c4c5specialists (?)Does GM still recommend 5/8ths lowering 4 performance w/'04 shocks

[JBsC5]

Does GM still recommend 5/8ths lowering 4 performance w/'04 shocks?
Does GM in its owners manual tape still recommend lowering the Z06 5/8ths of an inch with the new '04 shocks?

There was mention that the 2004 have stiff rebound and soft in the middle or the travel... or something like that?

I don't understand what they have done differently to the shock, I was just curious if lowering the car beyond the 5/8ths of an inch would negate the value of the 2004 shocks superior design?

Anybody thinking about retrofitting the shocks so you can minimize mid corner hop on their 2001 Z06?

I think the 2002 softened the rear shocks a bit compared to 2001's..and 2004 has a totally new design that might be worth considering..

Anybody changing the bushings & shocks off the 2004 at the same time? Does the car require an alignment afterward?

If so...what would be the time involved in doing so?

When will the new parts be available?

Any insight appreciated..(I've never liked the mid corner bump jump)

 

[c4c5specialist]

Hi there, Jonathan,
First, you are in luck, I got an 04 owners manual with my last of the 03 delivery.
There will be no video tape for the 04 model year. Only a CD, and a owners manual.
I will check on this type of mod and let you know what Corvette engineering tells me.
Allthebest, c4c5

 

[JBsC5]

Thanks Paul, I look foward to your insight.

JB

 

[c4c5specialist]

Hi Jon,
I have been told to stay in the bearings of specifications of the ride trim height set forth in GM service information for Corvette.
Due to the changed shocks, this is critical. Lowering the Z is not an option for 04.
This is how I will serve Corvette, and I am glad you asked, because I would not have thought of this.
Allthebest, c4c5

 

[JBsC5]

Paul, Please clarify if possible for me.

Hi Jon,
I have been told to stay in the bearings of specifications of the ride trim height set forth in GM service information for Corvette.
Due to the changed shocks, this is critical. Lowering the Z is not an option for 04.
This is how I will serve Corvette, and I am glad you asked, because I would not have thought of this.
Allthebest, c4c5

Paul, My Z06 has been lowered the 15 mm's (5/8ths of an inch) as described as a performance mod in the 2001 video.

I apologize if I have miscommunicated this but I would like to gain the maximum benefit of the 2004 suspension setup within reason on my 2001 Z06.

I am truly amazed at the concept being implemented on the 2004 z06 as it in many ways goes against previous idealogy on shock design for performance Corvette applications..

Because they stiffened up the outer ranges of shock travel yet left a more fluid design in the center ranges for better tire contact capability..
PS. I may not have stated this absolutely correct.



My question stands: Can a 2001 Z06 that has been professionally lowered 15mm's as GM specifies in the 2001 owners manual for performance applications...benefit from the 2004 Z06 shocks or does it need the bushings etc to work properly? Does it need to be raised back the 15mm's?

Paul, Are you saying...Leave the dam car alone? :lol:

Thanks

JB

 

[c4c5specialist]

Yes, due to shock design, I would leave them alone.
Allthebest, c4c5

 

[JBsC5]

UGH! LOL Thanks for the infomation. I guess its too late for me to do this mod.

Good to know. Thanks..

 

[JBsC5]

Expanded read of Sports Car International Article.

Here's the deal: A key measure of a shocks perfomrance is its force vs. velocity curve, which charts a shocks resistance(force) to an impact of a given speed (velocity). While its easy to optimize one area of that curve when force is changed in one area some proportion of that force typically carries throughout the rest of the curve. In other words ...and heres the problem ...while you can design a shock to, say, provide excellent high speed control, you usually inadvertently end up adding too much force in the lower velocity ranges which can hurt handling or ride comfort.

Previous z06 shocks suffered from one particularly problematic area of their curve, the real world manifestation of which was abrupt body motion during rapid directational changes. To overcome this problem without creating new ones, Dave Hills team particularly Corvette Ride and Handling Development Engineer Mike Neal, worked closely with shock supplier Sachs to devise a way to alter specific areas of the curve without affection others.

To Neals absolute delight, much of the testing and development for the new shocks was done at Germany's famed Nurburgring.....

//

The corvette team knew they were on the correct path when they were able to lap the circuit in less than 8 minutes---a time precious few road cars in the world can equal--while actually improving ride quality...As it runed out Chevy's elegant yet simple solution was found in revising the shock valves in a way that raised control at both the low end and the high end of the curve while reducing control in the middle..at arrangement that flies in the face of traditional shock absorber wisdom.

