Aged (hard) tires.
Excess clearance in the lower hub carrier
bearings, wheel bearings or inner control arm bearings.
-
Check and adjust bearing play. See
here and
here.
Use of urethane or other soft bushings
in place of the OEM bearings.
-
"Revert" to standard tapered roller bearings.
Soft upper subframe mounts
-
Replace mounts (Jag steel sheetmetal cage), or bushings (ERA tubular cage)
Too-soft damper settings or worn dampers.
-
Set the dampers as described in the manual. The adjustment is a small
screw near the bottom. You can experiment by going significantly stiffer
on all 4 dampers to see if that effects the hop.
If it seems like the damping is significantly soft with more than 5 clicks
off soft, you may have a bad damper. That can only be checked effectively
by removing the damper from the car and removing the spring from the
damper.