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

[Clod Reed]

This morning after heavy rainfall, I was going 80 KMH coming up to a stop sign intersecting a major highway. There was a 1/4 inch puddle that caused my regen to turn off and hydraulic brakes to become "unboosted" I almost blew right through the intersection. If I was speeding slightly, I would be T-boned.

This was my first "high-speed" experience with failure, and I'm scared now. My wife was petrified.

But what away to go

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[mikestyle]

But what away to go

Your right, its much better to die in a Porsche than a civic.

 

[dtich]

Just curious, if you search your VIN, does this recall show up on it or no? NHTSA site says 45 complaints and 12 recalls related to this. My VIN does not trip these recalls.

 

[mikestyle]

Just curious, if you search your VIN, does this recall show up on it or no? NHTSA site says 45 complaints and 12 recalls related to this. My VIN does not trip these recalls.

My car is Canadian, so I'm not sure its accurate. Is there a Canadian NHTSA equivalent?

 

[TDinDC]

But what away to go

You mean as the subject of a viral TikTok video over the soundtrack "I'm comin' in hot . . . "?

 

[Tooney]

My car is Canadian, so I'm not sure its accurate. Is there a Canadian NHTSA equivalent?

https://tc.canada.ca/en/road-transp...t-canada-can-investigate-your-safety-concerns

https://tc.canada.ca/en/road-transportation/defects-recalls-vehicles-tires-child-car-seats

 

[Crick]

I think it may be related to https://static.nhtsa.gov/odi/tsbs/2022/MC-10217260-0001.pdf ?

"The customer complains that the brake pedal travel is subjectively perceived as “too long” just before the vehicle comes to a standstill (< 12 km/h (7.5 mph))."

https://www.taycanforum.com/forum/threads/tsb-brake-pedal-travel-perceived-as-“too-long”-just-before-the-vehicle-comes-to-a-standstill-july-22-2022.12517

discussed here in the thread as well - i've definitely had it happen

This is exactly the experience that I have. It is scary when it happens - having to run the brake pedal much farther than expected hoping the vehicle will stop. Not confidence inspiring.

Approaching a stop with light to moderate pedal pressure from normal speed. Then if one feathers the break peddle (lift a little to reduce the breaking action) to prevent premature stopping, the brake pressure is lost and one must depress the brake significantly farther (which can be 'to the floor') to stop the vehicle.

 

[cccmanhattan]

Digging up an old topic here, but has anyone had any resolve on this?

I have a CT4S with PSCBs

For some context, I've been around the block on brake issues on my car, it's been back probably half a dozen times and spent over 100 days in service to solve the soft pedal issue. After the booster and ABS unit being replaced multiple times and having the system bled and rebled, the pedal behavior improved. Later I had an issue in the rain where the ABS didn't activate, the brakes locked and I barely avoided a car that pulled into my lane. This was fairly repeatable with the front left locking and the other wheels seemingly doing nothing, so I showed it to my dealer and they replaced the ABS unit again, seemingly fixing it this time.

Recently, I was having the issues described here in the rain, where the care would roll further than expected as it transitioned from regen to friction and then violently grab the brakes when I pushed harder on the pedal. What is new in this scenario now is that the brakes also shutter / groan and send a violent reverberation through the cabin (video attached). The sound in the video doesn't really capture it, I know that sounds like the ABS actuating, but it's more of a groan from the discs accomponied by vibration through the front of the car. This happpened first, multiple times at the end of a 35 minute commute home, although, admidetly the first time it happened was probably the fist time the friction brakes had to engage on the drive. It was still happening the next morning and I was planning on taking it straight to the dealer, but after 4-5 stops on the way in, it went away.

With this last rain, I was able to experiment a bit, replicate it and then "cure" it. It was doing it's thing when I first got in the car, so I made a few deliberate stops on the way down my road making sure to engage the discs and come to complete stop. Each time the groan got quieter and by the 5th time the brakes were quiet and feeling good.

I'm thinking this is largerly the post car was phenomenon, but it's made worse by virtue of the fact that our cars don't use the friction brakes that often and worse again by the PSCBs which have a lower coefficient of friction and are likely more subject to glazing and bad behavior when their cold.

I'm now wishing I saved the $$ and got the standard brakes.

Since running my 5-stop experiment the brakes have been working well and the pedal feels better than ever, so I guess I'll make that a bit of a routine thing to do when it rains or periodically to really bed the brakes. I do wish Porsche would come up with a solution though and while the brakes are feeling better and more confidence inspiring, I still hate the noise and pedal vibrations that you get when the servos that engage the discs are turning to catch up to the pedal travel. One of the main things that's been part of Porsche's identity for decades is fantastic brakes and pedal feel and we just don't have that yet with the Taycan.

