T1 or Coil Overs

[AutobahnZ06GT]

Does anyone race the Z06 with the full T1 race suspension...and how does it perform over the stock Z06 handling wise...I will be racing at Hockenheim Ring in Germany and at NurenBurg Ring and lots of high speed driving on the autobahn and I would like to upgrade my suspension for even better performance, I have already lowered it using the factory techniques....are coil overs better than the T1 for autocrossing or is it a matter of preference? Any suggestions or ideas are welcome..I am not concerned at all of giving up ride quality (Soft) for the stick you get with an optimized suspension.

Thanks,

Nick

[trumperZ06]

Well the General's spent a lot of Engineering Devolopement time ie. $$$ on the T-1 suspension. That goes a LONG way in influiencing my choice!

[Subdriver]

Well the General's spent a lot of Engineering Devolopement time ie. $$$ on the T-1 suspension. That goes a LONG way in influiencing my choice!

I concur with the above.
I have raced the Z06 with the complete T1 setup in four SCCA races now. All my impressions are seat of the pants as I didn't get a chance to run the same tracks before/after T1 install.
My general impression with the T1 setup is that it is very well balanced, noticibly stiffer, and much flatter in cornering. It does have it's downsides, especially if this is your daily driver. The end links in the anti-sway bars are all metal and they creak, groan and squeek.
In my first four races, I ran 275s up front, 315s in the rear and the car turned in well with trail braking, had mild-moderate mid corner understeer and was very stable with power applied at corner exit. Very stable, easy to drive.
I am going to try 315s up front, which are allowed in the T1 class, next time out to see if I can get rid of some of the static understeer. The bigger rubber up front may give a little better braking performance as well.
As to how much better over stock, I can't say for sure. I read an article in a car magazine several years ago that did back to back comparision in a FRC with and without T1 suspension and the T1 setup was over 3 seconds a lap faster. Not sure where that was. Somewhere near Michigan I think.
I have no experience with coil overs, but have read many posts about them breaking at the mount.
You might want to try the T1 setup in stages. Install the anti-sway bars first. DRM sells them. If you can live with the squeeking and groaning, you may add the stiffer leaf springs next.
I have even read that you can install the T1 sway bars with different end links to minimize the squeeking. That may be a better option for a daily driver.
Good luck choosing.

[AutobahnZ06GT]

Subdriver,


You sound like you have a lot of experience with the T1 and it seems to be pretty succesful for you. I was always thinking about the T1 suspension before as it was better than the Z06 setup I heard.
Did you get the T1 schocks as well and did you do the install. What alignment specs do you use with the T1 setup?
I also heard that the complete setup will lower your car about a 1/2 inch more..I already have it lowered using the factory bolts about 15MM or about 1/2 inch, should I raise it back up or will it be Ok lowered at the bolts and with the new lowered suspension?

Thank you sincerely for this information.


Nick

[Subdriver]

You sound like you have a lot of experience with the T1

Nick,
I only have four SCCA Regional races, and one practice day, which equates to 13 track sessions. I'm not sure that qualifies as a lot of experience.
I do have the full T1 setup, but am not running the camber plates right now. This includes stiffer leaf springs front and rear, stiffer anti-sway bars, Sachs shocks and new A-arms up front with harder rubber bushings.
If you install this setup, the lowering bolts will come off and I believe the T1 setup uses different bolts anyways, so your current setup won't matter.
My car is about an inch lower than stock with this setup. I won't give away exact camber, caster, toe-in settings as I am in competition now, but suffice to say, lots of negative camber is good for the Hoosiers and Kumhos.
And no, I didn't do the install. Phoenix Performance Inc in PA did my complete T1 prep.

[DJWorm]

Concerning T1 Suspension:

Is basically a "Trunk Kit" made by Chevy to upgrade the original LS1 Coupe and Vert to racing specs. Although the Z06 comes with a better suspension to start with the T1 Kit will still offer some enhancements and make the Z06 a better track car significantly.

The T1 Kit componants:
Sway Bars are bigger and stiffer with hemi jointed end links.
Springs are stiffer.
Sachs Shocks are tuned to be used with the T1 Bars and Springs. NOTE they should not be used alone.
A-Arms have stiffer bushings but are the same componants as on the Z06 except for the bushings. It would be cheaper to just replace the bushings on the Z06 A-Arms.
Camber Kit is used to increase Negative Camber settings (Max stock is around -2.4 degrees)

Analysis:
T1 bars are great but offer a harsher street ride. They will increase cornering speed and stability. You can use just the front T1 with a rear Z06 bar but you should NOT use just the rear T1 bar and a Z06 front for tuning. Best gains are with both T1 bars. First generation end links were NOT teflon lined and needed constant maintainance and did not like dirt. 2nd generation links are teflon lined.
T1 Springs are stiffer but not nearly enough in MHO. VB&P makes a better spring front and rear.
Sachs shocks are OK but there are better units. Penske or Koni are better. Penskes are the best as they are totally revalvable and rebuildable. They also can be had in Double Adjustable and Triple Adjustable. They can also be upgraded to coil overs. The Penske's can also be modified with shorter shafts for lowered cars.
VB&P makes a nice bushing kit.

