Ceramic Pad Brake Delay.. In the Rain... When it's Cold

[kayger12]

So now that the temps have dropped here, I'm reminded of this issue and wanted to get some feedback and education from the Family.

Background: When I bought Jersey Graphite last year, she came with BMW Perf rotors and ceramic pads (brand unknown). I've been very happy with the performance of the pads and lack of brake dust. There has only been one little issue that makes my applehole pucker on occasion...

The Issue: So last December I'm driving on the highway in the rain for about 30 minutes heading home. I line up for my exit ramp and get ready to enjoy rolling through the nice, tight 270 degree corner. I get to my braking spot and go to bleed off some speed before I take her in. I step on the brake and get.... nothing. I get the usual resistance from the pedal, but zero braking. I feel the 'ol adrenaline dump as my brain visualizes what my precious ZHP is going to look like after I end up scrubbing 30 mph of speed off with a guardrail. Then, after what felt like an eternity (but in reality was about 1 to 1.5 seconds), normal braking action returned and I was able to roll the corner with no drama.

Upon returning home I check a few things-- brake pads are fine, fluid is full, rotors look good. Hmmm.

I drive for the next 1,000+ miles with no issues. Then, about two months later, it happens again. Same thing: highway driving, rain, 1.5 seconds before the brakes start grabbing.

So the next time I'm driving in the rain a few months later-- I'm ready. I approach my exit and get on the brakes earlier than normal. And of course-- I get immediate braking with no delay-- wtf?

The Puzzle Solved: I happen to mention this little conundrum to Marc (zhpnsnv) while helping him put in his performance intake. Marc informs me that he has experienced this as well, but only when it's colder than about 55 degrees in the rain. Something to do with the heat not staying in the pads when it's colder. This jives with my episodes as I realize the only difference between the times when I have immediate braking vs delayed braking is warm weather instead of cold. This also makes sense because my brake response is fine in the cold/rain when I'm driving around town. It's only when I've been driving without using the brakes for 20 min or more that it happens.

My Question: So, is this normal in everyone's experience for ceramic pads? Do some brands exhibit this condition worse than others? Is there anything I can do to mitigate this?

I love my brakes and lack of dust, but I'm not excited to be back to the time of year when I don't have brakes for 1.5 seconds every time it's raining and I drive on a highway for 30 minutes. I can plan for early braking for an exit, but if I have to get on the brakes in a hurry for accident avoidance or anything like that, I'm going to be whistling the Jeopardy theme for the first 1.5 seconds...

Sorry for the long read. Thanks for hanging in.

Comments, experience, and suggestions welcome.

[ryankokesh]

Whoa. That's kinda terrifying. Just put ceramic pads on last month, but I haven't experienced this yet. Hopefully I won't ever...


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[danewilson77]

I have had the same experience with the ceramics, when cold.

I usually scub speed into a corner with a downshift, so I typically do not notice the delay....but I can "feel" it if that makes sense...

[kayger12]

Makes perfect sense, DW.

[M3TA5IN]

I don't brake real hard that much because I always downshift most of the time. I don't have ceramic brakes either but I have noticed on my car that sometimes I'll be on the brakes and it feels like it just decides to let off the brakes without me ever letting off the pedal.

Op, don't know if that's related to your problem. Curious if yours is directly related to ceramic pads though as I really want to get some after winter.

[kayger12]

I'm thinking it's definitely the ceramics. Never had an issue like this on my 325i with regular pads.

[M3TA5IN]

I'm thinking it's definitely the ceramics. Never had an issue like this on my 325i with regular pads.

Interesting, I might look into other options then. No brakes is scary as hell!!

[kayger12]

Interesting, I might look into other options then. No brakes is scary as hell!!

Yeah, that's kind of where I'm at. Hate the idea of all the dust on those 135s, but would hate to have a wrecked car with clean wheels...

I'm wondering if there are certain ceramics that are more susceptible to this than others.

[M3TA5IN]

Yeah, that's kind of where I'm at. Hate the idea of all the dust on those 135s, but would hate to have a wrecked car with clean wheels...

I'm wondering if there are certain ceramics that are more susceptible to this than others.

Yea I hear ya man, I was talking to someone the other day that said there are more options out there now for brake pads that don't give off dust, an they weren't talking about ceramic. I gotta figure that out cuz the break dust is driving me nuts.

[zj96sc]

I may have to do some more research, but I do no think this is a ceramic pad issue.

My understanding is that this is due to water on the pad and rotor. Apparently very prevalent on cars with brake cooling ducts since you're putting massive amounts of water into the wheel well.

The lack of braking and pressure you feel in the pedal is because there's water on the pad/rotor interface, and since water is incompressible, you get pressure in the pedal.