 

[bluegrassvroom]

i drive like a granda's grandma in the rain to avoid having this issue

i went a LONG WHILE without heavy rains - and there were a few updates - i thought it was fixed with an OTA update. but alas - i did experience it again in the last month or so

what chaps my @$$ the most about this - is the HEAD service guy at the local dealer rode with me, experienced the issue - then he drove my car, replicated it himself - then took another car from the lot - we experinced it. He called me later to say he replicated it in a different customer's car

months later - Porsche got back to him - 'operating as designed'

[insert world's largest face palm]

sounds like you're having different issues than did i - mine were solely, 100%, absolutely, positively in the rain. NORMALLY after going through a decent amount of water (or a puddle) then taking a turn - BUT it has happened on straight roads in traffic

we replicated it by finding a decent puddle coming out of a parking lot (2 inchers deep, i think) near the dealer, going through it, then immediately after it doing a U-turn, and the brakes would not work for that U-turn and sometimes the next stop as well. drove in probably 40 circle that day in the different cars replicating it

 

[cccmanhattan]

For me, the most recent issue which sounds a lot like yours is in the rain, or cold damp mornings where you can imagine there is condensation on the brakes. While I've only had one shot at running my experiement bedding the brakes, it did seem to work well. It seems that Porsche, particularly with the PSCBs, needs to make some kind of automatic bedding procedure that it condtucts periodically while giving you some indication of what's going on with a message on the dash. Basically do what I'm doing, but forcing the car to use the discs more for the first 5 stops after it's been wet. I know it does something like this on the first drive of the day, but it seems there could be an extended version with a bit more information for the driver so you know what to expect.

That and while the mirror finish on the PSCBs looks cool, I just don't think it's the right brake for thecar.

 

[cccmanhattan]

So more rain today and fairly cold and my brakes are behaving normally and the pedal is firm and consistent. I'm really thinking my reset, the 5 deliberate stops to bed the brakes helped and maybe recalibrated something between the pedal, booster and calipers.

The reality is I mostly just focus on driving smooth, not racing up to every stop sign and slamming on the brakes so I'm probably barely using the friction brakes in most conditions. With that being the case, I can see that they'd get glazed and behave poorly when you need them. Maybe that's further aggravated by PSCB brakes being lower friction on top.

I'll keep at it and post updaes once I've had month or so of regularly bedding the brakes.

 

[bluegrassvroom]

*******************************************
FOR THOSE EXPERIENCING THIS IN THE USA
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i was the one that made the the original report to the NHTSA. if you're experiencing this or HAVE experienced this and Porsche hasn't or won't fix it - then why don't each of you report to the NHTSA?

Don't be an A____ h____ and go straight to the gov't agency - give Porsche a chance first. But there's enough people who've experienced this that I can't believe it hasn't been fixed. The head of my local Porsche dealer's service dept was with me and drove y car and at least two others and reproduced it. It's a thing

i NEVER heard back from NHTSA but maybe if they get several more complaints on the same issue they couldn't ignore it.

There's also another way to escalate it further i didn't pursue. But i guess is should do that as well

 

[cccmanhattan]

*******************************************
FOR THOSE EXPERIENCING THIS IN THE USA
*******************************************

i was the one that made the the original report to the NHTSA. if you're experiencing this or HAVE experienced this and Porsche hasn't or won't fix it - then why don't each of you report to the NHTSA?

Don't be an A____ h____ and go straight to the gov't agency - give Porsche a chance first. But there's enough people who've experienced this that I can't believe it hasn't been fixed. The head of my local Porsche dealer's service dept was with me and drove y car and at least two others and reproduced it. It's a thing

i NEVER heard back from NHTSA but maybe if they get several more complaints on the same issue they couldn't ignore it.

There's also another way to escalate it further i didn't pursue. But i guess is should do that as well

I'll keep testing it, but I honestly feel like I've cracked it with the recent bedding procedure. When it first happened to the extent that I recently experienced, it was really bad, dangerous and annoying. I was ready to take the car back to Porsche and consider giving it back entirely, but it cured itself before I was able to get it there.

This is somewhat inline with what Porsche says in the owners manaul on how the brakes will rely on friction only when you first start out to bed the pads and that PSCB is subject to the need for bedding to a greater effect.

I'd say they're probably aware of it and have put those two notes in the manual to cover the bases, without highlighting how bad it is at the edge cases or laying out the more extreme bedding procedure you need to remedy it when the brakes are cold, wet and possibly glazed.

It would make sense for NHST to respond and for Porsche to issue a TSB on how to remedy it, but I imagine the public won't accept that their brakes could be shit on occassions unless they take on a fairly extreme bedding procedure in their first couple of miles of travel and I can't think of a good way that they can remedy it on existing cars unless they swap out to steel brakes... and if they do that, they'll then have complaints of corrosion.

With all that being the case, I doubt we'll see a solution offered by Porsche since it's a can of worms for them to admit it.

