Rack & Pinion
The designers at Mitsubishi decided to use a reciprocating ball steering gear box in their flagship sports car. This severely effects steering feed back and introduces un wanted play into the steering. Another problem with these units is age. The original steering racks in the cars are now 15 years old or older. Many leak or are worn to the point of being dangerous. Rack and pinion is desireable because of the lack of parts and its unique and simple design, this form of steering offers superior road feel, accuracy and responsiveness.
Here is an animation of the play in the steering wheel. Yup. That's all play too; the wheels don't move. It is not unusual for a StarQuest to have some steering play. This isn't necessarily due to the gearbox, but it does need addressing.
There are unlimited ways of approaching this problem. Most involve, somehow, adapting another car's steering rack to fit the StarQuest. There are serveral key points of the geometry to consider. These are important becuase even if your suspension works for basic driving, the real test is when they reach the extremes of their design... times when you NEED them to work with, not against you.
- The overall width must be be within safe adjustable limits of the rack.
- You must have a safe method to attach tie rod ends to the steering knuckles.
- The axis of the lower control or "A" arm must align with the pivot points of the rack or bump steer will occur.
- You must safely connect the steering column to the steering rack.
- Engine power steering hydrualics, or electrics will need to be adapted (when applicable)
My Solution - 240SX Rack
I chose the Nissan 240SX rack mainly due to availability. Also, this rack has alot of aftermarket support for drifting which is important to me. The HICAS rack also is a slightly better upgrade too. It has the same dimensions as a regular rack but with a quicker ratio (14.9:1 vs. 17:1). It's also less turns lock to lock (2.6 vs. 3.1). The Starion's steering was 2.8 turns lock to lock so 2.6 will be a small upgrade.
I was originally going to weld on brackets to the Starion crossmember, but I decided to use a 240SX crossmember instead. With this I will also be using Nissan's steering column, control arms and hubs. I will be able to use S14 5 lug hubs and 300ZX 4-piston caliper brakes. Also, this will not effect the geometry of the suspension nearly as much.
© 2012 Bowman Cybernetics