It is common for race car drivers in rain races to "check" their brakes before hitting the braking zone to clear water off the rotor. It supposedly also a good performance habit to have in rainy conditions anyway. E36 M3s shipped to the US with the brake cooling ducts blocked off with a plate, apparently for this reason....mainly that US drivers aren't trained to 'check' the brakes ahead of time to clean them up.

I've experienced this behavior on both of my E36 Ms (with block plates removed) and my ZHP. I've tried to make it a habit of just periodically tapping the brake to clean them up.

Again - could be wrong here, but that's what I think is up.

[kayger12]

I'm wondering if it's maybe that the ceramics cool down faster, whereas the semi-metallics hold the heat longer. I'm thinking the heat possibly evaporates the water from the pad surface longer?

Again, this problem appears completely temperature dependent. I can drive in a driving downpour for an hour when it's warm out and the braking action is immediate. It's only when it's wet AND cold out that it occurs.

Also, same roads/same conditions-- I never had it happen with my 325i with semi-metallics.

[ryankokesh]

I wonder if slotted rotors wouldn't fix this? I have slotted/drilled and have never noticed this with the ceramic pads.

[zj96sc]

Does/did the 325i have brake cooling ducts?

If it was a temperature issue, you'd notice it the first time you tried to apply your brakes cold too. So...do you?

Pretty simple test either way. After a good 20-30 minutes of no brakes in the rain, give the pedal two quick taps, and then lay on. Good brakes = water, delay = temp.

EBC kind of hints at it, i will see if i can find my original sources from a few years ago.


If brakes become wet it can have a negative impact on their performance, tapping and testing your brakes can help the rotors and pads to dry out.

more edits:

here's a thread based on similar "symptoms." Like I said, these discussions are common for E36M guys, basically anything with cooling ducts.

http://forums.bimmerforums.com/forum/showthread.php?t=1151652&highlight=rain+brakes

http://www.e90post.com/forums/showthread.php?t=409511

apparently new BMWs are equipped with a brake drying function, basically quick pulse on the brakes timed with the wipers to clear water off.

apparently also exacerbated by more open wheel styles....5 spokes, etc.

[zj96sc]

seems to be a pretty fair amount of material out there all indicating the water is the problem:

http://editorial.autos.msn.com/article.aspx?cp-documentid=435355


For example, Mercedes began using electronic brakes a few years ago. They can automatically sense when the road is wet and imperceptibly apply the brakes just enough to keep the brake discs dry. This way, brake performance, which can be weakened by moist discs and pads, remains consistent no matter the kind of weather the car is in. BMW added this feature, which it calls Brake Drying, to its 2006 BMW 3-Series. It's standard equipment.

apparently brake drying with 3ers hit the e9x.

[Hornung418]

Quick recap: When it's wet, proper procedure is to tap the breaks twice before needing to actually use them. What do you do for an emergency stop?

[kayger12]

Does/did the 325i have brake cooling ducts?

If it was a temperature issue, you'd notice it the first time you tried to apply your brakes cold too. So...do you?

Pretty simple test either way. After a good 20-30 minutes of no brakes in the rain, give the pedal two quick taps, and then lay on. Good brakes = water, delay = temp.

EBC kind of hints at it, i will see if i can find my original sources from a few years ago.



more edits:

here's a thread based on similar "symptoms." Like I said, these discussions are common for E36M guys, basically anything with cooling ducts.

http://forums.bimmerforums.com/forum/showthread.php?t=1151652&highlight=rain+brakes

http://www.e90post.com/forums/showthread.php?t=409511

apparently new BMWs are equipped with a brake drying function, basically quick pulse on the brakes timed with the wipers to clear water off.

apparently also exacerbated by more open wheel styles....5 spokes, etc.

Good info. Thanks. Not sure if my 325 had ducts. It had the sport package and 17" wheels, so maybe?

It's definitely partially a temperature issue (OAT, anyway), because when it's pouring out yet warm it never happens. Only when it's cold and wet as described in the threads you found. So water combined with cold temps is the trigger.

Looks like something I have to live with and just preemptively manage when the trigger conditions exist.

Does anyone else in a cold-climate area experience this? And if so (or not) what pads/rotors are you running?

[zj96sc]

Quick recap: When it's wet, proper procedure is to tap the breaks twice before needing to actually use them. What do you do for an emergency stop?

Its not a bad habit to form to occasionally do a 'confidence tap' on the brakes anyway. If you're cruising in pouring rain (and honestly even in clear weather) just make it a habit to put some pressure on every couple miles - should help mitigate any delay in a panic stop situation.

[M0nk3y]

I had this happen on my E46 325xi w/OEM brakes...Happened twice to me as well.

One at 35mph, one at 70mph on a exit. Both times I thought I was going through another car. Scariest feeling I've had.

