The Ultimate EVO Suspension, Project EVO IX Part 3

Energy front lower control arm bushings eliminate squishy rubber to help hold the suspension geometry true under high cornering loads. We only used the smaller front bushings, leaving the larger rear bushings stock as they have a spherical bearing from the factory.

Robi made sure we addressed other details that were necessary in building the ultimate EVO suspension. We replaced the front lower control arm bushings with harder Energy Suspension polyurethane bushings. The rear lower control arm bushing is a high quality rubber mounted spherical bearing and following Robi’s advice we left it stock, however Energy does make a hard urethane replacement for this part with a special tapered center bore to allow it to articulate.

Whiteline’s steering precision kit (part number KCA390) reduces bushing flex and bump steer by relocating the steering rack slightly and replacing soft rubber bushings with polyurethane.

We used Whiteline’s steering precision kit to mount our EVOs steering rack. The kit replaces the rubber bushings holding the steering rack with hard Urethane and moves the rack up slightly to reduce bump steer. The kit is designed to impart a more solid steering feel and improve the secure feeling of the steering when traversing bumpy surfaces.

Whiteline’s roll center kit (part number KCA395) helps raise the roll center on lowered cars, reduce bumpsteer and improves the camber curve for more front bite.

Whiteline’s roll center adjustment kit was also installed in the front suspension. This unique and innovative product is a boon to making your EVO handle well. We are used to having to hand fabricate this sort of part on our racing cars but Whiteline has simplified it to make it a bolt on product for the EVO. The roll center adjustment kit uses a ball joint with a longer shank. This effectively moves the lower control arm outer pivot downward and raises the roll center. In a lowered car, the roll center drops and the roll couple which is the lever arm for centrifugal force to roll the car over gets longer. Thus a lowered car often exhibits more body roll than a car at stock ride height all other things being equal. The Whiteline kit is designed to move the roll center closer to the stock location even on a lowered car.

You can see how much taller the Whiteline roll center ball joint is when compared to the stock part.

On a McPherson strut car, if the car is lowered so that the lower control arms are at an angle of more than 90 degrees to the strut itself, the suspension will gain positive camber under roll. This is terrible for grip and handling. The Whiteline kit helps reduce this effect, further improving handling. Unfortunately changing the location of the pivot in relation to the tie rod ends can create a lot of bumpsteer. Well, Whiteline has cleverly included some tie rod ends with longer shanks in the kit to keep the tie rod location in line with the new lower control arm pivots. Now you can do this former race car only mod for a surprisingly low price. What used to require over a thousand dollars of specialized parts and custom fabrication to accomplish is now a relatively inexpensive bolt on. If all of this sounds confusing and you don’t understand how suspension geometry works, quite simply, the roll center adjustment kit will reduce body roll and improve front grip without increasing the spring or sway bar rates.

You can also see how much longer the shank is on the Whitleine ball joint compared to stock.

For the rear suspension, we kept most of the EVO’s stock control arm bushings because they are high quality bearings rather than the soft rubber found on most stock cars. We did replace the soft gushy rear trailing arm busing with a hard Energy polyurethane piece. We also used Whiteline’s rear bump steer elimination kit. This kit uses an eccentric bushing to replace the inner pivot bushing of the rear toe arm. The eccentric is used to locate the pivot location downward. This reduces bumpsteer in a lowered car. Reducing bumpsteer gives the rear of the car a more secure feel at the limit, especially over uneven pavement.

Whitelines’s bump steer kit relocates the rear toe arm inner pivot upward which reduces bump steer in the rear suspension.

You can see how the inner pivot is higher than stock when the bushing is installed in the car.

Power modded EVO’s tend to develop wheelhop when launching from a dead stop or when accelerating out of a tight turn. Much of the wheelhop is caused by bushing deflection in the drivetrain. We installed Energy Suspensions urethane bushings in the rear moustache bar and front differential mount. These soft rubber bushings mount the rear differential to the chassis and replacing them with harder urethane reduces the likelihood of developing wheelhop and breakage of the axles, transfer case and rear differential. We did notice a very slight increase in gear noise from the differential but this was to be expected and was hardly noticeable.

Energy replaces the rear mustache bar and differential bushings with hard urethane to help reduce wheel hop

Finally we added Whiteline’s front and rear adjustable sway bar endlinks. These parts use solid spherical bearings to couple the swaybar to the suspension control arms. This ensures that every bit of suspension movement is coupled to the anti sway bar. This helps sharpen response in a very feelable way. The EVO uses a plastic ball and socket endlink stock which is way better than your typical rubber mounted endlinks. However, the beefy Whiteline parts can better take the stress of the big Robispec bars. Another important feature is that the Whiteline endlinks can be adjusted for length. This allows the user to adjust the length of the endlinks when the wheels are on the ground after the car has been cornerweighted to take the bind out of the swaybar. This ensures consistent handling from right to left. As a final nice touch, the Whiteline bits have rubber dust shields to help the spherical bearings last longer in the sometimes hostile street environment.