The on the road seat of the pants result of the new valving is that it gives more control without making the car abrupt. In fact the car is less abrupt in its motions yet more controlled. In comparision testing at Gingerman Raceway, a 1.88 mile 11 turn circuit in south Haven, Michigan, the differences between last years z06 and the '04 model was somewhat startling.

[after the road tester from Sports Car INternational pulled off 1.30's at Gingerman RAceway in the 2004 Z06..he jumps in a 2003 Z06 for comparision of the changes made..]

Here's his review:

Feeling totally comfortable and reasonably confident. I zipped off int he '03 at what I thought was a moderate pace to begin with. I accelerated through the Turn ONe Apex, flew down to turn Two, Taped the brakes, turned in and started accelerating. There are some bumps in Turn One's braking area and turn in point and the car felt immediately different from the "04. I had just stepped out of it, but undoubtedly owing to more moderate speed the significance of that difference didn't really register. The difference didn't register at Turn Two either because , being a slightly uphill, increasing radius turn, this right hander is forgiving and fast. Turn Three was a different story however.

Turn Three is a constant radius, slightly downhill 140 degree right hander. Though it doesn't descend much, there's enough of a drop to get the car slightly light. Thats where I spun the Corvette. Though no damage was done and I got right back on line, it certainly was embarrassing moment. Suddenly, and ever so graphically, the shock improvement registered. Six or seven more laps in the '03 followed by another stint in the '04 effectely etched the change into my cerebellum.

Compared with the '03 , the 04 z06 allowed me to attack each corner more aggressively because the car was more stable goin in, exhibiting decisively less body movement. And because it was more stable going into the corner, it was hooked up better through the middle and coming out. The diminished impact of yaw and roll was particularly noticeable in quick , transient maneuvers and in those areas where the road surface was bumpy or less consistent. And all of this from innovative shock valving! Andy Pilgrim was the correct, the difference really is incredible.

 

[HZ061]

Now I'm really confused about installing the '04 shock on an '03.

If I install the shocks I can't lower the the car... not even 15mm?
I've haven't lower my "03 yet, but did lower my '01 and had no problems. I would like to lower the this one and install the '04 shocks. If I leave the ride height stock, will the '04 shocks perform better than the '03? Is it worth the swap....I already have them on order, but are having second thoughts.

Any help would be appreciated...

Bud

 

[JBsC5]

my car is lowered 15 mm's..and has the 2004 z06 shocks..

I love the way the car is now!

HTH

JB

{edit..C4C5 was so cool after researching furthermany months back... ..he got further information that the 15 mm lowering as per GM's earlier owners manuals were ok to perform...We did it and the car rock and rolls)

Suspension design is tricky and staying within GM's parameters was paramount to me....C4C5 was great in helping me achieve those goals.

Just so you guys know this is a pretty old thread that was left in the dust as we moved to other newer threads on this subject.]

One of them the link I posted.

Hope this helped.

 

[JBsC5]

http://corvettemechanic.com/board/index.php?act=ST&f=3&t=55&

 

[HZ061]

Thanks JB...

 

[c4c5specialist]

HI there,
As a post script to this, after being completely reeducated by ride and handling engineering at Corvette, I stand corrected.
About a month after this thread was started, I had some time with the engineers.
I was corrected about this ride height change, stating that there is no damage to worry about, and it can be done, as long as it is the 15mm.
If the car is lowered more, than damage can happen.
I was pleasantly corrected, and I do apologize in advance for any confusion this may have caused.
Allthebest, c4c5

 

[trumperZ06]

: C4C5 ur the Best!!! Correcting yourself on the 04 Z06 lowering issue... my compliments!!!

For those of us who "Take It to the TRACK" (road course), lowering the car and corner balancing along with a "racing Alignment" are the very 1st things we do!

Then we look at brakes(racing pads), tires, roll bar/harness bar, and 5 point seat belts. Other safety issues are addressed, fire ext. high temp. brake fluid and stainless steel brake lines etc.

After this is done, Then we look at power enhancements!

Did you by chance get this info from Ken Brown, Corvette Factory suspension Guru?

This is WHY the Nurburgring's lap times with the production 04 set-up is truly AMAZING! Corvette probably left 10 seconds "on the table" by not being allowed to change suspension & alignment from factory settings. Oh, and HeinRocket was on "street tires" too! 7:56 is OUTSTANDING!!!!