Why no rear-engine RWD cars anymore?

Don Stauffer wrote:
> 223rem wrote:
>
>> My first car (a Renault Gordini) was RWD and had the engine where the
>> trunk of modern
>> cars are. From an engineering standpoint, this is the simplest
>> configuration.
>> Is there a reason for it being abandoned? (I know that Ferrari, etc
>> still use it).
>
>
> A rear engined car tends to oversteer. Oversteering is more dangerous
> than understeering unless the driver is VERY proficient. Ralph Nadar
> did in oversteering cars with his attacks on VWs and Corvairs. Liability
> won't let mfgs sell oversteering cars to general public now.
>
> The oversteer was due to generally rearward weight bias of rear engined
> cars. It is quite difficult to engineer out the oversteer with such a
> weight bias.

Understeer means you slide into the ditch face first.
Oversteer means you slide into the ditch backwards.
AWD means you slide into the ditch on your roof.
4wd means you get stuck in the ditch so far you have to wait until spring.

Understeer is only "safe" because when people do the natural reaction to
a slide (get off the gas) a car that understeers will begin to regain
steering control. For those of us with lead feet, oversteer is the way
to go.

Ray
(I coulda been a drifting champion...)

In article <74qEf.311858$tl.224488@pd7tw3no>, ray wrote:
>Don Stauffer wrote:
>> 223rem wrote:
>>
>>> My first car (a Renault Gordini) was RWD and had the engine where the
>>> trunk of modern
>>> cars are. From an engineering standpoint, this is the simplest
>>> configuration.
>>> Is there a reason for it being abandoned? (I know that Ferrari, etc
>>> still use it).
>>
>>
>> A rear engined car tends to oversteer. Oversteering is more dangerous
>> than understeering unless the driver is VERY proficient. Ralph Nadar
>> did in oversteering cars with his attacks on VWs and Corvairs. Liability
>> won't let mfgs sell oversteering cars to general public now.
>>
>> The oversteer was due to generally rearward weight bias of rear engined
>> cars. It is quite difficult to engineer out the oversteer with such a
>> weight bias.
>
>Understeer means you slide into the ditch face first.
>Oversteer means you slide into the ditch backwards.
>AWD means you slide into the ditch on your roof.
>4wd means you get stuck in the ditch so far you have to wait until spring.
>
>Understeer is only "safe" because when people do the natural reaction to
>a slide (get off the gas) a car that understeers will begin to regain
>steering control. For those of us with lead feet, oversteer is the way
>to go.
>
>Ray
>(I coulda been a drifting champion...)

A guy on a BMW forum has this sig:

Oversteer is when the passengers are scared!
Understeer is when the driver is scared!



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As I understand it, jacking adds more oversteer because the added
weight transfer to the outer wheel results less total grip at the back.

If you like trying to steer while backing up, that is, positive
reinforcements of your steering inputs, you'll love oversteer.

No one has mentioned susceptibility to sidewinds as a rear engine
disadvantage.

And Porsche has more or less engineered the problem away, but at great
expense.

AZ Nomad wrote:
> On Thu, 02 Feb 2006 09:06:19 -0600, Don Stauffer > wrote:
>
>
>
>>223rem wrote:
>>
>>>My first car (a Renault Gordini) was RWD and had the engine where the
>>>trunk of modern
>>>cars are. From an engineering standpoint, this is the simplest
>>>configuration.
>>>Is there a reason for it being abandoned? (I know that Ferrari, etc
>>>still use it).
>
>
>>A rear engined car tends to oversteer. Oversteering is more dangerous
>>than understeering unless the driver is VERY proficient. Ralph Nadar
>>did in oversteering cars with his attacks on VWs and Corvairs.
>>Liability won't let mfgs sell oversteering cars to general public now.
>
>
> Oversteer wasn't the only reason nadar had it in for the corvair. The corvair
> also had swing axles and nasty tendancy to flip over when cornered too hard.
>
> I didn't know nadar also had it in for the VW.

The type of swing rear axle used on both the Corvair and VW bug
contributed to their oversteer. He took on VW before he went after the
Corvair. The Super Beetle used a low pivot rear axle to reduce the
handling problems.

I guess I oversimplified when saying the oversteer problems of the VW
and Corvair were due to rear weight bias. It was also due to their
somewhat primitive suspensions also, which kind of exaggerated the problem.

