Poor initial braking when wet?

[elsanto]

I'm having a really scary characteristic when driving in pouring rain. If on the highway and the brakes haven't been used in a few minute, I push the pedal and the pedal feels normal but I have almost no brake performance.. after letting off then reapplying I get full stopping power.

this only happens when its raining, not snow, not dry.

was thinking about changing pads out as I'm not sure whats on the car, but want to make sure there isn't anything else to look at first.

Thanks

[pfr]

I believe it is because the ducts throw a lot of water to the discs. I've got into the habit of occasionally "dry" the brakes in heavy rain.

- Peter

[jsfbmw]

Brake pads play an important role. BMW pads have good initial bite, as well as graciously coating your wheels with dust; it's a trade-off. Don't know what aftermarket pads may do this better, i.e., good initial bite, less dust.

Back in 2006 with the E90 3-series, BMW programmed the brakes to be applied lightly during driving in the rain (guess it used the rain sensor and ABS) to do what Peter described. I had an E90 and never had wet weather issues, and never could tell the computer was doing the light-braking.

[LivesNearCostco]

I have a similar experience on my old Saturn since I put on ceramic aftermarket pads. I don't have to press the pedal twice, but when wet, there is a short delay between pressing the brake pedal and having the brakes bite. Do you have ceramic pads?

[elsanto]

Thanks guys, I'm thinking they are probably cheap ceramic pads as they certainly don't dust much at all.. on with trusty HPS i suppose.

[brettbimmer]

Thanks guys, I'm thinking they are probably cheap ceramic pads as they certainly don't dust much at all.. on with trusty HPS i suppose.

Hawk HPS = Good pads, but dusty! Keep a bottle of Sonax wheel cleaner close at hand. I know that we have other threads on here discussing pads so they may be helpful, though I've switched to Performance Friction Brakes Z-Rated pads all-around. Good pads, though not cheap. Incidentally I initially installed only one axle and was getting a lot of brake dust, so I would recommend swapping all four corners when you change them out to get the best bite and less dusting all around. They have far less dust then the HPS pads.

[derbo]

I believe it is because the ducts throw a lot of water to the discs. I've got into the habit of occasionally "dry" the brakes in heavy rain.

- Peter

This is definitely not the case. The ducts are not fully directed to the rotor itself as the rim blocks any direct water to them. I never experience this with OEM pads and I believe its the pad compound issue.

[kayger12]

Some good info in this thread.
You're not alone. http://www.zhpmafia.com/forums/showthread.php?t=5704


Sent from my SCH-I535 using Tapatalk

[echo46]

I agree with derbo. I think this is a pad issue. I always did/do well with OE and Akebono ceramics. PO, any idea what brand pad you are running?

[derbo]

I really suspect it has to do with the temperature range the pad friction material operates at. When it rains, its usually a cooler overall temperature and prevents the rotor/pad to heat up to it's normal operating temperature range.


If anything I think that the operating temperature range is higher than 60F which is why you are experiencing terrible lack of bite.. :\

[HokieZHP]

This is just simply water on the rotors. You're supposed to "clear" your brakes every so often when driving in heavy rain. This is why when you let off and reapply the brakes, they work normally again. I have to do it as well. I clear my brakes every mile or so just to keep the water off of them

[Vas]

Pad material and operating temp.

Good choice on the hps besides the dust. But racecar.

[kayger12]

This is just simply water on the rotors. You're supposed to "clear" your brakes every so often when driving in heavy rain. This is why when you let off and reapply the brakes, they work normally again. I have to do it as well. I clear my brakes every mile or so just to keep the water off of them

Not simply water on the rotors. At least not in my case.

Water is one component, but temperature (OAT) is the deciding factor.

Pads/rotors can be soaked for an hour and if it's 70 degrees out, braking action is immediate.

Same scenario and 40 degrees and there's a 1-2 second delay in bite.

Being OP is from central Jersey, I'm betting his issue will be temperature dependant as well.

Sent from my SCH-I535 using Tapatalk

[derbo]

This is just simply water on the rotors. You're supposed to "clear" your brakes every so often when driving in heavy rain. This is why when you let off and reapply the brakes, they work normally again. I have to do it as well. I clear my brakes every mile or so just to keep the water off of them

Definitely not. I have never needed to do this.

sent from Moto X Dev Edition

[HokieZHP]

Ok well I've had to do this in heavy rain regardless of temp which is why I suggested it. It's only in heavy rain though whether it be summer or winter

[derbo]

Are you on OEM pads?

[HokieZHP]

Are you on OEM pads?

I've experienced it on stock and aftermarket pads.

[elsanto]

used car, so no idea what pads are on it. but there is "zero" brake dust so im thinking some lifetime ceramic pad bs.. I've always liked the HPS performance and have had them on a bunch of my cars including the m3, brake dust is all relative after you've used race pads, the HPS dust is nothing.

thanks for the great discussion on the topic, I have to say I'm not comfortable with the thought of remembering to clear the water every few minutes.. anyone familiar with NJ drivers will understand why.

[kayger12]

I have to say I'm not comfortable with the thought of remembering to clear the water every few minutes.. anyone familiar with NJ drivers will understand why.

+1,000,000

[llll1l1ll]

I have the same delay issue in cold, wet weather. I just remember to keep them clean every so often!