<VV> Camber compensator

[Tony Underwood]

At 06:32 AM 9/18/2010, John Kepler wrote:

>The sole purpose of the rear leaf is to add some weight carrying support
>to the weak rear coils (which, along with the front roll bar, are the
>real "camber compensators" in this suspension), without adding to the
>roll height -- a sorta low roll cheater spring..


Well, not exactly.  ONE of its primary purposes is to transfer sprung 
weight support from the outer edges of the suspension support (spring 
perches/pockets) to the center of the car's axis (center mount for 
the transverse leaf on the bottom of the differential).


The '64 rear leaf increases axial body roll by virtue of the soft 
coil springs allowing the body to roll easier since a good percentage 
of the support to the rear of the car is resting on the center of the 
car's axis instead of being totally supported by springs that are on 
the outside edges of the car's track.   The farther out to the edge, 
the more resistance to body roll in corners and in the case of 
swing-axles, the more likely the car could experience tuck-under in a 
hard corner if it leans against one of those stiffer coils which also 
will unload the inner wheel, which in turn drops down as its 
relatively stiff coil pushes against it, raising the roll center of 
the car and bingo suddenly that outside tire's cornering force jacks 
up, the car leans even more because of the increased roll center, the 
tire tread rolls under its own bead and loses grip and the car will, 
as someone once "quoted" in a book, take a sashay through the boonies 
backwards.   Or, in bad circumstances, scuff up the roof.


The leaf spring in back helps prevent this by taking much of the load 
support OFF the edges of the car and transferring it to the center, 
allowing the rear (heavier) half of the car to roll axially instead 
of levering upwards, since the leaf transfers downward motion by the 
inside tire into upward (which is easier because of the softer coils) 
motion of the outside tire, preventing it from dropping down and 
jacking the rear of the car upwards because of the raised roll center 
that swing-arm axles deliver which worsens as the car leans into the 
corner, particularly if you get on the brakes at its apex.

The pivoting leaf shifts the weight transfer in the rear to the 
center which turns those potential levering/jacking actions caused by 
the swing-axles into axial roll instead.

This axial roll is then contained by the relatively stiff front roll 
bar that also came with the '64 suspension additions... and needed to 
be a part of the camber compensator as well, since using the camber 
compensator on a Corvair without a front roll bar tends to make for 
some interesting handling characteristics on hard corners.   Body 
roll (read: lean) tends to be excessive, especially when the 
compensator leaf is adjusted so that it works the way it 
should.   That camber compensator would work better (IMHO) with rear 
springs a bit shorter and a little softer, with a little bit of added 
adjustment on the end bolts to preload that leaf a bit.

...kinda like a "poor man's z-bar".


Although the '64 suspension is an improvement over the camber 
compensator, it's not like it actually does THAT good a job... it's 
just better than the suspensions before it.   It remains a 
band-aid.   GM got it right in '65.   Or rather, about as right as it 
was likely to get.



tony..