Autocross

[jrtoffroad]

Took my ZR1 to an autocross last weekend for the 1st time and wow what a blast, I've been on a high all week. I'm already anxiously awaiting the next event!

The balance and power of the zr1 is simply amazing. I've only autocrossed 2 times before, once in a GT Mustang and once in my 69' TR6, and while those were fun, the performance doesn't even compare. My tires are a little old, and that combined with cold damp conditions made it tricky. I found my best times by short shifting to second and keeping the revs down to help keep the rear end in check.

Although I'd really like to pickup some new sticky tires, I was still able to get 1st in my class (B Street Prepared), and 3rd out of ~20 novices.

Anyways, just wanted to brag. Next event is in 2 weeks, hopefully I'll get some video.

Anyone else autocross their Z? Any input on tires, tire pressure, or alignment settings?

-Jordan

[bobbyhi]

Took my ZR1 to an autocross last weekend for the 1st time and wow what a blast, I've been on a high all week. I'm already anxiously awaiting the next event!

The balance and power of the zr1 is simply amazing. I've only autocrossed 2 times before, once in a GT Mustang and once in my 69' TR6, and while those were fun, the performance doesn't even compare. My tires are a little old, and that combined with cold damp conditions made it tricky. I found my best times by short shifting to second and keeping the revs down to help keep the rear end in check.

Although I'd really like to pickup some new sticky tires, I was still able to get 1st in my class (B Street Prepared), and 3rd out of ~20 novices.

Anyways, just wanted to brag. Next event is in 2 weeks, hopefully I'll get some video.

Anyone else autocross their Z? Any input on tires, tire pressure, or alignment settings?

-Jordan




Don't know anything about the settings, etc. but good luck in 2 weeks:cheers:

Keep the rubber side down...............:)

[ZR1@gmx.com]

Sounds fun! I have never done it but would love the opportunity!

[QB93Z]

Thanks for telling us about you experience at the track. Try posting a specific question about setting in the General Section. You will get a lot more responses.

Jim

[tomtom72]

Waaay cool! 1st in class! :thumbsup:

You may want to call Doug Rippie or have a look at Dick Gulstrand's site for alignment suggestions....maybe even vette brakes & products might have something.

I would say maybe a set of Nitto NT05's or INVO's maybe; unless you want to have a set of dedicated track tires and another set for street use?

I know that this may sound stupid. In our pizza boxes is a small spiral bound book with the splash logo on it. That book is an owners' manual specific to the ZR-1, and it it there is an "off road" section. In that section it has a suggestion of alignment settings for track use....there is a whole bunch of info actually that I found good reading, JMHO.:o

:cheers:
Tom

[jrtoffroad]

Hit the autocross again today, here's a couple videos:

Interior (very shaky)-
http://www.youtube.com/watch?v=fY81J9M9DA8

Exterior -
http://www.youtube.com/watch?v=5JShaLf_EWc

Ended up getting 2nd in class, but still aways off the BTD. Car did GREAT, hope to get a new set of tires before the next event and maybe look into tweaking the alignment a little.

[94Admiral]

Thanks for the videos!! That looks like a real blast!!

Any hints on performance improvements you made or anything you learned about the car doing this? Thanks!

[jrtoffroad]

Had a drivers education event and another Auto-X this weekend.

This was my first event with the new alignment described in this thread: http://www.zr1.net/forum/showthread.php?t=14320

Here's the specs:
FRONT
Camber: -1.5 -1.6
Caster: 5.5 5.6
Toe in: 0 0

REAR
Camber: -1.2 -1.2
Toe in: 1/8 total (1/16 per wheel)

Really like the changes. Thought about trying to toe out the front a little, but didn't take the time. The cornering is noticeably improved, and, with a few tweaks to my driving style, kept the rear end a little more in control ;) I've been trying to keep the tire pressures at ~35psi front and 33psi rear (this of course requires constant monitoring as the pressure changes with temp). This looks good on the sidewall, I could go a little lower, but would like to try pyro gauge to make sure I'm getting even temp across the tread before I get too crazy. Staggering the pressures by 2 to 3 psi seems to work well on my Z with stock size tires and stock suspension.

Possibly against my better judgment, I ran this weekends event with the top off. The weather was just too nice :-D I'll probably build a crossbrace to go in place of the targa eventually but, honestly, I didn't notice a downside to racing without the top. I got 1st in class and FTD out of ~50 students in the drivers education course. Mind you, I was still ~3 secs behind the overall FTD...still got a ways to go to compete with the very experienced guys, but the gap is shrinking!

Next event is this Saturday.

[jrtoffroad]

Thanks for the videos!! That looks like a real blast!!

Any hints on performance improvements you made or anything you learned about the car doing this? Thanks!

Not too much yet.

