On Mon, 12 Apr 2010 18:12:54 +0700, the infamous John D.
scrawled the following:

On Sun, 11 Apr 2010 10:23:22 -0400, "Ed Huntress"
wrote:

John, enough. Here's a photo of an early, swing-axle Triumph Spitfire
jacking:

http://forums.pelicanparts.com/uploa...1090328641.jpg

WTF is this? Wasn't the talk about how the suspension handles
_cornering_? The front wheels are straight and both rear tires
cambered out in this pic. It looks like someone mashed the brakes and
was standing it on its nose, no cornering involved. Then there's that
strange smoke coming from the bottom of the rear wheels...


Here's a Triumph Herald -- same suspension, higher CG. This is the extreme
case: the inside wheel actually lifts:

http://herald-tips-tricks.wdfiles.co...ilt_herald.jpg

Wow! I'd call that "pronounced".


Here's an illustration that shows it:

http://www.rqriley.com/images/fig-17.gif

OK.

Your analysis is missing the primary forces at work here, which are the
inward force applied at the bottom of the tire, and the outward force of the
car as it goes through the turn, applied from the pivot point through the
half-axle, to the center of the wheel hub. The couple's effect is to tuck
the tire under the car.

Forget body roll for a moment and just look at how that force couple is
resolved -- by the tire tucking under, and the car "tripping" over the
outside wheel.

That's what happens. Compression of the outer spring from body roll
counteracts it. When forces are low, the body roll usually dominates. As
cornering forces increase, the outside wheel snaps from negative to positive
camber, the pivot point reacts by moving in the only direction it's free to
move -- upward -- and the car jacks.

You can see it clearly in the photos above.


Yes, I can clearly see it in the photos and certainly the wheels are
both positive.

I've read your description a number of times and I think something
besides cornering force is effecting the car.. As you describe it
cornering force alone overcomes every other force and lifts the entire
back of the vehicle enough for the camber, which would have probably
been at least a degree or so negative as a result of body roll to
suddenly go, from your pictures at least 10 degrees positive. But the
Internet is so slow here in the Marina that any research will have to
wait until I get back home to a faster connection.

Perhaps it's the mashing of the brakes which sets this up. Haul ass
into the corner, stomp the whoa-stop pedal, and crank the wheel, then
hit the gas again? But that effect would be momentary, going away the
instant the brakes were let off and the CG came back to f/r normalcy.


I had damned Nadar for all these years when he was right......but what
the hell, I'm not going to start lauding him with phrase, I plead the
rights of RCM to continue my own cockamamie view point, evidence to
the contrary be damned :-)

Nader crusaded against the result, not the root cause. His real gripe
_should_ have been owner maintenance and instead of forcing people to
be responsible for their own safety (pay attention or die, you
dip****s!), he forced the Corvair out of production. It's much like
what is happening in the healthcare biz today. Doctors give you one
med, then give you two more to reduce the side-effects of the first.
When my sister stepped in, Dad was on 17 different concurrent meds.
(This is not uncommon. I see the vast array on elderly folks' dressers
or kitchen counters when I go in to repair their homes.) She got him
down to 6 plus some herbs, and had him make a couple diet changes.


--
Climb the mountains and get their good tidings. Nature's peace
will flow into you as sunshine flows into trees. The winds will
blow their own freshness into you, and the storms their energy,
while cares will drop away from you like the leaves of Autumn.
-- John Muir