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      01-24-2013, 03:27 AM   #15
WTF does Stage 1 mean?
redux's Avatar

Drives: Bwm and such
Join Date: Jul 2011
Location: Singapore, Los Angeles, and such

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2011 1M  [4.60]
Originally Posted by bdaddylo View Post
You said you already removed the rear roll bar and that didn't help reduce oversteer, so why would you go with stiffer springs? That would help roll stiffness but also reduce rear weight transfer. Maybe a small roll bar and softer springs would do the trick.
I not try to reduce the amount of oversteer, I actually find that one of the more endearing features of the car. I'm just trying to make the break away characteristics more progressive and predictable. I would love to get a smaller bar, but finding one is proving to be somewhat of a challenge.

Originally Posted by HP Autowerks View Post
In our experience, larger anti roll bar will only add to the oversteer especially a snap oversteer.

If the main springs don't stay loaded in the inside rear corner during a turn, a snap oversteer may also occur.

What spring rates are you running?
I can't remember the rates off the top of my head, but they are relativity soft. I'm going stiffer and getting rid of the helper springs to better control the loads on the wheels. As it stands, removing the rear bar provided a decent boost in traction and made the rear end more predictable, but it not were I want it yet.

Originally Posted by Pete_vB View Post
I'm a bit surprised with your decision to pull the rear bar. Where are you getting this advice from?

I run one of my Porsches without the rear bar, but I wouldn't expect it to help stabilize the rear in your situation.

Running no rear bar means running stiffer rear springs to maintain overall roll compliance. Stiffer rear springs mean you can't put power down as well, causing the back end to step under power.

The other thing I could imagine contributing to instability is mismatched shocks. How have you tuned the shocks so far? Have you used principles like these to guide your shock tuning?
I have no problem with the back end stepping out on me, it's the rate of the transition that worries me. This was just an initial test of the baseline setup to get some numbers with the data logger. The dampers will go back on the shock dyno, valving may be changed, spring will be adjusted to suit, and the package will be track tested again. I have a long way to go with the street tire setup (at least 9 more test sessions) before I call it good enough to move on to things like R-comps and more horse power. By the time I done, every angle will have been investigated, and also tested by people that are much better behind the wheel than I am.