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.