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/showt...p?t=5704<br />

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.. :\