Kevin,
Here is a post from DJWorm that pretty much covers everything you're asking about. (I didn't save the link in the forum, I copied it to my computer)
Another DJ Worm set up/ modification doc.
You need to understand that the Chevy T1 package was engineered to upgrade a C5 for track use, not a Z06. It is essentially a "trunk kit" to make a C5 minimally track worthy. In addition it is used as a LIMITING specification by the SCCA (ie. "You can do THIS but NO more.") in a basically Showroom Stock class. It will however, improve a Z06's handling somewhat. There are good pieces in the T1 package and some lousy pieces. You should also know that the T1 springs and shocks are engineered to be used together and perform marginally or worse when used alone. The T1 Sachs shocks & T1 springs will actually increase the ride height of the car.
- IF you ARE going to turn the car into a T1 Spec racer...then the T1 package (limited as it is) is your only choice. AND you must use ALL of the T1 package as a package...you can't mix'n match with other aftermarket componants.
A further note here: It is probably MORE cost effective to buy a prepared t1 car from say Phoenix rather than convert yours to a T1 racer.
- IF you are NOT going to compete in T1 ...but rather enjoy track days, SCCA Solo I PDE, Time Trials & Hillclimbs or compete in non stock SCCA AutoX such as ASP & SM2 your options are better. Pick the best parts of the T1 package (namely the swaybars & end links and build a "better than" T1 Suspension.
You also need to understand what adjustable shocks offer and what coil overs offer and do not.
The advantage if double ajustable shocks are that they can independantly adjust Compression (Bump) and Rebound. For example, Penskes have 6 bump settings and 28 rebound settings. You initially set the rebound at mid range (position 14) and see how the car reacts. We needed more front grip and Turn In so we increased the front rebound to 21 and needed less in the rear to conteract a bounce on hard acceleration and braking so we decreased the rebound to 9 in the rear. Once set up the car handled the same in high speed track as it does in low speed AutoX transition and we have NEVER adjusted the rebound further, but we could if necessary. A dual use car daily driver and track car really benefits from adjustability especially in Bump. We use the softest settings (1 & 2) for AutoX, 3 for street, 4 for interstate and the stiffest, 5 & 6, for high speed track work. It is simple to set up and tune the car when changing from AutoX to street and back to track by just turning a knob. Additionally we can set up the car for wet conditions by using softer settings and use softer settings in the rear to increase rear traction. If we do oval work we can easily weight jack the car using the shock bump settings.
The Penskes at around $3000 new, seem expensive, but they add value to the car OR can be resold for 75-80% of the initial cost. I just sold a set for $2,500 so the cost over 4 years was about $47 per shock per year...pretty cheap. The Penskes look like a real bargin when you compare them to the new 4 way adjustable Moton's at $10,500 a set, of course they are the ultimate. Penskes are also rebuildable and revalvable and thus hold their value.
The Penskes are also upgradable to coilovers. I would not install coilovers unless the car is a dedicated racer or your are very serious in handling and high speed track.
The advantage of a coil over set up is that once individual corner weights have been determined individual corner spring rates can be selected and ride hieghts set INITIALLY. It gives you the best initial range of set up. I think it is a mistake to build a coilover set up on a non-adjustable shock however, in that you no longer have adjustability save for disassembling the set up to make a change. Not something you want to do at the track. You need a set up platform and need to corner weigh the car and then corner weight it or rely on someone elses recommendationms to properly use a coilover set up.
