Bilstein Shocks

The original shockers on my Disco 3 lasted a creditable 100,000km before they ran out of damping, at which point I opted for a set of Bilstein monotube struts.

These are more expensive than ‘throw-away’ shock absorbers, but have the advantage of being tuneable and rebuildable.

As with most modern independent suspensions, replacing the Landy shocks isn’t a simple job, because they’re integrated into a load-bearing strut.

With air suspension, there’s no need for a coil spring compressor, but it is necessary to have a new air seal kit and a bench-testing apparatus to check air spring integrity before the struts are bolted back on.

The boys at Sydney Shock Absorbers, Bilstein agents, take all this in their strides, so the Bilsteins were duly installed and we gave them a bush workout over the next 60,000km.

Initial impressions were that the Bilsteins felt ‘floaty’ over undulations, but were well-controlled over sudden surface irregularities. Paul Joyner, Sydney Shock Absorbers’ R&D manager, explained that the shock absorbers have ‘digressive’ working pistons that allow slow and high speed shock movements to be separately tuned.

Damper ‘bleed’ at slow shock speeds gives a floating feeling that can be softened or stiffened. Separate shims control sharp bump action, and this can also be made to feel softer or firmer without upsetting the low-speed damping.

After around 40,000km the suspension started to feel excessively soft over undulations. I asked Paul if he thought the original settings might be more Euro-oriented and not take into account the weight of my bush-prepared vehicle.

My Disco has an ARB steel winch bar and Warn 9500 up front, plus a heavy deep-cycle battery under the bonnet. At the back it has a 100-litre Long Ranger auxiliary fuel tank, drawer units and a fridge, plus a Kaymar swing-away spare wheel carrier.

Should the valving be adjusted to allow for the extra weight at the Disco’s extremities, I wondered? Paul thought that might well be the case, so when our busy schedules allowed, some 20,000km later, the Disco went in for a rebuild job. With the struts out, the shocks went into the Sydney Shock Absorbers’ dyno and were dismantled.

Soft valving was judged part of the front-end ‘float’ problem, but the piston seals had developed slight bypass leaks as well. With experience born of years playing around with shock valving, Paul dialled up a fresh plan for the fronts, using a stack of shims in precise order. For the rears he diagnosed a rally set, to better control the back end weight and all was checked for response characteristics before going back into the Disco.

Revelation. The ride over undulations was still quite smooth, but without the previous too-floaty feeling, and sharp-bump control was even more precise. We’re now lining up some serious bush work to put the rebuilt, revalved shocks to the test.

Price: Shock absorber rebuild on a per-vehicle basis, depending on spring and damper type. Contact: Sydney Shock Absorbers, bilstein.com.au, 02 9557 5930