: Sketchy brakes in wet and snow

12-13-10, 10:12 PM
My V is the first car I've driven that has an above average braking system on it, so I'm not sure what's "normal" for these brakes in wet and snow conditions.
Over the last month or so I've been noticing that the brakes feel somewhat strange in wet conditions (wet and mild, not just cold). I can't pinpoint the "strange-ness" but they just don't feel like they do in dry conditions. Is it normal for a "big break kit" like this to feel different in wet conditions?
As for snow, here's what I experienced. Winter officially arrived here the other day and I had my first encounter with my brake pedal suddenly going to the floor and little to no stopping. Thankfully it was on a local street (unplowed with about 6" of snow and a layer of ice underneath) and I was only stopping from about 10 mph. It scared the shit out of me though! I thought the cold had somehow ruptured a brake line, but the pedal almost immediately came back to life with a few quick pumps. Was this the stability control doing something? Or does something sound amuck with my brakes? Because I know the question will be raised: my brakes were properly bled and the fluid fully replaced just a few weeks ago, when I did the clutch fluid.

12-13-10, 10:15 PM
I think this was reported before. One theory, which may or may not apply to you, is air in the ABS and during your first activation (i.e. snow) the air somehow purges itself and causes a mushy pedal. Check to see if the level in the reservoir seems lower than you remember filling it.

The other thing I thought of is just cold/wet pads, which I was going to say should be fairly normal for a high performance braking system (unfortunately). But I don't think the pedal should go to the floor...

12-14-10, 08:36 AM
I notice my brake pedal is a bit stiffer in wet weather. I wont even try to take it out in the snow

12-14-10, 08:44 AM
Strange as in initial bite is soft ?

This may be attributed to the pad compound. See, these are heavy cars (mine weighed north of 3800 lbs with the 6-lug) with a big motor. Regardless of its rotor sizes, the pads will get up to high temperature immediately. Which means the pad compound must work well in the expected higher temperature it operates in. I always suspect that the OE pad compound is rated "higher performance".

This also means sacrificing a bit of low temperature performance. You may have noticed this. The initial bite becomes soft and as the pad and the rotor get warmer, the braking performance comes back. Once they are cold again (as in driving on highway for some time), the performance degrades again until things warm up upon first application of the brakes.

Now, there is a cheap trick to this. Do you see those air ducts on the front bumper just below the fog lights ? Those feed air to the front brakes when in motion. If you plug those up, the front brakes cool down slower. Maybe just about enough to keep the front brakes within operating temperature range of the pads.

You can always replace the front brake pads with ones with lower operating temperature. Which one ? No idea; as I'd never ventured into this.

12-14-10, 01:21 PM
Which fluid did you flush with? Mine felt like this until i put in some rbf 600. Still for some reason don't feel as good as my wifes v in relation to pedal stiffness. I do track it anyways and never had problems. i also went to hawk hp+ pads.

12-14-10, 03:54 PM
Yes, it's mostly initial bite that feels poor. I figured it was a temperature thing, but was very concerned with the other issue with the pedal going to the floor. I haven't encountered that again though and I've been driving around in the snow quite a bit.
As for the issues with stopping in the rain, it sounds like it's normal for the brakes not to bite when they're wet. I just have to be mindful of that and be a little more aggressive with the pedal when the brakes are wet.
To the last poster, does your wife's V (wow, that sounds personal) have the stock Brembo pads? I switched my fronts to HP+ too and they definitely don't bite as hard as the Brembos did. I'd be willing to bet your feeling the pad difference rather than a fluid difference. I'm putting the Brembos back in next time I'm in there.

12-14-10, 04:22 PM
my braking performance is also not nearly as good in the rain, and I had been attributing it to wet pads and rotors, especially given that the rotors are so large that they could theoretically be more difficult to dry out under heavy braking.

i don't have a mushy pedal, just reduced stopping power and sometimes what feels like a lack of power assist. this is also on initial bite. haven't driven it in the snow yet tho.

12-14-10, 07:20 PM
Every car with disc brakes (non slotted rotors I should stipulate) that I've ever driven always had a lack of bite in the initial brake application after driving for a while in the rain. i.e. cruising on highway for a few minutes and then applying the brakes. That being said, I only drive my V on 0% chance of rain days, so I cant comment specifically on it.

12-15-10, 07:12 AM
Both cars have the same in pads , fluid , rotors, and ss lines. Her initial bite is great. Same tires also. all around her brakes feel way better in pedal feel. i haven't done braking distance test but seem the same. Its just that my pedal is not as firm.

12-15-10, 08:30 AM
One thing about pedal going to the floor may be contributed to the active handling. Was the active handling engaged prior to the loss of brakes ?

12-15-10, 03:39 PM
active handling? do you mean the Stabilitrak?

12-16-10, 10:05 AM
Yes, Stabilitrak, I'm used to C5/C6 terminology :)

12-16-10, 03:34 PM
Every V owner, at some point, finds out real quick that in the rain, you better prime those brakes before the 1st hard stop after sitting or driving a while.........

It becomes second nature but it can scare the heck out of you!

12-17-10, 03:10 AM
POS - in my original post I mentioned that maybe it was the stabilitrak that causes the pedal to go to the floor. Since it hasnt happened again and I'm not losing any fluid, that must have been it.

As for the wet, it sounds like what I've experienced is par for the course.

Thanks everyone.

12-17-10, 10:03 AM
i must not be stopping hard enough in the rain... i can't say that they feel that much different. Although i do adjust my driving int eh rain due to the reduced grip of the wet road. Guess i will have to do some experimenting next time it rains

12-18-10, 10:45 AM
What pads are you running? What rotors are you running? I am running stock rotors up front with Hp+ and some UUC's in the rear with stock pads. The bite is still there in 20 degree weather with a two inches of snow on the road. Zero issues. I just switched off of HPS ceramics, which in the wet and the snow I might as well have had drum brakes off a Corolla.