pkh

The other day after finishing a track day at Thunderhill I had been driving back for around 2 hours, I ended up going down a bumpy road and started to come to a stop at an intersection. As I was slowing to a stop the entire steering wheel started shaking pretty violently (wheel going back and forth a full inch either direction several times a second.) The shaking seemed to be coming from the steering wheel but the whole car seemed to shake as well, it also was making a pretty nasty noise.

This started when I was slowed to less than 5mph and continued while I was fully stopped. The clutch was pushed in all the way. I had PASM off, SPORT button on, ESC + TC was enabled (button to disable not pressed.) No errors or warning lights flashed.

The shaking continued for maybe 10 seconds while I was figuring out if I should turn the car off (wish I thought to get video) then the light went green and when shifted into gear and let the clutch back out everything went back to normal. No more problems the remaining 1 hour of drive.

My intuition tells me its maybe something with the electrical power steering system? I dropped it off at BR Racing which was my plan anyway, and they were going to take a look. Some small google searches didn't turn anything up I could fine. Anyone hear of something like this?

ajw45

Yes! I had something similar happen to me on a wet skidpad. Steering freaked out while coming to a stop (sidewaysish) and continued chattering/vibrating back and forth for a few seconds. Turned the car off and on, everything was fine, no codes shown when I did a scan later. Seriously turned me off electric steering and I started looking at buying an older car for like a week after. That was over two years ago though and it's never happened again so I had totally forgotten about it till now.

pkh

Well good to hear that I'm not crazy at least! Its amazing it doesn't throw some sort of error code. I can only imagine how bad it would have been if I had actually been driving at speed and something like this happened.

venom51

It's just part of the GT car charm and ze fine German engineering.

GT3Bob

Ah, the nanny state! When I added excessive (in their mind) camber to the GT4, making it "Circuit Ready", the steering would pulse like mad when trail braking heavily into a slow corner (125 > 45 mph hairpin, lots of steering input). Violent, and felt like the front end was coming apart. And... this also happens when parallel parking over rough pavement. Embarrassing when bystanders in Park City think you're 'breaking the car'.

Porsche put a sneaky bit of software in the steering rack that cannot be disabled by ESC+TC. Ever. (Well ... it can be disabled, but that's a different story and comes with a host of other challenges). It's an "Intuitive Pulse Control" (or something like that - they have a name for it). This was announced by Porsche for the Cayenne/Macan models when Vanina Ickx tested one for the Christophorus Magazine article late 2017 (or 2016?) ... if anyone remembers the article, there was an overhead series of shots of her drifting through snow in a controlled slide.

When the roll, pitch, and yaw sensors see something they dislike, the "Counter Steer Control" gently aids the driver in opening the wheel. Uh huh, right. The programming genius behind this believes that by adding a 'counter-pulse' to the wheel, the driver will reduce the steering input, and all will be magically right with the world. i.e. .. no spin or crash.

Me? Rather than slow down and use less steering angle, we knocked back the camber 0.5 degrees. Problem mostly solved.

pkh

Very interesting! I do have pretty aggressive camber 3.6 F 3 R - what camber did you arrive at when you reduced .5 degrees?

GT3Bob

Ha - virtually the same. I had moved up to an aggressive 3.5 F, 3.0R. Dropped back to 3.1F, 2.7R, and oddly enough, really haven't seen a difference in front/rear tire wear. Lap times did not change. It really did reduce the wheel vibration under braking, (although it did go crazy on me parking a few weeks ago).

Do you have the headlight washers as an option? Apparently that ECU is different in hardware structure than the non-washer ECU . The three other GT4's in the shop do not have the headlight washers, and they do not have the steering vibe... (Both washer cars do have the problem).

pkh

@GT3Bob - yeah no headlight washers - I have been thinking about going back to less camber but I do like the way the car handles with camber now, seems like it still handles well after tires get too hot whereas before it was super slidey

I do think braking could be better with less camber- but I don't really have any hard data to support that

So far the crazy wheel shake has only happened once and it wasn't on track so I may just tough it out and see what happens

orthojoe

Happened to me twice on my .1 GT3. Both times were on gravel or rough road, tight turning. Pretty dramatic and unnerving, but goes away if you just shut down the car and restart. It must have something to do with electric steering getting confused.

Spyerx

125shifter

Not a GT4, just a 2014 CS but today I hit a speed bump leaving work at about 10 mph and the steering wheel started shaking violently. It continued for a second or two until I touched the brakes. Car has 52k miles, I’ve had it since new, drive it pretty hard and started tracking it a couple years ago. I was thinking suspension wear and tear but this thread and others have me wondering about the steering rack. Any more suggestions?

Space Coast GT3

This issue is not that uncommon. Actually occurs pretty often after track sessions when running Hoosiers. Seems the computer can loose track of the electronic steering sensor limits. Turn ignition off, then back on, then drive a tight figure 8 in each direction. The steering will recalibrate and your good to go for a while. Of course easier to do a few figure 8’s in the paddock than on the road.