Chassis Theory: Understanding Vehicle Suspension

Hi.

I have a question about suspension systems.

Let's assume we have two vehicles that are almost identical:
- same weight
- equal weight distribution

o only the suspensions are different (in terms of stiffness and height).

Is it true that the tendency for a tall, soft vehicle to "pitch backward" when starting causes its wheels to spin more easily than those of a different vehicle?

My tractor, with almost new Bilstein B4 gas shock absorbers with standard characteristics, spins all the wheels because it can't transfer the 250 Nm of torque to the road.

"Does a different firmware really offer a solution here?"

"Thank you."
m;

Yes, that's correct. Lowering the center of gravity reduces the dynamic axle load variation, which in turn minimizes the tendency to pitch forward during acceleration or backward during braking in a lowered vehicle.

Is it true that the tendency for a tall, soft vehicle to 'pitch backward' during acceleration causes it to spin out more easily than a different type of vehicle?

My tractor, with almost new Bilstein B4 gas shock absorbers with standard characteristics, spins out because it can't transfer the 250 Nm of torque to the road.

'Does a different firmware really offer a solution here?'


Hi Martin,

Your assumption is absolutely correct!

The higher and therefore lighter muzzle rotates more easily/quickly.

But honestly, you wouldn't actually want to install a new suspension system for that reason, would you?

Best regards, Georg.

@ Georg

I've been incredibly frustrated since "the Box" incident, especially because in the spring of 2003, I had four series mufflers installed.

At that time, I had a choice, and I didn't want to go deeper, because I also wanted to be able to drive through a field and plow it sometime.

If I had known that the box with the new dampers would still be so unstable, and that it would become almost undrivable with the tuning and 5 people on board, I would have at least had the factory-length but stiffer B6 sport dampers installed.

"This weekend, I was driving through the rainy city of Bonn with 5 other people, and the 185 Winter tires immediately started spinning whenever I even looked at the gas pedal."
Already fully engaged - 1500 RPM - oh, it could be a little faster - tap the accelerator - SHRUBB SHRUBB SHRUBB.

It's incredibly annoying, especially when driving in a straight line, but it becomes extremely uncomfortable when turning.
(and it also works with the 195-size summer tires).

I simply have too much torque (and no traction control).

m;

Oh, oh oh.

It's not beautiful anymore, and more importantly, it's not safe anymore.
It can quickly end in a 'disaster'!

Did you also notice, especially when accelerating in curves, that the heavy rear end had a significant impact on the light and nervous front end?
The car becomes almost undrivable in wet conditions because when the rear wheels spin, the front end steers instead of the driver.

Okay, be very careful!

'Stiffer shocks wouldn't have made much of a difference, as they don't really affect the axle load distribution. Instead, you should get better tires; I see the most potential for improvement there in the short term. Otherwise, lowering the car would help. Also, adjustable control arms and a strut brace in the front could make a difference.'

I'm familiar with the issue with my Fabia and its approximately 310 Nm of torque, but I don't need to use the ASR (Anti-Slip Regulation) very often.

The worst-case scenario of a fully loaded car is and remains always unpleasant. However, you can feel that in the gas pedal...

Better tires??

Okay, I understand your point about the Uniroyal MS Plus 5, but the Continental PremiumContact tires are already "very good" in the summer.

Are you doing well?

Well, then I guess I can't accelerate as much... that's a shame .

m;

Better tires??

Okay, I understand your point about the Uniroyal MS Plus 5, but the Continental PremiumContact tires are already 'very good' in the summer.

Are you doing well? A better option would be the Dunlop SP Sport 8000 or 9000, or whatever the current model is called... Since I need to get new winter tires this year, I'll probably go with the Conti WC TS 780, which is supposed to be quite good...


Well, then I guess I can't accelerate as much... too bad .

m; Also, it also saves costs...

Tires don't do anything. Unless you put on bigger ones, like 16" or at least 195s in the winter. I had the same problem with the old 1Z. It would even spin on dry pavement in the digital tachometer at 1600 RPM in 3rd gear with thin 185s winter tires. Okay, the 10c was also really wound up .

