Can anyone tell me the draw backs of using the stock bolts to lower?

 

The only drawback I've experienced is that it doesn't drop it quite far enough...

 

Since you didn't mention what year car you have, I'll say that one of the drawbacks is that the bolts may have been sitting there, un-turned, for up to 20 years......and might be frozen in place. Keep in mind, getting the bolts to turn within the threaded inserts, BEFORE the inserts spin in the spring (they're only 'bonded' to the spring), is the challenge.

 

Your ride might be a little harder, it would help if you had newer shocks I know it helped my ride comfort. Use PB Blaster to loosen the bolts, let them sit awhile or overnight. Those are just my thoughts.

 

Have heard of less traction from a dig if lowered all the way ... I'll let others chime in on this though..

 

The only drawback is there is a direct relationship between ride height and ride quality. So yes, your ride will get a little harsher if you drop the car, but the car will also feel more planted. For performance purposes, lower is better, unless you get so low the front air dam has less than 3.5 inches of ground clearance. The air dam creates a low pressure zone between the front wheels, which sucks the front end down at higher speeds. It needs 3.5 inches to function, so that ends up being the optimal performance ride height for a C5, but that would be a little rough to street...

 

Sub'ed for an enlightened discussion.

 

 

That's a new one!! I've never heard that mentioned before, and I've been around this site for a long time. You got me curious, so I went out to the garage, and measured that dimension on my car.....it's 2 and 5/8 inches..........

 

Mine is stock height, without being lowered on the stock bolts. It measured 3.5". So anything other than factory stock height will make the air dam not function properly?

 

When lowering, the first item to be concerned about is the ride height aspect (Rake) be maintained front to rear, the next item would be to make sure the shocks to not bottom out or the car is so low it hits the bunp-stops. Many use Bilstein shock to prevent this. Also you will have to have the car re-aligned or have unusual tire wear. If you are lowering the car to greatly improve handling then the car should be corner balanced during the alignment process.

The center front air dam is to redirect the under car air into the radiator and the side air dams were for redirecting the air from under the car. John Heinracy often comes to our club events, if he attends this Sunday, I will ask him about the ground effect of the air dam, as I have never heard of that ability up to now. I do know in 2001 when were were running at Waterford in new Z06 Corvettes, his car was sitting lower than mine and mine was lowered, aligned and balanced by Danny Kellermeyer. But we were only hitting about 115-120 down the back straights.

 

I'm lowered an inch on stock bolts. I've not seen anything overly detrimental, including increased temps. So far it's low enough for me in that I don't want to scrape the front air dam on everything I try and drive over.

If you do decide to lower, do not square up each side of the car by the threads on the bolts; turn them an even number of turns. If you turn one side 7 to 8 full revolutions (that was roughly an inch for me) then you need to turn the other side the exact same, even if it means more threads show on one side than the other. If you just turn the bolts all the way up as far as you can you run a risk, but not in all cases, of severely throwing alignment off.

This job is also made easier if you can get the car in the air and alleviate the pressure on the leaf springs. I don't have a lift, and so to get the car in the air I raise the entire rear first to get on stands and then each side up front. I could then just slide under the car, make my marks, lower, and then mark my new positions. Note that the car will need to settle. It could even look like it's sitting higher at first. It took me around 20 to 30 miles for it to level down to the new height.

 

Any idea how many turns you did for 1".. I am looking to lower mine by about that much maybe a bit less.

 

Creating a low pressure zone under the front end is standard design for underbody aero in racing(A lot of air going under means lift is generated, very little air going under lowers pressure beneath the car and sucks the car down to the ground), but based on what everyone is saying about their measurements, I feel like I might be remembering the height requirements wrong. So while yeah, the front air dam is definitely wrapped around the front wheels to deflect as much air as possible from getting beneath the car and there is a cut off height where it ceases to function correctly and will actually start letting more air under the car, if people are getting 3.5 inches of clearance to the dam at stock ride height, I feel like I'm probably remembering that part wrong.

I'll see if I can turn up a source when I have a little more time and get the height right. For sake of explanation though if someone were to take their air dam off, the car wouldn't just overheat. The front end would also be much less stable at high speed, because more air means more lift, and the area directly behind the dam is a mostly open engine bay, where uncontrolled air would create turbulence.

I was curious about C5 underbody aero because I'd heard people say it was both bad and good. Like the design of the C5's topside, the underbody aero is actually pretty fantastic. Flatter is better, so the back of a refrigerator look the C5's underside has is very functional. The sometimes decried bubble butt is a functional rear difuser as well. The form is function approach to exterior design is why I prefer C5's to C6's.