i drove my 2014 for 10 months and have my 2015 less than a week and noticed a few updates with screens in instrument cluster and infotainment, no big deal, not worth talking about to me. today its snowing in northeast pa.== time to read owners manual, NOW THIS IS WORTH TALKING ABOUT! track alignment's and how to get them, yes how to get them, last year many (me) could not get the NEG camber the manual had in it. manual also said do not remove any washers to get more neg camber == guys on this fourm said to remove one washer (there are two) ,between the upper control arms and frame( they were right) its now in the owners manual page 9-6 and now per the manual they say to run -2.0 rear camber. last year it was only -1.7 rear . im not saying what numbers to run just how to get them, GOOD THING the writer of owners manual read's this fourm and how to get more neg camber by remove one washer.

Baby's first snow

 

B Stead your post showed up in my email, not on this fourm? anyway, i run a6's soon to be a7's, do you really think i can go a far as -3.0 camber? talk about contact patch, im sure the whole 295/30/18 up front will lay flat in a turn. and yes zero tow, i have found out anything over -2.0 camber has to have zero tow not to tear up inside of tires.

 

Some of the R-comp tires call for 3 degrees of camber but I don't see the need. They are radial tires but they do have a square shoulder and stiff sidewall.

I would just use tires like the RS3, Star Spec, AD08 R, and Rival. A radial tire is said to be tolerant of camber. It's the bias-ply tire that is desperate for the perfect amount of camber at the cornering usage.

The Goodrich Rival tire manual suggests front camber of 2 to 4 degrees and rear camber of 1 to 2.5 degrees. (But the Corvette's rear suspension has camber change in bump similar to the front suspension. So the camber target might be 2 degrees front and rear. Also, the Corvette puts more of the cornering load on the rear tires.)

In my previous post, I just said to avoid the run-flat tires, use tires designed for track or autocross, and then not worry too much about camber.

Also, there is camber gain from car lowering
.

 

Good find in the 2015 manual. Wonder how many alignment guys take out washers from under A-arms? Can't understand why GM didn't properly engineer the car's toe link to have adequate rear toe adjustment when rear camber is set to track spec without having to remove washers under the upper A-arm.

 

lets not forget that as your trying to get rear NEG camber on c7 the rear wheels TOW OUT( oversteer), the last thing you want back there. this year as soon as i get a few more miles on the car( im at 130 now) i will remove washers( 16 of them, four per corner, and leave 16, four per corner) before going to alignment shop. i want to make it easy for him( and the car) to get my numbers front and back. also B Stead had a point about lowering the car( free, easy NEG. camber) and many wont like my answer to this but i dont want to shorten travel ! and hit bump stops ! lowering comes with its own bag of worms, and money to spend, GUESSING!!

 

Here are the track alignment instructions and settings from the 2015 owner's manual (page 9-6):

Alignment should only be done by
adjusting the lower control arm cam
bolts and by removing a maximum
of one washer between the upper
control arms and frame.

Alignment values are targets, see
your dealer for tolerances.

Front (per corner)

. Caster: +7.0 degrees
. Camber: -2.0 degrees
. Toe: 0.05 degrees toe in

Rear (per corner)

. Caster: 0 degrees
. Camber: -2.0 degrees
. Toe: 0.05 degrees toe in

Thrust Angle: 0 degrees

They obviously forgot to mention that alignment needs to be done with the toe link adjusters as well.

 

Gosh, lowering.

Lowering can tuck the tops of very wide tires and make a tire and wheel fitment.

Lowering with coilovers tends to maintain bump travel because the coilover usually has a shorter shock body instead of a shorter spring. It's loss of droop travel to watch out for. (If the car is trying to snap straight when going slightly off power in a curve that could be a problem of not enough rear droop.)

The camber gain from the lowering is very little trouble. The tires don't wear perfectly even on the street but last long enough.

The problem with the Corvette is that lowering with the lowering bolts gives up spring pre-load.

If ordering custom coilovers here is a spring rate scale:

Base level
Z51 level
Z06 level
T1 level

Also, there's a square-600-and-up for those with the same size front and rear tires. (Well, setups at 600/600 and 700/600 certainly don't jive with the T1 racing suspension at 582/850. Then Z06 is 531/782 and Z51 is 526/645. Okay, the Z51 has a four tire size difference from front to rear. The Z06 has a five tire size difference from front to rear.)
.

 

Do you mean when the bolts are maxed?

 

Spring pre-load does nothing to the rate of the spring, unless spring is non-linear. On a coil-over, spring pre-load means that the perch is turned up until the spring is compressed even when coil-over is off the car. Adding pre-load is what limits droop travel since damper cannot extend past the pre-loaded length. Say spring has a free length of 6" and you pre-load it such that its pre-loaded length is 5". At full droop, the coil-over cannot extend past this 5" length, losing you 1" of droop travel. At the limit, the lack of droop travel will pick up the wheel if there is enough roll.

 

Spring pre-load does not change the spring rate.

Spring pre-load does change the force range of the spring that is used by the suspension.

I can give a link to a source that shows three graphs:

The first graph is a stock spring. It runs at an upward angle from left to right.

The second graph is a spring with a higher spring rate. It runs at a steeper upward angle from left to right.

The third graph is the stock spring but with pre-load added. That graph is parallel to the first graph but higher up.


Use the base front spring rate of 420 as an example:

Lower the car 1/2" with the lowering bolts and that's probably about 50 pounds of pre-load. The first 1" of spring travel requires 370 pounds of force instead of 420. Then 2" of spring travel requires 790 pounds of force instead of 840. And 3" of spring travel requires 1210 pounds of force instead of 1260.


A stiffer spring is scale.

A pre-loaded spring is translation.

The explanation of spring pre-load is that it translates the use of the spring to a different force range of the spring
.

 

Preload adjustment can be used to fine tune both compression and droop of the damper stroke. Increasing preload (Raising the collars on coil-overs or changing the screw adjusters on a leaf spring car like the Corvette) increases compression stroke while reducing droop. Reducing the preload (lowering the collars) decreases compression stroke while increasing droop. That is of course if you're maintaining the same ride height via the lower-mount adjustment of a coil-over with that type of design. Preload adjustments basically allow you to place the piston at some specific location inside the damper body with the car at its static ride height, controlling how far it can travel up (compression) or down (droop when in rebound) before the piston reaches the limit of its travel.




For coilovers that look like the one in the picture ^ with separate preload and body length adjusters:

- upper gold collar adjusts preload (amount of pre-compressed spring length)
- lower gold collar locks upper preload collar
- lower mount in blue adjusts ride height
- collar in red locks blue lower mount in place.

Ideally you just want the gold collars barely snug against the spring (zero preload) assuming you have chosen the correct spring rate and free spring length for the application. Only in some cases to increase droop travel would you add preload.

On a Corvette with OEM suspension, you cannot adjust ride height separately from pre-load as you can with the coil-over type in the picture.

 

Thanks for the info. Good stuff here.

 

Wish I had saw this thread a couple nights ago. The dealer had a tough time reaching the track alignment specs.

I had to leave car overnight. Took them about 7hrs on my 2014 z51. Once they figured out they needed to remove the washers (8 total) they were able to get pretty close. Front camber -2.0 and -1.8, rear camber -1.7 and -1.6.