Taycan Brakes fail in wet conditions - NHTSA complaint March 2, 2023

[bluegrassvroom]

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to help see if your car has this issue....
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i have had this happen going straight on roadways - i'm talking 0° of turn in the road

HOWEVER, driving through a puddle while doing a sharp turn (1-3 mph) - or driving through a puddle THEN doing a sharp turn (like a U-turn) - THEN your next stop will do this (if your car is afflicted with this issue)

When i was with the service tech, we found a fairly empty parking lot, with a 1-1.5" (2-4cm) deep puddle - would drive through it, then do a U-turn and the next stop wouldn't stop.

i have a deep puddle coming out of work, but if i hit it going straight it doesn't tend to happen, only if i go through it then take a hard turn - THEN that next stop won't engage. IN MY HEAD - there are sensors of some sort slightly off to the side of the tire, and when the tire is turned it kicks enough water onto them to trigger them, then for some reason they disable the braking - but going straight doesn't tend to put enough water on them to get them to trigger.

Again - i hope your car ISN"T afflicted - but that's what does it on mine.

we're not talking submerging the car - this is the puddle that does it for my car

 

[DerekS]

******************************
to help see if your car has this issue....
******************************

i have had this happen going straight on roadways - i'm talking 0° of turn in the road

HOWEVER, driving through a puddle while doing a sharp turn (1-3 mph) - or driving through a puddle THEN doing a sharp turn (like a U-turn) - THEN your next stop will do this (if your car is afflicted with this issue)

When i was with the service tech, we found a fairly empty parking lot, with a 1-1.5" (2-4cm) deep puddle - would drive through it, then do a U-turn and the next stop wouldn't stop.

i have a deep puddle coming out of work, but if i hit it going straight it doesn't tend to happen, only if i go through it then take a hard turn - THEN that next stop won't engage. IN MY HEAD - there are sensors of some sort slightly off to the side of the tire, and when the tire is turned it kicks enough water onto them to trigger them, then for some reason they disable the braking - but going straight doesn't tend to put enough water on them to get them to trigger.

Again - i hope your car ISN"T afflicted - but that's what does it on mine.

we're not talking submerging the car - this is the puddle that does it for my car

Ok since you have a repeatable scenario:

What happens if you press the brake twice?
Not pumping like crazy, just tap, release, tap+hold.

I learned back in driver's ed a million years ago to pump the brakes if they don't respond.

 

[FlyingPoint]

Known issue - from the Taycan manual:

"Be aware of braking behavior in rain or snow
In heavy rain, while driving through water or after
leaving a car wash, the brake disks are coated with a
water film, the braking action may be delayed and
increased pressure may be required."

 

[Dee]

I would like to know what Porsche did to solve the "issue".
Did they change the brake pads to see if that makes a difference?
They may be glaced during run-in, maybe even stuck on the disk, this will surely be a reason for poor performance when braking on "wet" and cold brake disks.
Are there any color differences/marks on the disks?

Is the ABS unit faulty? (it may engages way too early on wet brakes)
Are you able to engage the ABS when you push hard on the pedal when the brakes are dry on a warm and clean road? (you can feel it when it does).

 

[Pope]

In my experiences with similar cases, inspecting the discs usually provides enough evidence as to the cause. The friction surfaces gets slimy.
Essentially, the water and salt - and all the other things that can be mixed into a liquid on the road - coats the disc and pad faces and the end result is a coating that the combination must 'cut' through before friction is realised.

Here in the UK we throw fantastical amounts of rock salt on the roads and that seems to cling especially well in the conditions following a cold, damp spell (most of the rest of the year?!)

The condition seems to build up - the surface area of the brakes on the car is massive - consistent use of the car in certain conditions eventually leads to the need to 'clean' the discs; general use enables enough friction surface to remain usable but it's also noticeable that owners that brake later and harder seem to not suffer theeffects at all. I have inspected discs on cars with the complaint that they have failed completely and found there to be almost no unaffected friction surface remaining - entirely coated in a slimy, slick liquid - but after a drive intended to 'clean' the brakes the friction surface is restored and the brakes return to their specified performance.

Where we have Fording crossings there are signs saying 'dry your brakes'; it's not a new issue, but the blended application of the brake systems IS new and it is another thing that needs to be considered when driving.

The cumulative effects of consistent use in certain conditions; combined with the efficient, usually primary braking, regen system gives more chance of experiencing the 'whoah' moment. Sometimes a fog-horn type noise created through resonance from the mechanical brake as it tries to bite through the coating as the car stops is heard - the brakes need help; from the driver.

In the case above with the puddle scenario, are the brakes entirely clean before driving through it or are they already affected by prior conditions?

 

[Tucks TS]

I'm glad there's a complaint. Maybe Porsche will actually look into it.

I've witnessed a few times that the brakes didn't engage nearly as much as expected and I had a distinct "long pedal feel" followed by a panicky slamming of the brakes. Always happened to me during conservative driving early in the morning, in the cold and wet (ie when the car is 'cold soaked'). Not very reproducible, I'd say it happens about once a month when driving daily here in the PNW winter.

The reason that I'm not running to get it fixed is simple: the only thing I get from dealers is "well, we've never heard of this before" and "when we drive the car around the block it works fine".

I've had it happen often enough, and I've heard others report it frequently enough that I believe it to be real. If I had to guess, under some circumstances the car thinks it's getting enough regen braking so it doesn't "boost" the conventional braking, but in these situations regen braking actually isn't doing enough to slow down the car (bc of the cold). Then when it does pull in enough 'conventional braking' the disks are wet/cold/rusted and take a split second to get up to temp.

