"Dave Plowman (News)" wrote in message
...

FWD cars typically have relatively primitive rear suspensions and still
handle pretty well because the rear suspension of a FWD car doesn't
have a lot to do but keep the rear bumper from dragging on the
pavement! ;-)

That's what many makers would have you believe as it keeps costs down.

In a former life I was an automotive engineer in a department that did
development of future cars for one of the USA big 3.

Part of that job was suspension design and analysis. It is hard to
effectively lie to me about steering and suspension design. ;-)

But the better handling FWD cars also have decent rear suspension.

Right, but doing whatever you are doing right is far more important than
which general setup you pick.

Even longitudinal leaf springs with a live axle done right can work well on
reasonably smooth surfaces. High unsprung weight only matters on bad
surfaces, which unfortunately seems to prevail these days.

For example people like to **** on FWD cars with simple trailing arms and a
beam axle at the rear. However the beam axle is unsurpassed for keeping the
wheels near vertical to the pavement which is very important for developing
maximum cornering force. If the wheels are not powered, unsprung weight can
be kept low. Get the trailing arm geometry right which is often done, and
you have a nice vehicle - stable but still adequately nimble.

The gold standard is upper and lower control arms, but that soup gets ****ed
in at least as often as it is done right. ;-) Many compromises come when
encroachments on the passengers and luggauge are to be avoided.

In article ,
Arny Krueger wrote:
But the better handling FWD cars also have decent rear suspension.

Right, but doing whatever you are doing right is far more important than
which general setup you pick.

Even longitudinal leaf springs with a live axle done right can work well
on reasonably smooth surfaces. High unsprung weight only matters on bad
surfaces, which unfortunately seems to prevail these days.

No suspension at all can work quite well on a smooth surface.

For example people like to **** on FWD cars with simple trailing arms
and a beam axle at the rear. However the beam axle is unsurpassed for
keeping the wheels near vertical to the pavement which is very
important for developing maximum cornering force.

A beam axle keeps the wheels parallel to each other, but that's about all.
With body roll - and in practice all cars do this - the important thing is
to get the relationship between the wheel taking the load and the pavement
correct. Which a beam axle is poor at.


If the wheels are not powered, unsprung weight can be kept low. Get
the trailing arm geometry right which is often done, and you have a
nice vehicle - stable but still adequately nimble.

The gold standard is upper and lower control arms, but that soup gets
****ed in at least as often as it is done right. ;-) Many compromises
come when encroachments on the passengers and luggauge are to be avoided.

That is true. But it can be done.

--
*Money isn‘t everything, but it sure keeps the kids in touch

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Arny Krueger wrote:

But the better handling FWD cars also have decent rear suspension.

Right, but doing whatever you are doing right is far more important than
which general setup you pick.

Even longitudinal leaf springs with a live axle done right can work well
on reasonably smooth surfaces. High unsprung weight only matters on bad
surfaces, which unfortunately seems to prevail these days.

No suspension at all can work quite well on a smooth surface.

Yes. However, that kind of perfection is not required for a longitudinal
leaf springs with a live axle done right rear suspension to be effective.

They do loose traction on rough roads, badly.

For example people like to **** on FWD cars with simple trailing arms
and a beam axle at the rear. However the beam axle is unsurpassed for
keeping the wheels near vertical to the pavement which is very
important for developing maximum cornering force.

A beam axle keeps the wheels parallel to each other, but that's about all.

That's why you need to be careful with how you do the trailing arms.

Its all about things like roll center. Pick that right and the not only will
the wheels be parallel to each other, they will be perpendicular to the
pavement. Hitting those two goals goes a long way towards good cornering.
Most of the rest of the discussion then becomes about fore/aft balance of
which a great deal relies on the front suspension.

With body roll - and in practice all cars do this - the important thing is
to get the relationship between the wheel taking the load and the pavement
correct.

Agreed.

Which a beam axle is poor at.

Disagreed.

If the wheels are not powered, unsprung weight can be kept low. Get
the trailing arm geometry right which is often done, and you have a
nice vehicle - stable but still adequately nimble.

The gold standard is upper and lower control arms, but that soup gets
****ed in at least as often as it is done right. ;-) Many compromises
come when encroachments on the passengers and luggauge are to be avoided.

That is true. But it can be done.

So can the two variants of the beam axle we've discussed. I've owned
vehicles that handled well on even rough roads with unpowered beam
axle/trailing arm rear suspensions.

Just because someone screws up a car, doesn't mean that every technology it
embodies is inherently flawed.

Arny Krueger wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
Arny Krueger wrote:

But the better handling FWD cars also have decent rear suspension.

Right, but doing whatever you are doing right is far more important than
which general setup you pick.

