Adjustable Koni Shock
Installation on a Range Rover 4.0/4.6/p38A
Introduction
Choice of Shocks
1. Compression for Fitment
2. Insufficient Thread Length
3. Compression Rubbers
Results
More Information
Photo:
Comparison of Koni (left) and OEM (right) shocks.
Introduction
The genuine shocks on the 4.0/4.6 give a fairly harsh ride compared to
the Classic. To improve the ride, Allan Hogan replaced his shocks
with adjustable Konis -- and was very happy with the result. On their
softest setting, he feels they soak up the bumps very well on broken
surfaces (certainly much better than his worn stock shocks), and
provide a smooth ride under freeway conditions. Details of Allan's
installation appear below.
Choice of Shocks
In 2006, Allan acquired a
late 1999 RR4.6 HSE (Bosch system) with
about 103k (65,000 miles) km
on the clock. When he took
delivery, he wanted to upgrade it to new condition as much as possible.
Allan makes the following observations on his decision process in
selecting the Koni shocks:
Apart from replacing the usual consumables - tyres, fluids,
plugs, HT leads and hoses,
I took some time to decide on the shock absorbers. A couple of
the local Land Rover specialists seemed quite content with the Bilstein
option. Having had Bilsteins
in a previous (non-4wd) vehicle, I had found them most satisfactory and
was initially inclined that way.
The thought occurred to me however that a damper with some form of rebound/compression adjustment might be a better option given the prospect of heavy loads and badly corrugated roads common to outback Australia. Ultimately I chose the Koni adjustables from the "Heavy Track" range - Part numbers 30-1597 (F); 30-1598 (R) They cost about A$240 ea +GST...not cheap... however..
The supplier strongly advised that the dampers be left on the factory default (lowest /softest) setting for a comfortable ride over most conditions for the first 25,000 km or so. The middle setting could be a good option later for long trips on very rough roads and max all up weight.
With these words of advice I set about what I thought would be an hour or two leisurely work before Saturday lunch...not so! Below are listed the main issues and solutions encountered during the installation.
1. Compression for Fitment
There is no mechanism provided to retain
the damper in a compressed
state to ease fitting. A spare "S" shaped heavy gauge wire from a
lesser brand was quickly distorted by
the force of the expanding shock absorber. While the Konís need to
be in the expanded state to adjust them properly, no explanation is
offered as to how they might be safely compressed. I finally
resolved the matter with a hydraulic jack, a metre of 5mm stainless
steel wire rope and a pair of u-bolt
wire-rope shackles tightened to form simple nooses top and bottom
...
2. Insufficient Thread Length
When the washers,
insulators and nut are all assembled on the "pin" end, insufficient
thread has been machined onto the stem to allow proper tightening of
the nut. When tightened to the limit of
the thread, the nut / washer still sit slightly proud of the
rubber insulator (see photograph
below left). The thickness of the receiving
suspension bracket is insufficient to take up the slack and so the nut cannot be tightened
to achieve the correct
compression of the rubber insulators.
A comparison of external dimensions of the
Koni product with the OEM component being replaced is in the photo
below at right. The inclusion
of a captive "pin" nut
(blue arrow in photo) on the OEM product
is a superior design feature: it not only takes up the slack
allowing the retaining nylok nut
to be tightened against the compression rubbers to the requisite
torque, but also provides for secure purchase on the body of
the shock absorber while tightening the retaining Nylok nut. For
the
first (front RHS) replacement, I utilized a spare
washer from the OEM shock
absorber and added two circular spacers to get the appropriate
thickness. The spacers were fashionedfrom a nylon kitchen
cutting board (wife not happy!)with
a hole saw prior to adding the supplied washers and
rubber mounts but it has done
the job. For the other 3 mountings, I slipped
a larger but snug
fitting Nylok nut
over the pin to act as a spacer prior to fitting the supplied metal washers and rubber
mounts.
|
|
Illustration of insufficient
thread length after fitting rubber bushings on Koni shock.
|
Comparison of Koni (left) and
OEM (right) shocks. Note captive nut (blue arrow) on OEM design.
|
The Range
Rover manual specifies 33 ft-lb
while the packing slip with the Koni product recommends 58
ft-lb. I took the RRnet advice and tightened the
nut to achieve sufficient compression without "pancaking" the rubber
bushes.
Results
I recently completed an 8 day 3,000 km ( 1900
miles) round trip on a mix of sealed -freeway/secondary roads and well
formed gravel with minor corrugations. The general handling was
better than I had anticipated, not being accustomed to live
axles for many years! The vehicle cornered with
relatively little body roll and the ride was most comfortable,
though I noticed that the rear axle tends to hop a little out of
line on corner corrugations irrespective of load conditions.
I sent an email to the
Australian Koni importer/distributor and was
pleased to receive a prompt reply including the fact that he had
forwarded it to the Koni people in the Netherlands regarding the length
of the machined thread on the pin.
PS: Notwithstanding the loss of a cutting board, wife
was impressed with the improvement in the ride of the vehicle!
More Information
4.0/4.6
Parts Sources page: Sources for genuine, OEM and generic shock
replacements for the 4.0/4.6
(see the "Suspension" section)
Air Suspension Diagnosis
and Repair section:
Information on air suspension problems, solutions and upgrades appears
in the .
Range Rover Suspension page:
Discussion of the pros and cons of different suspension setups.