Unsettling behavior under hard braking

[BTFPTM]

I do stay at the Holiday Inn Express once in a while.
Might not be a joke you understand as it might be only a USA commercial.

I certainly do know this joke, I may live in Germany and speak german but I'm as American as apple pie and the president's epic hair-do. I've even stayed at a few Holiday Inn Expresses myself

Thanks for the continued feed-back, guys!

It's also good to hear someone else chime in who has a similar problem. And yes, it is damned freaky at 200kmh when the nose starts pulling left and right. If this is actually a result of the electronics that are supposed to improve stability, whatever engineer programmed this needs to be beat with his own Birkenstocks.

I'll do the tie rods as I have time, and I'll work with lower pressures and see if it helps. And as someone else also mentioned, I have in fact had the feeling that the tail seems to float, so maybe that'll solve that one, too.

I had first suspected a sticking caliper, too, as someone also mentioned, which is why after I did the rotors and pads I had VW do a complete flush and bleed of the system to rule that out. The new parts did make the problem less extreme, but didn't eliminate it completely, same as with the tires.

Thanks again, guys, I'll keep workin on it and report back.

 

[drrck]

The other thing I was thinking of is here:
https://drivetribe.com/p/performance-vcds-tweaks-Dky7b-PTQpqIwVFrasMoeA?iid=CjMS5X6_Q7igNwstTVI_VQ



The "Straight ahead brake stabilization" setting is known to cause this unsettling behavior. I coded it out before getting this car on track, and I have no issues with normal brake use coming down from ~110mph repeatedly at track days.

I also would vote for this. I have tracked my car with this on and off and much prefer it in the off setting.

 

[donefor]

If this is actually a result of the electronics that are supposed to improve stability, whatever engineer programmed this needs to be beat with his own Birkenstocks.

Haha, yes unfortunately this is true. On the Mk6, there are combinations of steering position sensor and rates that can cause an "implausible signal" fault and subsequently remove power from the steering rack! We recognize that not all combinations can be tested for, but to pull the plug on the rack is just a bad decision in any situation.


Thanks to everyone for pointing out the "straight ahead brake stabilization" setting, another thing to make sure's off...

 

[BTFPTM]

Hi everyone,

It's been an age since I posted, I thought I'd close out this old post I put up in case it helps others here.

As folks have posted above, I tried a bunch of stuff to rule out possible causes of the scary braking.

- Adjusted tire pressure to 2.4 and 2.5 bar, didn't change anything with braking but it did help, as someone here mentioned, with the feeling that the tail was floating. So thanks for that, at least one improvement was made.

- Both lower ball joints replaced, both inner tie rods replaced, both outer tie rods replaced. Didn't change a thing. Ruled out mechanical stuff.

- Experimented with the suspension settings, and discovered that the "normal" shock damping setting was significantly more stable under braking than the "race" setting. In other words, the car otherwise in "race" mode but with "normal" shock damping braked notably better. It was very obvious that weight shift under braking was better this way, even in sweeping highway curves. This leads me to believe that the race setting is too stiff for fair- to poor-quality road surfaces which are often the case in Germany (most highways are several decades old). The suspension literally can't react quickly enough to uneven surfaces because the dampers in race mode are too stiff which amplifies the effects of the straight-line braking stability system which is probably panicking because it notices that the two front wheels are changing speed differently over the varying road surface.


I never did get to try deactivating the straight-line-stability system, sadly I don't have the car anymore (will post on that in a bit), but doing that and testing the normal- and race-mode damping settings again would be an interesting experiment. In the mean time, for those who also have this problem with their similarly equipped GTI, put the suspension in normal mode with everything else in race mode and see what you think.

Hope this helps, and hope everyone is staying safe and healthy in these wacky times.

 

[rbboutback]

Hi, last year i bought a 2013 mk7 gti performance. I started to notice exactly the same issue when breaking hard. The tyres had only a few thousand kms left so eventually i got michelin ps4. The problem remained. Then I changed brake rotors and pads, but did not solve it. I started investigating about new shocks, bushings ,..but after reading your post I used obd eleven to deactivate "straight ahead brake stabilization". Took the car to the highway and after a few hard brakings from 130km/h i noticed a big improvement. No side to side movement! Its too good to be true, so i'd like to test it more extensively, but in any case your post was a great help. Ruling out mechanical parts can be expensive and time consuming. Thanks!