Wanting to lower my 2015 Z06/Z07 package on stock bolts for now and get the free initial dealer allignment. I'm just over 3000 miles on the ODO. Anyone have experience with dealers doing the drop on stock bolts, and then provide the free initial allignment? Or will I need to do the drop myself, and if so will dealers agree to do the free initial allignment? I haven't called my dealer yet (Freeland Chevy- Nashville).

 

There is more to lowering your car than setting height and correcting the alignment. Changing the height also changes the weight distribution (front to back and side to side) of your car. The dealer is not going to have the equipment necessary to properly set weight balance. This can only be done with a set of scales, one under each wheel. When the car has been lowered and the ride height is the same all the way around, you should put it on a set of race scales and set the wheel loading to get the proper weight distribution side to side and front to rear to preserve the handling characteristics you paid for when you bought that Z07 package. If you don't wish to spring for a set join your local SCCA chapter. There will almost always be someone who knows someone who has a set of scales that would be only too happy to help you.

Much 'mo bettah' than tossing 8 grand out the window by letting the dealer guess about where your suspension is actually set. I use a set of Longacre 72582 accuset II's to get mine right.

 

Don't know where you live but if you call around I'm sure you probably can find a specialty shop that does four corner balances as described above. That's the only way to properly set height for optimum handling. In my area I have a Corvette specialist shop that set my car up that way.

 

I'm sorry but lowering the car about an inch all round is not going to change the weight distribution significantly if it is set right to start with. If you track the car there are so many other factors that will come into play that any minute difference in balance caused by lowering will not have any effect on handling. I'm talking differences in road surface coefficient of friction/ camber etc from one side of the car to the other, tire composition, pressure or temperature differences front to rear and side to side. Get the alignment set but don't worry about any change in balance would be my advice.

 

Thanks for the input guys, very helpful. I'm in Nashville, found a shop in Hendersonville with experience lowering and then alligning other Z06/Z07 with good results.

 

Since you have a Z07, if you lower the front any and you track the car, you are almost guaranteed to drag the CF splitter. That's why they don't lower the car when they do the track alignment at Ron Fellows Spring Mountain.

I have their alignment specs for Z07 if anybody is interested. They are track specific, from GM, for 2015/16 Z06/with Z07 and A8.

 

1/4 turn more on just one bolt will increase the wheel load at that point and unload the opposite side. The differences in wheel load can be large with no measurable difference in ride height. I know autocrossers that will sell their children into slavery to move just 50 pounds on a 3300 pound car. Changing the ride height at any corner will change the cross-weight percentage.
If you raise the ride height at a given corner (put a turn in or add a round of wedge), the weight on that corner will increase, as will the weight on the diagonally opposite corner. The other two corners will lose weight. If you lower the ride height at a given corner, that corner will lose weight as will the diagonally opposite corner. The other two corners will gain weight. This will not change the left-side or rear weight percentages. To add weight to a given corner, raise the ride height at that corner or lower the ride height at an adjacent corner. For example, if your initial setup is 52 percent cross-weight, and you want 50 percent cross-weight, lowering the right front or left rear corner will decrease cross-weight percentage. You could also raise the left front or right rear ride heights to do the same thing.
It is best to make small changes at each corner, instead of a big change at one corner. This keeps the ride heights as close to ideal as possible. In the above example, to go from 52 percent to 50 percent cross-weight, try lowering the right front and the left rear one-half turn on the weight jack bolt or spring perch while raising the left front and right rear the same amount.
Always record the cross-weights and ride heights for reference at the race track in case changes are needed.Measure control arm angles after each change. The angles are another way to set the suspension for the desired ride height and cross-weight percentage. The distance from the ground to an inner suspension arm pivot point will also accomplish the above goal.

Remember that changes in stagger, tire pressures and springs will change the ride height and alter the cross-weight percentage. The only way to know is get the car on scales and measure it.
Cross-weight percentage compares the diagonal weight totals to the car's total weight. To calculate cross-weight percentage, add the RF weight to the LR weight and divide the sum by the total weight of the car. Cross-weight is also called wedge: If the percentage is over 50 percent, the car has wedge; if below 50 percent, the car has reverse wedge.

