Stock Brembo's not working in the rain
 

Back in November I bought a 2018 BRZ (new) that came stock with Brembo's (SportTech RS). I've been having trouble when trying to stop on the highway if conditions are wet. Basically, if I drive for a while in the rain or snow (about 10 minutes plus) without using the brakes, then, when I do press the pedal braking is significantly reduced. Meaning, it takes much longer to stop then normal. I'd describe the feeling as if the rotors are covered in oil so that the pads are smoothly slipping and not applying as much force as normal. After applying the brakes a few times it's almost as if they've been cleaned off and braking returns to normal.

For further reading on the issue:

• https://mechanics.stackexchange.com/...ps-in-the-rain
• https://mechanics.stackexchange.com/...the-car-is-wet
• https://mechanics.stackexchange.com/...e-car-when-wet

I've taken the vehicle into the dealership a number of times now. They've confirmed there's no leaks in the system, the brakes are visibly in perfect condition and this is not an issue with the tires.

Yesterday Subaru Canada called me suggesting that this may be a problem with ALL Brembo setups on the BRZ. Leaning towards the idea that these are performance racing rotors and not necessarily designed for driving in the rain for a long period without braking.

I'm a little skeptical here and not entirely certain on how to proceed. Has anyone else experienced anything similar to this?

https://www.ft86club.com/forums/showthread.php?t=133236

Yes, There have been other threads about this....

Thanks^^ still trying to figure out the forum. I tried searching but couldn't find anything related.

Google is the best search tool. Type what you are looking for and add "Ft86club" , then you should have better luck searching.

2017 BRZ Performance Pack (basically same as SportTech RS) here. I noticed this same behavior with my Brembo's as well. Same circumstances too. Drive 10+ minutes without using the brakes and they seem to go away, then return after you've used them.

I've found it only to be an issue in the cold however. Any snow/rain under 30 degrees and it would occur...not every time, but often enough. It hasn't returned since it warmed up around here though, even when it rains.

I would describe it almost as if the brake booster stopped working. Like I had to really hammer down on the pedal to get it to slow down. Kind of scary when you're getting off the highway and suddenly your brakes aren't there.

Is it possible the discs ice up? Maybe the brake fluid isn't great in the cold? I'm not sure why it does it. But I've kind of stopped worrying about it since it warmed up. I'll be following what you find

Scary shit..

Yeah the more I look into this the more I'm finding others having the same situation with the PP. Originally I was considering it to be a cold weather situation but I was driving in 10 degrees (C) temperatures and it still ended happening frequently. Hopefully once it gets really warm here it won't be as noticeable. The dealer suggested switching out the brake booster vacuum hose but they decided not to because apparently if there was a leak, it would be noticeable at all times (and not just in the rain).

Yeah I mean I cant say for sure its only a cold weather thing that's just my experience so far.

That other thread was a good read. It's nice knowing I'm not the only one with this issue but I didn't see any real solutions there.

I'll be keeping my eyes peeled

This is another thread with the same issue:

http://www.ft86club.com/forums/showthread.php?t=125666

The solution as of now seems to be to swap out the pads :(

I've experienced this on an older bmw i used to own. It was 100% caused by the brake pads I was running. Some crappy hawks at the time. Switched them out for something else [sorry can't remember the brand] and it was fine.



But I'll take them off your hand .. for scientific research purposes, in exchange for some nice stock brakes. :)

Ahaha, yeah I'm definitely going to swap out the pads. And I'd actually take you up on that but the plan right now is to keep this set for track days

I have this same issue with my AP Racing BBK. It's always a bit of a butt-clencher when you are on the highway in the rain, and go to use the brakes, and not much of anything happens for that first second-or-so. I'm running APF404 pads, which are apparently almost identical to Ferodo DS2500s.

My 2 cents

Street pads for the street and autocross (low dust, kind to rotors)
Track pads for the track (squealing rotor eaters)

Whilst high temp pads are required for the track, they are a definite hazard on the street.

You WILL lose stopping difference between the 2 when cold.

I use to just swap them out prior to the first session.

Easy peasy lemon squeezy

The problem is people are having this cold-bite issue with the OEM pads.

OP, everything I've read sounds 100% like the pads are either not bedded properly or (more likely) under temperature. I don't know how to fix this, besides either (1) riding the brakes a little (terrible solution); or (2) getting a more daily-friendly brake pad. I'm not sure what the OEM pads are on the PP, but if they come with a "hybrid" type pad like a DS2500, then you should ditch those and get some basic ceramics for street use.

That doesn't make much sense. You're saying its temperature-related, but then how does that jive with the fact that my DS2500s work fine when its 20 below zero here in Chicago, but suffer this issue when it's 90 degrees and raining.

I still think it has nothing to do with temperature/compound, and everything to do with water getting caught between the pads and the rotors. The brakes don't suddenly grab because very light brake application for 1 second caused them to warm up. They suddenly grab because it took a second for water to be removed, and for the pad to begin making contact with the brake rotor. At least that's what it feels like. It doesn't at all feel like the pad is suddenly coming up to temperature, and my experience with that pad in a wide range of temperatures here in Chicago pretty much disproves that theory anyway.

2017 Brz with performance package here. I have noticed the same breaking issue. Basically I see it arise when I park outside and it rains heavily for a while. If when I drive later that day and do not break decently hard to clean off the rotors, once moving at a decent speed the break pedal becomes decently hard and applying the break feels like I’m using smooth glass as rotors. Full o shit pressure seems to get my car to stop, but scary. Not sure why this happens but only after a very heavy rain. I assumed rust build up, but the super firm pedal part I can’t explain.

I have a stock old acura legend as my daily, literally rusting apart. Same issue in the rain. I am running a single piston caliper up front, not a type 2 dual piston even. Metallic pads up front or all the way around. Napa gold. Not organic compound.


Point being, how many people race on a track in the rain?? If they made it like a normal street pad we would be complaining instead that there is dust everywhere and they only last x amount of miles. They tried to do a compromise or relied on Brembo's engineers and didn't validate themself. Look at how Toyota delayed the Supra more because they were not totally satisfied with (waterpump???) reliability. The part is actually changed but not on the BMW.



Swap out the pads to a more street one and report back. Answers help a forum!


Ps- Imagine your same issues with a cold temp automatic where torque convertor is staying locked up I think. Literally trying to hold it back from pushing me through the first stop sign some days. Now that can be scary.

The last time I had a car that did not stop in the rain was when Drums were on all 4 wheels!