Braking in Wet Highway Conditions

[Naz24]

Sorry if this has been covered already, but i rarely drive my M3 in the rain, and i have a few observations

I know its typical that when driving at highway speeds in a rain storm for stopping power to be reduced if you do not continue to engage your brakes (as the rotors get wet and the friction is reduced). However, i noticed it to be REALLY bad in this car. To the point where initial bite is literally non-existent. This has not happened to any other cars i've owned. Is this normal? Recommendations? It was quite scary having zero braking power for 2-3 seconds...

[minn19]

Originally Posted by Naz24

Sorry if this has been covered already, but i rarely drive my M3 in the rain, and i have a few observations

I know its typical that when driving at highway speeds in a rain storm for stopping power to be reduced if you do not continue to engage your brakes (as the rotors get wet and the friction is reduced). However, i noticed it to be REALLY bad in this car. To the point where initial bite is literally non-existent. This has not happened to any other cars i've owned. Is this normal? Recommendations? It was quite scary having zero braking power for 2-3 seconds...

Do you have CCB?

I have the regular steel brakes and do not have this problem. The car has a system that tries to keep the pads and rotors dry in the rain.

[Naz24]

Originally Posted by minn19

Do you have CCB?

I have the regular steel brakes and do not have this problem. The car has a system that tries to keep the pads and rotors dry in the rain.

I have steel brakes.

[RowanBuds]

Originally Posted by Naz24

Sorry if this has been covered already, but i rarely drive my M3 in the rain, and i have a few observations

I know its typical that when driving at highway speeds in a rain storm for stopping power to be reduced if you do not continue to engage your brakes (as the rotors get wet and the friction is reduced). However, i noticed it to be REALLY bad in this car. To the point where initial bite is literally non-existent. This has not happened to any other cars i've owned. Is this normal? Recommendations? It was quite scary having zero braking power for 2-3 seconds...

This sounds like what I have experienced with the CCB's and what I've seen people criticize them for. Your comment of non-existent initial bite is the correct description. After two or three times I realized you really have to put your foot and leg into pressing the pedal firmly when you've been driving in the rain without using them for a couple of miles. The initial bite is still bad, but they dry off very quickly and then bite hard - modulating this isn't the most natural but you can get used to it. I don't daily the car so rain is a rarity, but it's me a few times.

Originally Posted by minn19

Do you have CCB?

I have the regular steel brakes and do not have this problem. The car has a system that tries to keep the pads and rotors dry in the rain.

(CCB question answered) . If there's a pad squeezing function in the wet I'd get that checked by the dealer. Let me know if you find that this is a function because in that case I'll also be looking into it.

[SD ///M4]

The fastest, shortest, and safest way to stop in rainy conditions is to use the ABS on your car (all cars have been required to have ABS for years). The proper way to engage ABS is to push the brake pedal to the floor, hard, and leave it there. The ABS will pulse the brakes up to 15 times a second, resulting in the the fastest and safest stop possible, far faster than you can by attempting to modulate the brake pedal.

One of my post-retirement jobs was a driving instructor for a few years. I've also been an Instructor/Coach at the Tire Rack Street Survival events co-sponsored by the BMW CCA Foundation for several years. Although ABS stands for "Anti-lock Braking System", we tell students it also stands for "Allows Braking while Steering". With the brakes locked, ABS allows the tires to rotate enough to allow some directional stability as well. We engage students in various exercises to illustrate this, first on dry pavement, then we wet the surface down using a water truck with a slightly soapy water solution and let them really see how it works. We teach the students how to counter-steer if the back end starts to come around. The condition of your tires also has a huge effect, as well as the water depth. If the tread isn't deep enough to channel away the water, you will hydroplane, and there's not a lot you can do about that.

[Colinv6]

Yes! I've had this several times in very wet conditions (steel brakes) and it's horrible!

Never had this on any of my other cars or other BMW's.

[JohnsonJ718]

I frequently experience this as well, like you with the the non-CCB brakes. If I go for a long period of time without using the brakes on the highway it takes what feels forever for the brakes to work after I press the pedal. I used to feel this in my STi but not to this extent, it can be terrifying. However I am now used to it and periodically scrub my brakes on the highway to keep from having this problem. I guess this is typical?

[04RC51]

I get that with my CCBs but just know enough to pump the brakes before exiting the highway after a long run.

Not sure why the steelies would be having that happen to them?

[minn19]

Originally Posted by RowanBuds

(CCB question answered) . If there's a pad squeezing function in the wet I'd get that checked by the dealer. Let me know if you find that this is a function because in that case I'll also be looking into it.

Just checked the Owners Manual and it looks like the M3/4 does not have the self brake drying feature.

From the manual Page 158:

Driving in wet conditions
When roads are wet, salted, or in heavy rain, press brake pedal ever so gently every few miles.
Ensure that this action does not endanger other traffic.
The heat generated in this process helps dry the brake discs and pads.
In this way braking efficiency will be available when you need it.

[RickFLM4]

I've also seen this with CCBs.

[rr006rbc]

Boy I'm glad southern CA is in a drought. I haven't driven in longer than 10 mins of rain to experience this issue; hope it's not a problem all across the board for steel and CCBs.

