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Unread 04-09-2015, 06:31 PM
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Fair! Fair! is offline
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Join Date: Jul 2004
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Default Re: Vorshlag Budget TT Build: Project DANGER ZONE

Project Update for April 9, 2015: Wow, I started writing this about 3 weeks ago (March 18th) and never finished. I lost the last 3 weeks to our new CNC machines, which I have been manning non-stop 24/7, trying to build a lot of parts to fulfill backorders. Somewhere in the last month - and I'm having trouble remembering back that far - we ran NASA @ MSR-C, and the weekend before that (COTA). We also prepped and took 11 cars to the Optima event March 28-29 at TMS, where I raced a C5 Corvette. Anyway, we took the TTC C4 and our TT3 Mustang to the NASA event, but I will break up the "race report" into another post. Let's look at the prep work that we managed to sneak into the C4 before this latest NASA race. It was a lot of work, but maybe not quite enough...

Roll Cage + Nets + Dash Rework Completed

About 3 weeks before the MSR-Cresson event I pushed the C4 onto Ryan's plate and he took over the front half of the roll cage fabrication plus the remaining safety gear that needed to go into the car before the next event. It took him less than 30 hours to do all of the work below. I wish this could have started sooner but our schedule is always packed and we can only squeeze in work on our shop cars when we get a small gap.

The "back half" of the cage was built as a bolt-in roll bar, since we ran out of time to fully cage the car before the January event.

We noted that my helmet was in a tough spot when making the 4-point roll bar in January, and as you can see above, any roof cage structure that was kept inside the window frame would be INSIDE my helmet. As it was the targa structure was touching my helmet - this car is narrow inside, up top. I didn't think me leaning at a list to starboard was the safe way to drive, so we pushed those upper cage tubes outside the window track.

Will this affect airflow? Maybe. Will this positively effect drag reduction and top end speed? I highly doubt it, and nothing short of wind tunnel testing could prove it either way. Is it safer this way, keeping a piece of 1.75" steel tubing away from my helmet? OF COURSE IT IS. So we did it - its the safest, most common sense routing for this car and this driver. It looks a little odd, but its the right solution - this side of getting a shorter driver. My seat is already touching the floor - which we cannot alter.

The front, upper cage tube near the windshield surround also follows that contour closely, again - to keep it away from my head. It sits as high up as possible, to prevent the cage from restricting my forward field of view. The unusual angle of the upper tubing junction there was later gusseted with more tubing, shown lower in this thread.

An "FIA" style vertical crush prevention bar is also added, which narrows the side door opening but makes the heavily raked windshield and A-pillar structure much more "pancake" resistant in a crash that put the car on the roof. I would like to keep my head and spine as delivered, thank you very much.

Note the tight joint fit-up in the above right pic. After this point in the cage build (we missed taking pics of the door bars) pretty much everything was built and tacked in place, then the cage structure was completely pulled out of the car, in sections, to do the final welding.

Sub-assemblies like the NASCAR-style door bars and load plates (above) were welded on the fab table, for easier access to get to the bottom of tubes. The FIA bar was welded to the A-pillar bar, things like that. Standing on your head to weld upside down inside a car is the suck.

After the roll bar and cage sections were removed the B-pillar roof hoop was cut out of the car, lickity split. Yes, this was deemed necessary to gain access to the upper tubing joints for welding. The cage structure far exceeded the OEM rollover protection of this piece, and it was welded back in later. Luckily there was a body seam there that covers up the outer fiberglass cut. It won't have to be body worked.

The picture above skips ahead a bit, where the cage is almost fully welded and back in the car, and the roof structure hoop was welded back in place. At this point it is getting close to being done. The upper front corner gusset tubes are shown here, and yes, they do land on the FIA bar. It was another compromise to keep from having to cut a giant chunk of the already weak windshield frame away at the A-pillar. The roof diagonal is also shown in this top-down shot.

The tubing above ties the front downbars into the firewall at one of the few places that has any metal. This is still a mostly fiberglass car, and the front half of the floor pans, trans tunnel, and most of the firewall is all just thin fiberglass. Can't exactly weld or land metal tubing onto that structure. So Ryan picked the farthest outer edge of firewall, which is metal at the base of the A-pillar, and tied some short pieces of 1.5" tubing from there to the main cage. This is to prevent TIRE INTRUSION into the cabin in a heavy crash, and for a car like this, well worth it. It doesn't pass through the firewall or tie into any major structure there. The upper OEM A-pillars are still free floating, since there is no roof structure (its almost identical to a convertible in this respect). With the OEM targa roof removed and the windshield out, the windshield surround is surprisingly weak and flexible. Oh well... we cannot tie into the A-pillar in any substantial way without taking more performance points for TTC/PTC.

The door bars are pushed outwards to almost the skin of the fiberglass doors, and the factory impact beams were removed. This is to give a lot of ROOM to the driver's arms, and the extra room is appreciated. These bars have a lot of curves in them, to fit this crazy chassis, so they were tied into the outer frame rails in 2 additional spots, as shown above. This makes them stronger in a side impact, and the bars and frame would both have to deflect a lot to touch my arms. I'm rather fond of my arm and would like to keep it attached to my body.

Another thing the upper side cage bars do is go UPWARDS from the B-pillar joints/factory roof structure hoop, to give me more head room in a rollover. The seat is bolted right down to the floor, without a slider or any risers, to increase headroom. The only other trick left is to lower the floor - which costs performance points in TTC, which we don't have to spare. Everything in racing is a compromise.

Non-Cage Stuff + Safety Upgrades

Our friends from Titan Auto Glass (above) came out to re-install the windshield after the welding was complete. They had already been out a few weeks earlier to remove the new windshield they had installed in January - an added expense of doing the cage in two different time periods, with a race in between. Always, always get the windshield out of the way for a cage job.

The 14" wide panoramic mirror from Longacre was mounted to fit my driving position. With the driver's side mirror I have an unobstructed rear view. The passenger side door mirror is broken and useless, for now.

continued below

Last edited by Fair!; 04-23-2015 at 08:44 AM.
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