P3D Braking scare in the wet...

[Orizu]

I live in BC. And it rains here a lot at this time of year. The other night I drove home in a big rain storm. It’s about a 30min drive on the freeway. At one point towards the end of the drive I had to brake fairly suddenly when someone moved unexpectedly into my lane. The brakes were not responsive at all. I was pretty scared. Brakes seemed OK later on the same drive if a little softer than I am used to still. Has anyone else had this problem? I read something similar on an old model S thread in here - seems the brakes can get unresponsive if they get really wet and perhaps aren’t used as much owing to the regenerative brakes doing the work most of the time

 

[Ames]

One thing that I have noticed with 3 years of Model S driving, is that because I hardly ever use the brakes I end up accidentally pressing both pedals during emergency braking!

What happens is that I tend to place my heel in one spot and just rotate my foot to brake. Since the brake pedal is closer than the accelerator, this works fine with light braking; I could go a year or more without ever needing to press the brake beyond the level of the accelerator. Recently and within a period of three weeks I had two incidents where I had to slam on the brakes. I felt that the car wasn't responding quickly enough and also heard a Tesla warning beep. To me it felt like the braking performance was very poor and that there must be something wrong with the car. Anyway, things quickly went back to normal but when it happened a second time I realized what I had done.

Thankfully the car is programmed to cancel power in this situation, but not immediately. That is why the braking feels poor (and scares the hell out of the driver).

I have had to retrain myself on how I slam on the brakes with this car with a few practice runs!

Of course your problem could be completely unrelated...

 

[ewoodrick]

If the wheels aren't on the ground because of water, there isn't anything that the traction control can do.
A boat just steers like crap.

 

[TANGO SUKKA]

happened to me in dry weather once. had to hit the brake hard but was only getting ~50% braking power.. then the emergency braking kicked in and it bit down hard. never had the issue again, but it still scared me.

 

[mswlogo]

If the wheels aren't on the ground because of water, there isn't anything that the traction control can do.
A boat just steers like crap.

I don't know how the car behaves in these conditions. But it could warn it's sensing poor grip before it gets to bad.
It could also slow power to wheels that have grip until the one that lost grip gets back in sync.

Of course lots of common sense applies too.

 

[fluxemag]

My house is a short distance from the freeway, so in the mornings I end up on the freeway with cold brakes. Then I drive for 10 minutes in heavy rain fairly often. When I get to the off-ramp I've got cold, wet brakes that hardly work at all when first pressed. This has been the case on my Model S, BMW 428 and Model 3. It only takes one firm stop to get them up to operating temp.

 

[Msjulie]

Often when driving in rain, water gets between the pads and the disc - bits are in place to help prevent this but it's not 100%. I've gotten into the habit of pre-pressing the brakes when on side streets, in anticipation of an actual stop, to help squeegee off the water.. that process won't help the emergency braking situation though.

Also might be worth using your brakes (more than just a little) maybe once a week or so? depending on how much rust/etc can build up on the rotor in your local weather. I love regen/1-pedal driving but I do try to remember to try and keep the rotors clear/cleaned.

 

[JasontheBeaver]

I live in BC. And it rains here a lot.

I fixed that little error you made there. Just removed the "this time of year."
But seriously, you bring up a great point about cold wet brakes trying to stop a car at freeway speeds. That sounds disconcerting!
I know race car drivers are reminded to warm up their brakes when they're coming in for a pit stop.

 

[Msjulie]

I know race car drivers are reminded to warm up their brakes when they're coming in for a pit stop.

Sure you don't mean when they enter the track? Cold brakes coming into pit lane was never an issue I had

 

[JasontheBeaver]

Sure you don't mean when they enter the track? Cold brakes coming into pit lane was never an issue I had

I should've been more clear... oval track race car drivers are reminded to warm up their brakes when coming to pit lane. Nice catch!

 

[Orizu]

Often when driving in rain, water gets between the pads and the disc - bits are in place to help prevent this but it's not 100%. I've gotten into the habit of pre-pressing the brakes when on side streets, in anticipation of an actual stop, to help squeegee off the water.. that process won't help the emergency braking situation though.

Also might be worth using your brakes (more than just a little) maybe once a week or so? depending on how much rust/etc can build up on the rotor in your local weather. I love regen/1-pedal driving but I do try to remember to try and keep the rotors clear/cleaned.

Thanks I am going with this advice. I think this was the problem. It was pouring rain and I don’t think I had used the brakes much at all (the actual brakes not the regen). Going forward I am going to tap them a bit more often especially in the wet and see if this helps. Cheers

 

[Stan007]

The same problem is experienced with motorcycles. If it's cold out and you haven't used your brakes for a while you always need to drag them lightly to warm them up to get good stopping power.