The Z-link is adjustable for...
The Z-link is adjustable for rear steer also. It is less adjustable than the four-link, but can be made to steer. Remember, when choosing spring rates in the rear that most swing arm designs where the spring is mounted on the forward link instead of on the axle tube either clamped or on a birdcage, that there is a motion ratio. The car "feels" about half the rate of the spring. The motion ratio is squared and multiplied times the spring rate to find the wheel rate. This is very important to understand.
• Setup changes to solve corner entry problems?
We never want to make changes to our spring rates, sway bars, weight distribution, or moment centers to try to solve entry problems. When we do that, we will certainly change our mid-turn handling in a negative way. We should have already tuned the car so that the mid-turn handling was balanced correctly.
There is an exception to the above rule. We can initially plan out our spring selection so that our entry transition is best for the type of track we will be running. For flatter tracks, running even spring rates across the front, or a softer RF spring rate as opposed to the LF spring rate, will help the transition into the corner. It is best to make that choice before you go to the track so you won't need to make changes after you tune the mid-turn.
Stiffer RF spring rates over the LF spring rate can help the transition into a high-banked track where the outside of the track rises up to form the high banking. In this case, the vertical forces are high at the RF on entry and we need more spring rate at that corner to control those forces to limit excessive RF wheel travel.
• Throttle modulation on entry can help solve problems with abrupt release of the throttle If we quickly jump off the throttle and into the brakes, we can upset the car to where it affects our entry speed and stability. It can also cause us to slow too quickly and attain a slower speed than is necessary to maintain through the entry portion of the turn.
This is a real phenomenon that occurs with a number of drivers. The practice of early release and later application of the brakes helps with the transition from acceleration to braking. The method is one of the primary tools taught by Mike Loescher in his driving school at Finish Line Racing-and it works. Many entry problems simply go away with an improved entry strategy.
Corner Exit Handling
Most of the time, solving the mid-turn handling will solve corner exit problems. If we were tight in the middle, we would most likely be tight off or tight/loose off. If we were loose through the middle, then we would be, well, loose off, of course.
The process of increasing mid-turn speeds means that we have also increased our exit speeds, or the speed at which we begin to accelerate. This is a big deal and the reason why we spend so much time perfecting the mid-turn balances and trying to increase speed through that portion of the turns.
The ways some tracks are laid out contribute to corner exit problems. A flat track offers less grip than a banked track because we have none of the dynamic downforce created by the banking to help provide more overall grip. So, we need to enhance bite in other ways. The transitions in the track banking angle on higher banked tracks may also contribute to exit woes.
Loose Off Condition-Rear Steer
For the left side link on...
For the left side link on a three-link rear suspension, the angle can be changed to increase or decrease the amount of rear steer as the car squats coming off the corner and while under acceleration.
To solve loose off If we know we are good through the middle, then a loose off condition can be solved with the application of rear steer that happens only upon the application of power. Basic rear steer from chassis roll does not help us because it will change our mid-turn handling.
There are ways to utilize the rotation of the rear end, if using a lift arm or pull bar, so that the motion of the rotation of the rear end causes the rear wheels to move fore and aft to create rear steer to the left to tighten the car off the corner.
Think this process out and try to arrange the components on your car to utilize this process. If definitely works. If you must run a solid third link or other type of rear suspension where the rear end can't rotate, then go to the next step.
Shock rates can increase the crossweight percent on exit to tighten your car off the corners. If you run shocks with a stiffer compression rating on the LR corner than on the RR corner, then when the shocks move as the car squats coming off the corner under acceleration and while the loads transfer to the rear, then the LR corner will carry more load and the LR and RF will then share that increased load.