My recommendations for a NON T1 Spec suspension is as follows: NOTE: this can be done progressively if funds are limited in the general order listed (the first 7 items done initially then add the T1 sway bars and progress to stiffer springs or coilovers if necessary)
- Lower as far as possible using:
- Hardbar Titanium rear spring bolts
- Hardbar SS Front spring bolts with Delrin Bushings
- Competition alignment (mark street, AutoX & track settings)
- good & proper size set of race wheels & tires
- VB&P Poly Graphite Bushings
- Penske DA shocks
- T1 Sway bars
- Teflon Lined adjustable end links
- Baer "Tracker" Toe & steering rod end bushing (if necessary)
Options:
- Hardbar keyed Camber plates (locks in settings)
- VB&P Extreme Springs OR
- Coilover upgrade to Penskes (Hyperco springs and Hydraulic spring perches)
- Custom billet spindel/hub uprights
- Custom A-Arms
Brake upgrades for track: (likewise all the basic options first)
- Cryo'd & slotted rotors
- Race Brake Fluid (Motul 600, AP600, Wilwood EXP)
- Initially Bleed ABS with Tech II Analyser
- Race pads
- Goodridge SS lines with -AN connectors
- Speedbleeders
- DR SS caliper Pistons
- DR Cooling Duct Extension
- LG Spindel Ducts
- Pegasus or Mallett Bleed Catch Bottle
Options:
- MPC H2O injection/mister
- VB&P F1 vented Titanium tipped caliper pistons & caliper hone
- Extrude Hone rotor interior vanes
- Meta-Lax stress relieved rotors
- Heat barrier protective coating on selected surfaces
- Heat release coating on selected surfaces
- Anodize selected surfaces
- OR Big brake kit (Alcon, AP, StopTech)
Wheel & Tire selection:
C5 Z06;
305/30x18 on 10.5x18 with +0.25" offset FRONT
315/35x17 on 11x17 wiith +0.25" offset REAR (T1)
T1 Wheel/Tire optiion (other than stock sizes)
315/35x17 on 10x17 FRONT-> Limits tire effectivness
315/35x17 on 11x17 REAR
C6 Z06:
305/30x18 on 10.5x18 with +0.25" offset FRONT
335/30/18 on 12x18 with +0.25" offset REAR
__________________
Williams GT Engineering @
www.WilliamsGTEng.us
F1 Technology, Parts and Preparation for Competition Corvettes
I've had my '02 Z06 for about 6 months and have taken it to the track(Thunderhill) once so far. It was lowered approximately 1 inch when I bought it. The car is my daily driver but I plan to take it to the track 2-4 times per year. I am severly budget limited so my modifications were done on the cheap. With DJWorm's info as a base, plus talking to a lot of people and searching for deals, here is what I ended up with.
About $610, Hotchkiss sway bars, comes with teflon endlinks.
From forum vendor LAPD
About $350, DRM brake ducts with Phoenix spindle mounts.
From forum vendor PFYC and Phoenix, the
customer service from PFYC kind of sucked.
$200, '06 Z06 shocks.
From forum vendor Fred Beans.
About $230, New slotted rotors. Found from online ebay search.
Nothing special, but I wanted zinc plated to keep
rust away.
About $75, Slightly used Carbotech brake pads.
From forum member.
About $100, Braided steel brake lines. Add another $100+ for
Motul RBF600 fluid.
$700, New F1 Goodyear tires. From forum member. I
wanted PS2's, but I couldn't pass up this price.
$160, Lifetime alignment from Firestone. My local store
has done the alignment twice so far to my specs,
which are:
Front Camber -1.1
Castor L 7.0, R 7.3, with me seated in vehicle.
Toe +.08 total(.04 +.04)
Rear Camber -.9
Toe 0.0 (I might need to go a little neg next time)
My car had 18,000 miles on the original tires and I needed new ones right away. So for about $2,500 I got suspension, brakes, and tires, your dollars and mileage may vary. The car seems to handle and brake better, but still feels fine for commuting. It is a little darty on rough freeway surfaces but it's worth it to me. Overall I'm pretty happy with how everything's working. I just need to drive a little on some windy roads so I can get the rear sway bar adjusted for the right amount of grip at the next track day.
Good luck on whatever upgrade path you choose.
Dog
Oops, I forgot to add $500 for used hardbar and Simpson belts. From a forum member. That brings me up to $3,000.
) ...what shoud I do ? Suggestions? Thanks 
...i personally wanted the car to be a little lower (not a whole lot) to the tune of 3/4 of an inch to maaaybe a full inch (max) to reduce some of that wheel well gap and make the car have a much more agressive stance* ...so you guys are telling me there's basically no way to do this while improving the handling of the car ? Thanks.
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