E brake after brake change
- Thread starter Pondy
- Start date
At the summit of the picturesque fens
I think my problem is that I am a Mechanical Engineer, not an Electronics Engineer.
The electronics still have to convert all that sh*t into a mechanical action. I didn't understand any of the attached cr*p, sorry (and got bored reading it).
A lot of the stuff in Rob's (attached info sheet) post has to be bullsh*t. There are no temperature sensors on the discs, pads or pistons. It HAS to be down to current switches. IE the Ebrake checks after a given period (easily done thru Etimers) and puts a squirt of juice to the motors. If the current switch is made, nothing happens. If not it turns the motor until the switch does make.
I may be wrong, of course. It has happened before (Once)!
The electronics still have to convert all that sh*t into a mechanical action. I didn't understand any of the attached cr*p, sorry (and got bored reading it).
A lot of the stuff in Rob's (attached info sheet) post has to be bullsh*t. There are no temperature sensors on the discs, pads or pistons. It HAS to be down to current switches. IE the Ebrake checks after a given period (easily done thru Etimers) and puts a squirt of juice to the motors. If the current switch is made, nothing happens. If not it turns the motor until the switch does make.
I may be wrong, of course. It has happened before (Once)!
I've thought about this some more! 
When the ebrake motors release it doesn't pull the pistons back (I know this from winding the actuator by hand; the pistons didn't move, I had to physically compress them), it only releases the pressure or EMF which I presume is Electro-Mechanical (or Motive) Force, which will make them retract a tiny amount to free them from the disc otherwise they would bind.
I have noticed that after about ten minutes of the car sitting idle, the red LED goes out on the ebrake; this is allied to all sorts of other "noises", I presume these are cancelling "primed" circuits for driving, maybe fuel pump release and also a "test" of the ebrake. This would make sense to my simple brain.
When the ebrake motors release it doesn't pull the pistons back (I know this from winding the actuator by hand; the pistons didn't move, I had to physically compress them), it only releases the pressure or EMF which I presume is Electro-Mechanical (or Motive) Force, which will make them retract a tiny amount to free them from the disc otherwise they would bind.
I have noticed that after about ten minutes of the car sitting idle, the red LED goes out on the ebrake; this is allied to all sorts of other "noises", I presume these are cancelling "primed" circuits for driving, maybe fuel pump release and also a "test" of the ebrake. This would make sense to my simple brain.
Pondrew said:I think my problem is that I am a Mechanical Engineer, not an Electronics Engineer.
The electronics still have to convert all that sh*t into a mechanical action. I didn't understand any of the attached cr*p, sorry (and got bored reading it).
A lot of the stuff in Rob's (attached info sheet) post has to be bullsh*t. There are no temperature sensors on the discs, pads or pistons. It HAS to be down to current switches. IE the Ebrake checks after a given period (easily done thru Etimers) and puts a squirt of juice to the motors. If the current switch is made, nothing happens. If not it turns the motor until the switch does make.
I may be wrong, of course. It has happened before (Once)!
It’s official bmw bullsh*t
No temperature sensors, the value is calculated by the dsc unit.Rob
Pondrew said:I've thought about this some more!
When the ebrake motors release it doesn't pull the pistons back (I know this from winding the actuator by hand; the pistons didn't move, I had to physically compress them), it only releases the pressure or EMF which I presume is Electro-Mechanical (or Motive) Force, which will make them retract a tiny amount to free them from the disc otherwise they would bind.
I have noticed that after about ten minutes of the car sitting idle, the red LED goes out on the ebrake; this is allied to all sorts of other "noises", I presume these are cancelling "primed" circuits for driving, maybe fuel pump release and also a "test" of the ebrake. This would make sense to my simple brain.
Yes, I think the e89 takes around 30mins to fully go to sleep.
Rob
Smartbear said:It’s official bmw bullsh*t
Rob
I tried to iterate (maybe unsuccessfully) that I wasn't implying you were talking bullsh8t. Please don't hate me just cos I don't like your weird fence panels
The value cannot be calculated by the dsc unit; it just can't. The electronics are not that clever.
The amount of expansion (and subsequent contraction) of a steel brake disc is TINY; like thousandths of a mm. These cars do not have sensors that could measure those tiny increments. It MUST be done using current switches and timers. I would love to be proved wrong (for the second time)
flybobbie said:
See we are going back to the OBD reader nonsense. Why would an electro-mechanical motor have a counter? They don't. I promise you.
I have done this in real life, the only thing the motors do is wind further on until they are happy there is piston pressure. If they had as you suggest, my car would be in the river by now
Pondrew said:Smartbear said:It’s official bmw bullsh*t
Rob
I tried to iterate (maybe unsuccessfully) that I wasn't implying you were talking bullsh8t. Please don't hate me just cos I don't like your weird fence panels
The value cannot be calculated by the dsc unit; it just can't. The electronics are not that clever.
The amount of expansion (and subsequent contraction) of a steel brake disc is TINY; like thousandths of a mm. These cars do not have sensors that could measure those tiny increments. It MUST be done using current switches and timers. I would love to be proved wrong (for the second time)
I don’t mind if you don’t like my wierd railings, that’s fine :wink:
The dsc is actually cleverer than that as it calculates individual brake disc temperatures & it uses the hottest one to chose the temperature map it references for the re tensioning times.
Rob
Smartbear said:Pondrew said:I've thought about this some more!
When the ebrake motors release it doesn't pull the pistons back (I know this from winding the actuator by hand; the pistons didn't move, I had to physically compress them), it only releases the pressure or EMF which I presume is Electro-Mechanical (or Motive) Force, which will make them retract a tiny amount to free them from the disc otherwise they would bind.
I have noticed that after about ten minutes of the car sitting idle, the red LED goes out on the ebrake; this is allied to all sorts of other "noises", I presume these are cancelling "primed" circuits for driving, maybe fuel pump release and also a "test" of the ebrake. This would make sense to my simple brain.
Yes, I think the e89 takes around 30mins to fully go to sleep.
Rob
I’ve sent you a pm
Rob
