Pylons

test 'n' tune yesterday in Winston-Salem

great time...I've been autocrossing for about a decade, but this was the first time in this car (I had done one previous event in a C5Z).

Great familiarization day...I got 10 runs, co-driver got 8 (on a 45 sec course). Great weather with a fair amount of sun and mid-60's.

Got the jitters out early in the morning...nearly spun on run 1, put it in the grass on run 2. Took a break to work the course for a while...later on started to get it figured out (my other cars have had at most about 1/2 the power as the LS3). Once I started letting the car be fast instead of trying to make it fast, time dropped quickly.

Ran about half of the runs on 285 front, 295 front (left over from autoxing a Chrysler Crossfire last year). Switched to brand new 295's and 325's for the last few runs. Newer/wider tires were about .6 to .8 secs faster, but some of that was probably just due to repetition.

Weighed the car pre-event with about 1/2 tank...it was 3171 w/o driver.

Ran at first with shocks (Pfadt) set at 10 all the way around. Car wouldn't push, so we kept bumping the fronts up. Ended the day at full stiff front and at 10 rear.

Given that it wouldn't push and that I could use some more help putting power down, I'll definitely think I need a stiffer front bar, just have to decide which one...I was thinking Pfadt SS bar, but I'm wondering if it goes stiff enough for a C6 Z51. Any other suggestions?

Had it aligned Friday. -2.2 camber front, -1.2 rear. Zero toe front, about 0.1 toe in rear. Something slipped at some point yesterday...steering wheel was crooked as I drove to work this morning...I'll find out what the deal is in an hour or so.

What a blast though...awesome car. It was just a practice event, but hopefully some times will get posted at some point...I don't recall seeing a fendered car go faster than me (although a shifter kart surely did...by 3+ secs)

VetteDrmr

Are you saying you couldn't get the fronts to push on corner entry, at the apex, or on corner exit?

With a 285/295 f-r combo I would expect the car to experience a fair amount of oversteer. With your 295/325 setup I'd expect the car to be pretty neutral. That's of course holding all other things constant.

Have a good one,
Mike

Pylons

it didn't push anywhere on either set of tires

(except for the couple times I broke too late, got off-line, and got into the marbles)

TedDBere

Sounds like you're just not going fast enough!

Pylons

I dunno...I did put it in the grass once.

Pylons

It was one of the adjusters (the rearward one, I think) on the right front...bolt seemed to still be tight, but it had slipped quite a bit--camber was down to -1.3 and toe was all out of whack. All back in place now with a little extra grunt...marked everything with some touch-up paint too so any future slips will be easily identified/rectified.

Z06Fix

You can try softening up the rears a couple clicks. It will help with putting the power down.


How do you like the shocks over all?

VetteDrmr

Take it from one that's done exactly that: braking WAY too late and experiencing the sheer terror of going off the pavement for not going fast enough!

Have a good one,
Mike

Datawiz

I run 5 in the fronts and 12 in the rears. Pfadt recommends 5-6 front, 10-12 rear. Your settings seem odd to me.

High Performance Handling Chart

To Decrease...........To Decrease
Understeer..............Oversteer....... ....Adjustment

Higher.....................Lower........ ......Front Tire Pressure
Lower.....................Higher........ ......Rear Tire Pressure
Larger....................Smaller....... ......Front Tire Section
Smaller...................Larger........ ......Rear Tire Section
More Negative.........More Positive......Front Wheel Camber
More Positive..........More Negative.....Rear Wheel Camber
Toe-out.................Toe-in...............Front Toe
Toe-out.................Toe-in...............Rear Toe
More Positive..........More Negative.....Front Caster
Soften...................Stiffen........ ......Front Springs
Stiffen...................Soften........ ......Rear Springs
Smaller..................Larger......... ......Front Anti-sway bar
Larger...................Smaller........ ......Rear Anti-sway bar

Pylons

yeah, in retrospect, I wish I would've tried softer in the rear at some point...but I really think a stiffer front bar is going to make a very nice different

So far, I like the shocks...hard to beat the easy adjustability...it'll definitely take some more seat time to figure out just how well they're really working though

Pylons

you're running a Z06 on very grippy concrete though

I'm in a Z51 and that was very mediocre asphalt

throw in possibly different driving styles and I'm not sure there's any reason to expect the setup needs to the same

of course, it's also the first time I've run the car...I didn't want to monkey with too much while I was still on the steep part of the learning curve

In retrospect, I think I should've softened the rears instead of stiffening the fronts to balance the car better, but I'm pretty confident that your settings would have resulted in several end-swapping events for me

EvilBoffin

Bryan -

I am right there with you about trying to figure out what's best for autocrossing an '08 Z51. Just glad to see someone else around NC that's willing to put some development time and $ into an LS3 C6 for SuperStock. It is a REALLY great car, isn't it??

Since I currently run 285/315 Hoosiers, I'm most interested in your progress with your 295/325 combo. I am also seriously considering the Pfadt shocks & the SS front bar.

I've talked to Dave O'Malley and Aaron Pfadt about the SS bar vs. Street front bar. O'Malley ran the stiffer Street bar on his C5Z06 last year, but had to leave it on full-soft, or the car would understeer. And I think that Datawiz's Z06 needs a much stiffer front bar then we do, to balance-out his thicker rear bar and stiffer springs. He can then use a softer front shock setting (5) to dial-out any understeer.

If anything can be surmised from this info without actually trying each bar ourselves, is that it seems the SS bar may still be a bit too soft, while the Street bar could be a little too stiff for our needs. Unfortunately, it doesn't sound like Aaron has plans to offer something in between these two bars any time soon. That makes me guess that the SS bar would probably be the best choice for our C6Z51's.

... But I could be wrong ...

.

EvilBoffin

Being very familiar with the Fairgrounds location that the event was held on, I'm not surprised that you found the grass.

It's a great venue, but there can be lots of 'opportunities' for off-course exploration at that place ...

.

Datawiz

This happened to me just about every time I raced until I found out the alignment guy was NOT using a torque wrench. I got the proper settings from DavidFarmersStuff.com and they now torque everything down and no slippage.

Your rear tire, likely driver's side, is pushed in.

JiminVirginia

The Pfadt SS front bar starts off at 30 percent stiffer than the OEM Z06 bar (using holes farthest out from the bar itself). I don't know how this translates relative to the Z51 package, but it leaves lots of room for further adjustment for us Z06 drivers.

I have found with my Pfadt adjustable shocks that tinkering with the settings makes a real difference in how the car turns in and comes out of a corner. It makes sense to soften the rears, to see if this helps plant the back, before investing in a front bar.

Anyway, thanks for the post. It's interesting reading for those of us who are tinkering with the set ups on our own cars.

Pylons

nope...see above...the right front had slipped

Datawiz

Can't wait for March.

Pylons

fyi, this is not necessarily true...it's totally dependent on which side of optimal pressure you're on

Pylons

looking at the pfadt site, there's a different "SS" bar for the C6Z, right? but it appears to be essentially the same as the "Street" bar in stiffness (although it looks like it has a different shape). Any idea what the story is there? (i.e., why there appear to be 2 different bars that are nearly identical performance-wise)

Also, anyone have any idea what the dimensions and stiffness of the eibach bar are?

Pylons

Just found that on the tirerack site...eibach is 1 1/4" and is 15% stiffer than Z51.