Designing an angle kit for an Audi A4
The last 2 weeks Josiah has been busy designing a “one off” angle kit for an Audi A4. He came across a number of differences but found a few similarities with other chassis’s and used those to his advantage.
The challenges were:
the A4 is an AWD car, this poses a few difficulties as the frame rails are usually wide, control arms short and all to allow for an axle to steer and have clearance. This was ok to overcome by widening the track width but the biggest issue was that the steering rack is located ABOVE the transmission, seems ok right? Wrong, the kinematic changes that happen from lock to lock, and the bump steer was horrendous. This is because the upper control arm on most chassis is shorter than the lower. (A quick explanation why the upper is shorter, to give it a KPI angle “king pin inclination) this helps with self steer, stability and handling of the vehicle.) I’m back on track, so after designing a knuckle to have the tierod mounted up top we had to allow for a lot of bump steer adjustment, as the suspension compresses the wheels toe out, this will not be good for drifting but because the upper control arms are so short, they push the top of the knuckle outward causing the tierods to pull in a toe the wheels out. What a nightmare, so we are going to allow adjustment so when the vehicle is at ride height we can make it as good as it can be given the circumstances.
another challenge was the wide frame rails, we overcame this issue by increasing the track width by 75mm each side, and design a heavily clearances control arm.
Another issue, garbage wheel bearings with annoying bolt patterns, we fixed this by building a knuckle that uses a 350z wheel bearing which is a bolt on hub assembly.
the good things about the car is, the control arm and shock mount location was similar to our 350z arm, so we only had to make minor adjustments to get this arm to work well on the car.
thank is all for now, the kit has been completed and is being powder coated, this will be tested at a later date!
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