Description

For the first time in 30 over years, the IRS on the 300ZX/Z31 and 200SX/S12 is no longer an archaic monstrosity to be ashamed of. This kit replaces the bushings ends of the trailing arms with sturdy rodends, and highly adjustable hardware. Once converted, the trailing arms allow you to correct unwanted negative camber, while fully correcting toe adjustment. Camber and toe can be set within factory specification, even with the vehicle lowered beyond drivable, something that can’t be done safely with any previously available options.

Type I:
This variant of the kit is designed for the advanced Z31 or S12 owner, someone who needs alignment correction badly, and knows exactly what settings are ideal for them. Type I allows greater installation flexibility, such as track width modification for wide-body racecars, or removing over 5 degrees of negative camber. Also possible is maintaining perfect toe, while retaining moderate negative camber for that stanced look. This version is does require some forethought in stud placement on the main backing plate, as each position gives only a range of about 2 degrees of adjustment. If the studs are welded or locktited, this can be difficult. Pre-planning the installation is essential.

This is not to be confused with merely slotting the subframe, which by it’s very nature will not correct camber enough on most lowered cars, and in extreme cases will cause excessive uncorrectable toe. Nor is it as limited as using two highly eccentric bolts or bushings. These recipes have been used for years, and have eaten many tires doing so; some people have refused to acknowledge how bad this is, others have accepted it as the price to pay. This no longer has to be the case.

Another side effect is elimination of the sloppy eccentric bolts that like to move out of alignment, or seize over time. Perhaps the best part is that it eliminates any possible binding from bushings at extreme adjustment, something other approaches have failed to do. There have been attempts to twist the trailing arm back into alignment with shims and jackscrews, and failures at the subframe mounting tabs have resulted.

Installing requires no modification to the chassis, or to the subframe, or any other part except the trailing arms. As such, the kit becomes portable, or even resaleable. If the vehicle is ever involved in a serious accident, the trailing arms can easily be transferred to a new chassis within minutes, while the camber and toe alignment that was set previously will also carry over as well.

Included parts:

• 2x mounting plates
• 4x turnbuckle adjusters
• 4x clamping hardware with fasteners
• 4x rodends with spacers and jamnuts
• 4x toe lockout washers
• 4x gussets
• 1x adjuster wrench

Notes:
The REGULAR kit is not designed for drag racing or cars exceeding 450ft-lbs of torque, which is also about the limit of the factory axle stubs. This doesn’t mean the kit can’t handle higher horsepower vehicles, only that drag racing is extremely hard on parts, and any design needs a healthy safety margin to avoid premature failure, or complications. For road racing with slicks, or frequent drag racing with slicks below 500ft-lbs of torque, it is highly recommended to opt for the ENDURO version of this kit. The ENDURO hardware is more robust, and will tolerate the sustained/repetitive loads possible with dedicated racing tires.

Vehicles of greater power output, or specifically built for drag competitions, should opt to convert to a multi-link rear suspension from more modern RWD Nissans, using either the Type I or Type II Subframe Swap Kit instead. Both can be found in the main 300ZX/Z31 category on the left. The improved design of the CV joints, and the larger/stronger mid-90’s Q45/300ZX/GT-R axle shafts can handle much greater power levels.

Also with the solid mounting of the trailing arms, it is recommended to use either new rubber or polyurethane bushings for the subframe and differential mount. By doing so, the subframe can absorb much of the vibration or harshness, while the trailing arms themselves won’t deflect out of perfect alignment, even under hard cornering.

Warning:
Increases in trackwidth may require axle spacers, or custom axle configurations to work properly. For installations using hybrid VLSD axles, the already increased length may be perfect for the added distance.