I'll be the first one to admit that lowered cars look sexier, but I just got these pictures back from a track event at Sebring. If you look at the pictures, it is very obvious the car "squats and goes" under hard acceleration, and also shifts the weight to the front very effectively under hard braking (It's a stock height 02 with 04 shocks). If the wheel gaps don't tell you the story, look at the distance between the front air dam and the surface of the track. A big to the Z06 engineers and designers! Great vehicle dynamics.





MD

 

Nice

 

Actually, while the stock height is good for drag racing (or so I hear) - for road race activities the engineers advise dropping the vehicle 20mm to hit the sweet spot in the stock shock valving for best rebound/compression dampening results.

...Glad you enjoyed yourself and didn't break your Z...

 

Lower = Lowered Roll Center = LESS Transverse Weight Transfer =
More Even Weight Dstribution during turns = better traction at the tires
and a more balanced feel during hard cornering.

 

I guess coil overs are a waste of money? lol

 

Did you by any chance read my reponses to guys who were looking to lower their cars?? I've been saying If you lower your car It will most likely be stiffer and therefor the weight will not transfer to the rear wheels like It would with a stock suspension. Resulting In less traction. That's what I've said on these forums. It's true though I'm sure of It.

 

I don't think anyone would suggest that were true...

 

For taking off and going in a straight line you can be absolutely sure of it.

But... how about going thru a turn at the limits of adhesion both front and rear. You are at the turn exit and want to nail the throttle.
Don't forget... you're still at the limit of tire adhesion. Do you want to nail the throttle, have the weight transfer off the front and add to the rear which either:

A) Causes the front to break loose and your car plows ahead so you have to lift the throttle and hope the front tires grip again before any obstacles come up. Believe me, this ain't fun.

B) The additional load transfered to the rear tires causes them to lose traction and you have to lift the throttle and counter the oversteer.

Lowering doesn't have anything to do with the 'stiffness' of the suspension however.
That's all in the 'spring rates'.

 

Well people are sayng by lowering your car you are causing your car to lose traction...coil overs lower your car...

 

You also mentioned that "lateral weight transfer was reduced because you lowered the roll center". Let's clarify it a bit... The amount of total weight transferred per lateral g is a direct function of the CG height. Roll center height has an effect on how many degrees of roll you get, but the amount of weight transferred is the height of the cg times the mass, times the lateral g, divided by the track. The higher the cg the more total weight is transferred. Lowering the roll center only reduces the amount of weight transferred by the suspension. What happens is that if you only changed the geometry to lower the roll center, the springs and sway bars would have to take up the slack, and you would get more body roll for the same g. It isn't the roll center that controls the total weight transfer, it is strictly the CG height (all else being constant).

The roll stiffness in cornering is the sum of the spring stiffness effects, the sway bar effects, and finally the geometry (ie roll center) effects. The contribution to roll stiffness of the geometry, is esesentially the height of the roll center with respect to the cg. If you lower the car you lower the cg by a specific amount, essentially how much you lowered the car (less the effects of the unsprung mass, which in this case we will ignore). But also the roll center can drop, and in some cases (depending on geometry) it can drop a lot more than the reduction in cg height caused by the lowering. If the roll center drops more than the amount of cg height change, you actually loose effective roll stiffness. That is, the roll center will be lowered more than the CG height change. This effectively reduces the roll stiffness of the suspension due to geometry, and while the springs and bars can still dominate, it can negate some to the good effects of lowering.....If the roll center drops more at one end than the other (again dependent on geometry), then you can and will change the balance of the car. This is one of the reasons why some of the best racing shops aren't slamming our cars to the limit of the stock bolts, they have found that the cars are faster lowered, but not that low...

 

[QUOTE=Z06-Nomad]I'll be the first one to admit that lowered cars look sexier, but I just got these pictures back from a track event at Sebring. If you look at the pictures, it is very obvious the car "squats and goes" under hard acceleration, and also shifts the weight to the front very effectively under hard braking (It's a stock height 02 with 04 shocks). If the wheel gaps don't tell you the story, look at the distance between the front air dam and the surface of the track. A big to the Z06 engineers and designers! Great vehicle dynamics.

Whats the diff of 04 shocks vs 02 or 03 shocks

 

Yup stock ride height to no more then 1/2" lower then stock for optimal vehical dynamics.


Great pics

 

Actualy if the 20MM is correct that works out to just a bit over 3/4 of an inch (.7874 to be exact). I would not lower any more than that. The guys cutting bushings and lowering to the max amount of stock bolts are changing the geometry of the suspension in ways that can cause big problems. I have read lots of posts about high speed instability and other problems on lowered cars.

 

[QUOTE=BWATSONZ06]The shock valving was changed again for the 04 cars. Better all around. You need to do all four. The backs were changed in 02 from the 01's. Don

 

That is for sure. I had to raise my car UP when I put on the aero body parts for high speed stabilty.

 

For stability at speed.....I ran my car top of 5th to a HUD display of 171 mph. A week later I lowered it on stock bolts all the way front and rear (exaclty 3/4" lower) and had it re-aligned and ran it top of 5th again and it went 174 (same road, same conditions). I didnt have the all too common wind buffeting with the hood/front end around 140-150 at stock height with it lowered. So at least in my case it helped mph, wind buffeting was much less and helped a hell of a lot in handling through the twisties which I run 12 miles of them almost everyday.

You guys can keep your vettes stock height if you like and go 4 wheeling on the weekends with them...i prefer to be able to haul *** handling with it 3/4" lowered vs any kind of drag launch advantage (which is very little as most of you guys dont have drag racing suspension setup on your Vettes).

 

Yeah I see what you guys are saying now. I don't have any experience with lowered cars, I only had one lowered 1" once and It was really stiff so assumed that the weight wouldn't transfer to the rear wheels during take off like It would with a softer suspension. That was a good reponse you guys wrote~I was a little lost lol but It was good non the less. If I knew more about the subject I would understand It better. This was just a theory of mine.

 

This is what I've heard and I will keep it at 1/2" if I choose to lower it at all.

 

If you get it too low on stock shocks you will run out of travel and get onto the bump stops without much effort, and it will feel really stiff... That is more likely what you were experiencing... Lowering itself won't change the stiffness, but running out of travel sure will...

 

Yeah, too low is not good. I had to raise my car up a couple of turns. I was hitting the bump stops and getting a slight wiggle at the bottom of a small hill on one track in particlular. raised it up a couple of turns and the problem went away.