I'm learning a ton each event, but most of that applies to my own driving. The car really has amazing performance in stock form. Mine has a few engine mods but, for short course racing like this, I think before modifying the engine I'd look into a lower set of gears to help get your Z into the power band faster and keep it there. As it is, the courses are a little fast for 1st, but 2nd never gets me into the meat of the power.

A little more extreme alignment (as I mentioned above) helps a lot, as will purpose built tires (hopefully I can report back on that soon). The only change to the suspension on my car is a lower ride height, which I highly recommend. I may eventually play with sway bars, but have been pretty pleased with the performance of the stock setup.

Stock brakes (GS calipers, fresh fluid and vented rotors) and cooling seem adequate thus far, although on a longer race or with stickier tires that might change.

One other thing I want to look into is potential weight savings.

Not sure if that helps, but I'll keep this thread updated with my findings.

[JThomas]

Jordan, it sounds like you're hooked! I have only autocrossed my '92 ZR-1 on two ocassions. Once at the National Corvette Museum and at my local club's event, here in Michigan.

I have also run my stock C5 coupe, with Z51 suspension and C6 Z06, which is also stock.

You are headed in the right direction, by making alignment adjustments, tire pressure checks and searching for the right tire. All of that is very important, but if I may offer some advice, you may want to look at a dedicated tire if you get real serious. If you continue to use your street tire, you will consistently find yourself 2-3 seconds slower than the guy with a race tire.

If you don't compare yourself to others, then use the street tire and keep having fun, just improving YOUR times and skills. "Seat Time" more than anything else will help you be a better autocrosser, and you seem to be on your way.

Congratulations and be safe in experiencing your Corvette!

[jrtoffroad]

Went to my 10th autocross for the year yesterday and the ol ZR1 made me VERY proud.

Held FTD all morning, losing it to a c5 Z06 in the afternoon, but coming out 2nd overall (raw time) in a field of 84 cars. The course was long and fast, just what the ZR-1 likes. On the back straight I was just about at the rev limiter in 2nd before braking for a 3 cone slalom leading into a sweeper.

No recent changes to the car. Surprisingly the Nitto NT-01 really hooked up well even with cooler temps. Pressures were kept at ~33 front & ~30 rear hot.

No video, but will post some pics later.

[jrtoffroad]

Well, had another Auto-X Sunday (10/30) and took home FTD in a field of ~60 cars!

Only change on the car was properly torquing a few very loose rear suspension components (A couple nuts were just finger tight!!!). Ran the tire pressure VERY low for this event, ~28 front and ~26 rear. Traction was great, but car felt a little loose on the edge, probably run them a touch higher at the next event.

Even cooler at this event (high of ~60), and the NT-01's still did not disappoint.

Overall great event, with a slightly smaller turn out than usual we were able to get 8 runs in (with each averaging ~50sec).

[JThomas]

Yep, you're hooked! Keep it up.

[jrtoffroad]

Here's a quick update for 2012:

Didn't have a chance to work on the car this winter (too busy building an ultra-4 racer & prepping for KOH). So, with the same configuration as last year I've now raced the Z in 3 Auto-x's this year. One of which was a 2 day event put on by the local corvette club where I got 28 runs!

The car has been doing great. I did find a little slop in the d-side lower ball joint, so the car is down right now while I replace all 4 just to be safe. Figured this is as good of time as any to throw some poly bushings in the suspension. Hopefully I can get it all done in for this weekends race! Glad I'm doing it though, some of the stock bushings are in pretty rough shape. Very excited to see if there's a noticeable change in the feel of the car.

After I get the bushings in and the ride height tweaked (plan to bring the rear down just a touch) I'll need to have the alignment checked. I did not go with the offset lower bushings. I've been pretty happy with my settings from last year and plan to stick with those for now (~-2deg front / ~-1.25deg rear, no toe front & 1/8" in rear). I don't think my street tire budget can stand any more camber, and doubt I would gain much at the track.

I've still got a little life left on the NT-01's. They don't seem to stick quite as well as they did last season (been through a lot of heat cycles now), but still are worlds better than street tires. Just for fun I ran my new NT-05 street tires at the last event to compare performance, and while they may be great street tires, my times really suffered. When the NT-01's finally cord I'll be ordering another set.

On the brakes I've been switching between my carbotech (12 front 10 rear) and hawk HPS brake pads. The carbotechs are amazing and stop MUCH better when hot, but hard to live with on the street. Unreal amount of dust. The hawks are OK and much nicer for daily driving. I find for short slower Auto-x courses the Hawks do just fine, it's really only the high speed stuff where the carbotechs make a difference. For this weekend I'll be back on the Hawk's.

Anyways, still need to shoot some more video, but the Z continues to be very competitive, pretty consistently winning BSP and usually in the top few for FTD.