Just looked through titles of many previous posts on lowering. Not much discussion on the impact to ride quality of the Z06.

I took the back down on the stock bolts. Definite improvement in looks, but found the ride to be choppy, unending bounce on the rear spring, annoying.

Just did a bit up front. No problem with bounce on the front spring.

Basically removed the rake, car was level. Had a 4 wheel alignment done after it settled.

At the Motorsport Ranch, felt like I was fighting the car around the track, very tiring and didn't feel as fast. Car is now back at stock height.

For all you guys riding around on lowered Z06's, are you just putting up with the "bounce" or did you fix it somehow?


[Modified by TooManyIDs, 10:58 PM 7/29/2003]

 

:confused: Did I read this right, you only lowered the backend :confused:
If so :eek: :banghead:

 

:iagree: That could be the worst case scenario

 

Just did a bit up front.

Basically removed the rake, car was level.

 

I slammed mine, lowered it 2" you can see pics on z06vette.com ask people on there to see there pic and opinion.

as for mine...I lost big time, sometimes I hit pot holes and just brace my self. but the look is really good, and I wouldnt have it any other way.

 

Lowering the ride height reduces suspension jounce travel an equal amount, and you will be hitting the bump stops more offen. This is why a lowered car will have a choppy ride. Also, hitting the bump stops while cornering will result in poor handling. Hitting a front bump stop will cause the front end to washout - heavy understeer. Hitting the rear bump stops in a corner will make the tail want to snap around.

In the range of normal suspension travel, dynamic response is "linear" and the handling will be predictable. Once you hit a bump stop dynamic response goes non-linear and the car is likely to be a handful. Chevrolet did a lot of work on the rear bump stop design to keep the suspension off the bump stops at high cornering force on a typical road or race course. If you lower the car, you negate a lot of this good engineering.

If you want the car to handle well at the limit on real world roads, don't lower it, or only lower it in very small increments - say a quarter to a half-inch until the handling degrades, then raise it back up to the previous setting.

Duke

 

Good to read this from someone that I have noticed is knowledgeable in the forum.

I occasionally subject my car to the high cornering forces you are speaking of, under controlled conditions ;) if you know what I mean. I have always resisted the temptation to lower because I KNOW that the car handles great the way they delivered it. I don't want to find out differently in a 90 MPH sweeping turn after I lowered it. The unlowered look is a hell of a lot better than the "hit the wall at high speed" look.

I agree the car LOOKS better lowered. But the honest people at the track tell me there is very little REAL difference in the handling, if any.

I know a bunch of people will respond " Well the video that comes with the car says to lower it if you are going to track the car " That is true, but the guy that said that is a race development guy that can tell when he went too far and why. I don't know squat about suspension dynamics. I am not going to screw with something that was declared REALLY GOOD by some of the best engineers in the world to "improve" it.

I'm a weekend warrior and an amateur at that. I will never be able to drive the car as fast as it can possibly go, even the way it was delivered from the factory. Andy Pilgram could jump in my unlowered car and probably run 15-30 seconds faster PER LAP! . I take that to mean the one that needs to be modified is me, not the car... :D

 

Another excellent explanation from you :)

Noor.

 

What is a bump stop? I'm not aware of any on a Z06, like on a an F body for example. I think you might mean Jounce stop which is when the shock piston is fully compressed. Your right about the effect . :chevy

 

I used "bump stop" to indicate "jounce stop", but I should have used the proper GM-speak terminology, which I think is jounce bumper. It's the rubber bushing inside the top of the shock tubes. There is also a rebound stop that I think is built into the shock and limits its travel. By far the jounce stop is more important than the rebound stop.

When the jounce stop is encountered the effective spring rate dramatically increases which increases the roll stiffness on that end. The jounce bumper is specifically designed to gradually increase the rate. If it was solid the rate would effectively become infinite, which would cause the front end to completely washout or snap spin the car it the rear hits a solid stop. The jounce stop is also critical to passing the severe pothole test by attenuating the shock load that is transmitted to the shock mount.

During C5 development (as documented in a SAE paper) the development engineers found that in limit handling the rear suspension was encountering the jounce stop. To compensate they changed the anti-roll bar diameter, but later redesigned the jounce stop to reduce the shock load on the mount from the severe pothole test and it the process they shortened the overall length of the jounce bumper, which allowed more jounce travel before the bumper was engaged, and, as a result, were able to install the original rear anti-roll bar size.

You'd be surprised at how much engineering can go into a simple part like a jounce bumper, but GM did their homework and sweated the details.

Duke

 

I was told that after lowering your Z06, lets say 1 inch, and you get some better shocks, like the Bilstein Sport shocks, your handling will be improved. That sound right to you Duke?

 

Lowering the z06 as low as the stock adjustment range allows has had no negative effect daily driving or autocrossing for me nor any of the (many) z06 autocrossers I know.

and you don't need better shocks when lowering it that much.

if your handling got strange after lowering, it may be do the alignment getting out of whack. camber and toe will change as you lower. You need to get an alignment after lowering it.

 

:iagree: :yesnod: :yesnod:

Les

 

Did that (alignment). Street & autocross handling wasn't a problem. It was the bouncy / choppy ride that bothered me in those cases. At the Motorsport Ranch, where turns are taken at 70+ mph, it took more effort to get the car through the course. The lowering was a detriment there.


[Modified by TooManyIDs, 11:02 PM 7/29/2003]

 

yeah I've never done any roadracing.
Very possible that prolonged high speed turns are bouncing you off the bumpstops.

have you corner weighted your car?
A lot of racers do this and it will lead to a slight increase in ride height as you balance everything out. Maybe that will be what you need.

 

I hate to sound like Slick *****, but it depends on what you mean by "handlling". If you are racing or tracking your car then lowering it and firming up the both the jounce and rebound damping rates might improve times as long as the course isn't so bumpy that you regularly hit the jounce bumpers, but the car will ride a lot stiffer on the street. Also, who knows what the damping rates of the Bilstein Sport shocks are versus OEM or other aftermarket alternative. Shocks are probably the least understood component of the suspension, but they are the most critical to fine tuning ride/handling. My choice is always adjustable shocks if they are available. They are usually more expensive, but in the long run are usually more economical because you can adjust the damping for you specific driving conditions and preferences.

My understanding is that the Z06 damping rates have been changed again for '04 based on development at the Nurburgring, and the new shocks have resulted in measureably better lap times on The Ring and other venues. Buying and installing the '04 Z06 shocks on a prior model year Z06 might be the best suspension upgrade available. I don't think the springs and bars have changes since '01. The only change to the Z06 suspension has been recalibrated rear shocks in '02 and recalibrated front and rear shocks for '04.

Duke

 

The Bilstein Sports dyno out almost identical to the Z06 '02 shocks but are 3/4" shorter. :chevy

 

i lowerd mine with stock bolts -

definite performance improvement, car feels more stable on the freeway and handles better overall!

Front definitely looks lower, rear looks abit lower.

conclusion - love it :D

 

Thanks Duke, you always give excellent advice. :flag

 

Perhaps Im slow...but what is the difference between using the stock bolts, getting the aftermarket bolts, and cutting the bushings, if anything? Is it possible to lower the car just a small amount with the stock bolts? Can the same be done in the front? Sorry for all the questions, but after using the search function, Im thoroughly confused. I only want to lower mine a small amount, without compromising ride quality or handling, and would prefer not to have to cut or alter anything permenantly. Thanks for the help :cheers: