Re: Why Sliding block on racers

[Richard Welty <rwelty@xxxxxxxxxxxxxxxxxxxxxx>]

At 10:58 AM 1/15/99 -0600, Simon Favre wrote:
>You're comparing two very different animals here. The watts linkage on
>transaxle cars was used with a deDion tube (no matter how you spell it).
>The GTA and GTAm, all had a classic live rear end. The sliding block
>was a very solid way to locate the rear axle during hard cornering, and
>it lowered the rear roll center. I believe you can achieve basically the
>same result with a properly designed and installed Panhard rod. The watts
>linkage is much more complicated, correct?

the panhard rod, sliding block, and watts linkage are all basically trying
to do a couple of things:

1) control lateral motion of the axle tube

2) control the location of the roll center.

live axle vs dedion tube isn't actually all that big an issue; both need to
be located and have the roll center pinned.

the degree of success varies depending on the method and the implemention.
panhard rods work "well enough" for detroit, and with stiff racing
suspensions, they work "well enough" for many applications (NASCAR
stockers, for example.) they are not "theoretically correct", however.

the sliding block locates the roll center and limits lateral motion quite
well, but at a cost in complexity and maintenence.

the watts linkage effectiveness depends on the implementation. the alfa
implemention behaves as Will Owens describes. inverting this, so the axle
is pinned on the ends and the link attaches to the body, produces geometry
similar to the "ideal" sliding block implementation. neither sliding block
nor the "ideal" watts linkage are common street car implementations.

richard

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