Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB

- Suspension | Chassis | Brakes -- Sponsored by 949 Racing (https://www.ft86club.com/forums/forumdisplay.php?f=59)

- - Rainy day rotors (https://www.ft86club.com/forums/showthread.php?t=133236)

How much water are we thinking gets stuck to the rotor as it spins at 4000 rpm? How much pressure would a pad require to displace this seemingly insurmountable volume in relation to the pressure to stop a 3000 lb vehicle? How long would that pad take to clear the rotor in one revolution?

I have the PP Brembo's, running the OEM pads, my car brakes fine, wet or dry, I like the OEM pads due to their initial bite when cold.

The only issue I have in the wet is my Hankook RS4's, so when it rains, I drive to the conditions.

The way I look at it, in every racing series and track day I go to, no one, and I mean no one uses drilled rotors.

Actually thats incorrect, I have seen them used, only to be replaced soon after.

And yes, when it rains here it pours.

But, in the end, spend your money how ever you can justify it.

I spray mine with WD40 when it rains.+1 for fish oil!

Solid rotors + ventilation on the perimeter = best braking. Crossdrilling is largely for poseurs. Jhooks on some ap racing discs for clearing debris.
https://www.brembo.com/en/company/ne...008-vs-f1-2018
https://www.apracing.com/Info.aspx?I...&ProductID=976

Quote:

Originally Posted by jsimon7777 (Post 3191864)

Sure.

Quote:

Originally Posted by remhex (Post 3191558)

Vacuum mode to the seat engages when nothing happens...lol. I mash the brakes harder until they grab. Usually I pre-emptively ride them to dry them off. Only happens in certain spots where road is covered in standing water or pooled up in the frost heaves. Pads are stock performance package. Brakes are amazing to me when its dry out.

Dude, I am experiencing the same thing... and I was thinking the same as you about the rotors. Let me know how it works out. I might not get around to working my brakes until I hit 7500 miles.

I can't say I ever noticed this on the OE Brembos. Nor on the AP Sprint. But I do find that the brakes get cold awfully fast, and cold braking feel is never quite as good.

Quote:

Originally Posted by fatoni (Post 3191851)

60mph is about 830rpm at the wheel... or brake rotor. 4000 is nearly 300mph.

I've honestly never experienced what you guys are describing. The closest is a general feeling of "soggy" pads after my previous vehicle got sat in a puddle during a rainstorm for awhile. Organic material brake pads tend to intensely dislike sitting in standing water. Otherwise, I can't imagine what would cause what you're describing. I don't have PP Brembos, though.

Quote:

Originally Posted by ZDan (Post 3191815)

My theory:
It's the PP Brembos… They're great, but the the fixed caliper holds the pads nearly perfectly parallel with rotors at all times. When there's a lot of water, there becomes a thin uniform film between pads and rotors that isn't easily displaced with pressure. You press on the brake pedal and get very little response for a very short but very noticeable amount of time.

Sliding calipers will have the pads a bit cocked relative to the rotors, so there's a wedge of water that is easily immediately squeezed out with pressure applied.

I got this phenomenon in a big way on my FD with ST40 Stoptechs. And now I get it with my BRZ PP. Particularly when exiting the carwash! Rotors have to be "cleared" of water before the brakes operate normally.

Very noticeable, very real phenomenon.

I've experienced the exact same with my PP Brembos as well. I posted about it last summer, and have it happen every so often when it's extremely wet out. I mentioned it to the dealer when I was getting a service done, but they told me everything looks fine down there. I attributed it to a combination of brake design and pad material and just make sure to give them a little stab every now and then so I have a pedal if needed. Carwash is a great example as I get it every time as well. Regardless, it is a very unsettling feeling for sure!

Quote:

Originally Posted by cjd (Post 3191928)

I can't say I ever noticed this on the OE Brembos. Nor on the AP Sprint. But I do find that the brakes get cold awfully fast, and cold braking feel is never quite as good.

60mph is about 830rpm at the wheel... or brake rotor. 4000 is nearly 300mph.

Yeah I didn't think I needed to be all that accurate to get the point across. My bad.

Clearly this is a design flaw covered up by big brake disc manufacturing!

Do what's right for your car, switch back to drums! These new disc type brakes just aren't tested well enough, drums were good enough for my grandpappy and they're good enough for me and my kids!

If water layer is a problem a slotted disc should fix the problem.
If it doesn't then:iono:

Here's a better idea.
Don't drive like a moron in the rain.
Notice that like 50% of FTS cars are salvage title.
That's because these cars are owned by idiots

Quote:

Originally Posted by GrantedTaken (Post 3192100)

Here's a better idea.
Don't drive like a moron in the rain.
Notice that like 50% of FTS cars are salvage title.
That's because these cars are owned by idiots

So using that logic... If I haven't crashed my car, then I'm part of the 50% of owners that are not idiots?

Makes sense to me. :cheers: