Re: [AMC-List] my 62 classic project (50-63 front suspension)

[<francis.swygert@xxxxxxxxxxxxxxxxxx>]

Tom Jennings wrote: "People who slag this suspension as generally "no
good" simply don't know what they are talking about. It's a fine design,
if a bit old-fashioned, 40+ years later. It's got a lot of fail-safe
subtleties in it as do more modern cars; it just has too many parts
(read: labor costs) for modern tastes. "

Just to clarify, that's mainly to many parts/labor costs for PRODUCTION.
The upper assembly on the old cars consists of two arms with bushings,
the trunnion itself, trunnion bushings which screw onto the trunnion and
into the arms, large o-rings that serve as seals for the trunnion
bushings, a thrust bearing, spring seat tower, bolt to hold the arms
together, a bumper mount/spacer that goes on that bolt and between the
arms, and the rubber bumper (that limits downward suspension travel).
Then this all has to be assembled into one unit. It's not that hard, but
takes time. For production that can be costly. Repair costs go up when
someone unfamiliar with the design has to study it and take the time to
figure it out as they go. 

In contrast, the single arm design has one large A-arm (dies cost more,
but once made part doesn't cost much more than the two arms) with two
bushings, the ball joint, and a pivoting spring seat. Costs less to
manufacture, and less to install. It's a bit easier to repair, but not
really cheaper assuming you're replacing the ball joints, bushings, and
spring seat pivot. The trunnion is pretty simple and easy but takes a
little more time. With the later design taking the pivoting spring seat
apart and reassembling with a new bushing takes more time than replacing
the trunnion with all those parts -- at least most of the time. It
depends on how badly worn the pivot is. 

Production costs drives more changes to cars than real improvements.
Theoretically efficiencies in production should improve quality due
mainly to fewer possible mistakes, but that's a fallacy in the real
world. Take McPherson struts, for instance. There is no control over
camber changes at all, and the wheel changes camber as it moves up and
down in a shallow arc, but not much. It's cheaper to produce as a unit
and install the same way though (a true McPherson strut with integral
shock/spring/spindle, not the many modifications such as the Mustand and
Camaro, and some Japanese cars that simply replace the spring and shock
with a strut, but are multi link suspensions). The old Rambler
suspension is better in terms of handling and ride once the spring rates
are tuned to modern conditions. Camber changes occur, but in a
controlled manner, and the suspension can be adjusted much more, though
caster is limited in the 50-61 big car design (-63 small cars), a bit
less limited in the 63-69 design when adjustable strut rods are used. 


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