More wedge means that the car will likely understeer more in a left turn. The advantage to wedge is that the left rear tire carries more load, so the car drives off the turns better. But in a right turn, the opposite occurs and the handling is worse. In almost all cases, the loss of cornering performance in one direction is greater than the gain in the other direction. One of the most important aspects of racing is having a good handling balance. Setting static weight distribution and adjusting cross-weight percentage is one way to assure good handling. Taking the time and making the effort always pay dividends. Failing that your lowered car will likely handle poorly, turn in inconsistently for left and right turns and, in the case of someone who just turned the lowering bolts without a clue as to what is going on in a 4 wheel independent suspension, the car will likely handle so poorly you will wonder what happened and yearn for your old minivan. The dealer doesn't have toe tools to fix what was messed up and interest in the car will fade very quickly. Get it in the rain, and the vehicle in the hands of a nimrod could be tragically unsafe. Imagine driving your Z06 on a flat (not banked) road with a 'S' turn i the middle. In the rain. You got the crossweight wrong so on entry the car understeers and when you wind the other way in the middle of the 'S' the understeer changes to oversteer and you, my friend, are about to wet your pants and have a very unpleasant experience!

 

https://www.corvetteforum.com/forums...lts-sweet.html

 

Stance is one thing, handling is a horse of another color. That looks really sweet, but then, so did my first wife.

 

Fitz has posted some really good information on the topic but the OP made no mention of tracking the car.
The car comes from the factory with ride heights in a specific range. A safe range I hope and assume.
Therefore if you adjust all four adjusters the same amount of turns all should be fine as far as keeping the same ratio front to rear and side to side.
I have tracked 7 or 8 corvettes since 1985. I lowered all of them and did the alignments in my garage. None were ever scaled. Your results may vary.
Nothing wrong with scaling but that is my experience.

Fitz,
I have scaled race cars but the corvette is just not as sensitive to change.
What happens to the alignment on a corvette after it is scaled and the owner who weighs 250 pounds gets in the driver's seat? We both know. Yes, the car can be scaled with the driver in it. Then you start a track day with a full tank of fuel and the last session is with an empty tank of fuel. Then throw in tire temps, etc. and you see how complicated it gets.
So for a non tracked car keep the lowering adjuster turns equal. The nannies are really quite good on these cars for the street.
BTW: What did you mean by throwing $8,000 out the window?

 

Dave:
Most of my track experience is SCCA Spec Miata. Those cars are quite sensitive to balance, especially crossweight. I scale my car with my backside in the drivers seat and a half tank of gas. Which accounts for the median in weight distribution. It takes some time and a good notebook to get the settings on the car so that things like fuel consumption and tire temp changes don't upset it too much, but after a few years, trends from the the notebook get memorized and adjustments for tire temps and pressures are easier and more intuitive. That only works with a tire you 'like' not every tire you could use.
The C7 Z06 Corvette is different. Gargantuan torque and more power than most of us are willing to use. I have not lowered mine yet, but I will. There is a group here in Arizona with some very experienced racers (Old Farts) in Corvettes and other marques and types. I am learning from them but I do know from experience that small changes are wisest. The Z07 package gives a huge step up in handling and agility over the C6 Z06 that went in trade for my C7. I also have had the experience with that C6 of some buffoon in changing the suspension settings during a ' 4 wheel track alignment' that he did not know how to do correctly. That mistake took a bit of time to sort out and I have no desire to have a Z07 car that I paid 8K extra to get the handling it is capable of only to have it have it handle worse than an old, stock C4 because I made gross changes in the suspension settings. Hence my cautionary comment on blindly turning the suspension bolts to drop the stance. I really do not know just how sensitive to those changes the car actually is and I suspect that someone who never presses the car will notice the difference.

I would notice the difference and, since I have the tools and space to statically set balance on the car, I will do that. That's not to imply that everyone MUST set up their car that way or that it cannot be enjoyed if it is not done.

I really do like the lowered stance! Like you, I am not new to Corvettes. This is my 4th Z06, and my 13th Corvette.

 

Can you send me the alignment specs. I am thinking of doing something a little less aggressive that track but more aggressive than street.

Thanks

 

Conmax, do you have the alignment specs and ride height for the non-z07 2015 Z06? I lowered mine but want to reset, align and corner weight for track purposes.