Braking in the wet with Mission E wheels

[Squire1976]

My Taycan has recently been back at Porsche after I went straight over a roundabout when my brakes failed in the wet . They said there was air in the brakes and all would be fine . They did the recall also whilst it was in but said that wasn’t an issue .
I’ve since been out again in the wet and the brakes didn’t work unless fully pressed and then there was a huge crunching noise after a delayed slow.
I’ve seen a few threads on this but has anyone ever got Porsche to actually do anything or do I just need to accept the car is crap in heavy rain ?
thanks and I promise I am not a terrible driver , I’ve had other fast cars and never had a problem like this .

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[BjörnfromHamburg]

Are we talking about the brand, well known for providing one of the best brakes on production-cars since forever?
No, of course you cannot accept this.

 

[Squire1976]

Are we talking about the brand, well known for providing one of the best brakes on production-cars since forever?
No, of course you cannot accept this.

Helpful !!! Thanks Bjorn

 

[SergeyIndy]

Could you help understand what brake setup you have assuming PSCBs with MissionEs. What is your tire tread depth? Also, have you done the ARB0 brake hose campaign and PSM campaign that has full brake fluid flush and reprogram of the brake blending.

Also, when you say brakes did not work, the car only using physical brakes when cold for a short period of time and then at very low speeds. Otherwise it is all Regen. Do you see the green Regen bar when you are braking when going about the round about.

I live in a round about land and tires are key in having good grip on round abouts. However, I have to say that when it is wet the grip is not very good on perfectly good all season Conti tires, so I do not push it. I do not use brakes when I am on a round about already as I have PDCC and PTV+ that do the work.

 

[Travis]

My Taycan has recently been back at Porsche after I went straight over a roundabout when my brakes failed in the wet . They said there was air in the brakes and all would be fine . They did the recall also whilst it was in but said that wasn’t an issue .
I’ve since been out again in the wet and the brakes didn’t work unless fully pressed and then there was a huge crunching noise after a delayed slow.
I’ve seen a few threads on this but has anyone ever got Porsche to actually do anything or do I just need to accept the car is crap in heavy rain ?
thanks and I promise I am not a terrible driver , I’ve had other fast cars and never had a problem like this .

I am experiencing the same thing in cold-wet conditions when first driving and using the brakes. I apply brakes which feel like they have no grip, it takes a long time to bring to slow like the brakes have no friction, then a loud grinding/rubbing sound from the pads. This happens “mostly” at slow speeds under 10 mph, like approaching a stop sign at a slow speed and hit brakes to fully stop but just end up keeping rolling, push brake pedal extra hard, loud noise ensues and car jerks to a halt, it looks like I don’t know how to brake. It’s quite a problem as it’s cold and wet in NE USA right now.

 

[Squire1976]

Could you help understand what brake setup you have assuming PSCBs with MissionEs. What is your tire tread depth? Also, have you done the ARB0 brake hose campaign and PSM campaign that has full brake fluid flush and reprogram of the brake blending.

Also, when you say brakes did not work, the car only using physical brakes when cold for a short period of time and then at very low speeds. Otherwise it is all Regen. Do you see the green Regen bar when you are braking when going about the round about.

I live in a round about land and tires are key in having good grip on round abouts. However, I have to say that when it is wet the grip is not very good on perfectly good all season Conti tires, so I do not push it. I do not use brakes when I am on a round about already as I have PDCC and PTV+ that do the work.

Hi - recalls all completed and tyres are 6mm tread so all good . You are correct it’s not at high speeds I get the issue it is when I try to come to a stop and the physical brakes have to kick in , I bought the car in July and had no issues at first but I live in Manchester where it rains about 150 days a year and since November it’s lost all the enjoyment as I don’t feel secure coming up to traffic lights or roundabouts etc in the wet in case again it overshoots the stop line again.

I am experiencing the same thing in cold-wet conditions when first driving and using the brakes. I apply brakes which feel like they have no grip, it takes a long time to bring to slow like the brakes have no friction, then a loud grinding/rubbing sound from the pads. This happens “mostly” at slow speeds under 10 mph, like approaching a stop sign at a slow speed and hit brakes to fully stop but just end up keeping rolling, push brake pedal extra hard, loud noise ensues and car jerks to a halt, it looks like I don’t know how to brake. It’s quite a problem as it’s cold and wet in NE USA right now.

sounds like you have the same problem , it really ruins the experience , the recon braking does the first part of slowing perfectly but it’s the actual stopping that’s an issue on mine , but so far only when it’s raining hard and especially if I’ve been on a motorway and had lots of surface water hitting the wheels .
If you find a solution let me know as it’s killing the experience of owning a Porsche for me . Thanks

 

[f1eng]

If I understand it there is a specific bleeding procedure for the blended braking system and these symptoms are exactly what you would expect if there was air in the system.
My brakes are excellent so it certainly isn't inherent in the Taycan. This type of fault has been reported by a few people and IIRC bleeding properly fixed it.