The T1 kit will make a Z06 handle better on any road course.

My basic ultimate set up would include:
T1 Bars F/R with teflon lined hemi jointed end links, to also include the Chevy HD sway bar mounts (shimed where necessary)
VB&P poly graphite bushings
VB&P F/R extreme springs
Penske Double Ajustable shocks

[Mark Olson]

Like Subdriver said, is all good information, You may want to consider a set of Penski or JRZ double adjust shocks. I'm also using the T-1 front bar end links with a stock bar and have no noise problems. Sub your noise may be the A-arm bushings? Then I may have the only quiet ones. If this is you road car an racer (track day) You may find that the Hole T-1 package a bit much for daily road use. and the harshness could cause other squeaks and noises over the long run. Plus void your warranty if that is an issue. Tires and shocks may be you best ban for the buck at first.

[DJWorm]

As to Coil Overs:

Coil overs offer some advantages
1. Truely independant suspension with no "cross talk"
2. Ultimate tunability concerning ride height, corner weight and independant spring selection and preload.

The down side of coil overs is expense and testing required to achieve the right set up.

C5R's use 2 different shock coil over set ups
1. Penske Triple Ajustables
2. JRZ Triple Adjustables

Both use Hyperco Springs

My ultimate set up (which I am going to will include all of the above - in the previous post) and Penske Triple adjustables.

There has also recently been some data released that Titanium springs are being considered.

VB&P also offers better engine mounts and trany/diff mount that remove any torque steer.

There are also some "Bump Steer" Kits available on the market which should be considered.

Please note that coil overs are not legal in most classes.

[vette1]

Check out the June Corvette Fever they did an article on redoing the C5 Z06 suspension & brakes the used coilovers & larger sway bars,may help you a little to decide.

[Mark Olson]

It may all sound good on paper in a Mag. that has advertisers to make happy. Truth imo. The C5 frame was never meant to handle shock load an spring load in the same place on the structrue, It will just cause flex were it was not meant to be. Its all different when a frame is work with a cage an tri-angle to handle the loads of a coil over system.

[DJWorm]

Important NOTE:

Mallett strongly suggests weld in upper shock mount reinforcements for coil overs.

I have heard of these snapping off but nrver have seen one do it.

I have also heard of some of the cheaper setups breaking the upper shock eye.

In addition LG Motorsports and Doug Rippie have quality coil over units.

I feel the Penskes however are the ultimate set up and have the greatest serviceand parts availability.

[sandy]

i had t-1 bars and heim links fitted recently to my z06 at dick guldstrand's place in burbank, and the wheel alignment tweaked and tire pressures adjusted [32 psi front and 34 psi rear, stock wheels and tires].

the bilstein gas over oil shocks are this week delivered and instaled i hope...

the car is far better in cornering; today we went to ventura and returned on the pch thru topanga cyn, sheesh that was a lot of fun!

[jackmott]

regarding autocrossing
the fastest z06 autocrossers are competing in superstock, which basically totaly stock cars. Some have added adjustable shocks, but lately Chris Ramey has been beating everyone with a totally stock car.

Ive seen one car prepped for ASP with some of the T1 components, but it wasn't being driven well enough to tell if it was any faster than a stock one.

[AutobahnZ06GT]

Thanks for all of the information, it certainly has been helpful. I think that I am leaning towards the full T1 suspension but maybe add some other shocks besides the Sachs, there are some being produced with titanium springs, has anyone heard of them? I do not care if I give up ride quality as a daily driver because I want the feel of an extreme gripping car. I love this forum, it has been very helpful.

Nick

[Redshift]

Hey Nick, I will be driving Nurburgring in late May and Hockenheim in June while I'm in Europe. Maybe we can meet up!

Now, my thoughts on adjustable suspension components are basically this: how do you know you have it adjusted right? Unless the setup was designed specifically and tuned specifically for your car under track conditions, I *highly* recommend sticking with OEM parts.

I'll be taking off my HAL adjustables and selling them and putting the OEM shocks (perhaps '04 shocks once they are available) back on because I know those are designed and matched to my car's suspension. Shocks and/or coil overs are really hard to adjust without a lot of testing and data and most all of us (even the racers) don't have that kind of information except seat of the pants.

The '04 shock setup on an otherwise identical to '02 or '03 Z06 got GM's test driver around the 'ring in under 8:00, the fastest production car run to date I believe. If you can beat that, you must be in the wrong profession!

Point being, we should trust the development of GM or other aftermarket tuners only when there is a LOT of data to backup the setup. Trying to do it yourself is probably a bad idea IMO.