Looking for alignment advice...
Thread Starter
Burning Brakes
Joined: Apr 2018
Posts: 763
Likes: 268
From: California
Looking for alignment advice...
Since I know many Z06 owners track their cars I hope to get some good advice here. I will start by saying that I am a seasoned track driver, but have not yet tracked my personal C7 ZR1. I've tracked quite a few cars but most of my seat time has been in my heavily modified (and supercharged) Z4 M Coupe. With that car I ran -2.5fr/-2.0rr camber on both track and street - as the car served both purposes. I got relatively even tire wear with this setup - I think because when street driving I tend to take all corner quickly. My ZR1 will be mostly driven on the street, but when tracked it will be driven hard.
Something I would like to reduce is the bump steer/kickback that I experience driving the car. I presume this would involve a significant caster adjustment. But I wouldn't want to loose steering feel. So looking for advice on this too.
Now...the tricky one: Rake. After coming back from the ZR1 school I really want to lower my ZR1's nose by 12mm. But as things are now I just barely don't scrap going onto my driveway (minimum gap is the thickness of my finger) - or lightly scrape if I go slightly too fast. And there are some unavoidable light scrapes in places around town even when creeping over them at 1mph. So...do I risk damage to the splitter? Or...what if I lower the front 6mm and raise the rear 6mm. That would be the same rake as the GM track recommendation, overall the same roll center as street, and a 1/2 way hedge on the aero. Thoughts?
Something I would like to reduce is the bump steer/kickback that I experience driving the car. I presume this would involve a significant caster adjustment. But I wouldn't want to loose steering feel. So looking for advice on this too.
Now...the tricky one: Rake. After coming back from the ZR1 school I really want to lower my ZR1's nose by 12mm. But as things are now I just barely don't scrap going onto my driveway (minimum gap is the thickness of my finger) - or lightly scrape if I go slightly too fast. And there are some unavoidable light scrapes in places around town even when creeping over them at 1mph. So...do I risk damage to the splitter? Or...what if I lower the front 6mm and raise the rear 6mm. That would be the same rake as the GM track recommendation, overall the same roll center as street, and a 1/2 way hedge on the aero. Thoughts?
Tech Contributor
Joined: Oct 1999
Posts: 41,055
Likes: 9,817
From: Charlotte, NC (formerly Endicott, NY)
Describe what you mean by bumpsteer kickback or what you are feeling in the way the car behaves. Congenital wisdom is to leave C7 at stock ride height for the track. Are you familiar with the discussions about rear caster settings and what they have to do with powering off a corner?
Bill
Bill
Thread Starter
Burning Brakes
Joined: Apr 2018
Posts: 763
Likes: 268
From: California
Describe what you mean by bumpsteer kickback or what you are feeling in the way the car behaves. Congenital wisdom is to leave C7 at stock ride height for the track. Are you familiar with the discussions about rear caster settings and what they have to do with powering off a corner?
Bill
Bill
2) GM recommends lowering the front of the ZR1 1/2" for track use, hence my idea about altering the front/rear heights to attain that rake but wondering if it might have a negative effect on aero or handling due to a change in roll centers.
3) No, please direct me if you have links. Also curious to what extent they would apply to a ZR1. I assume they would if the Z06 and ZR1 share the same rear suspension architecture.
Tech Contributor
Joined: Jan 2015
Posts: 5,692
Likes: 1,451
Hopefully you're taking it to someone that can verify rear caster. Otherwise an aligment is all but useless on the rear of these cars for the track. They can really mess up the caster and you wouldnt know.
Gm recommended alignment spec with +0.7 caster on the rear is good
Gm recommended alignment spec with +0.7 caster on the rear is good
Last edited by BrunoTheMellow; Aug 4, 2019 at 10:00 PM.
Thread Starter
Burning Brakes
Joined: Apr 2018
Posts: 763
Likes: 268
From: California
Hopefully you're taking it to someone that can verify rear caster. Otherwise an aligment is all but useless on the rear of these cars for the track. They can really mess up the caster and you wouldnt know.
Gm recommended alignment spec with +0.7 caster on the rear is good
Gm recommended alignment spec with +0.7 caster on the rear is good
Melting Slicks
Joined: Dec 2004
Posts: 2,656
Likes: 635
From: Dallas TX
On the C7 the rear control arms have two small locator holes that 2 pins on a jig slips into then a digital angle gauge is put on said jig and the rear caster is measured.
Burning Brakes
Joined: Jul 2008
Posts: 1,236
Likes: 270
From: Rattlesnake, FL
Not exactly. Bump steer is the tendency of the car's wheels to steer due to the suspension stroke. It is not the sensation of hitting a "bump" and having to correct for any potential change in path.
Last edited by breakskeet; Aug 5, 2019 at 11:14 PM.
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