@wrkinprogress wrote: "Are there measurements I can take or spots I can shine a flashlight on to tell the status of my suspension? E.g. how much lowered, whether caster shims are already in place."
Yeah, well, kinda-sorta if you know where to look, but it really depends a lot on the wheel and tire size, any suspension mods and so forth, so while some things can be spotted, it might not be easy and the relative body height can vary greatly from one car to the next mostly due to owner reference - Some like them higher than others.
Take caster shims, for example; The shims are inserted between the front suspension beam's bottom horizontal tube and the corresponding depression in the chassis headset (what the beam bolts to up front). If you get in there with a decent LED flashlight and look closely at that area you might be able to see a single or doubled (two stacked) shim in place (if you have them). If you don't have the shims (Beck cars don't need them) your car may feel light over 60mph or may follow the crest of the road or chase bumps. Adding the shims to increase caster to 5º - 7º makes the car more stable and eliminates that wandering due to bumps/etc. Here's a quick explanation:
But we don't throw a set of shims in there just for the hell of it. First, you need to get the car on an alignment rack to see what the front suspension is doing. There are specific measurements for all aspects of the front end, just like any other car. We want to have the same specifications as a 1965 VW sedan, if the front end has link pin spindles, or a 1970 VW sedan if the front end has ball joint spindles, EXCEPT for the front caster.
Because we start with a VW Beetle sedan chassis that expects to sit quite a bit higher and then lower it way down for the proper stance of a Speedster, we throw the suspension into a tizzy by screwing with the suspension angles. Most stuff stays the same, but because of the "trailing arm" design of the front suspension, lowering it causes the caster to go a little weird (it goes low or "negative" on us versus the spec). In order to return the car to a stable driving platform we increase the caster to compensate and "bingo!", sports car handling.
That's the thumbnail explanation. Any car alignment tech should be able to explain it better, but I'm not one of them.... 