solo2@uswest.net writes:
<<
I'm wondering how some are able to get their cars low enough in stock
trim to hit and then run on the bump stops? >>
A shock condition know as "jacking down". As the car rolls or hits a bump
the shock compresses, but an extreme rebound rate will prevent the spring
from extending the shock back, or at least at a very reduced time rate.
Think of a road race vehicle running over rip-rap chatter bumps at high
speed, the vehicle can actually lower itself onto the bumpstops under these
conditions. However, some of the supposed high tech claims expressed here
recently have been slightly misrepresented. Just watch the Neon's of Daddio,
Chiles, etc. in turns and slaloms; they actually do have a fair amount of
roll, with the inside suspension extending quite a bit. You'd be surprised
how much roll you can get away with when you can achieve 3+ degrees of
negative camber from crash bolts.
The use of hydraulic configuration and increased rebound will result in
slightly lower static ride height for most Stock vehicles; some of it is from
the absence of extending gas pressure, some of it is from the rebound valving
overcoming spring extension force. However, don't get caught up in thinking
of shocks valving as simply stiffer or softer; the shape of the cycle
frequency vs stiffness force curve as it relates to low speed and high speed
valving is very important, i.e progressive, digressive, or linear. The
combination of generally smooth sites and low vehicle speeds allows you to
get away with autox shock tuning that would put you off the track in a road
race, particularly with bump/compression valve tuning. Same holds true for
alignment.
Don't be afraid to consider the unconventional.
M Sipe
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