Aaron Pfadt

Well, I've posted some video of the maiden race of our C6Z at Miller Motorsports Park and talked about how the brakes have basically fallen off the car. I guess that was to be expected. I wanted to do a nice documentation of the build and all of the parts concepts that are going into it. Here is the story.

This is how the car looked this spring. Here it is in full street trim at Katech Track Attack 2009.



Here is the car in Race trim at Miller a couple of weeks ago. Not a whole lot of difference in looks.



I have been documenting the build of our Z as we have moved along with it. Many of you have seen our Pfadt C5 and how we built that car into it's Nationals winning form. That car is retired and we have shifted our focus to this Z. With the C5 we took the car down a path exploiting every advantage and modifying things as needed. It became a very pure race car, but eventually shared little with a production C5 Corvette. We even went so far as to shorten the torque tube to move the engine (and CG) rearward. At some point it became it's own animal and things that we did to that car had little relevance to the Pfadt product line and most importantly, to our customers cars. With that in mind, we are building our C6 Z06 with a different philosophy.

There are 3 tenants to our build philosophy. We have decided that we can change or remove something from the car if it serves one or more of the three following goals.

1. it makes the car more reliable
2. it makes the car safer
3. it makes the car easier to service

The power of the LS7 in the Z06 is very adequate. For example to make NASA ST1/TTU weight to power, 500 to the wheels is what is needed to be right at the limit of the class given a realistic race weight. With that in mind we can achieve 500 to the wheels with some bolts ons like exhaust and a tune. Those serve an additional purpose of adding reliability in the form of reducing heat in the engine compartment and freeing up some space for serviceability. That is the thought process that we have used with all of our decisions on this build.

We want a Corvette that is ST1 fast, and still retains all of the manners, looks and reliability of a stock C6Z.

In the past we had upgraded the radiator to a thicker Dewitts radiator to give us the ability to test here at Miller without overheating. The altitude and thin air make cooling more difficult. With this 'race' build we started with two more modifications. First we added an ARE Stage 1 Dry sump kit. The oiling system is a necessary upgrade if you do not feel like buying a new LS7 from GM. This particular car had lost a motor at the track with it's original owner. With the warranty waning, GM probably will not install another one

The second modification we did was to install the cage. It is a requirement for wheel to wheel racing and is the single largest modification required to turn a street car into a race car. In the past, cages have been one-off units, each built individually for the car. It is a time consuming (read expensive) operation especially in an aluminum framed car like a C6Z or ZR1. With this conversion looming, we at Pfadt decided to engineer a cage solution for the C6 and C6Z.



This cage will change the way even experienced shops will cage Corvettes. This comes as a kit of bent tubes, each 'fishmouthed' to mate perfectly with every other tube. The installation process involves stripping the car, test fitting, tacking in place and finish welding. No tube bending, grinding, and trial and error fitting. This cage goes together and fits.

Here we are stripping the car.



Notice we wrapped the car to protect the paint during construction



The roof and targa bar cover unbolt, the factory aluminum hoop does not. We place our main hoop up very high, it replaces the center section of the main targa hoop. Here I am removing that piece. This is the most intrusive part of the install.



Here is how the trimmed piece looks, we leave the fiberglass so that the hatch will still seal.



We cut out sections exposing the rear frame rails. That is where the rear legs will attach



Here we are test fitting the tubes. We never used the grinder to modify a single tube during the whole install. That is what CAD and great manufacturing will do for you. Note the fit in these photos.





We test fitted the entire tube set with help from a few tie down straps.



We even confirmed that our big eared Cobra Evo seat would fit before we tacked a single piece together




More in the next post!

Aaron Pfadt

Test fitting complete, we marked the holes where the cage would be bonded and bolted to the aluminum frame and tacked the mounting feet (of course included with the kit) to the tubes. We welded them outside the car to ensure 360 welds and strength.







The feet sandwich the frame and bolt into these backing plates that are fed into the frame though the tie down holes in the underside of the rails. We bond those joints with appropriate epoxy for extra strength.



In the rear, we saddle the frame with brackets and through bolts. The spacers keep the frame from crushing with the through bolts. These joints are bonded with epoxy as well.





We provide all of the attachment brackets as well as a bunch of extra pieces that can be used for stiffening the chassis if you rule set allows. In NASA the cage can be attached in as many places as you want, so we added all of them to this cage.

These are to the under dash brace (as close to a firewall as you get tin a Corvette)





This ties the main hoop to the b-pillar at the seatbelt mount point



This ties in the a-pillar bar to the windshield frame



With the test fitting done, It's time to weld and paint. Since I was welding, I didn't get any of those cool photos with the blue light and me wearing a sweet flame painted welding helmet

Here are some photos of the masking and painting






From there was re-assembly time!











Here are some photos of the car complete as it sits today. The rear x-brace in this cage is removable for easier service on the car. Also note we installed Lexan windows in it instead of putting glass back in. We'll document that in the near future.











Stay tuned for more on this build. It's just beginning...

-Aaron

Kubs

Cool build! I will be watching this one!

gtpvette

What hardware are you using on that removable x-brace???

Thanks!!

burners

Very nice job on the cage.

wmckeenster

WOW!

I want one of those rear diffusers Aaron!

Aaron Pfadt

Its a lap joint that we designed in house. I don't have a closeup photo of it, but it uses a 3/8" socket head in single shear. The halves of it each weld into the end of the tube.

Here is a rendering:



-Aaron

Aaron Pfadt

You are getting ahead of us Wayne

Look for that in a future installment. Come check ours out at Nationals, by then we'll be through more of the testing and analysis.

-Aaron

Z06Fix

looks great guys

Darrell ST1

0RAAMaudio

As always, top notch quality, engineering, functionality and beautiful to behold

Rick

BrianCunningham

Why in single shear??

BrianCunningham

I thought I'd put this up on the SCCA forums

I'm sure someone will be needing one!

http://sccaforums.com/forums/ShowThr...=373990#373990

http://www.sccabb.com/forum_posts.as...366&PN=1&TPN=1

0JoshS

Hey Brian,

Aaron is out today so I will try and answer your question.

First, this is a removable X in our cage because we are experimenting with a few different fuel system options for the 25 Hours of Thunderhill. This really required that this X was removable. One thing to keep in mind is these tubes are extra bracing which are not required by rule so, attachment method is open. In the production cages the experimental fuel system will not be a design constraint so, the X will be a standard fully welded design.

Second, for our X brace to be practically removable it really required the use of this type of joint. If the joint was a double shear, clevis style joint it would require that all of the joints aligned in the same direction. While this is simple to accomplish in CAD, when trying to weld these together it would be inevitable that one would be at a slightly different angle and thus make the removable X... not so removable.

We wanted to avoid having to fight to get the X in and out.

The other option would be that the joint would have enough play that it could be welded and removable in the real world. This would cause the joint to be loose and render it less effective in stiffening the chassis. Also, the constant movement in the joint would cause rapid wear.

Probably more explanation then you were looking for...

Take care Brian!