Regarding bump stops:
When fully relaxed, the shock carries the full weight of the axle,
wheel, tire, trailing arm, further powered by the spring because there
is not lower bump stop. The point at which it stops is the same as that
which the bump stop stops the lever arm action. I imagine that a lot of
extreme driving where you were lifting the rear wheel off the ground a
great deal or hitting a lot of very deep potholes could stress the shock
at the bottom end and pull at the tower thus pulling at the frame
mounts, but that seems extreme and should be mitigated by the shock's
damping action anyway and besides it's supposedly got a lifetime
warranty. If anyone can think of a way to test how often and under what
driving conditions the bottom actually got hit, I'd sure like to try it.
I would suggest, however, that when using these, the suspension not be
allowed to drop suddenly when you are up working on stands.
At the extreme upper end, when I jacked the wheel all the way up,
without the spring installed, the shock hit its top with about 1/8"
remaining before the upper bump stop hit it contact point. The contact
point on my car is "cupped" inward. When I held a piece of plate steel
across the contact point, then the bump stop hit it just before the
shock hit its top. I think it would be very simple to weld on a shim to
the bump stop contact in the wheel well so that the upper bump stop
would contact before the shock topped out.
Later, after reinstalling the spring, I raised the wheel by jack until
the car just started to come off the stands, ie, road steady state
conditions, and measured approximately 2 ½" of free-play remaining in
the shock shaft out of a total maximum shaft extension availability of
about 4 ", which seemed to allow more than enough room to move without
topping out. . BTW I did ask the local shock installation shop head
mechanic about the likelihood of KYB brand shock topping out in this car
and he said it was very unlikely. He also commented that this was, in
his opinion, a very good shock and it seems highly unlikely that the
shock would ever max out, given spring load, shock damping and the
light weight of this car and in all but truly extreme driving
conditions, unless the shock was worn out.
My conclusion is that the lack of bump stops is not a major issue, and
the more critical upper bump stop could be made operational with a
simple shim if one were worried about it. Making the bump stop
operational would also prevent the trailing arm mounting point from
being cracked if you did top out the shock and the lower mount or the
shock shaft did not give way to the sudden stress. ( remember that hole
is like ½-3/4" in diameter so it seems possible that the lower rubber
mount would pass through it and the shock mount washer would break and
come right up over the shaft before the trailing arm itself would
break.)
continued in next section....
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