Anyone know how the automatic brake drying function works?

[Darren M]

Hello folks,
Anyone know how the automatic brake drying function works? Any sensors for wet roads/weather?. A while ago had an intermittent fault that's recently got worse having seemingly resolved itself a while ago (fine for 2 months). In the last week the tyre puncture warning has been coming on but when checking the tyres there is no fault. Once reset after 10 miles it came on again.Been fine again for a few days but today the car started feeling a little strange while moving (including some wheel wobble) and the tyre warning sounded again. On closer inspection after stopping, the front passenger side wheel felt rather hot and heard loud clunking for a while from the car which seemed to be related to the brake on that side as it cooled down. Weather has been wet the last few days and might be related, or might simply be a dodgy caliper.
Also today stopped behind a bus and as I pulled away and having not even used the handbrake it sounded/felt like at least one of the brakes was engaged.
Car is going to be left at current location (200 miles from home)for a dealer to collect and investigate but would like to try to understand what might be wrong. Car is due for Inspection 1 in 2000 miles so going to get this done now too. Might be fine again but now don't want to risk it

 

[Wondermike]

It comes from either the rain sensor info or the wipers being switched to high speed, not sure which is correct. You would have an error on the dash if the DSC module was playing up, so maybe a sticking caliper as you say.

 

[Dogmatic6]

Here you go -

What kind electronic stability control is the E85 M Roadster equipped with?
The E85 M Roadster is equipped with Dynamic Stability Control Plus (DSC+), an evolution of the earlier DSC system that retains Dynamic Traction Control (DTC), Dynamic Brake Control (DBC), and cornering stabilization (all of which can be defeated via a dashboard switch), but adds the following permanent features: brake fade compensation (increases booster pressure to adjust for rising brake temperatures), brake standby (readies the brake system for sudden braking when there is sharp lift off the accelerator), brake drying (activates based on data from the rain sensor and monetarily brings the brake pads close to the rotors in order to remove any water) and start-off assistant (applies the brakes for a few moments when the driver first releases the brake pedal in order to prevent roll-back).

 

[goon]

The one I like is the start off assistant feature,at first I thought a calliper was sticking though it only seems to come into effect when the car is facing uphill and not down for some reason.

 

[srhutch]

The one I like is the start off assistant feature,at first I thought a calliper was sticking though it only seems to come into effect when the car is facing uphill and not down for some reason.

No reason to work going down hill, just don't take your foot off the brake. oke:

 

[Skelts]

The one I like is the start off assistant feature,at first I thought a calliper was sticking though it only seems to come into effect when the car is facing uphill and not down for some reason.

Is this standard on all Z4MC's?

 

[Wondermike]

On all post-facelift Z4s I think.

 

[goon]

yes on all2006 on as I actually read the hand book to see for myself.

 

[sixspeed]

Sounds like a sticking caliper to me. I had it on my Z4M as well (and promptly upgraded to APs). It's quite common on the E46/Z4M calipers unfortunately.

Had exactly the same symptoms as you when I suffered with mine. The tyre pressure monitor is a result of the excess heat in one wheel causing the air to expand in the tyre (as it would on track) and increase the pressure, but on one side only.

 

[Darren M]

Thanks for the replies. Dealers have indeed found a sticking caliper. All parts are available in the UK luckily.Caliper and new discs and pads being fitted to be ready for collection on Saturday after the service is also done. Will be good to get back into the Z after driving a 1litre Yaris halfway round the country since Sunday :driving:

 

[mmm-five]

I hope this is under warranty, as I don't think a caliper(s) and disc(s) will be particularly cheap - about £300 & £200 respectively last time I looked.

 

[Darren M]

No warranty here . Car has done 74k miles approx most of which in my hands so I can't really complain. I have my car fund that I pay into (instead of paying for a warranty) and that will have to be eaten into a fair bit. They are doing a discount however. Still happy NOT having a warranty although won't be so far in profit and therefore not quite a smug about what I've saved by not having a warranty

And even with a warranty, would they really have replaced the whole lot for free considering some parts are wear items that have covered 74k miles?

 

[Wondermike]

No I think you'd be lucky to get anything for the discs or pads anyway - maybe a small contribution of sorts, where you pay through the nose then get a bit back, like they're doing you a favour.

 

[Aliv6]

Hummm...Wondering whether mine has a sticking caliper...

My disks are farily old, however just replaced the pads and i get terrible vibrations through the pedal "Occasionally!!" then it settled down?! Weird! It's on the rears and there is very little lip!

 

[mmm-five]

No I think you'd be lucky to get anything for the discs or pads anyway - maybe a small contribution of sorts, where you pay through the nose then get a bit back, like they're doing you a favour.

Depends if the sticking caliper had damaged the disc/pad though - and you wouldn't replace them on only one side.

I had a caliper go on the M5, and they were £800/side - although they were 4-pots - and BMW would only pay for one side while insisting they had to replace both sides (the other side at my cost) for safety reasons.

 

[buzyg]

Had exactly the same symptoms as you when I suffered with mine. The tyre pressure monitor is a result of the excess heat in one wheel causing the air to expand in the tyre (as it would on track) and increase the pressure, but on one side only.

I think it measures the speed of rotation of the wheel, not the tyre pressure directly. A difference in pressure gives a difference in circumference, on the tyre, which creates a difference in the rotation speed.

The brakes holding on for a moment on a hill start can be a pain reversing off my drive.

 

[Mr Fish]

The brakes won't hold on if the clutch is out. Therefore if you roll backwards in neutral with the clutch out the hill hold won't work.

 

[Darren M]

Car now back in my hands and feeling great :driving: . Big bill but inspection 1 also now done. Caliper was £273 inc vat

 

[sixspeed]

Had exactly the same symptoms as you when I suffered with mine. The tyre pressure monitor is a result of the excess heat in one wheel causing the air to expand in the tyre (as it would on track) and increase the pressure, but on one side only.

I think it measures the speed of rotation of the wheel, not the tyre pressure directly. A difference in pressure gives a difference in circumference, on the tyre, which creates a difference in the rotation speed.

The brakes holding on for a moment on a hill start can be a pain reversing off my drive.

Yes, you're correct that the TPMS works off the ABS sensors and measures wheel speed not tyre pressure directly, however the reason for the monitor to show a fault is the same. I was just explaining the reason why the monitor had gone off though.