ray wrote:
> Don Stauffer wrote:
>
>> 223rem wrote:
>>
>>> My first car (a Renault Gordini) was RWD and had the engine where the
>>> trunk of modern
>>> cars are. From an engineering standpoint, this is the simplest
>>> configuration.
>>> Is there a reason for it being abandoned? (I know that Ferrari, etc
>>> still use it).
>>
>>
>>
>> A rear engined car tends to oversteer. Oversteering is more dangerous
>> than understeering unless the driver is VERY proficient. Ralph Nadar
>> did in oversteering cars with his attacks on VWs and Corvairs.
>> Liability won't let mfgs sell oversteering cars to general public now.
>>
>> The oversteer was due to generally rearward weight bias of rear
>> engined cars. It is quite difficult to engineer out the oversteer with
>> such a weight bias.
>
>
> Understeer means you slide into the ditch face first.
> Oversteer means you slide into the ditch backwards.
> AWD means you slide into the ditch on your roof.
> 4wd means you get stuck in the ditch so far you have to wait until spring.
>
> Understeer is only "safe" because when people do the natural reaction to
> a slide (get off the gas) a car that understeers will begin to regain
> steering control. For those of us with lead feet, oversteer is the way
> to go.
>
> Ray
> (I coulda been a drifting champion...)
Understeer is stable, though. That is, the problem is that you are
trying to drive around a corner at a radius at which the lateral
cornering power of the car is less than the centrifugal acceleration at
that speed and radius. With an understeering car, the car will only
plow till the turn radius increases to a point where the cornering power
is equal to the CF. It will then be okay. This is true even if driver
takes no corrective action.

With an oversteering car, one MUST initiate corrective action to the
problem. It will NOT recover by itself. Oversteering seeks an even
tighter radius, where CF is even higher than available cornering force.

wrote:

> No one has mentioned susceptibility to sidewinds as a rear engine
> disadvantage.
>
> And Porsche has more or less engineered the problem away, but at great
> expense.
>
The sidewind problem in the bug was enhanced because the aerodynamic
design of the bug had a very forward center of pressure, well ahead of
the CG. If the design had more lateral area in the rear, as with FINS,
it would have helped greatly.

In article >, Don Stauffer wrote:
>AZ Nomad wrote:
>> On Thu, 02 Feb 2006 09:06:19 -0600, Don Stauffer > wrote:
>>
>>
>>
>>>223rem wrote:
>>>
>>>>My first car (a Renault Gordini) was RWD and had the engine where the
>>>>trunk of modern
>>>>cars are. From an engineering standpoint, this is the simplest
>>>>configuration.
>>>>Is there a reason for it being abandoned? (I know that Ferrari, etc
>>>>still use it).
>>
>>
>>>A rear engined car tends to oversteer. Oversteering is more dangerous
>>>than understeering unless the driver is VERY proficient. Ralph Nadar
>>>did in oversteering cars with his attacks on VWs and Corvairs.
>>>Liability won't let mfgs sell oversteering cars to general public now.
>>
>>
>> Oversteer wasn't the only reason nadar had it in for the corvair. The corvair
>> also had swing axles and nasty tendancy to flip over when cornered too hard.
>>
>> I didn't know nadar also had it in for the VW.
>
>The type of swing rear axle used on both the Corvair and VW bug
>contributed to their oversteer. He took on VW before he went after the
>Corvair. The Super Beetle used a low pivot rear axle to reduce the
>handling problems.
>
>I guess I oversimplified when saying the oversteer problems of the VW
>and Corvair were due to rear weight bias. It was also due to their
>somewhat primitive suspensions also, which kind of exaggerated the problem.

Again I'll plug for Autozine Technical School
http://www.autozine.org/technical_school/, an excellent resource. On
http://www.autozine.org/technical_sc...uspension2.htm
they explain graphically why the swing axle suspension induces oversteer.

--
/"\ Jan Kalin (male, preferred languages: Slovene, English)
\ / http://charm.zag.si/eng/, email: "name dot surname AT zag dot si"
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On Fri, 03 Feb 2006 08:19:24 -0600, Don Stauffer > wrote:


wrote:

>> No one has mentioned susceptibility to sidewinds as a rear engine
>> disadvantage.
>>
>> And Porsche has more or less engineered the problem away, but at great
>> expense.
>>
>The sidewind problem in the bug was enhanced because the aerodynamic
>design of the bug had a very forward center of pressure, well ahead of
>the CG. If the design had more lateral area in the rear, as with FINS,
>it would have helped greatly.

Not only that, but susceptibility to crosswinds is very much a function
the ratio of side area to weight. A tall featherweight vehicle will always
suffer from side winds.

> Corvair. The Super Beetle used a low pivot rear axle to reduce the
> handling problems.

I'm just going by memory here, but I think VW deleted the swing axle
and changed the Bug to CV joint/shafts a few years before the Super
Beetle even came out. The later Super Beetles had a different front
suspension (Macpherson struts instead of the frame thing) as well as
the CVs.

On 3 Feb 2006 11:18:49 -0800, > wrote:


>> Corvair. The Super Beetle used a low pivot rear axle to reduce the
>> handling problems.

>I'm just going by memory here, but I think VW deleted the swing axle
>and changed the Bug to CV joint/shafts a few years before the Super
>Beetle even came out. The later Super Beetles had a different front
>suspension (Macpherson struts instead of the frame thing) as well as
>the CVs.

That sounds about right. IIRC, swing axles went out around '68; the superbug
was introduced around '71.