I imagine we'll see new brake technologies developed specifically for performance EVs.... think something like the PSCBs that won't corrode, with a different surface treatment or pad to give it more bite when the brakes are cold and wet. Having been to a Brembo seminar at the Porsche Experience center where they were showing off the evolution of PCCBs from the old black carbon to the new ones that are coated and look almost like steel, I would be surprised if Porsche and Brembo don't already have something in the works.

 

[bluegrassvroom]

I made a few deliberate stops on the way down my road making sure to engage the discs and come to complete stop. Each time the groan got quieter and by the 5th time the brakes were quiet and feeling good.

so am i paraphrasing correctly - jam the _____ on the brakes 4-5 times when you first get into the car, and you haven't experienced it since doing that?

i've had this brake issue happen at the end of a medium length trip when the other 15 stops were fine, i am fairly certain it's rain (or water of any sort) build-up in a sensor on the wheel well that tells the mechanical brakes not to engage (for some reason). One key facet to the problem i've had - The brake pedal goes "soft" or "limp" as some people have described it. Have you experienced that during your issues? I also haven't found the issue to happen in just cold - only during a medium to heavy rain (or driving through puddles after a rain)

i don't know that doing what you've described would make a stop 15 stops after that work better - walk me through your logic on that? also - several people without the PCCB's have reported this as well

I'M ALL FOR DOING WHAT YOU'VE SPELELD OUT to prevent my imminent death. I just want to understand it fully. I'll start my rainy day journeys doing that and drive with confidence - and report back

 

[cccmanhattan]

so am i paraphrasing correctly - jam the _____ on the brakes 4-5 times when you first get into the car, and you haven't experienced it since doing that?

Not so much jamming on the brakes. It's tricky since to some extent, no matter how hard you brake the car slows 100% with regen until the last bit where you need to come to a complete stop. I belive in normal braking the regen stops and the discs take over <5mph. So with that, I pulled out of my driveway and went down my road with no traffic behind me, coming to a normal and complete stop a few times, making sure theat I continued to press on the pedal below 5mph when the discs were engaged to come to complete stop. After about the 5th time it cleared.

i've had this brake issue happen at the end of a medium length trip when the other 15 stops were fine, i am fairly certain it's rain (or water of any sort) build-up in a sensor on the wheel well that tells the mechanical brakes not to engage (for some reason). One key facet to the problem i've had - The brake pedal goes "soft" or "limp" as some people have described it. Have you experienced that during your issues? I also haven't found the issue to happen in just cold - only during a medium to heavy rain (or driving through puddles after a rain)

I have experienced a soft pedal or it dropping a bit before grabbing and stopping violently just beffore I would have hit something. That was last year's brake issue and different from what I've been talking about here more recently in the rain. Porsche has a TSB out on the "long pedal travel" issue and mine went back several times, for weeks at time to get this fixed. They first bled the brakes and it got better for a bit, then the problem returned. They then replaced something (brake booster or ABS module) as the TSB stated and once again, it got better for a bit, but then returned. The next time i brought it back, they bled the brakes again, but when it still wasn't 100% right made the spurious claim that there were still "mircro bubbles" in the lines and they didn't have the right, $10,000 machine to bleed the brakes properly. I didn't really buy that, but took it as a sign that that dealership wasn't equipped to fix it. I took it to another dealer, that bled the brakes again may have replaced some of the same parts again and that problems was finally resolved. A few months later, i had the left front wheel lock up without any ABS intervention and almost rear ended someone. I took it back to them again, was able replicate the issue consistently with their tech in the car and they eventually replaced the ABS module again and it's since been working.

So, that's a long winded way to say if your pedal is going soft, it's different than the recent poor braking behavior I've had in the rain and you may have something else going on. Could it be something like a wheel speed sensor with cracked connector, getting wet and letting the wheel keep spinning as some kind of false ABS intervention? Maybe, but they should be able to check that and someone with better knowledge of the ABS system should know what the failure mode is.

i don't know that doing what you've described would make a stop 15 stops after that work better - walk me through your logic on that? also - several people without the PCCB's have reported this as well

I'M ALL FOR DOING WHAT YOU'VE SPELELD OUT to prevent my imminent death. I just want to understand it fully. I'll start my rainy day journeys doing that and drive with confidence - and report back

When this most recent issue happened, I had driven my full commute home and it happened as I was getting off the highway, which was likely the first time I came to a complete stop and used the discs so the amount of driving you do beforehand or before rewetting the brakes probably doesn't matter.

This morning after a thorough soaking overnight, I fully expected for the brakes to be acting up again and thought I would have to rebed them again as I did over the weekend, but they were fine. i don't really know how to explain that other than possibly the brakes had built up some kind of glazing and rebedding them knocked that off. The pedal also feels better overall, so I'm thinking the multiple repeated stops somehow recalibrated the pedal.

I can't say for sure this has fixed it for good, but it's rainy all week and through the weekend here, so I'll keep playing around with it and see if it returns.

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