Parking Brake malfunction

[autoque]

I like the electronic parking brake because with a manual parking brake, the brakes' cable seem to stretch and don't become effective anymore after some use.

Autohold to me is useless though. It's grabby when it engages and the passengers feel that. And If I come to a stop really slow, using the least amount of brake power, like in a congested traffic, it sometimes feels like it's half-engaged, meaning the light on the dash says it's engaged and stopped, but the brakes aren't holding the vehicle firmly, making a bit of a noise and the car almost goes forward a tiny bit. So once again if I firmly apply the brakes while it still says engaged and the car stationary, it doesn't seem to do that any more.

[Penguin]

Originally Posted by autoque

with a manual parking brake, the brakes' cable seem to stretch and don't become effective anymore after some use.

True, but I always use my parking brake when parked, and my experience with the cable brakes is that a cable adjustment is only needed every 50,000 miles or so.

Frankly I like manual cable parking brakes because they use to be know as "Emergency brakes," and that's still part of their function. For emergency use, I figure the simplest system tends to be the most reliable, which is what you want in an emergency brake.

While not common by any means, batteries have been know to fail suddenly with an "open" when a cell interconnection fails. I wonder if the X5 brake would work with no power?

[ukwildcat]

Interesting conversation.. Makes me think of a few things.

For one, I LOVE AUTOHOLD. I think the weight of the vehicle almost makes it NECESSARY, as it is very prone to roll (forward or backward). I do not think it would be a terrible BURDEN without it, but I do like having it.

Someone mentioned the space it saves on the center console, too - a very big plus, I think. The ergonomics are all very clean, and there are few "mistakes" on this vehicle, although I notice the Park Assist is not convenient on the X5, but it's right where it should be next to the shifter on the 5 series (oh well).

Mine does grab a bit but not often and not usually too bad, but yeah, sometimes it will jolt. I have noticed lately - probably after having to do a hard stop yesterday - that the brakes themselves will grab like nobody's business, but thankfully of course the vehicle will dive only slightly.

The reasons we could debate until the end of time, but..

I wholly disagree with the notion that "expensive gadgets" serve no real purpose. When I was a kid, I remember that most German cars were "driving machines" but had few (if any) creature comforts. I also remember when those German cars started to acquire gadgets - and all the problems they had - (remember the Audi 5000 automatic?) but they've come a loooooong way since then.

I think some gadgets are next to useless. (I'm just going to cite Audi by reference and leave it at that) I did not order the automatic cruise control, for example, although there are days it seems like it would be quite useful.

But everyone told me the HUD would be useless - and nothing could be further from the truth. It is undoubtedly the single most used feature in my X5, next to Park Assist. To others it's probably a useless gadget - "what kind of driver are you if you need blah blah blah."

It is certainly a different era, and one in which many gadgets play a vital role. Traction control, anyone? Sophisticated computer control of the entire drivetrain for best performance AND efficiency? Just the way it is these days.

Speaking of which.. Just how many computers are in this car?

[Penguin]

Originally Posted by ukwildcat

But everyone told me the HUD would be useless - and nothing could be further from the truth. It is undoubtedly the single most used feature in my X5, next to Park Assist. To others it's probably a useless gadget - "what kind of driver are you if you need blah blah blah."

Just to be clear, I don't mind extra gadgets, such as HUD, increasing the complexity, particularly when it's an option. I do not have HUD for a couple of reasons, but when I test drove an X6 with HUD, I found it to be helpful and I would use it if I had it. If the HUD stops working, it isn't going to affect the ability of the X5 to function as transportation, so that feature is simply one of cost vs. benefit.

But I do have an issue when they make things needlessly complex which are fundamental to the operation of the vehicle and increase the odds of getting stranded for limited, or non-existent gains. Over the past few years I have seen quite a few people who have posted reports that they were either stranded, or at a minimum had to make a dealer visit due to a malfunctioning parking brake on an X5. I don't recall seeing any posts of a person that's been stranded due to a malfunctioning manual/cable brake.

The AUTOHOLD function, if I remember correctly, really has nothing to do with the parking brake (unless you shut off the engine), it simply has been integrated into the button/system, i.e. you could have a manual parking brake and still have autohold. My understanding is that the autohold uses the normal service brakes, and not the parking brake to accomplish its task, i.e., BMW could have gotten the benefits of autohold without making the parking braked needlessly complex and prone to malfunction. If someone knows otherwise, please correct me.

I don't mind additional complexity, and the associated lower reliability, for things like traction control, DSC, etc., but when one talks of systems that can strand you and require a flatbed recovery, I think the benefits need to be significant before adding complexity.

P.S. Here is an example of where I think BMW has taken a step backwards from performance in the name of luxury:

"Fading Assistance - This function assists the driver in applying the braking force when the brake temperature is very high due to an extreme driving profile which requires a higher braking force in order to achieve the required braking effect."

Frankly, if I am using my brakes so hard that they are starting to fade, I would like to know it by noticing increased braking pressure is required. With the X5 automatically compensating for the brake fade so that you don't notice you are overusing the brake, it would seem to me that it would be much easier to get yourself into a bad situation going down a mountain road.

[ukwildcat]

I see what you mean.. It's a "feature" when it works, and a "defect" when it breaks.

Totally agree about the "Fading Assistance" - I did a double-take when I read that 'feature'.

I do not think - at least, I don't WANT to think - that some of these gadgets/features are intended to put you in a place you ought not to be. Rather, many are intended to keep you from doing just that.

Sorry if I can't pull a better example, but it happens I looked very very closely at the redesigned GX460 when it came time to buy (I had a GX470 prior). Remember how quickly it came out from Consumer Reports how its traction control didn't seem to work the way it should (it kicked in later than most did). OK, maybe that IS a safety item..

