What is the maximum ZR1/C4 front negative camber setting? The 1990 ZR1 included a ZR1 Driver's Manual. In the Off-Road Driving section alignment settings are discussed as follows: "Standard ZR1 alignment settings are suitable for street or track. However, racetrack performance can be improved by a change to the following settings: Front Caster: +5 Front Camber: -2 Front Toe-in: 10 ft. Rear Camber: -1.25 Rear Toe-in: 25 feet. These are baseline settings for racetrack use...Always change back to standard ZR1 alignment settings for public road use." They do not describe how that much front negative camber is obtained. The rest of the settings are possible. I do not know any ZR1/C4 drivers who can get much more than Front Camber: -1 without doing major work or using non-factory parts. Is Front Camber: -2 possible with factory adjustments? If so, how is it accomplished? Is this procedure listed in a GM service manual as a range of suspension and/or alignment adjustment? (1989 Corvette with Front Camber: -0.8 and hoping for more.) Thanks
Maximum ZR1/C4 front negative camber?
- Thread starter jefmd
- Start date
Hib Halverson
Technical Writer for Internet & Print Media
I don't have a 90 owner's manual to read but if it says toe-in specs are 10 and 25 feet respectively, something is really wrong. Toe is usually expressed in fractions of an inch (such as 1/16th or 2/32nds) or in degrees.
As for how much negative camber you can get in the front, you may or may not be able to get 2 deg. neg per side. It depends on the car's ride height, the condition of it's front structure and the existing caster setting.
In many cases I'd think -2 may be hard to get withou using offset control arm bushings.
Are your tire temperatures at the track telling you that more front camber is necessary?
As for how much negative camber you can get in the front, you may or may not be able to get 2 deg. neg per side. It depends on the car's ride height, the condition of it's front structure and the existing caster setting.
In many cases I'd think -2 may be hard to get withou using offset control arm bushings.
Are your tire temperatures at the track telling you that more front camber is necessary?
- Thread starter
- #3
This information was printed in a 16 page 3-part series of Corvette Quarterly in the Summer, Fall, and Winter issues of 1990. The editor’s note indicated it was provided as a separate Driver’s Manual for 1990 ZR1 owners in addition to the regular Owner’s Manual and was relevant to both L98 and ZR1 owners. The Winter 1990 issue included the information about off-road driving and alignment suggestions.
Yes, I agree the toe-in values do not make sense, but I suspect is incomplete data to make adjustments at the track. There is reference in another thread to an alignment system designed by McPherson (of McPherson strut fame), which shows 10 ft and 25 ft reference points. I use 1/8 in toe-out in front and 1/8 toe-in in back.
I have the base suspension and resultant ride-height. I use single adjustable Koni shocks all around. Front Castor is about +5 both sides. To get Front camber of –0.8 all the removable shims were removed. I have asked my mechanic if the inside upper control arm round bushings could be removed (or replace the larger front with the smaller back bushing and leave the back bushing out) to gain additional negative camber while maintaining castor.
This appears to me a very reasonable way to gain additional negative camber while maintaining easy return to stock settings, using stock parts, and adjustability. My mechanic is hesitant to do this, as he has no information as to whether the suspension was designed for the additional adjustability.
My 1989 coupe has 51,000 miles, is garaged, is used weekends regularly spring thru fall, had new lower ball joints last spring, and new hubs, rotors and brakes 1 ½ years ago. Except for a Borla exhaust the car is otherwise stock. The car is maintained regularly using stock parts or equivalent. I enjoy autocrossing regularly.
Tire temperatures do indicate a need for more camber if possible. This has been more of a problem the last several years with Hoosier and Kuhmo tires. It was not a problem with Yokohama A008 or BFG Comp T/A R1 tires. The current Hoosier, Kuhmo, and Yokohama tire information all suggest more negative camber is helpful. Currently I use air pressure, shock settings, and regular tire rotation to try to compensate. More negative camber would also help achieve better tire wear.
I have owned this Corvette since Feb 1990, and continue to be impressed with its durability, reliability, serviceability, and performance. Thank you for your help.
