Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register
  • Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
  • Tesla's Supercharger Team was recently laid off. We discuss what this means for the company on today's TMC Podcast streaming live at 1PM PDT. You can watch on X or on YouTube where you can participate in the live chat.

Braking in rain

This site may earn commission on affiliate links.
Thanks for all the triage efforts on this issue...I have definitely experienced it. I notice it most when I first leave a touchless car wash versus normal driving in wet/rainy conditions.

Yep. Happened to me again coming out of a touchless car wash yesterday. Almost drove into a live line of traffic coming out of the wash when the brakes finally grabbed just as I was at the curb. That really gets the bloodflow going :crying:
 
Yep. Happened to me again coming out of a touchless car wash yesterday. Almost drove into a live line of traffic coming out of the wash when the brakes finally grabbed just as I was at the curb. That really gets the bloodflow going :crying:

Exactly my experience - panicked and nearly standing on the brake when the car wouldn't stop at the curb before ending up broadsiding someone in moving traffic.
 
I believe that this braking issue happens on all cars. Some more than others. My brother had a one car accident due to this issue on a Chevy Malibu. There are two standard solutions that he explained to me. He is a former GM.engineer who designed brakes and transmissions. 1. Holes in the rotors. These are common enough in high end vehicles. They were on the test mule for the Model S. They allow cooling of the rotors and in this case allow water to shed quickly. 2. One can put grooves in the rotors. This can be done to existing rotors cheaply. Sometimes the grooves are on the pads. Either solution works but both decrease cool, dry stopping ability.

I have only noticed this after the car gets very wet and only for a very brief time. I now try to anticipate this lag in braking in wet situations. The dry and moist stopping ability of this car is by far the best I have ever experienced.
 
I believe that this braking issue happens on all cars. Some more than others. My brother had a one car accident due to this issue on a Chevy Malibu. There are two standard solutions that he explained to me. He is a former GM.engineer who designed brakes and transmissions. 1. Holes in the rotors. These are common enough in high end vehicles. They were on the test mule for the Model S. They allow cooling of the rotors and in this case allow water to shed quickly. 2. One can put grooves in the rotors. This can be done to existing rotors cheaply. Sometimes the grooves are on the pads. Either solution works but both decrease cool, dry stopping ability.

I have only noticed this after the car gets very wet and only for a very brief time. I now try to anticipate this lag in braking in wet situations. The dry and moist stopping ability of this car is by far the best I have ever experienced.

I think you are incorrect (sorry not trying to be a jerk). I've never had this happen on my Lexus and my Honda. Never!! (I owned the Honda for 3 years and the Lexus for 7).
 
Bhuwan, I had it happen to me in my Audi A4 in heavy rain a couple of times. Fortunately not in tight situations and no consequences other than momentary panic.

However I recently had an accident in my MS when traffic stopped suddenly on Rt 9W when the exit ramp to 95/128N backed up. I was cresting a small rise at about 40MPH at normal distance behind a pickup. I slammed the brakes but they felt like they weren't gripping, at least at first. The pickup just barely stopped before the van in front of him and I hit the pickup into the van, bending the pickup's rear bumper and denting the van's rear doors. The pickup's trailer hitch went through my nose cone and caused more damage. Nothing structural but lots of expensive parts. Dry roads but I think due to extensive one-pedal driving my brakes probably had a film/buildup of whatever that kept the pads from gripping sooner and possibly avoiding the accident or at least significantly reducing the damage.

This was only the second real panic stop I've done after almost 17K miles. The first, to avoid a large skunk last June, was when I only had 3K or fewer miles on the car and felt completely different. The body shop is currently working on 10 or 11 other MS's and said most of them are similar front end impacts. Seems like a pattern to me - thoughts? Going forward I will use my brakes more, especially after getting wet, and do panic stops every few weeks but I hope Tesla looks at this and develops a better solution.

hazuta5e.jpg
 
I think you are incorrect (sorry not trying to be a jerk). I've never had this happen on my Lexus and my Honda. Never!! (I owned the Honda for 3 years and the Lexus for 7).

This happens on all cars, otherwise BMW wouldn't bother with a brake drying feature:


Now that Tesla has hill hold worked out, maybe they can follow suit and add brake drying next.
 
Last edited by a moderator:
Bhuwan, I had it happen to me in my Audi A4 in heavy rain a couple of times. Fortunately not in tight situations and no consequences other than momentary panic.

However I recently had an accident in my MS when traffic stopped suddenly on Rt 9W when the exit ramp to 95/128N backed up. I was cresting a small rise at about 40MPH at normal distance behind a pickup. I slammed the brakes but they felt like they weren't gripping, at least at first. The pickup just barely stopped before the van in front of him and I hit the pickup into the van, bending the pickup's rear bumper and denting the van's rear doors. The pickup's trailer hitch went through my nose cone and caused more damage. Nothing structural but lots of expensive parts. Dry roads but I think due to extensive one-pedal driving my brakes probably had a film/buildup of whatever that kept the pads from gripping sooner and possibly avoiding the accident or at least significantly reducing the damage.

This was only the second real panic stop I've done after almost 17K miles. The first, to avoid a large skunk last June, was when I only had 3K or fewer miles on the car and felt completely different. The body shop is currently working on 10 or 11 other MS's and said most of them are similar front end impacts. Seems like a pattern to me - thoughts? Going forward I will use my brakes more, especially after getting wet, and do panic stops every few weeks but I hope Tesla looks at this and develops a better solution.

hazuta5e.jpg

Wow that's not cool. And you think this is 100% due to brakes slipping on rain? Unfortunately looking at that photo it looks very dry out that day...
 
Bhuwan, I had it happen to me in my Audi A4 in heavy rain a couple of times. Fortunately not in tight situations and no consequences other than momentary panic.

