Quote:
Originally Posted by bradsm87
fe1rx, do you have a theory on dynamic toe and camber as a result of bush deflection when launching? I saw your other thread showing that there is very little bump steer with everything unloaded. I'm trying to decide whether it's justifiable getting M3 guide rods. Every review I've seen, people have also upgraded other items. I already have M3 subframe bushes. I've been happy with my setup for over two years but now I have more power and traction is a real issue.
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Bottom line is you need more rear rubber to launch 400+hp.
I am not so sure moving to spherical bushings will help launching much. The stock bushings are able to absorb energy which helps aid in off-the-line traction. However, this "wind-up" effect also has to rebound and un-wind which is bad for handling and wheel hop.
People moving to spherical bushings in drag racing seem to mainly do so because the torsional effect when launching on poly bushings can cause them to tear and fail.
Spherical bushings will help you maintain alignment, yes. The stock bushings actually toe-in under load as they deflect. Again, this aids in straight line stability.
The deflection measurements of OE vs M3 have been graphed. The M3 parts deflect significantly less which results in less of the "side-to-side" motion people describe.
Question is, do the benefits outweigh the costs? For most people that seems to be a yes. The soft stock suspension doesn't match the power of the car at all.
Once you stiffen one aspect of the car (like the springs) you then cant help but notice every other soft busing in the car... engine mounts, transmission mounts, control arms, differential bushings, and then there is the lack of alignment options with stock toe/camber arms. It's all made from insanely soft rubber that's designed to give a luxury ride, not performance. It's a slippery slope... replace it all and you've got a beast of a car on track though.