Does anyone know...

[bfi2906]

My car's telling me I'm coming up for new front brake pads - This is via the warning when I start the car. The number of K's until it's due keeps dropping - as you'd expect, but not in line with the number of K's covered since last stop / start. As an example, if I start the car, it might say it's due in 1,100K's, I drive 50 K's. The next time I start the car, it mighs say it's due in 950K's.

Does anyone know whether this is some computer based arithmetic calculation, or is it based on the actual sensor, and its diminishing distance from the rotor as the pads wear?

Also, when the number gets to zero, will I have metal in metal? Or is that when the sensor will hit the rotor, and thus some distance to go before metal on metal.

I know it's kind of academic, but I like to know how things work.

Cheers.

[kaitan]

This computer tells you based on the condition..so it recalculates like every 50 km or less...but i do know it depends on the driving condition and style....for eg if computer says uve got 1100km before needs to change but then u go and track it for 100km it does not mean that u have 1000km to go. Makes sense? But the computer is telling u on estimation.....when u pass the zero km left u would still have some meat left on the pads...its just telling u that its time to change as the pads have eaten into in the sensor

[510135]

Originally Posted by kaitan

This computer tells you based on the condition..so it recalculates like every 50 km or less...but i do know it depends on the driving condition and style....for eg if computer says uve got 1100km before needs to change but then u go and track it for 100km it does not mean that u have 1000km to go. Makes sense? But the computer is telling u on estimation.....when u pass the zero km left u would still have some meat left on the pads...its just telling u that its time to change as the pads have eaten into in the sensor

+1 My car said it had 6000kms till change on the rears however on inspection the drivers side outside rear pad was wafer thin. We changed the pads and the sensor was reading from the inner driver side (which was meatier) hence why I changed them early.

[Stuart@BMRAutowerkes]

Computer based calculation based pretty much on fuel economy... heavy fuel economy = heavy braking = lower distance to replace.

Best to inspect the pads and go via that.

[bsm135]

Agreed. Best to check the pads and go from there.

Mine said -1100 for front brake pads by the time I replaced mine. There was still a few mm across the whole pad before it would have got critical...

[bfi2906]

Thanks guys - appreciate the insights

[BBK]

Depends how you drive... I did about 10,000kms past the indicator with no problems :-)

[bfi2906]

Originally Posted by BBK

Depends how you drive... I did about 10,000kms past the indicator with no problems :-)

That's interesting - Did you get any additional indication as to how you were going during that period past the "computer" indicator? I'm thinking something like the light scraping sound you get when the sensor is actually touching the rotor.

It does beg the question - what's the point of an indicator that "goes off" so early. I guess they have to be conservative, while catering for every driving "style". But for the 90% of "normal" drivers, it kind of dilutes the value of having an "indicator" at all.

[BBK]

Originally Posted by bfi2906

That's interesting - Did you get any additional indication as to how you were going during that period past the "computer" indicator? I'm thinking something like the light scraping sound you get when the sensor is actually touching the rotor.

It does beg the question - what's the point of an indicator that "goes off" so early. I guess they have to be conservative, while catering for every driving "style". But for the 90% of "normal" drivers, it kind of dilutes the value of having an "indicator" at all.

No got no indication other than it telling me to change them. I just knew they were ok by the feel of them. Was waiting for the scraping sound but it never ended up coming, so changed them anyway.

I would say it's extremely conservative more so to do with customers having to have to buy them more regularly thus more profits.

[Moocow]

mine are getting very squeeky!
no grinding thou.

car's done 55K Km's. I've owned it for 15K. Would it need rotors soon, or just pads? (never been tracked).

what the best go for replacing the pads? I don't need blistering performance, as I don't track the car. Something with less brake dust would be nice!

cheers

[bfi2906]

Originally Posted by BBK

I would say it's extremely conservative more so to do with customers having to have to buy them more regularly thus more profits.

Ohhhh! The cynicism ..... I'm sure money has nothing to do with this being the shortest life brakepads I've had in over 15 years, and 4 BMW's.

I'm sure it's all for my own good, and in the name of safety