Ed,
As I understand it, the shorter shock should help prevent bottoming out, not contribute to it. The shorter shock, when fully compressed, is shorter than the long shock when fully compressed… Using original length shocks on a lowered car means that the shocks are not starting at their neutral position — they’re compressed by however much the car has been lowered…
Let me use this example, though my numbers are hypothetical, and not real VW numbers. Let’s say the stock suspension provides for 6″ of total travel, and sits at the mid-point when on the ground, loaded. The stock shock length provides for this travel. That’s 3″ of upward movement and 3″ of downward movement. Then, by whatever means you lower the car 2″ without changing the shock mounting points. That 2″ of lowering is subtracted from the 3″ of original upward travel, leaving only 1″ of upward travel before the shock bottoms out. But, that 2″ is added to the downward travel, now allowing 5″ of downward travel before that tire gets lifted off the ground because the shock is fully extended…
Now, lets run those numbers with a shock that is 2″ shorter, when fully compressed, even if it only provides 4″ or perhaps 5″ of total travel. However, it’s starting position, under level load, now more closely matches the 2″ that the car has been lowered. So, it provides at least 2″ (perhaps a full 3″) of upward travel before the shock bottoms out. Conversely, the wheel travel downward is limited by the extended length of the shorter shock — at least two inches less than the original shock, or something akin to 3″ instead of 5″ of downward travel that the stock shock provides. That two inch shorter shock is acting more like the original shock did in its original position before lowering…
So, it will tend to limit downward movement of the inside wheel in a turn, similar to how the sway bar operates… This limiting of extension is what I was talking about in another thread when discussing the “Sway Away” or “Sway Adjust” coil-over springs that used to be available for VWs. They clamped onto the shock top and bottom (not like the common “overload” coil-overs where only one end of the spring is fixed), and their spring tension limited the extension of the shock the same way that it added to force needed to compress it…
The lowering is done by cutting and allowing the center section of the lower torsion tube housing to move (grub screw and all), when the 150-180 lbs is temporarily added to the front end, then it is welded back into place — so the grub screws top and bottom are in a different relationship (as are the torsion bar center leaves) that when you began. Perhaps “preload” is not a good term to describe what has been done…
I may be using poor terminology or not communicating well, AND I may be missing something here, but I don’t think I’m all-wrong in this thinking. The top shock mount has not been moved, though the car is lowered. The lower shock mount has moved closer to this top mount by the distance the car has been lowered. Consequently a longer shock will bottom out more quickly than a shorter shock…
KentT2013-05-30 23:34:20
Early FF TDr on 69 VW pan
Slowly coming back from the ashes...