Glad you didn't have to make a panic stop.

[joeyb26]

I experienced this yesterday actually. I have the steel brakes as well, it is pretty scary but I found that after initially pushing the pedal if i let go then push it immediately again it seems to bite much better. Kind of like pumping the brakes but not as extreme

[JDubz]

Weird - my 335 is really grabby in the rain. Sometimes I feel like the computer in the car somehow detects the moisture and (over)compensates.

If this is the case, I wonder is it's something like this with the m3 - but gone a bit haywire

[tke743]

Originally Posted by Naz24

I have steel brakes.

I have steels and this is normal for highway driving when you haven't touched the brakes for a long time. True on the 330i zhp and true on the M3. Simple physics, water coats brakes. Brakes need to make heat to stop. Water stops both friction and heat....

Tap them to clear them, then use as normal.

[ben1233]

Originally Posted by JDubz

Weird - my 335 is really grabby in the rain. Sometimes I feel like the computer in the car somehow detects the moisture and (over)compensates.

If this is the case, I wonder is it's something like this with the m3 - but gone a bit haywire

I know my old e92 335i had the brake drying feature. I think it was new back in that generation, thus it got some press in all of the marketing materials. Since then, I haven't heard much about this feature.

Sounds like the F8x's do not have this feature based on the excerpt from the manual above. That is interesting...and it would explain the perceived difference in your 335, perhaps.

[bimmerboyE92]

The 19s are much worse compared to the 18s with keeping the brakes dry in the rain.

[nicknaz]

Originally Posted by bimmerboyE92

The 19s are much worse compared to the 18s with keeping the brakes dry in the rain.

Must be.

I drove on the a bahn in the rain and from pcd to socal in torrential rain and didnt have any issues (steel brakes + 18s)

[dzvero]

Originally Posted by SD ///M4

The fastest, shortest, and safest way to stop in rainy conditions is to use the ABS on your car (all cars have been required to have ABS for years). The proper way to engage ABS is to push the brake pedal to the floor, hard, and leave it there. The ABS will pulse the brakes up to 15 times a second, resulting in the the fastest and safest stop possible, far faster than you can by attempting to modulate the brake pedal.

One of my post-retirement jobs was a driving instructor for a few years. I've also been an Instructor/Coach at the Tire Rack Street Survival events co-sponsored by the BMW CCA Foundation for several years. Although ABS stands for "Anti-lock Braking System", we tell students it also stands for "Allows Braking while Steering". With the brakes locked, ABS allows the tires to rotate enough to allow some directional stability as well. We engage students in various exercises to illustrate this, first on dry pavement, then we wet the surface down using a water truck with a slightly soapy water solution and let them really see how it works. We teach the students how to counter-steer if the back end starts to come around. The condition of your tires also has a huge effect, as well as the water depth. If the tread isn't deep enough to channel away the water, you will hydroplane, and there's not a lot you can do about that.

You are calling for disaster! Never do that in wet unless its last resort ! I wont expect something from person who claims hes instructor bla bla .....
Its ok in the track but not in the road, freeway etc

[FC4]

Originally Posted by SD ///M4

The fastest, shortest, and safest way to stop in rainy conditions is to use the ABS on your car (all cars have been required to have ABS for years). The proper way to engage ABS is to push the brake pedal to the floor, hard, and leave it there. The ABS will pulse the brakes up to 15 times a second, resulting in the the fastest and safest stop possible, far faster than you can by attempting to modulate the brake pedal.

One of my post-retirement jobs was a driving instructor for a few years. I've also been an Instructor/Coach at the Tire Rack Street Survival events co-sponsored by the BMW CCA Foundation for several years. Although ABS stands for "Anti-lock Braking System", we tell students it also stands for "Allows Braking while Steering". With the brakes locked, ABS allows the tires to rotate enough to allow some directional stability as well. We engage students in various exercises to illustrate this, first on dry pavement, then we wet the surface down using a water truck with a slightly soapy water solution and let them really see how it works. We teach the students how to counter-steer if the back end starts to come around. The condition of your tires also has a huge effect, as well as the water depth. If the tread isn't deep enough to channel away the water, you will hydroplane, and there's not a lot you can do about that.

LOL

[trey100]

Originally Posted by JDubz

Weird - my 335 is really grabby in the rain. Sometimes I feel like the computer in the car somehow detects the moisture and (over)compensates.

If this is the case, I wonder is it's something like this with the m3 - but gone a bit haywire

My 335 doesn't grab initially in the rain. I have the MSport brake option which I think may be the culprit. Do you have the standard brakes?

[JDubz]

Originally Posted by trey100

My 335 doesn't grab initially in the rain. I have the MSport brake option which I think may be the culprit. Do you have the standard brakes?

Yep. It's a 2013 with regular brakes... Don't know that they offered the m brakes when I ordered. - I do think it must be the brake drying feature as mentioned above.... Pretty cool.

Weird that the m doesn't have it for whatever reason

[Wills2]

Braking performance on wet roads is appalling in my car, zero bite from the brakes and car veers to the left (a lot) I hate driving on very wet roads in this car.

It seems to completely lose the plot when the roads are wet.