A telescopic shock absorber (damper) can be compressed and extended: the so-called bump stroke and rebound stroke. Nowadays, nearly all shocks are of the telescopic configuration and mainly 'double acting', which indicates hydraulic resistance in both bump and rebound.
Telescopic shock absorbers are subdivided in;
1. bi-tube or twin-tube dampers, available in hydraulic and gas-hydraulic configuration. The gas-hydraulic version is also known as low-pressure gas shock.
2. Mono-tube dampers, also called high pressure gas-shocks (only available in gas-hydraulic configuration).
Koni's are supplied with the adjuster at full soft, as this is the recommended setting for the particular vehicle that is to be fitted with Koni's. The adjuster is primarily a wear compensation device, and should be used only when necessary. Do not overadjust.
If for instance, after many thousands of kilometers, the suspension has
softened and the damping effect of the shock absorber has diminished,
the rebound damping forces of the KONI shock absorbers can be adjusted.
The adjusting nut (10) on the threaded end of the piston rod can be turned
up, closing one or more bleed holes (C).
This will stiffen the damper in rebound at lower piston velocity (which
can be noticed manually). At the same time, spring (9) is compressed further,
resulting in increased rebound damping at higher piston velocities.
Many Koni dampers have a bump stop inside the top of the dust cover. (This
will be evident by a groove 1 cm from the top of the dust cover). If so,
this must be removed before the damper can be adjusted. Fully extend the
damper, insert a small rod or similar through the two holes in the top
of the dust cover. Push the rubber down until it can be seen at the bottom
of the dust cover. As it is split, it can be peeled of the shaft. (Note
which is "up" with the bump stop). Now follow the instruction
below.
Fully compress the shock absorber, simultaneously gently twisting the
dust cover (or piston rod) until the cams of the adjusting nut are felt
to engage in the recesses of the footvalve. In case of a low-pressure
gas shock, it must be compressed against the gas pressure. (this requires
some care!)
If the damper is still unadjusted, the rod cannot be turned anti-clockwise
as a distinct stop is felt (minimum position).
However, the damper may have been adjusted before. Turning the rod anti-clockwise
is then possible. If so, count in half turns until a distinct stop is
felt. Stop turning and DO NOT USE FORCE.
If at minimum position, adjust two half turns (360 degrees) clockwise,
while keeping the shock absorber compressed. In case of prior adjustment,
only half a turn (180 degrees) should be added to the number of half turn
previously found.
Usually the adjusting range is 4 to 5 half turns.
Extend the shock absorber - with dust cover / piston rod facing up - by
1cm WITHOUT TURNING, to disengage the adjusting mechanism. The dust cover
(or piston rod) may now be turned freely. Low-pressure gas shocks will
automatically disengage because of the gas pressure as soon as the dust
cover (or piston rod) is released. The damper can now be extended, so
the bump stop (if any) can be replaced. When the bump stop is fitted around
the shaft, compress the damper and give it a push to make the bump stop
"click" back into the groove at the top of the dust cover.
NOTE:
Adjusting half a turn from minimum position will increase rebound forces
by 10 to 15%.
Adjusting two half turns will add 25 to 30%.
Adjusting three half turns will add approx. 50%.
Adjusting four half turns will add 75 to 80% to the rebound forces.
The fifth half turn (if any) will increase rebound forces up to 90 - 100%.
KONI dampers (as prescribed for normal street use) are not adjustable
in bump. Bump forces are preset by KONI and are not (usually) subject
to wear.
GRAPH (Fig. D)
This is a sample graph showing the damping forces of a KONI shock absorber.
The full curves I and II represent the unadjusted shock absorber forces
at lower and higher piston velocities (0.33 m/sec and 0.66 m/sec).
The dotted curves Ia and IIa represent the forces of a fully adjusted
shock absorber under the same conditions. Between these curves are the
adjusting possibilities up to 4 half turns.
Please note that the bump forces are not normally adjustable.
