powdrhound

I figured I would start a build thread here that some of the track guys here might find interesting. About a year ago at the end of the ‘20 season I parked the car and took it to CTS for a complete down to the tub teardown and rebuild. There was nothing wrong per se with the car and it performed beautifully all year easily winning the NASA Rocky Mountain Region TTU championship. What makes this notable is that the car did it in essentially street legal form still wearing a license plate on the back. The reason for the full teardown was to install a full weld in cage so the car would be legal to race wheel to wheel. My plan for ’22 is to race it in both NASA and HSR, the latter being a fantastic series based an all accounts. The main benefit of having a full cage is naturally the vastly improved safety this will bring. I had been lucky up to this point running the car with just the OEM IMV 997Clubsport rear cage but it was time to put safety first because all it takes is a blown tire at speed which can quickly make for a very ugly result.

I just got my car back from the shop after having a new roll cage installed. The finished product turned out fantastic. This cage is replacing the above mentioned OEM IVM 997 Clubsport bolt in roll bar that was in the car. While the OEM Clubsport roll bar was a great product for a dual street/track use car, it was totally inadequate for the use that the car was operated under. The new cage will bring an amazing amount of additional stiffness to the chassis and above all, vastly improved safety to the driver.

The new cage is built to the latest FIA regulations utilizing the newest techniques to distribute impact forces throughout the chassis and away from the driver This is evident with the additional rear bracing which ties the cage into the tub. The whole cage is constructed from T45 Seamless Steel Tube FIA / MSA Motorsport grade material and welded to the body at 18 points.

Numerous gusseting and reinforcements are welded in throughout the chassis including both front and rear strut towers. The rear strut towers are encased with a full steel "dome" which is welded to the existing strut towers thus drastically increasing the strength in an area which is highly stressed especially on applications using stiff spring rates, in our case, 2100 lbs per corner in the rear. This technique to beef up the rear strut towers is used on all the later generation Cup cars. Additionally, a full weld in strut bar is used to tie the rear strut towers together with the tub.

The front strut towers are reinforced via additional gussets added between the towers and the frunk firewall. In addition, the thin front OEM bolt in diagonal strut braces are replaced with a full bolt in transverse strut bar which ties both strut towers together and at the same time triangulates with the main firewall for a significant improvement in stiffness even over that in a 996/997Cup. Two quick disconnects were added to the strut bar allowing for quick removal of the center cross bar for easy access to the fuel tank lid/pump underneath where the battery would normally be located. In our case the battery is in the main cabin.

The door bars are made of continuous one piece tubing along with a diagonal A pillar bar which is a change in the latest FIA mandate. This is employed on the all 991 and later Cup cars. All 996 and 997 Cups used 3 bar door segment which were gusseted in the center, a design which is naturally much weaker. Two additional transverse bars run underneath the dash from side to side for increased side impact protection. Finally a door sill bar is used on each side to significantly improve cockpit intrusion in a low side impact. Neither 996 nor 997Cups have the dash or door sill bars. As part of the cage install, all the various brackets that are present in the street car tubs were removed including the heavy transverse floating crash tube which runs from one side of the car to the other enclosed in the rear seating area. This is only installed in the street car tubs and weighs about 20lbs. With a weld in cage, this bar is totally unnecessary and as such, the removal of it results in a significant weight saving.

When it was all said and done with, the full installed cage as seen here weighs just 90 lbs. thanks to the light weight and high strength of the T45 FIA motorsport grade tubing . This is amazingly light. My previous OEM 997 Clubsport rollbar weighed 40lbs and that was just the rear section. The front Clubsport section which I did not install weighed 21 lbs. Considering that 20lbs was removed from the tub during the install of the new cage, we only added a net of an additional 30 lbs. With a full weld in cage, we are changing out the OEM solid steel roof panel with a Manthey Racing carbon fibre roof which if I recall nets a 15 lb weight saving from the top of the roof. The Manthey carbon roof is a gorgeous product but for safety reasons I would only recommend it on a car with a full weld in cage with roof bars.

I must tip my hat to both Brian and Sam at DS Autosport who installed this cage for me. These guys are absolutely top notch fabricators and the go to place for anything having to do with a roll cage. Brian and his shop built the cage for David Donohue's highly modified Pikes Peak 991Cup and they have vast experience with all the required certification paperwork from the various governing bodies including SFI and FIA. I don't get impressed very easily, but the quality of their work simply blew me away. Their attention to detail is really impressive with the main hoops built very tight to within a few millimeters of the body. I never actually realized how much skill goes into building a full roll cage and it is absolutely mind boggling how they manage to weld every joint a full 360º even in the tightest spaces. Welding a cage like this properly is akin to building a ship in a bottle and is a definite skillset. Brian told me this is probably one of the most complex cages they have done as it involved over 100 weld joints. I was told that on a typical cage they will use about 3/4 of a full bottle of Argon. They used 3.5 on this one and spend over 120 hrs welding the cage. Thanks for an amazing job guys! Later on this week he car goes into the shop to get the whole cage and interior painted body color. Then in goes back to CTS for the reinstallation of all the components. Essentially everything in the car is being addressed including completely new aero, Cup doors, Cup windows, LED RSR lights, carbon clutch, Motec ECU, etc. etc. The engine, gearbox, and suspension will be largely unchanged for the time being. The end goal is to have the car at 2750 lbs ready to run with 800hp at the wheels and 1000+ lbs of downforce at speed. Target for testing and initial set up will be March when the weather improves.

Goofy1

That cage looks like art!

Jferrante

Impressive John, what classes will this car put you in for NASA and the others?

Brainofjjj

That's beautiful. I've been 2 NASA / WRL cars in the past 8 years and finding a proper shop for the cage build is always the most important part. Very cool that you went with that tubing, i imagine it wasn't cheap given all steel has gone through the roof. What thickness is it?

powdrhound

With NASA, car will be in GTSU which is unlimited or if restricted to approximately 400whp, it could run GTS5. With Motec, selecting the appropriate hp map will be easy. Could also run Super Touring with NASA. With HSR, it would be in the Global GT series. I'll have to look at the series in detail and run through the formula to determine the HP limitations for each class and then map the engine accordingly to remain under the limit.

powdrhound

The FIA tubing is 1.5mm.

Zeufenhausen

Looks amazing John. Thanks for sharing. It'll be interesting to see the aero package you work out. How are you dealing with the seat mounting ? I imagine you need to get it lower in the car for headroom clearance.

powdrhound

Thanks. I have several options for there seats. One is the existing Brey Krause side mounts I used with my previous Recaro Spa seat and also a flat plate mounts which will allow the seat to mount about 1.5" lower. We will cross that bridge when we get to it but the seat does not need to be super low as the roof bars are tightly snug up against the roof.

SCraigB

I am so glad you have a build thread for this. I have been drooling over your signature and little bits I pick up from reading your posts.

moburki

WOW! Absolutely world class. Can't wait to see this beast run!

2fcknfst

Stunning stitch work, functional art, I like it very much.

You bring new meaning to how deep the rabbit hole goes; I look forward to seeing it back together.

TheDeckMan

Wow that is a work of art John!

kamlung

one thing in life i hope i can learn one day is to weld.

2fcknfst

Welding is fairly easy once you get the concept down; doing the above is a whole different type of skill set.

m54samrr

Between image 2, 6, 13 and 14... one of those would be my phone screensaver if I were you. What a bitchin job that was done, looking forward to seeing the end result.