much you can do about it, other than brake ocasionally to dry em off a bit. Tends to be an issue in that sort of light rain / low level spray conditions, rather than in heavy rain or standing water.
E90's onwards have "autodry" strategy in the ABS ecu so don't suffer from the same problems
E90's onwards have "autodry" strategy in the ABS ecu so don't suffer from the same problems
Max_Torque said:
E90's onwards have "autodry" strategy in the ABS ecu so don't suffer from the same problems
Which, along with all the traction control driver aids that also operate by using the brake discs, causes a lot of owners to complain that their brake pads and discs don't last like they used to! (Some owners have even gone back to BMW Dealerships claiming the car to be faulty due to excessive brake wear!)
I have to say that I've noticed on My E36 328i Sport after long periods of motorway driving when the brakes haven't been used (and not just in the wet), when you come off at a slip road and come up to the junction, the cold brakes don't feel like they want to stop you as quickly as they usually do (in fact they feel like they're barely working! - giving the impression that something might not be right!).
Then, after a couple of applications all is well again and they feel great!
I just got used to it and a bit brake sooner after a Motorway run than I would normally.
4rephill said:
Max_Torque said:
E90's onwards have "autodry" strategy in the ABS ecu so don't suffer from the same problems
Which, along with all the traction control driver aids that also operate by using the brake discs, causes a lot of owners to complain that their brake pads and discs don't last like they used to! (Some owners have even gone back to BMW Dealerships claiming the car to be faulty due to excessive brake wear!)
Max_Torque said:
The reason modern cars are wearing out their pads and disc faster than before has nothing to do with DSC / ABS! It's because modern cars are heavier than ever before, and also faster than ever before, and finally, easier to drive than ever before. Most drivers simple arrive at a junction, press the very light brake pedal and a one and a half tonne car stops from say 60mph in a very short distance with no drama. Add in people who "accelerate and then brake" repeatidly even when driving in a straight line (like on the motorway!) and thats your problem. Autodry causes no measurable pad/disc wear, and if you are relying on DSC heavily enough to be experiencing any significant wear on a road car, well, lets just say you're either gonna be dead or in prison pretty soon anyway......... (we do a lot of chassis dynamics tests, and the biggest limitation is simply keeping the test car in tyres. I have wrecked a grands worth of tyres in under and hr doing DSC work etc)
Whilst modern cars have become heavier, the size of the discs and pads have grown in proportion to compensate:BMW E36 (328i) = @1400Kg Brake size F: 286x22mm(vented) R:276x19mm(vented)
BMW E46 (330i) = @1490Kg Brake size F: 325x25mm(vented) R:320x22mm(vented)
BMW E92 (335i) = @1600Kg Brake size F: 348x30mm(vented) R:336x22mm(vented)
(and yes, the real limiting factor in overall vehicle braking performance is tyre grip rather than actual brake disc size).
Brake discs have become softer and brake pads have become more aggressive to compensate for material changes forced upon the manufacturers to maintain similar braking ability, which causes higher brake wear, that's just a fact of life these days.
Added to to this material change, with more systems now operating the discs for various applications, and regardless how how gently they operate, they will still increase the disc/pad wear, that's just another fact of life, brakes wear to one degree or another, whenever they operate.
I had this conversation with one of BMW's technicians because I was curious about someone complaining about requiring their rear brake discs replacing so soon, and it was his opinion that part of the problem was the materials used and another was the cars reliance on using the brakes for so many systems these days. He said that he's noticed rear pads wearing out on the newer cars a lot sooner than they used to and believed the brake applications were to blame to a degree.
The front pads have been wearing out faster for quite a few years now, due to the materials, but suddenly he'd noticed a lot more rear brake wear.
As I see it, it's a combination of the vehicle weight, the brake materials and and the systems operating on the brakes all causing their own amount of wear.
(Oh!, and as for Myself ending up dead or in prison any time soon due to relying on the DSC systems too heavily, I highly doubt it!, I've only got ASC+T! - The brakes seem to last well though!
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