It's All About The Damping - Project 350Z - Suspension Install

We replaced the rear mid-link control arm on our Z with SPL's adjustable aluminum unit (front). It comes with an integrated adjustable spring perch, monoball outer end and a hybrid camber/toe adjuster. The kit also features an aluminum upper spring hat as well as spring washers to eliminate spring noise.

We replaced the rear mid-link control arm on our Z with SPL's adjustable aluminum unit (fr

After talking to our friends Steve Mitchell (with the M-Workz time attack Z) and the guys at SPL Parts, both of whom campaign time attack cars on Moton Clubsport suspension, we decided on using a 1,100 lb/in (20kg/mm) spring in front and a 1,000 lb/in (19kg/mm) spring in the rear. Normally, we would use the same spring rate for the front and rear, but because of our stiffer Nismo antiroll bar in the rear, more spring might cause the car to rotate too much, which is not good for a car this powerful and fast.

Eibach offered a wide selection of springs to choose from in its ERS line and we opted to use 2.5-inch inside diameter springs in 6-inch lengths in front and back for the race rates. We also added a softer tender spring in the front to help absorb minor wheel movements. A tender spring is an auxiliary spring that many coilovers will use to help the suspension extend under droop, but also absorb small suspension movements. Tender springs are different from helper springs seen on most coilovers because they're stiffer, have differing linear and progressive spring rates and are not fully compressed under the car's weight. Helper springs come in only one spring rate and are fully compressed at static ride height. Eibach also supplied a set or street-rate springs that we spec'd out to half our race spring rates. To compensate for not over-lowering the Z on the softer street springs, we increased the front spring length to 8 inches and the rear to 7 inches, as well as eliminating the tender spring.

SPL also offers front and rear pillow ball upper mounts for the Z and the Moton suspension because the company sells the entire kit.

SPL also offers front and rear pillow ball upper mounts for the Z and the Moton suspension

The last part of mounting coilovers on a 350Z is finding a way to mount the rear springs. Nissan went to great lengths to move the rear spring inboard of the shock to reduce unsprung weight as well as sticktion in the rear suspension. While we could just pull out the old springs from the stock rear mid-link and use the adjustable perch on the Moton coilovers, the rear upper mount wasn't designed to support the vehicle's weight and we'd be undoing all of Nissan's handiwork. Instead, we opted to replace the stock rear mid-link, that the rear spring sits in and use a lightweight CNC-machined replacement link from SPL Parts. The link comes with an integrated treaded spring perch sized for 2.25- or 2.5-inch coilover springs as well as an aluminum upper spring seat and monoball outer pivot that replaces the stock rubber bushing. Bang for buck, this is the best way to update the rear suspension for coilover use as it maintains the same light weight without using heavy tubular steel control arms, eliminates the rubber bushing that plays a critical role in unwanted rear toe change under heavy loads and also has a secure method of holding in a coilover spring. The mid-link also integrates in SPL's hybrid adjuster for a more wider range and precise toe and camber adjustments in the rear suspension. SPL also came to our rescue with its pillow ball upper mounts for the Z that fit our Moton coilovers because they sell the entire kit.