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Getting rid of tons of bump steer is one of the problems we attacked with the design of the front suspension in the Team America BNR32. The stock geometry was so bad we had to drastically redo stuff. Note that we still used the stock front upright. We followed the guidelines shown in the previous picture. Due to the front differential placement interfering with the ideal place to put the steering rack, we didn't get it 100% perfect but it is much better than stock.By learning what effects changes in the suspension geometry have in how a car behaves, you can now go out and tune and adjust your suspension in much the same way that racecar crew chiefs do. Understanding these geometry traits and setting up your car to be able to adjust them is a powerful tool when trying to eke out cornering performance beyond what the general aftermarket can give you. If you are a racer, autocrosser, drifter or just a hard core canyon carver, these tools offer a significant edge when taking your setup to the next level.
On a VW, moving the tie rod higher has the Whiteline bump steer kit does, places it in a more favorable location to reduce bump steer.
Although the Nissan S chassis is engineered pretty good so as not to have too much bump steer, when you fix the roll center in a greatly lowered one, bump steer once again comes into play. We added spacers to put the tie rod end in line with the ball joint and then a little more to give the car a little toe out under roll to sharpen turn in response and reduce some mid turn understeer.Toe Steer
Toe steer is a close relative to bump steer except it pertains to the rear suspension of the car. Toe steer is a change in toe in and toe out caused by the suspension links of differing lengths and mounting locations swinging through differing arcs as the suspension moves through its travel. These changes in toe can cause unpredictable and unnatural handling quirks in a car.
Toe steer is steering of the rear axle caused by body roll or suspension movement. Toe steer can make a car suddenly oversteer or understeer or get unstable under acceleration or braking.
Beam axles can toe steer with 3 and 4 link suspensions depending on the link locations even on leaf spring equipped cars and trucks if the front and rear mounts of the leaf spring are not on the same plane. If the rear leaf spring mount is higher than the front, the axle will roll toe in, if it is higher, it will roll toe out.. I stole this image from an SCC article I wrote a long time ago.
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I lowered my 991.2 Carrera GTS (2017) by approximately 30 mm in the front using Öhlins shocks. The lower control arms are hence directed somewhat upwards, however, the rod is also directed upwards. Maybe, they are nearly parallel. I am not sure if I should compensate for bump steer or this modern car compensates it automatically. I do not know if it developes a significant amount of bum steer as it is now.
As long as you didn’t correct the roll center you will be ok.
If I see it correctly, the roll center is lowered by lowering the car.
No