 

[f1eng]

If I understand it there is a specific bleeding procedure for the blended braking system and these symptoms are exactly what you would expect if there was air in the system.
My brakes are excellent so it certainly isn't inherent in the Taycan. This type of fault has been reported by a few people and IIRC bleeding properly fixed it.

Just a note to say maybe only a Porsche dealer has the right kit, but I may be wrong, the procedure is more involved than normal brake bleeding and I don't know where air gets left in the system if done in the wrong sequence.

 

[SergeyIndy]

I agree with @f1eng about air in the system could be the issue. Also, this sounds like hydroplaning as tires are not able to channel the water. What is your tire setup?

 

[Travis]

This is definitely not hydroplaning or air in the system as the braking issues are in very specific conditions and repeatable. There is TSBS about the issue and my understanding from reading many many threads on here is there the issue is inherent of the Taycan (and blended braking in general) and that is can be “improved” with tuning the brake booster.

 

[Flying ace]

A lot of variables at play, here are the possibilities:

Does this only happen in the wet? What about subsequent braking after the first brake?

- park outside? Could be environmental sediments (water, dirt) settled on rotor surface. This will only affect initial braking. After surface has been scrubbed by first braking session, car should behave normally. I get similar initial lack of brake feel after I wash the car.

- change brake fluid again, there could be air in your lines.

- PSCBs, PCCBs, steel?. Each feels differently in their initial bite. I have PSCBs and first braking on a cold day squeals and have friction sounds. Still a hard bite.

-low tread tires, though based on your description it doesn't sound like a tire issue.

 

[Gkwan]

I am experiencing the same thing in cold-wet conditions when first driving and using the brakes. I apply brakes which feel like they have no grip, it takes a long time to bring to slow like the brakes have no friction, then a loud grinding/rubbing sound from the pads. This happens “mostly” at slow speeds under 10 mph, like approaching a stop sign at a slow speed and hit brakes to fully stop but just end up keeping rolling, push brake pedal extra hard, loud noise ensues and car jerks to a halt, it looks like I don’t know how to brake. It’s quite a problem as it’s cold and wet in NE USA right now.

Damn, that's exactly how it felt on my last 50km round city trip.
It's my 1st sportscar, 0 experience so I thought it was just me doing something wrong, or my feeling wasn't correct but what you describe is exactly how it felt.
I've had my Turbo since 24th Dec, braking incredibly well in cold (-4 / +5°c) + dry conditions - even on a small layer of snow it was ok despite having no winter tyres.
But then came a few days with ~0° + fair amount of rain, and then what you described happened to me, several times.

Today, 35km roundtrip, ~11°c + very moderate rain : no problem, brakes are like the 1st time I experienced them and was impressed.

A new headache? lol....damn

 

[Travis]

I still have the issue. Anytime it’s cold below 40F and moderate to heavy rain my car literally can be tough to stop. I have to pump the brakes often when driving. I get caught off guard frequently going to apply the brakes and expecting the normal breaking performance and the deceleration is WAY slower so then I have to really slam on brakes and can lock them up.

 

[Gkwan]

I still have the issue. Anytime it’s cold below 40F and moderate to heavy rain my car literally can be tough to stop. I have to pump the brakes often when driving. I get caught off guard frequently going to apply the brakes and expecting the normal breaking performance and the deceleration is WAY slower so then I have to really slam on brakes and can lock them up.

really dangerous, you can't go on like this

 

[SergeyIndy]

Braking performance has been a topic for some time. These are common things you can do.

- Check that you have had the Brake system recall completed if that applied. This results in full Brake fluid flush and calibration. I did that and observed the process, and I can say that straight line stopping braking performance improved.

- OEM tire on my 21-inch Mission Es are Continental All Season. They seem to be very slippery when new or when not warmed up, however, under slippery conditions such as rain, snow, or when pushing them around sharp corners, they do not have much lateral grip.
++ Adding: I have PTV+ and PDCC and that still cannot overcome poor lateral grip when for example coming out of not too tight highway merging loop. This kind of caught me off guard when the rear slipped and swerved.

- Straight line stopping under slippery conditions is just physics as the car develops a lot of forward momentum, so do not expect short stopping distance and keep plenty of room in front. However, what you can do to help with that is use Auto regen during those conditions that will help slow down the car well in advance when a vehicle in front is detected.

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