A couple of questions on the M4 if anyone can answer. Twice during driving in moderate rain/wet and for several miles without having to apply the brakes, that when I did need apply the brakes to slow/stop quickly/promptly, I had to push HARD on initial application to avoid hitting the car in front of me. Immediate successive applications were normal, until several miles later, (again in rain and after not having had to apply for a while) and the same thing occurred again. Is this normal, or do I need to 'seat' the pads properly? Was not told CCB pads needed that procedure. Only 1500Mi on car. Also, on a very tight turn/circle, I notice a much larger circle/area needed to turn 180+ degrees. Is that normal? I've not seen any thread or comments on either of these topics. Help appreciated, thanks!
I have zip experience w/ ceramic brakes - good question for your dealer tho; I kinda recall reading something about some BMW's having automatic brake drying, basically lightly applying the brakes every so often when it's raining to keep the rotors from getting so wet that what you experienced happens - if your car is supposed to have that, maybe then a malfunction & something needs to be checked out (unless some performance setting like turning off one stage of DSC, etc. also disables auto-brake dry, assuming M4's do that, and you turn off/change DSC, etc.). To me, sounds like what I'd typically expect as a symptom of cold & wet brakes, as in the conditions you experienced - but, that doesn't help to make it any less unsettling! I wouldn't know if there's a particular bedding-in/seating procedure for your brakes, but I'd kinda think 1500 miles of normal street driving would pretty much do it. If you headed right out on a 1500 mile highway trip, maybe not. No clue on the turning, but if it has the variable electric power steering, again good thing to ask the dealer. Charlson here should have some better answers than I do!
First off nice car! Yes what you described for the ceramic brakes is normal when driving in the rain. I have had a few people raise concern on this with the M5's and M6's. The reason is because ceramic brakes work best between a certain temp range to cold and they don't bite enough and to hot well all brakes don't do well to hot. When you drive in the rain it acts as a coolant to the brakes and thus cools them sometimes enough for you pads to not be in there normal operating range and then the problem with performance. Like Mgarrision mentioned there is a DSC function that dry's the brakes when the vehicle senses rain. This is great for normal brakes but for carbon ceramic it is not always enough to get the heat back into the brakes. This function can not be shut off with the DSC button either. Hope that kinda makes sense. As for the turning radius I'm not sure what your comparing it to, another M4?
Thanks again for your reply, I wanted to give some follow up. Took the car to my local BMW dealer, and they called the area BMW engineer/tech. They stated that not only were they were aware of the problem, but also have a 'software update' to the computer algorithm re: the brakes (not sure if auto brake dry specifically, but that would make sense). They did the software download, so we'll see. In regard to the turning radius, that's just the car, it was even noticeable on the 4-series loaner I had during the brake service.
Thanks for your reply, here is some follow up that I posted to Mgarrison. The area BMW engineer/tech had the dealer download and install a 'software update' to the computer algorithm re: the brakes (not sure if auto brake dry specifically). The turning radius, that's just the car, it was even noticeable on the standard 4-series loaner. Merry, blessed, and meaningful Christmas to you!