The demonstration videos were all over the place, and sure, it LOOKED scary. But many others who reviewed the vehicle had no problem with it.. If you were driving like that in the first place, you SHOULD wreck, just to teach you a lesson that the forces of physics are not to be "dissed."

I never READ it, but my thought was "maybe they did that on purpose.. to make sure you KNOW you overdid it before they corrected it for you." Who knows.

From my aviation hobby.. When the Boeing 777 was going through trials, one MAJOR flaw that came out was the "asymmetric thrust" feature. It was intended to make the aircraft easy to handle in the event of an engine failure.

The problem was that it worked SO WELL that pilots could not even tell that they HAD lost an engine.. And they decided that was NOT a good thing, no matter how proud the engineers were that they pulled it off.

Like the old axiom.. "Just because you CAN do a thing, it does not follow that you SHOULD."

[Penguin]

Originally Posted by ukwildcat

Like the old axiom.. "Just because you CAN do a thing, it does not follow that you SHOULD."

BMW sometimes gives in to this temptation, e.g., they put in a system to do something usefull called "X" which, with a little tweak, could do "Y," so they add-in "Y" just because it seems "neat" and is cheap to add.

Case in point? The first gen Z4. It had electric steering assist, so it was easy to change the amount of assistance. As a result, they made the Sport button do three things: (1) make the electronic throttle more sensitive (or touchy, depending upon whether or not you liked it), (2) automatically put the auto transmission into Sport Mode, and (3) reduce the steering assistance boost.

Now, I drove both versions and frankly could never figure out why when you wanted to do some "sporty" driving, you would want the steering wheel to turn harder. It's not like with the design of the EPS you got any more feel or feedback with less boost, and it wasn't a variable boost with speed sensitivity or a variable ratio. No, it just turned harder.

I figure they did it simply because they could do it.

[Penguin]

Originally Posted by ukwildcat

When the Boeing 777 was going through trials, one MAJOR flaw that came out was the "asymmetric thrust" feature. It was intended to make the aircraft easy to handle in the event of an engine failure.

The problem was that it worked SO WELL that pilots could not even tell that they HAD lost an engine.. And they decided that was NOT a good thing, no matter how proud the engineers were that they pulled it off.

I'm not up on Aviation, but many years ago I was the product planning manager for a major aircraft engine manufacturer (which means GE, Pratt, or Rolls). I would have thought that they would have left that "feature" in the system and either made it into a manually activated option, or left it as automatic with an alarm/"pop the priority warning message to the display screen" operation.

[JCL]

Originally Posted by ukwildcat

I wholly disagree with the notion that "expensive gadgets" serve no real purpose.

I used the phrase "expensive gadgets" above, but I was discussing gadgets that didn't in fact serve a real purpose. I am with Penguin, I like DSC and traction control, which cost money, but which serve a purpose. It is those gadgets that bring needless complexity without real benefit that get me. I would put power tailgates in that category. I had one on a rental Navigator. It fit with the Cadillac-ish soft nature of that vehicle. It doesn't fit on a driver's vehicle, IMO. I also had a Z4, with the variable assist steering that Penguin mentioned. When steering was built with variable ratios, the quicker ratios were harder to turn. Making the steering harder to turn, while not changing the ratio, just because you can, is silly. It is like putting a motor in the seatback just to push on you, so it feels like you are accelerating when you aren't. That same Z4 had lots of sound deadening. Someone was worried that they couldn't hear the engine, apparently. So BMW installed a sound-port, essentially a tube running from the engine compartment, to channel engine noise to the driver. They ran it right through the sound-deadening material. I guess it never occured to them to reduce the sound deadening material, thus making the car lighter.

[autoque]

But buyers' of the 7 series or any other high end vehicles think that features like the power tailgates are part of a luxurious experience that comes with purchasing and driving expensive vehicles. These car buyers, and dare I say many of them, are not drivers with particular interest in the Nurburgring lap times. So to them, the latest gadgetries, no matter how unuseful, make quite an impression. I guess soft-close doors is also one of those luxurious features that differentiates high end vehicles from lowly Toyota/Honda. Stepless/stageless doors are quite cool too to those who are unfamiliar. It goes well with bragging rights, self-satisfaction, and sometimes, god forbid, being actually useful.
The latest Audi A8 I read online has a feature that can recognize a hand-writing. To me, that'll be useless. But CEOs looking to make themselves feel more important will appreciate just having such gadget, even if they never intend to use it.

And should anything break, the cost to fix will be less than what they spend weekly with their golf buddies at the country club.

[ukwildcat]

Originally Posted by Penguin

I'm not up on Aviation, but many years ago I was the product planning manager for a major aircraft engine manufacturer (which means GE, Pratt, or Rolls). I would have thought that they would have left that "feature" in the system and either made it into a manually activated option, or left it as automatic with an alarm/"pop the priority warning message to the display screen" operation.

Ah.. Sorry, I didn't complete the "story," sorry..

Oh yes - the feature was left in, but you're right.. It was made MANUAL (have to press the button to turn it on) and they decided they wanted an a chime. If it happens to also catch fire in the process of failing, the regular fire alarm goes off too.

Sounds a little foolish, in a way, but it's the old "let's not panic anyone" thing, when such an event often occurs during the most stressful phases of flight (takeoff and landing).

I like that the BMW chimes for events. I know that whenever I hear that sound, something is amiss. Parking brake on, cold outside, low on fuel, going too fast, etc.

The Lexus wouldn't even chime when the low fuel light came on. You just had to notice it. I never ran out, but there were more than a few times that I easily could have had I not noticed it.