However I recently had an accident in my MS when traffic stopped suddenly on Rt 9W when the exit ramp to 95/128N backed up. I was cresting a small rise at about 40MPH at normal distance behind a pickup. I slammed the brakes but they felt like they weren't gripping, at least at first. The pickup just barely stopped before the van in front of him and I hit the pickup into the van, bending the pickup's rear bumper and denting the van's rear doors. The pickup's trailer hitch went through my nose cone and caused more damage. Nothing structural but lots of expensive parts. Dry roads but I think due to extensive one-pedal driving my brakes probably had a film/buildup of whatever that kept the pads from gripping sooner and possibly avoiding the accident or at least significantly reducing the damage.

This was only the second real panic stop I've done after almost 17K miles. The first, to avoid a large skunk last June, was when I only had 3K or fewer miles on the car and felt completely different. The body shop is currently working on 10 or 11 other MS's and said most of them are similar front end impacts. Seems like a pattern to me - thoughts? Going forward I will use my brakes more, especially after getting wet, and do panic stops every few weeks but I hope Tesla looks at this and develops a better solution.

hazuta5e.jpg

Wow!
 
Wow that's not cool. And you think this is 100% due to brakes slipping on rain? Unfortunately looking at that photo it looks very dry out that day...

Not due to rain, it was dry. Traffic was moving smoothly and stopped very suddenly with little warning. It was just as the road went downhill and I had even less warning because I couldn't see anything in front of the large pickup in front of me, who just barely managed to stop.


Is this because Tesla's brakes normally get use very little? It may be new situation for brake designers.

I probably would have hit him anyway, but think because the brakes get very little use they were slipping at first and didn't slow me near as much as expected despite stomping on them. The other driver and I could see intermittent tire marks on the road so it was clear my ABS was active just before I hit him, but initially it felt like the brakes weren't grabbing. My local SC manager suggested doing a panic stop every 2-3 weeks to ensure they are clean. The other possibility is if there was air in my brake lines. Once the body work is done they are going to inspect my brakes at the SC.
 
This happens on all cars, otherwise BMW wouldn't bother with a brake drying feature:


Now that Tesla has hill hold worked out, maybe they can follow suit and add brake drying next.

That's really interesting. Wouldn't help coming out of a car wash, but would be handy in more dangerous highway travel. Plus it seems like we already have all the sensors and things required to make it work. Cool stuff.
 
Very sorry to see your accident, PeterK.... glad you are OK however.

While I can say that I've never had braking performance diminished when the brakes are dry (and I use regen for the vast majority of my deceleration needs...), this wet performance is different than any other disk brake car I've owned: Toyota Avalon, Volvo Sedan, Mercedes E Class, Toyata SUV's, Toyota Celica, Nissan Coupes, etc...

I think the combo of metallic brake pads and the rapid oxidization their resulting dust produces not being scrubbed off due to regen allows them to hold a water layer such that other cars don't...
 
It used to be that most cars with disc brakes positioned the pads just so the surfaces of the pads kissed the rotors. No real hard contact, but just a nominal gap of zero. This will constantly wipe any water film off the surfaces of the rotors. But tolerances being what they are, the pads would often touch the rotors and provide the slightest bit of drag. I suspect what many are experiencing is that Tesla purposely has dialed in more of a gap (for less drag) and a water film is able to form on the rotor.

As for the car-wash-being-worse example, I've had this on most cars and I think it's the soap/treatments sprays being much more slippery that plain dirty rain water.
 
What service bulletin? Have a link? I've searched for a service bulletin on this issue and can't find one. I thought service bulletins of this nature had to be listed with NHTSA.

Does Tesla keep some of the service bulletins silent/secret? I thought service bulletin disclosure was required.

No link available but two TSB were applied today to my car. Here is a copy:

Concern: Customer states: Replace front brakes due to wet slipping and add dust shield if car


does not have them.


Corrections: Brakes Discs & Calipers General Diagnosis


performed sb-14-44-001


Corrections: Install Rear Dust Shields, Front Brake Pads Without NVH Masses, and Front


Rotors With As-Cast Outer Hats


performed sb-14-33-001, installed rear dust shields, installed updated front pads and


rotors


Parts Replaced or Added


Part Quantity


SVC FR BRAKE ROTOR W/ AS-CAST


OUTER HAT (1025099-00-A)


FR BRAKE PAD & NOISE SHIM KIT


(6006429-00-B)


RR BRAKE ROTOR DUST SHIELD LH


(6006432-00-A)


RR BRAKE DUST SHIELD RH (6006433-00-


A)

So basically the fix entails new rotors with a different outer hat, new pads without NVH mass dampeners and rear dust shields.

I'll test it with next rain but I can say that the loaner I have today brakes much better than mine in dry condition so maybe I had some other issues.
 
I just had my annual service and the brake pads were replaces with a new type of pads for this specific problem (sorry don't know the details about the exact kind of pads). It just happened to be raining on the way home. The brakes definitely feel better, including on the highway. How much of this is just due them being new brakes I don't know, but so far very happy with them. I'll see if they continue to do well in future rain storms.

I was told they are going to be shipping these new pads to the service centers but mine got shipped overnight since I was having this problem and the car was already there for the annual service. Great job by Erick at the Rockville Service center.
 
All,
This morning I had the poor braking in rain issue return. It took me by surprise since I have not had any problems for a long time and the pads and discs had been replaced by Tesla. Basically after driving on the highway in steady rain (no brake use) in almost freezing conditions I slowed down at a traffic light but the brakes would engage only very softly. Scared me to hell but I avoided hitting the car in front of me. Will bring it up on my upcoming service. May be a good practice to dry the brakes by applying some pressure before you actually need them. Be careful!
 
Last edited: