The option part TD330303 ‘toe-in and kick-up inserts’ provide extra tuning options for the ’408 series of vehicles.
When we talk about pivot blocks, we refer to them by two initial designations. The first of these refers to which end of the car it belongs to – F for front and R for rear. The second of the designations is the front or rear most of the blocks. RF, for example means R – REAR of the car, F – front most facing of the rear hinge pin holders. FF means the FRONT block at the FRONT of the car.
The option inserts for the 408 provide extra options over the kit setup of the DNX408, DEX408 and DNX408T. These control the front ‘kick up’, rear toe-angle and rear anti-squat.The front kick-up is the angle of the front of the chassis and the suspension follows this in kit setup with neutral inserts that add or subtract nothing from the chassis angle of 10degrees. The option inserts give the option to change the angle by up to 1 degree in either direction using just the FR block – or on the DEX408 and DNX408T the FF block can also be tuned using the same inserts to give double the range of adjustment.
More Kick-Up will tend to ride the bumps better and the steering response will be reduced slightly. The vehicle will tend to ‘dive’ more under braking.
Less Kick-Up will tend to ‘hop’ over bumps rather than absorb them, the steering response will be sharper and there will be less dive under braking.
Right: The kick-up inserts used in only the FR block
The kick-up inserts are left and right handed and are marked with a dimple to show which way round the setting should be read.
The dimple facing upwards means you’re offsetting the pin by the labeled figure, and with the dimple facing downward the setting is subtractive. When using these inserts in the FR block then raising the hinge pin would effectively reduce the kick-up angle and vice versa for lowering the pin.
The DEX408 and DNX408T use revised designs for their pivot blocks which allows the use of these offset inserts in the FF location also. Using the inserts on the FF block (only possible on the DEX408 and DEX408T) would give the opposite effect to on the FR block, and moving the pin up (+1) will add kick-up angle. Using the inserts in the FF location along with the FR location gives a greater range of adjustment to the settings – between 8 degrees and 12 degrees total kick-up angle.
It is possible to fit the DNX408T FF hinge pin block on the DNX408 – giving the ability to use the option ‘kick-up’ inserts in the FF brace as well as providing more strength.
The rear inserts are split between anti-squat inserts in the RF block – and toe-in inserts in the RR block.
The possible settings with the standard roll-centre (RR blocks bolted direct to the chassis plate) is shown above and below. The example below shows the maximum possible anti-squat (5 degrees) using the shown insert – the red line shows the minimum anti-squat possible in this setup, which as explained in the illustration above, is 1 degree.
When using the +2mm high roll centre mod you’re raising the rear hangers 2mm whilst the front stays in place. As a consequence of this you need to raise the front of the hinge pin to keep a similar anti-squat setting.
What does it do? Take a look at the article we put together on the mod here: +2mm Rear Roll Centre
With the +2mm rear raised roll centre mod on your car, you can expect the rear end to support itself more and have less roll in the corners – also helping the car over bumpy tracks and prevening it from bottoming out too easily.
The possible settings with the +2mm high roll centre mod are shown below. The example shows the maximum possible anti-squat possible (3 degrees) using the 5 degree insert shown below in the RF hanger. The red line shows the minimum anti-squat using the 2 degree insert, which is ZERO.
TOE-In explanation and effects:
Toe-In refers to the angle of the wheels when viewed from directly above. On the rear of the car this is set by both optional hubs and in this instance by the inner hinge-pins via the inserts. The inserts included in the optional kit give the ability to tune from 2.5 to 4 degrees of inner toe-in and when using the 1 degree hubs this setting can be tuned an extra 1 degree in either direction if desired.
More toe-in at the rear will help stabilise the back of the car and keep it tracking straight. The car will have a tendancy to understeer and feel easier to drive on power. This is best suited to looser tracks.
Less toe-in at the read will be faster in a straight line as there will be less tyre scrub. The rear of the car will be looser and the car will turn more easily. This is best suited to higher grip tracks.