[Mtnman]

Keith,
I have Ceramics. I have noticed something similar, but never been able to identify the issue. By that i mean sometimes, rarely, my brakes feel different than normal, like it takes longer to stop. I thought (and still may be the case) this was just in my head. After reading this thread, I will pay more specific attention to these details. Of course, we just got through 3 cold rainy days, but there will be more this winter. Ill post after I have something worthy of reading.

[kayger12]

Keith,
I have Ceramics. I have noticed something similar, but never been able to identify the issue. After reading this thread, I will pay more specific attention to these details. Of course, we just got through 3 cold rainy days, but there will be more this winter. Ill post after I have something worthy of reading.

Thanks, brother.

[Go Horns!]

I have OEM rotors and pads, and experience the same problem this past weekend. Drove on the highway for 5 hours in rain and 40 degrees. I just had to remind myself that every few minutes I needed to give my brakes a tap.

I think it is the cold water constantly running over the pads and rotors. Kind of like putting a beer in cold water cools it down faster than putting it in a freezer.

[ryankokesh]

Good analogy :drunk

[kayger12]

Good analogy :drunk

Haha, yep. Made perfect sense here.

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[danewilson77]

It all comes back to beer.

[static667]

I have a similar issue, but it is mainly just wet conditions. Any time I'm driving in a good rain, my braking can be delayed, kinda like you have experienced, Keith. Its because your rotors and pads get damp. I make sure to periodically dry/warm mine when its raining by applying the brakes lightly with my left foot. I do this regularly in the rain. I've had some of those pucker moments due to wet brakes.

[RVAzhp]

i've experienced this with stock pads. i was always taught to tap the breaks light in wet weather anyways to make sure you're stuffs ready. first time it happened it did take me by surprise as i was in traffic ... aka my butthole did pucker.

[Crickett]

The owner's manual mentions it:

It is a good idea to periodically dry the brakes with a gentle application when driving in rain or on wet roads. Watch traffic conditions to ensure that this maneuver does not endanger other road users. The heat generated in this process helps dry the pads and rotors to ensure that your brake system will respond with undiminished efficiency when you need it.

[iZHP]

I had this happen to me too in the rain. Scary at first because I was going fast. I guess I need to "dry my brakes" more often!

[zhpnsnv]

As discussed, this happens to me with the stock pads. I do practically all highway driving, so I've figured it out, but the pucker always happens.

I've heard that newer bmws put the pad closer to the rotor when wet to keep them from cooling too much. That hasn't been verified but I've never heard of this issue with stock e90s.

First time I ever experienced this was on my e30 with upgraded pads/rotors in the rain.

[iZHP]

I've heard that newer bmws put the pad closer to the rotor when wet to keep them from cooling too much. That hasn't been verified but I've never heard of this issue with stock e90s.

So doesn't that mean faster brake wear?

[zhpnsnv]

So doesn't that mean faster brake wear?

I think we are talking about fractions if millimeters but I can't say either way. Id love to know if it's actually true.

[rdhamill]

Anyone think that slotted or drilled rotors would help?

[danewilson77]

Anyone think that slotted or drilled rotors would help?

My drilled BMW Performance rotors have dyno'd @ +9Hp.

HTC Thunderbolt+TT

[kayger12]

Anyone think that slotted or drilled rotors would help?

I'm sporting BMW Perf rotors.

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[danewilson77]

Anyone think that slotted or drilled rotors would help?

My bust. They're not drilled.... They are cast w/ the holes.

HTC Thunderbolt+TT

[Hornung418]

My drilled BMW Performance rotors have dyno'd @ +9Hp.

HTC Thunderbolt+TT
Pics of Dyno Chart?

[ryankokesh]

Anyone think that slotted or drilled rotors would help?

I haven't experience this problem yet with my drilled/slotted rotors and ceramic pads...

[terraphantm]

My 330 used to have major delay in the rain... I always used stock pads too. Getting drilled rotors seemed to help, but I'm sure the root cause of the issue was still there.

[Jesse M]

happens to me often when driving long distances in the rain without hitting the brakes. (stock setup though). Just bought some goodies I'm installing this weekend. :)

[kayger12]

^I forgot about this. It's that time of year again...

[BimmerWill]

I have had this issue once or twice in the time that I've owned the vehicle. Luckily its not been at a crisis moment but still made me nervous when it happened. I haven't noticed it happening since installing the drilled and slotted rotors from smilez...also am running normal compound stoptechs not ceramic. Im with others on water being the culprit here plus with the colder temps it causes the rotors to cool down more than usual. This issue caused me to be hesitant about purchasing ceramic pads but I may end up getting some in the future just form a habit of checking the brakes every now and then.

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