PP Brembos & Wet Conditions
 

Hi All,

2017 BRZ Limited PP w/~9500 miles...

I had an odd issue last week when I had to drive about 350 miles for work. It was extremely wet (Illinois and Indiana got some huge storms last week).

I first noticed it when I had to brake suddenly for some traffic on I-80. The pedal felt very soft and spongy, and the brakes did not bite at all. It happened again about an hour later when exiting an off ramp. One or two pumps of the pedal and it cleared up, but it's a pretty concerning feeling to not have instant brakes available. It almost seemed like the pads had to dry out or something. It was also kind of reminiscent of the pad knock back I felt occasionally when I had WRX 4pots on my 2.5RS.

I've had this happen before with this car when coming out of the car wash (touchless of course) as well. The issue seems to point to driving in wet or humid conditions, but knock back may also play a factor. On the highway, I was not driving aggressively or anything like that.

Car is going in for an oil change this week at the dealer, and I will mention it to them as well.

Has anyone else experienced this on a PP car?

Since you mentioned Illinois/Indiana... was it at or below freezing when that happened? You can have ice build up on the rotors which can result in a scary amount of "no brakes" for a good second or two if you haven't used the brakes much.

Nope, this was last Tuesday when the temps were in the 50s and 60s.

If it was alot of rain its not unreasonable to assume you had alot of water on the rotors and that was effecting the stopping performance.

This is similar to as you pull out of a car wash have you ever noticed your braking is dramatically effected for your 1st stop if you go to stop immediately after pulling out.

I was out last Tuesday in torrential scary stuff (well, I assume scary sure to the speeds everyone was going) and didn't notice this, but I'm always giving myself extra room and being more gradual in the reason anyway...

If I drive it on the stock brakes again in the reason I'll test this out. I probably won't though.

Yes, in my OP I indicated I had felt this before coming out of the wash :)

I noticed that after posting I did not go back and edit my post. Either way same concept.

Yes. This is common even if you've doused drum brakes with water.
It's called driving to conditions.
Stuff on the clamping surfaces has to come off before optimum performance.
Motorcycles, trucks and my stock 86 too.

No worries at all :)

Agreed, but I've never got this specific feeling from any other vehicle (cars, trucks, motorcycles, golf carts, side by sides..etc) in those kinds of conditions. Regardless, dealer is aware and is going to check it out on Wednesday. If they find anything I'll report back.

Cheers!

It's a characteristic of the PP/OE Brembo caliper, pad, and fluid type. Also, if you haven't changed the brake fluid recently, we recommend you get the brake fluid changed out for a more consistent feel.

I also had this happen on mine after a lot of highway driving on a very rainy and cooler (50ish degrees) night. I'd say it's either the pads not breaking through the wet surface well enough or not being warm enough. Slotted rotors and/or a different pad compound may help with this.

Dealer checked it out and said everything appears kosher. I agree with what others have said in this thread that it's a combination of environment conditions, and the brake setup (calipers, pads, fluid) that are causing it.

Just something for others to be aware of I guess...

I ran into the same thing with my FD on Stoptech calipers. I think the issue is that rigid fixed calipers maintain the pads more parallel to the rotors while not braking, whereas sliding calipers kind of flop around. With the pad held parallel to rotor, you get a uniform film of water between them which due to viscosity and surface tension requires some effort and time to get pushed out of the way. Vs. with a sliding caliper which will have more of a wedge of water which is more easily squeezed out.

That's my theory anyway... For sure it is a noticeable phenomenon that does not exist with sliding calipers (at least I've never experienced with them).

Upon driving down a road that basically a river my PP brakes had very little braking power until they warmed back up, only a couple seconds. The longer I drove without touching them the longer it takes, so 30m wasnt noticable but after an hour it was a couple seconds. I have also noticed if you do not dry off the brakes they stick after washing and leaving parked.

Note: my car had less than 1000 miles on it