IIRC Tesla also faced an issue where the auto-regen braking in some cold conditions had unexpectedly weaker braking. I wouldn't be surprised if this is the kind of stuff all the different companies need to work through as they launch their EVs. Where Porsche is different from Tesla is that Tesla has the actual brake pedal always skip past regen into normal braking, so Tesla avoids the "oh shit" feeling when the actual brake pedal seems to be too weak.

Unfortunately, this has happened to me a number of times when it is raining.

 

[Dr.Ericthedrill]

I have a similar issue with my 4S.
It does not matter if its wet or not.
I get this spongy feeling in the brakes at low speeds.
It seem to affect the last few inches of pedal travel.
For example, in a car park or when I am approaching an intersection, as I almost some to a complete stop the last bit of brake pedal travel goes spongy requiring me to really press hard to stop the car.
The dealer said it was a servo problem and replaced mine under warranty.
Now it seems fine.

 

[Dee]

I would like to know what Porsche did to solve the "issue".
Did they change the brake pads to see if that makes a difference?
They may be glaced during run-in, maybe even stuck on the disk, this will surely be a reason for poor performance when braking on "wet" and cold brake disks.
Are there any color differences/marks on the disks?

Is the ABS unit faulty? (it may engages way too early on wet brakes)
Are you able to engage the ABS when you push hard on the pedal when the brakes are dry on a warm and clean road? (you can feel it when it does).

Still waiting for a reply.

 

[charliemathilde]

You're lucky enough to live in a relatively rain-free part of the country, assuming your Monterey is CA. (But you're unfortunately in California as well) You get less than HALF the nation's average rainfall, and one-third what i get. Also, according to the statistics and professionals, there are fewer downpours there, more like light rains and spritzes.

ahahahahahahahahahahahahahahahaha

you wrote that in March 2023 ? After we’ve had more storms and rainfall since … historical records began ?

ahahahahahhaha

ps we know the issue hasn’t caused accidents because there are no NHTSA reports of such. Better fucking believe I’d file one if I believe the car failed me and I needed to fork over my deductible

 

[charliemathilde]

I have PSCBs and my experience has been the same. But I’m going to purposely do some more rain driving during the coming storms and see if I can trigger it.

either his particular unit is defective / in need of maintenance / or he’s just not braking hard enough. I drive PCCBs in the cold and rain, on the taycan and 911. The blended brakes have a different feel which I consider compromised for regen. Both need some extra pressure under poor driving conditions.

in the rain, hit the pedal harder. There’s no great conspiracy. Blended brakes on other cars are much much worse.

 

[charliemathilde]

******************************
to help see if your car has this issue....
******************************

i have had this happen going straight on roadways - i'm talking 0° of turn in the road

HOWEVER, driving through a puddle while doing a sharp turn (1-3 mph) - or driving through a puddle THEN doing a sharp turn (like a U-turn) - THEN your next stop will do this (if your car is afflicted with this issue)

When i was with the service tech, we found a fairly empty parking lot, with a 1-1.5" (2-4cm) deep puddle - would drive through it, then do a U-turn and the next stop wouldn't stop.

i have a deep puddle coming out of work, but if i hit it going straight it doesn't tend to happen, only if i go through it then take a hard turn - THEN that next stop won't engage. IN MY HEAD - there are sensors of some sort slightly off to the side of the tire, and when the tire is turned it kicks enough water onto them to trigger them, then for some reason they disable the braking - but going straight doesn't tend to put enough water on them to get them to trigger.

Again - i hope your car ISN"T afflicted - but that's what does it on mine.

we're not talking submerging the car - this is the puddle that does it for my car

when she’s really wet, she needs it harder

 

[Domy69]

This weekend I did a Porsche Experience session. Throughout the day, the brakes are applied very hard. At one point on the circuit (after only 15min of circuit) I also had this situation, only once. After that I didn't have it anymore. At high speed on the circuit I pushed the brake harder and everything went very well

My feeling was to think that there was a problem with the regenerative brake and when you push harder and the mechanical brake takes action it brakes very hard and very well.

I don't think this is a major safety risk but Porsche should have a look into it anyway as it is not normal.

 

[Marmolata]

reading this thread, bit sad that some people are always so aggressive.

Anyway, I have the white caliper brakes, and have, so far absolutely zero issues. In fact in was pouring rain today and did some testing. I would say the brakes work as well as 911 brakes. Just be aware you are stopping a 2+ ton machine. It will feel different than stopping a 911 or 718.

 

[bluegrassvroom]

{snip}
in the rain, hit the pedal harder. There’s no great conspiracy. Blended brakes on other cars are much much worse.

oh golly gee, thanks. so pressing in the pedal 1" and wishing really really hard for the car to break doesn't do it?? wow i must be an idiot.

this is from my very first post on this issue: https://www.taycanforum.com/forum/t...i-die-please-have-my-family-sue-porsche.9048/

"I HAVE TO LAY ON MY BRAKES SO HARD, THAT MANY TIMES, THE GREEN HOLD IS LIT ON MY DASH AFTER ATTEMPTING TO STOP. (if you didn't know - if you're stopped, and then press the brake pedal even harder, a green HOLD lights on the dash, you can take your foot off the pedal, and your car will sit there and not slowly inch forward)"

 

[DerekS]

Please get your car fixed or make them buy it back. This is not normal.