The new car has a Bilstein coilover suspension, while the old one had the standard suspension. With the 195/50 tires in the summer, it's rare to be able to let the wheels spin even when starting from a standstill, whereas with the old car, it was no problem. With the winter tires in 185/60R14, it's easier, even in second gear with the standard engine output (the new car is not tuned). However, it's only within a reasonable range and for a very short time. My car doesn't exhibit any noticeable body roll with the new suspension, which was quite noticeable in the old one.

Since you probably have a version with a softer suspension, it might be a good thing that it's even more pronounced there with the standard suspension. Besides, the car will naturally have a slight tilt when fully loaded, which is not ideal for the traction of the front-wheel-drive system.

Otherwise, consider lowering it by 30mm with stiffer dampers, and add sway bars and possibly strut braces. However, you should choose a slightly less aggressive lowering setup, for example 30/15, because your Variant might otherwise visually appear as if it's constantly fully loaded in the rear .

I should have taken the B12 - a friend of mine took it with Variant - at first, it was too harsh for me - but now this monkey business is really getting on my nerves.

Well, the next one will be better...

m;

Tires don't do anything. Unless you put on bigger ones, like 16' or at least 195 size in the winter. I had the same problem with the old 1Z. It would even spin on dry roads in drive mode at 1600 RPM in 3rd gear with thin 185 size winter tires. Okay, but the 10c was also really revved up :DYeah, of course...

Well, get a car with rear-wheel drive; then the 'tipping' can even be an advantage .

Hello.

Okay, so my G3 AFN + 10ct also spins through the second gear even in wet conditions.
However, purely from a physics perspective, a stiffer suspension will not significantly minimize this effect. The weight on the front axle decreases considerably during acceleration, regardless of the incline.
While the weight distribution should generally become more negative again at high VA (voltage amplitude), those few centimeters of tilt might be enough to compensate for a few kilograms.
However, if the stiff shocks/springs don't absorb as much energy, you'll have better traction on dry roads.
Every mountain biker knows how much energy is absorbed by the suspension systems that could otherwise be used for propulsion.

ObenbeiMutti wrote:

Every mountain bike rider knows how much energy that could be used for propulsion is absorbed by the suspension systems.

Yes, but only because the foot pushes the entire bicycle downwards instead of the crank.

Does a car have a hand crank? Or does your G3? *facepalm*

I've been incredibly frustrated since 'the Box' incident, especially because in the spring of 2003, I had four series mufflers installed.

At that time, I had a choice, and I didn't want to go deeper, because I also wanted to be able to drive through a field and plow it sometime.


Hmm, if you hadn't wanted to lower the car significantly, I would have recommended the adjustable Koni (red) shocks. I've installed them twice in a Golf 4 because the drivers didn't want a very low ride, but they wanted less body roll and less nose dive during acceleration and braking. I personally don't think it's the best solution, but it does provide a fairly comfortable ride.

What's also an option are the anti-roll bars from Eibach, but they only reduce body roll.

My tip:
Install the Eibach Pro-Kit; it lowers the car by about 30mm, but the handling will be excellent again, and you'll be able to put the torque back on the road. You already have new shocks, which is a very good starting point.

@ wolfi

Ultimately, it doesn't matter what forces are pushing downwards on the dampers.

It shouldn't be the case with cars that a portion of the energy from each crankshaft cycle flows into the dampers, that's obvious. It was just an example, related to bicycles.
Certainly, the electric kinetic energy (E-kin) is converted into heat within the damper, and raising the front of the vehicle may, in some cases, additionally convert some of the E-kin into unnecessary electric potential energy (E-pot).

Therefore, as someone from a working-class background, I'm considering optimizing the acceleration of my car at traffic lights by using an extremely stiff suspension system.

(But I'm keeping it as close to a production model as possible, and that's not going to change. I also want it to be suitable for unpaved roads and comfortable to drive.)

Disable the 10ct function when it's raining, and engage second gear at 1500 RPM.