I wasn't specifically talking about IRS or beam in my last post. You are correct about the IRS. I was refering to the same car, winter vs. summer, over the same roads, with or without IRS. In most cases, differences in ride and handling is noticeable by temperature...to me, at least.

Perhaps, in your case, your LS460 is such a smooth car to start with that you don't notice any significant difference between summer and winter. You do notice, however, with some products.

 

If its REALLY cold at first the LS will ride a little harder, but that goes away once its warmed up.

 

Anyhow, I'm going to take your advice LOL. I'm about done on this subject. Jill and the others can argue it.

 

I highly doubt you are correct. An engineer would likely have the answer and more than likely there is little difference. You Verano is creating so much friction, resistance and generating so much heat rolling down the road that different temps outdoors will likely have the slightest if any affect on the car.

 

So much fuss about the rear suspension of the Astra / Verano / Cascada, just to get the facts wrong and incomplete. No, these Delta II platform cars do not ride on an independent rear suspension but they don't ride on a solid rear axle either; they ride on a simple and elegant (by virtue of their simplicity) semi-independent twist beam (or torsion beam) rear suspension.

The design allows some independent movement of the two wheels relative to each other but they are joined so are not completely independent. In fact, look at an independent suspension with an anti-roll bar: Without the bar joining the two wheels there may be too much body roll during cornering, especially at higher speeds and on rougher roads. The bar joining the two wheels is nothing but a torsion bar, just like the torsion beam in the twist beam suspension. With the bar joining the 2 wheels, the independent suspension becomes less independent, but the ability of the torsion bar to twist along its length allows some independent movement of the wheels relative to the other while still being joined, which reduces roll. This is what the torsion beam offers.

The twist beam suspension is not only cheap to produce, but it is simple, with far fewer parts prone to wear and break (it is durable, increasing reliability). It is light in weight and it is a neat, compact package that takes up very little space under the rear cargo floor. It is this reason why the early VW Rabbits / Golfs (including the GTI) model rode on a twist beam rear suspension until Ford's Control Blade rear suspension in the late-1990s Ford Focus proved that an independent rear suspension could be compact, and simple and cheap to build, and forced VW to offer IRS on its Golfs.

These reasons -- inexpensive, durability and reliability, compact package -- make it the ideal suspension for a price-sensitive compact or sub-compact car (or even a mid-size car, as evidenced by early Nissan Maximas).

 

We don't have it incorrect, a torsion beam suspension is still a solid rear suspension, and you still have all the handling drawbacks we've discussed (this is the "modern" nature of the suspension mmarshall discusses). It's still an economy suspension setup, and not something that you would find in a premium vehicle.

 

I understand the unsettled aspect of live axle. Never seen it described as busy.

 

Unsettled and busy sort of mean the same thing.

 

A "busy" ride, in auto-speak, usually means a significant number of up/down motions over uneven surfaces.

 

A twist beam / torsion beam suspension is not (despite a similarity in name) a solid beam suspension.

A twist beam is designed to twist along its length, thus transferring some of the movement of the wheel under compression to the other wheel; this is the anti-roll effect. When one side of the suspension is compressed, the twisting force of the torsion beam transfers some of that compression to the other side, preventing roll and also largely maintaining the camber of both wheels. This is safer than the action and reaction in a solid beam axle.

A solid beam is solid and not designed to twist, so the compression of one wheel causes the exact, equal and opposite reaction on the other side; this causes massive roll of the vehicle. This roll motion is fine off-road but not wanted on-road. When one side is compressed and the other side stretched, wheel camber is also greatly changed; this is not as safe as an (semi-) independent suspension.

The torsion beam suspension is a simple and elegant (by virtue of its simplicity) design. No, it will not do everything that a true independent suspension will do, but for the mass-market compact cars on which it is offered, it does a good enough job.

 

Not quite, but close enough. When I refer to a solid rear axle in a FWD Passenger car I'm referring to a torsion beam suspension, that's what basically all of them are. No doubt it does a good enough job on mass market compact cars, my point is when buying a "premium" Buick, which they claim to be you want an ideal setup, not an economy car suspension that does a good enough job. Their selling proposition and reality are different things.

In a Corolla I wouldn't care, it's just basic transportation, but they're trying to say that this is a premium car...in our Prius I didn't care...but even Toyota has moved the Prius from a torsion beam to an IRS setup.

A solid rear on say a truck is also "semi independent". The two sides of the axle do not react in an exact equal way.

 

way off topic and enough said. closed.