Boomer111

^^I agree the newer narrow bodies seem to be higher.

MisterMidlifeCrisis

By the way, I re-measured after finding that I'm scraping a bit more when exiting my garage. The ride height has dropped to 26 7/8 RF, 26 15/16 LF, and 28 1/4 RR, and 28 5/16 LR.

Had one opportunity to do a freeway drive and fuel economy was up by about 1 MPG (31 MPG at 70 MPH) over about 150 miles. That may or may not be due to the lowered ride height.

It sure does handle better though.

Gearhead Jim

I just re-measured the numbers in post #59 and edited the post, my car has "grown" even though everything is now colder (tires pressures adjusted to still be 30 psi cold).

Since my car takes so long to settle after a height adjustment, I'm unable to do an immediate "before and after" handling comparison. But in my casual handling tests in a parking lot, I can just barely feel a slight degradation from the combination of replacing Z51 shocks with base shocks, and ride height about 1/4" higher than original (but still below 2009 Service Manual specs). The air dam definitely scrapes less than originally.

I suspect that the higher trim height specified for the 2012 cars is part of their program to get alignment correct at the factory, that the 2012 trim numbers are for "at the factory" and the earlier years are for "in the field, after settling". But I can't prove that.

Cavi

From reading this what I have noticed as a common ground, is that most have about 1 1/4 inch difference from front to rear, and those with lower suspensions are roughly 1 inch lower than those with higher suspensions. to me the front to rear difference of 1 1/4 inch is key.

LFZ

1 1/4 inch difference front/rear is key for what?

JoesC5

A lowered Vette has a lower Cd and has less air moving under the car, thus improving gas mileage.

Cavi

Key to knowing if you are in the correct ballpark front to rear. This is my take from seeing all the different numbers. Again, different tires will give different height numbers from one car to another, but the important factor is to have the correct rake no matter what height you have your car set at.

LFZ

But the C6 can handle being low in the rear without the significant forward rake...

MisterMidlifeCrisis

Joe, I also got a zero toe alignment at around that time too. I think I had about a quarter toe both front and rear as it came from the factory. One thing I do notice is that before, when I would release the parking brake in my garage, it wouldn't roll, but after the zero toe alignment, it s-l-o-w-l-y rolls backwards out of the garage on its own. So probably a combination of lower ride height plus less tire scrub

By the way, I did a 180 mile freeway drive and got 34.2 MPG averaging about 67-68 MPH with a slight tailwind on a cool day with moderate traffic. Oh, and non-ethanol gas in that case too.

cadguymark

as far as I am concerned, unless you have a way to measure flatness of the surface, measuring height to front air dam is useless. nether-the-less, mine is 2 1/2" (where is everyone measuring?, mine is at radiator support)

lower in front, translates to less lift at high speed is my theory

my front wheel well is 26 1/4 drivers side
26 passenger
both rears are 28 1/8"
these tires are ~3/10" less diameter than OEM SuperCars according to Tire Rack specs (which I am highly dubvious of)

some of you Drama Queens would likely get all upset about the drivers side being 1/4" high, after I set my 200 pound azz in, I'm guessing the front is fairly level.

narrow body 2007 Z51
I have brand new Michelin PS2 Super Sports, 235/40-18 and 275/35-19

talking about rake is utter BS, you don't know what it is supposed to be, and how it affects airflow, so shut up

Gearhead Jim

If you use the GM tool and measure the suspension points properly to meet the specs, then you do know what the rake is supposed to be because you have it set.

cadguymark

and we know how well that worked for you

I was referring to the fact that people were saying the rear was supposed to sit 1.25" higher than the front, or whatever difference they were saying

it's BS, if you deviate from the spec you have no idea how it affects air flow (in fact you have no idea what the air flow is if it meets spec, just that it apparently is how GM says it should be)

but don't let that stop you from playing with the height

BTW, measuring the fender lip is highly inaccurate, car can settle in suspension based on how you were driving it before you parked and measured it. I suspect the reason mine sits higher on the driver side is once I get my fat azz out, the suspension rebounds slightly.

JoesC5

Independent wind tunnel tests show that just adding passengers in your Corvette will lower the Cd of the car. You wouldn't think that just the added weight of the passengers would lower the car enough to affect the areo drag(lessens it), but it does.

JoesC5

Air flow under the car is important to the car's aero. A car with a forward rake is preferred over one that is level or has a rearward rake. Having the front end lower, minimizes air flowing under the car and having the rear of the car higher then the front creates a slight vacuum under the car to reduce lift.

http://www.up22.com/Aerodynamics.htm

Gearhead Jim

GM says my tire pressures should be 30 psi cold for normal driving, and that's what I set. Perhaps my gauge is a little off, or on any particular day my tires may warm up a little more or less than expected. So chances are, my tire pressures are never exactly correct, but I do my best.
And if I'm a little off, we have general tendencies how that will effect the car but don't know for sure unless we spend a lot of time on testing. But it's much better than adding air until the tires "look right". Same thing with suspension height.

I think at a 1 1/4" front-rear difference in wheel arches is pretty close to what you get with the Service Manual trim height, I'll do some more math when I think of it.

Finally, measuring wheel arches is no more "highly inacurate" than measuring the trim height with the GM tool. The Service Manual tells how to load and prepare then car, then says to bounce the suspension upward 3 times and take the measurements, then bounce it downward 3 times and take the measurements, then average them. When we did it on my car, the difference between the sets of measurements was less than 1mm.

inner3

I will have to get a new set of shocks when I get my car back and am thinking about having it lower some. I just updated my z51 to a wide body kit with z06 wheels. If I lower the rear as much as I can and don't do the front quite as much, maybe a half inch would that work or does it need to be the same height lowered all the way around? I will also have the zr1 lip spoiler added later this month but I'm very careful entering and exiting areas so I almost never scrapped in the car. Should the front not be lowered as much because of the spoiler?

TMyers

While reading over the instructions for my coil over installation Pfadt provided some ride height specifications.

C6 Stock
Front 26.9
Rear 28.1

Z06 Stock
Front 26.7
Rear 27.6

Pfadt Recommended
Front 26.4
Rear 27.3

My height, never touched the suspension

Front 26.4
Rear 27.5

cadguymark

I have two sets of wheels for my car, both Michelin PS2 (for dailey driving), but one is ZP, the other Super Sports (for track)

I just swapped out the SS for the ZP yesterday and measured the fenders
car was raised 1/4" all around which makes sense since the ZP tires are .3" greater in diameter than the SS (according to Tire Rack specs) actually the car should have measured .15" higher, but Tire Rack specs may not be accurate ( I know they aren't since the only go to nearest .1")

my fender heights seem to match two others pretty much exactly

what I object to is somebody stating 1 1/4" rake (or whatever) being the correct rake

I am not even going to attempt to explain why, not worth the trouble, yes, lowering car improves performance (which is why my track tires are what they are) but it also affects cooling negatively.

enjoy