4WD Touring Australia — October 2017

094 | 4WDTouringAustralia

THESHOCKING

TRUTH

TRACKSIDE MECHANIC

REAL ADVICE

FROM OUR

MECHANICAL GURU

M

ost modern 4WDs have moved to independent front suspension. It makes for a more comfortable drive and

these massive 4WDs, that were once very agricultural, now feel more car-like.

Most people opt for an upgraded suspension kit that lifts the 4WD two inches, but lifting a vehicle two inches

doesn’t always mean you gain two inches of ‘travel’ as well.

There are a number of other limiting factors that can make a lift height vary. Especially when it comes to things like

the weight of accessories, things such as aluminium bars winches with synthetic rope as opposed to wire cable.

ADAM ADLER

DOWN TRAVEL

Down travel refers to the length of the shock. This will vary

depending on accessories, as a heavier load will cause the

spring to sit lower in the stroke of the shock.

When the 4WD is jacked up it will give you more down

travel, whereas a lighter load will see the shock sit higher

in its stroke and will be closer towards the top of the shock

which will limit down travel.

Down travel can also be governed by different spring

designs. A heavy duty spring will extend less than a lighter

spring because the thicker coils will limit the length it can

travel. A lighter coil will be made of thinner wire, which will

stretch further.

Bump stops and control arms all play a part as well.

Upper and lower control arm conguration along with CV

lengths and angles are also limiting factors which govern

the length of a shock.

STANDARD VS UPGRADED

It is not always a given that if you t a two inch spring that the

shock should be two inches longer. There are many variables

here too.

The shock really just needs to dampen the spring within

its length of travel.

Occasionally, using a longer shock can also cause a

spring to come out of position on full articulation, which can

be dangerous.

If you put a standard shock and an upgraded shock

side by side, the lengths of the assemblies will basically be

the same.

However, the upgraded shock is done with bore size and

internals. The length needs to still work within the limits of

the control arms and bump stops.

SOLID AXLE

A system like in a Patrol or an 80 Series LandCruiser is totally

different. With solid axle, you can t longer shocks because

you have room to lengthen it all and replace components

like longer upper and lower control arms, etc, because the

solid axle doesn’t have these limitations. You can get heaps

more down travel from a set up like this.

There are also rules which govern the height and length

of a suspension kit that is allowable for tment without the

need for engineering. Check your home state’s rules before

you embark on anything.

BRANDS

If you compare different brands you will always see a

difference. ARB have different part number shocks for

different springs which are designed to dampen differently

for different reasons. They will have a softer shock for a

lighter spring and a rmer shock for a heavier.

Lovell actually use the same part number shock for each

load-rating spring, while Bilstein, Koni and Tough Dog are

all different again.

You may be able to compare shock absorbers by asking

for their open and closed lengths and this information might

give you an idea on how much more travel it will gain. Again,

loads on the 4WD will also affect this.

Gaining extra travel is great, the longer you can keep

both wheels on the ground the better, as you will have

more traction. A soon as you lift a wheel it will spin.

So when choosing a suspension kit, the height and load

you are carrying are key, but shock travel is also important.

Unfortunately it’s also a difcult one as it is not an exact sci-

ence for the reasons I have listed above.

GO NUTS! – Adam

A simple explanation

on ‘Lift’ & ‘Travel’.