acadianbob

Here's another hypothesis. If you were traveling in serious rain, your tires may have been hydroplaning. Your ABS probably kicked in. It felt like the car released the brakes due to the hydroplaning. Once you were out of the deeper water, your tires regained traction with the road and you got some braking. I'm thinking that this is why you think the brakes released and then re-grabbed. My bet is that your car is just fine. The answer might be to steer around deeper water and/or slow down in these conditions.

scrmorling

Cruise control can also apply the accelerator if you're slowing down while hydroplaning with alarming consequences. We shouldn't use cruise control in the wet. Steve

acadianbob

Yes, perhaps a little off topic, but also true on ice.

14Q5

Alright, has happened recently again, including on the weekend.

Wetish conditions, braking on a off ramp and the person infront of me jams their brakes. I brake harder and the brakes released and jam, sending my Q5 into a nose dive. Previously happened in hard wet braking.

My thoughts are the wet conditions cause the brake pads to slip (had this issue on my Tiguan) and purging the brakes would clean off the water. In 2013, VW even started advertising this 'new' auto pulse braking feature when the wipers were on, obviously because it was a known issue. I think in the Audi case, the computer sees the brakes are applied, but the brakes are slipping or not slowing at the calculated speed causing the computer to pulse hard. Nearly rear-ended someone because of it. Car nosedives hard.

Its been over a year, maybe someone has encountered this now?

Redd

Coming from the days when disc brakes were a high-end oddity and DRUMS were the norm, I will say that disc brakes "don't" slip in the wet. Compared to the way that drum brakes would and sometimes did stop you on the far side of an intersection after going through a puddle, I would be very curious to actually see an explanation for disc brakes showing any significant "slippage", i.e. for more than one wheel revolution.
But I'll accept anything as possible.

If you are in the US, please contact the national Highway Transportation & Safety Administration at nhtsa.gov and FILE A COMPLAINT. If they receive multiple reports, they can order an investigation and recall. If they receive no reports--NOTHING WILL GET DONE. If you didn't report it a year ago...notice that nothing got done?

There is also a search tool on NHTSA's web site, you can search to see if anyone else has reported this, on other models as well.

Since our brake pedals are just pacifiers, I would expect this to be more of another software glitch issue, that can and should be addressed by a software update across the model line.

FWIW a classic description of hydroplaning is that "the brakes just let go" and there was no brake response. After a split second, an ABS system would then kick in resulting in "no brakes" followed by slamming. Could be perfectly normal for a modern car.

Hydroplaning on water feels just like driving on black ice.

14Q5

I dont think its hydroplaning. Also I have winters on and it began with summers last year.

I did not think of contacting Transport Canada. But i happen to have a good buddy who works there so ill call and see if anything has been reported. Thanks!

14Q5

Went for a drive tonight and got it to replicate in the wet conditions.

https://www.youtube.com/watch?v=Zxk5...ature=youtu.be

14Q5

I took it out last night to get the above youtube video. I tried what you were stating and the car stops without issue. So much so that at points the tires started screeching. Then it started to rain. I was able to replicate the issue 3 times after some highway driving. Once after going through a large puddle. The issue occurred and ABS also kicked in. Second time was entering the on ramp to return back to my area, occured and no abs. Third time (video) the issue occurred cleanly and no abs activated as well. This is what I've experienced before. During the video, the 'thud' is the release and reactivate of the breaks, and the gforce sensor in my camera actually picks up the change. The mount muffles the cam mic, its even louder in the car.

newmoon

Looks like just a SINGLE pulse of the ABS. You may have been braking over a wet patch which was just enough to cause a wheel to lock up for a split second, causing the ABS to release the brakes, then reapply them once the wheel was turning again.

Note that the ABS does not necessarily continuously pulse the brakes. It just works in a feedback loop. If the wheel does not lock up again, then it will not continue to pulse the brakes.

This could be where you are braking just on the threshold of grip so the wheels may or may not lock up, or the road surface is inconsistent (especially in the wet) so the wheels may lock up in one patch, but not a different area.

14Q5

Hmm, so do you think this is normal? I only question because no one else seems to have experienced this.


I'll upload the video of it happening and the ABS kicking in after, because the sounds/feel are completely different.