If anyone's in central NH Saturday

[batchman]

My first question and related rant is about alignment. Much to my surprise when my wife dusted off her Z51 to try autocrossing the thing was just about undrivable. Factory alignment settings are presumably lawyer induced, set for understeer, but with power on tap the rear can become just as, if not more, evil.

If I recall correctly (and I may not), the by-the-book alignment includes positive front camber. That's just nuts. And many places won't vary from the book....

Best,
- Jeff

[tomtom72]

Now see, I knew I joined up for a reason! LOL I just never thought about alignment...well, not seriously anyway. Thanks Jeff!

I'm gonna dig out my results sheets and the FSM and look to see what are the settings. Then I'm going to get the book from the pizza box as I remember there are suggested alignment settings for track days in there. I also think that Dick Gulstrand's site has some suggestions also....if I remember right?

I don't know why I didn't expect the car to slide the front now that I think about it. I think, all things considered, I should have expected that to happen in very tight ( hair pins or switch backs ) corners. I guess I never spent too much time doing really tight stuff.


Tom

[batchman]

CJ's* alignment for C4 "spirited driving":

(* = ol' Crazy Jeffrey)

- most negative camber you can get in front with both wheels the same
(probably -1.25 to -1.5 degrees)
- 0 toe in front
(this may be a little darty on rutted highway, if so crank toe in yourself, in half-turn
increments, until it behaves)
- caster as you like it, with both wheels about the same
(more caster = more effort, more return force, more neg camber gain in roll)
- twice as much negative camber in rear
(1.5x for zr-1)
- 1/4" total toe-in in rear
(1/8" for zr-1)

Your mileage may vary, and for gosh sakes find a parking lot to try these settings before any shenanigans on the street!

A good setup will give you neutral handling and allow either end to give up first depending on whether the deranged monkey is flailing the steering wheel or the throttle.

I find no matter what I do with ZR-1 stock brake setup I get big understeer under braking. That might be part of what caught you out also. The car really needs more rear bias, but the big thing to me is long pedal syndrome. Makes me very hesitant to change master cylinder (to fix the pedal) fearing I'll make bias problem worse...

Good luck!
- Jeff

[tomtom72]

Brakes? Oh, that's the pedal in the middle....I always wondered what that did.... I prefer my braking just like fine spirits...straight only. No Jeff, JMHO but the loose nut behind the wheel has to take full responsibility...I went to roll thru with to much...err, ahem, too much roll & proly the wrong line for my amount of roll; add in not enough tire temp too. The D3's need a lot of heat. One of these days I will buy a few books and try to learn useful stuff about car control...like trail braking! I have a feeling that might have been useful in this circumstance?

I still haven't dug out my alignment sheets....yea I save every one of them. I know, I know...I need help.

Oh about those ruts....very common where I live, and yes I do fight with them even now. LOL Although I hear the D3's are particularly adverse to ruts. I should ask my buddies who run PS2's about that?


Tom

[efnfast]

Tom, my PS2's don't seem to follow ruts to bad, but keep talking, I'm learning a lot.

[tomtom72]

Originally Posted by efnfast

Tom, my PS2's don't seem to follow ruts to bad, but keep talking, I'm learning a lot.

Not from me! But yes Jeff, keep talking!

Steve, you can ask Doug and Lou for for an evaluation of the depth of my ( I'm loath to use words like 'talent' or 'knowledge', but I ain't got no choice LOL ) knowledge and or talent.

Oh, you should see some of the ruts we have down here. My Cobalt almost gets lost in them! Summer heat + trucks + asphalt = 2' sea state....

[batchman]

Keep talking? But what if I run out of smart sounding things to say? Come to think of it, that's never stopped me before!

If you want a handful try giant sticky slicks plus an aggressive alignment on truck ruts. Now that's exciting!

Best,
- Jeff

[tomtom72]

Chit! I can't find my alignment sheets. I knew I should have fixed my filing system...or cleaned my apartment.


Jeff, you just keep teaching and Steve and I will just listen.


Tom