Even longitudinal leaf springs with a live axle done right can work well
on reasonably smooth surfaces. High unsprung weight only matters on bad
surfaces, which unfortunately seems to prevail these days.

No suspension at all can work quite well on a smooth surface.

Yes. However, that kind of perfection is not required for a longitudinal
leaf springs with a live axle done right rear suspension to be effective.

They do loose traction on rough roads, badly.

For example people like to **** on FWD cars with simple trailing arms
and a beam axle at the rear. However the beam axle is unsurpassed for
keeping the wheels near vertical to the pavement which is very
important for developing maximum cornering force.

A beam axle keeps the wheels parallel to each other, but that's about all.

That's why you need to be careful with how you do the trailing arms.

Its all about things like roll center. Pick that right and the not only will
the wheels be parallel to each other, they will be perpendicular to the
pavement. Hitting those two goals goes a long way towards good cornering.
Most of the rest of the discussion then becomes about fore/aft balance of
which a great deal relies on the front suspension.

With body roll - and in practice all cars do this - the important thing is
to get the relationship between the wheel taking the load and the pavement
correct.

Agreed.

Which a beam axle is poor at.

Disagreed.

If the wheels are not powered, unsprung weight can be kept low. Get
the trailing arm geometry right which is often done, and you have a
nice vehicle - stable but still adequately nimble.
The gold standard is upper and lower control arms, but that soup gets
****ed in at least as often as it is done right. ;-) Many compromises
come when encroachments on the passengers and luggauge are to be avoided.

That is true. But it can be done.

So can the two variants of the beam axle we've discussed. I've owned
vehicles that handled well on even rough roads with unpowered beam
axle/trailing arm rear suspensions.

Just because someone screws up a car, doesn't mean that every technology it
embodies is inherently flawed.


yeah. You should try an XJS with a bent kingpin..

makes nonsense of a double wishbone


--
To people who know nothing, anything is possible.
To people who know too much, it is a sad fact
that they know how little is really possible -
and how hard it is to achieve it.

On Tue, 10 Apr 2012 14:32:28 -0400, "Arny Krueger"
wrote:


Yes. However, that kind of perfection is not required for a longitudinal
leaf springs with a live axle done right rear suspension to be effective.

They do loose traction on rough roads, badly.

In the late 60s and early 70s, Ford Escorts with precisely that setup
were unbeatable in rallying. All they added for the rally cars was a
second parallel longitudinal link, and a Watts linkage for transverse
location.

Gas dampers by Bilstein completed the setup.

d

In message , Arny Krueger
writes:
[]
Its all about things like roll center. Pick that right and the not only will
[]
That reminds me of one of the royal state coaches - one of the big ones,
that only comes out on very special occasions, that has a roughly
spherical body, on long curly suspension to big wheels fore and aft;
apparently though magnificent to look at, it's not popular with the
royals because it rolls and wallows like - well, something nautical.
--
J. P. Gilliver. UMRA: 1960/1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf

a little bit of me still feels that some southerners think we northerners are
issued at birth with doomed kestrels. - Alison Graham, Radio Times,
3-9/11/2007.

In article ,
Don Pearce wrote:
Yes. However, that kind of perfection is not required for a
longitudinal leaf springs with a live axle done right rear suspension
to be effective.

They do loose traction on rough roads, badly.

In the late 60s and early 70s, Ford Escorts with precisely that setup
were unbeatable in rallying. All they added for the rally cars was a
second parallel longitudinal link, and a Watts linkage for transverse
location.

But that was a long time ago, when no comparable RWD car had decent IRS
anyway. But what works well for sport isn't necessarily best for road work.

--
*Always borrow money from pessimists - they don't expect it back *

Dave Plowman London SW
To e-mail, change noise into sound.

On 09/04/12 14:12, Dave Plowman (News) wrote:

Jaguar showed in the '60s that decent independant rear suspension could be
made for a medium priced car. It took BMW (and others) 30 years to work
out how to do the same.


This has gone very off topic, but it's available in cheaper cars too. Ford
have been fitting independent rear suspension to the Focus since it came out
in 1998. VW have since followed suit with the Golf. Honda appear to have gone
backwards, as the current Civic does not have independent rear suspension but
the previous generation did.

In article ,
funkyoldcortina wrote:
Jaguar showed in the '60s that decent independant rear suspension
could be made for a medium priced car. It took BMW (and others) 30
years to work out how to do the same.


This has gone very off topic, but it's available in cheaper cars too.
Ford have been fitting independent rear suspension to the Focus since it
came out in 1998. VW have since followed suit with the Golf. Honda
appear to have gone backwards, as the current Civic does not have
independent rear suspension but the previous generation did.

What works reasonably well on a FWD car is no real guide as regards a RWD.

--
*It was all so different before everything changed.

Dave Plowman London SW
To e-mail, change noise into sound.