Plaid jumps and undeersteers when sharp turning at 3MPH

[dbeiler]

There are only two reasons why a car will push and hop the front wheels.
1: The front toe alignment is way off. This will cause Ackerman angle to be incorrect while turning. Such severe misalignment would be very evident from extreme tire wear.
2: The more likely scenario: The car is attempting to power wheels that should not be powered during a tight turn. The front wheels must rotate much faster than rear wheels during a tight turn. If the car attempts to power both front and rear motors at the same rate, the mismatch will cause wheel hop. The rear wheels must rotate at different rates. If the car attempts to power both rear wheels at the same rate, the front wheels will hop. Racecars equipped with mechanical LSDs set to a very high preload suffer from this same wheel hop issue.

 

[dbeiler]

I mentioned the "effect" not the angle.

Explaining the "Ackermann Effect" in the 2014 Corvette Stingray - McGrath Auto Blog

If you take the all-new Stingray for a drive, you may notice something before you even leave the parking lot. This little something may seem like a defect, but it’s not. It’s called the “Ackermann Effect”, and although the issue was resolved 200 years ago, Chevy left it alone on the Corvette...

www.mcgrathautoblog.com

The journalist who wrote the quoted article clearly doesn't understand what ackerman really is. This is evident by the repeated usage of the term "ackerman effect" to describe the symptoms of a LACK OF ackerman. He's got it switched.

The C7 Corvette indeed has near zero ackerman front suspension geometry. The tie rod pickup points on the knuckle are directly in line with the knuckle pivot points. This near zero ackerman will absolutely cause front tire hop on tight turns.

Are you suggesting the Model S also has zero ackerman front suspension geometry?

 

[Dangerous Fish]

The journalist who wrote the quoted article clearly doesn't understand what ackerman really is. This is evident by the repeated usage of the term "ackerman effect" to describe the symptoms of a LACK OF ackerman. He's got it switched.

The C7 Corvette indeed has near zero ackerman front suspension geometry. The tie rod pickup points on the knuckle are directly in line with the knuckle pivot points. This near zero ackerman will absolutely cause front tire hop on tight turns.

Are you suggesting the Model S also has zero ackerman front suspension geometry?

Like it or not, the term "Ackerman effect" is commonly used to describe what people like the OP experience.
That was one article out of hundreds I could have posted to demonstrate that.
Sometimes it's just not worth being pedantic when a technically incorrect expression conveys meaning well enough.

 

[trayloader]

Drove the PLAID on the week-end.
Super car, everything refined, and the issue described is IMHO a "nothing burger".
The new car has a MUCH smaller turning radius, and in combination with the wider wheel that´s a normal issue. Every Porsche shows this too.

I prefer this symptom to the lame truck like tuning radius the old models had.

 

[Plaid2021]

So, this is all normal. Cool.

 

[Dan D.]

The thread seems to be leading to a conclusion that this thumping is "normal" for low speed turning, and is the intended design for the suspension and steering systems, or a byproduct of the design.

If that is so, would this put stress on the suspension and steering components, thus perhaps explaining some of the whompy wheel damage seen over the years? In an underdesigned suspension component could this effect be causing premature failure?

If you look at many of the NHTSA Tesla customer complaints, the car was damaged at low speed, often in the driveway. Damage may be initiated at this point, only to fail completely later on, perhaps while driving.

 

[Dangerous Fish]

The thread seems to be leading to a conclusion that this thumping is "normal" for low speed turning, and is the intended design for the suspension and steering systems, or a byproduct of the design.

If that is so, would this put stress on the suspension and steering components, thus perhaps explaining some of the whompy wheel damage seen over the years? In an underdesigned suspension component could this effect be causing premature failure?

If you look at many of the NHTSA Tesla customer complaints, the car was damaged at low speed, often in the driveway. Damage may be initiated at this point, only to fail completely later on, perhaps while driving.

I think you're overthinking it. This happens on lots of different cars including Mercs and Porsches with suspension that can't be described as 'underdesigned' in any way. It's just the tyre scrubbing on the ground. There won't be enough stress or force generated from that to damage anything. In summary, it feels worse than it actually is.

 

[Dangerous Fish]

Had the same issue, showed the service center and they had replaced control arms. Make sure you go on a dry day to present the issue. Good luck!

Your issue was almost certainly not the same as the OP's issue. How old is your MS?

 

[MP3Mike]

The thread seems to be leading to a conclusion that this thumping is "normal" for low speed turning, and is the intended design for the suspension and steering systems, or a byproduct of the design.

If that is so, would this put stress on the suspension and steering components, thus perhaps explaining some of the whompy wheel damage seen over the years? In an underdesigned suspension component could this effect be causing premature failure?

If you look at many of the NHTSA Tesla customer complaints, the car was damaged at low speed, often in the driveway. Damage may be initiated at this point, only to fail completely later on, perhaps while driving.

As far as I know the suspension on the refresh Model S is completely different than the suspension on the older Model Ss.

 

[Dangerous Fish]

Some useful insights in this video

 

[URBAN LEGEND]

All normal.
I had a 2015
Z/28 and 2018 ZL1 with wide Michelin 305 fronts. The hopping is part of the game. Corvettes get the same deal. No biggies.