Yes, I agree the toe-in values do not make sense, but I suspect is incomplete data to make adjustments at the track. There is reference in another thread to an alignment system designed by McPherson (of McPherson strut fame), which shows 10 ft and 25 ft reference points. I use 1/8 in toe-out in front and 1/8 toe-in in back.
I have the base suspension and resultant ride-height. I use single adjustable Koni shocks all around. Front Castor is about +5 both sides. To get Front camber of –0.8 all the removable shims were removed. I have asked my mechanic if the inside upper control arm round bushings could be removed (or replace the larger front with the smaller back bushing and leave the back bushing out) to gain additional negative camber while maintaining castor.
This appears to me a very reasonable way to gain additional negative camber while maintaining easy return to stock settings, using stock parts, and adjustability. My mechanic is hesitant to do this, as he has no information as to whether the suspension was designed for the additional adjustability.
My 1989 coupe has 51,000 miles, is garaged, is used weekends regularly spring thru fall, had new lower ball joints last spring, and new hubs, rotors and brakes 1 ½ years ago. Except for a Borla exhaust the car is otherwise stock. The car is maintained regularly using stock parts or equivalent. I enjoy autocrossing regularly.
Tire temperatures do indicate a need for more camber if possible. This has been more of a problem the last several years with Hoosier and Kuhmo tires. It was not a problem with Yokohama A008 or BFG Comp T/A R1 tires. The current Hoosier, Kuhmo, and Yokohama tire information all suggest more negative camber is helpful. Currently I use air pressure, shock settings, and regular tire rotation to try to compensate. More negative camber would also help achieve better tire wear.
I have owned this Corvette since Feb 1990, and continue to be impressed with its durability, reliability, serviceability, and performance. Thank you for your help.
- Thread starter
- #4
Apparently not much interest in this subject. Or perhaps has been addressed 10-15 years ago. I was hoping someone might have been aware of the ZR1 Drivers Manual track adjustments. It does not appear the upper control arm will fit correctly without the inner round (washer) bushings. My control arm bushings, upper ball joints, and hubs seem to be okay. I will continue to do the best I can with what I have. If anyone knows of some links to C4 alignment engineering, please let me know. Thanks.
froggy47
Well-known member
www.guldstrand.com Very knowledgeable c4 suspension guy.
Watch your mods depending on what class you run. I run scca solo2
Watch your mods depending on what class you run. I run scca solo2- Thread starter
- #6
froggy47
Well-known member
So far I like the QA1's a LOT. they are 1/2 the weight of Koni's & with the adjustment knob at the bottom you can adjust the rears without taking the shock off the car (rear only).
Cost was about 50 bucks more than 4 Koni's, they look very cool - polished aluminum.
So I can drive to a race with street (soft) settings, crank em up to race, & reset to street for the drive home.
I did have to fab up a bump stop for the front, it does not come with one (unlike Bilstein or Koni) but it's not a big deal to do.
I'm not knocking Koni's - they are great shocks - but on a Vette the rear - well most guys pick a compromise setting & leave it there - not many will remove the shock to adjust for race & then do it all again to drive home. If it's a trailer car then that's different.
If anyone puts them on let me know & I'll post how I did the bump stop in the front.
Cost was about 50 bucks more than 4 Koni's, they look very cool - polished aluminum.
So I can drive to a race with street (soft) settings, crank em up to race, & reset to street for the drive home.
I did have to fab up a bump stop for the front, it does not come with one (unlike Bilstein or Koni) but it's not a big deal to do.
I'm not knocking Koni's - they are great shocks - but on a Vette the rear - well most guys pick a compromise setting & leave it there - not many will remove the shock to adjust for race & then do it all again to drive home. If it's a trailer car then that's different.
If anyone puts them on let me know & I'll post how I did the bump stop in the front.
You can get all the negative camber necessary if you reduce the spacer and replace it with shims. I have been told its not legal for SCCA events, but its not a problem for me, as Im a track guy and dont go for any points when autocrossing.
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