It would be fantastic to have a few Challenge legal cars running together, and it was great fun racing with you at TWS. It is just magical to see and hear another equally prepared Challenge car running alongside. Although, I do think I had more tire than you did that day. I really hesitated to "outlaw" my car, and if there had been more interest from others in running 100% Challenge legal cars I would not have started down the slippery slope. But once the fuel cell went in, and the glass came out, then we decided to make it lighter, then improve the aero, then the exhaust, then I fell in love with this car: 8into1 race exhaust, Motec.... Image Unavailable, Please Login
randy, What is up with the triangular bar with the apex pointing toward the right aspect of the pedal box???? That does not seem to have a purpose like stiffening the upper part of the frame. What is that?
Actually the second picture is Dana's car, which was done a little differently from my car, the first picture.
I've always been a bit concerned about the 355's fuel tank location and potential for fire in a crash. I'm even more concerned about this in street cars than race cars, because I'm more likely to spend my time on the street, with the occasional track excursion. What do you guys thing about a front fuel cell location in a street car, without a full race cage? I know the luggage space would be gone of course. The weight addition can be offset by lightening the front of the car as previously mentioned.
That's not Mark's car. That was another we did. The angled tubing goes to the knee bar behind the dash that also tied into a diagonal in the cage. It's added driver protection as well as stiffens frame up to shock absorbers without stiffening the crumple zone....this diagonal is part of our IMSA rollcage complete.
Interesting...do you have pictures of the complete IMSA cage? From the picture it looks like the base of the triange to be no where near the shock towers but closer to the upper pick-up points. How did you tie into the shock towers?
It attached right next to the upper pickups which were reinforced as well. Every 355 I've seen that has done numerous track events, the shocks actually push up and tear the steel structure loose where it is only spot welded. We reinforce and stich weld the area. The cage actually is integral with the a-pillar and a-b pillar structure. We split this structure and place the tubing into it and then stich weld the whole thing in place. This adds a lot of structural integrity to the "life cell" but also allows MUCH more head room and the addition of a Recaro SPG Pro with the helmet wings. Even a guy with a tall torso like me can fit in the car with helmet on without hitting the roof. The cross bar above the dash on the challenge version bolt in cages is gone. We install a proper a-pillar to a-pillar bar behind the dash and that is where the "V" from the front ties into at the mid point behind dash. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Very nice application of NASCAR bars. Tying them into the sill tube is the right way. Too often I see these floating out into open space making them more of a liability than an asset. What do you think about following the B piller so close? You got great space in the interior but don't you think the acute angles can compromise the primary purpose of the rollover hoop which is to support the car in a rollover? More angles in the hoop make for more yield points. Taking this into account did you say up the wall diameter of the rollhoop to say 120 wall and to test this design by history of past rollovers? I kept the B-piller of the rollhoop as straight as possible to maximize crush strength but sacrificing cabin room. I'm only 5'6" and my custom 20 degree layback seat is only 3" from the harness bar. There is no way a 6 footer could use my car unless he did a 0 degree seat. Image Unavailable, Please Login
I also like your application of the low petty bar. Usually these are at the roll hoop to the forward cage foot. You sacrifice some cage rigidity by not making it to the rollhoop but you drop several pounds in weight by going to the harness bar and you make the cage much safer because your head cannot hit the bar in a side impact crash. I like it. What is your feeling about a frontal impact pushing that low petty bar into the harness bar and bending it? If that happens your 6 point harness tension goes to nothing...very bad. The traditional petty bar to the roolhoop is supported more in the fore aft direction by the rear rollhoop stays. The harnessbar is unsupported in the fore aft direction except by the pulling in collapse of the rollhoop side tubes. What is your opinion on that tradeoff? I wish I could see more of the front of your cage. So few thought out custom cages are done in 355's.
Oh, I forgot to ask...what did you do with all the extra space where the oem tank was? Did you run tubes from the rollhoop side support through the firewall into the rear suspension?
The b-pillar is stich welded to the roll over hoop as well as the cross brace that duals as a seat belt retention intersects at the point of the bend and is gusseted too. We had a specified budget for this cage in question and had some compromises, but I think it is far superior to any bolt in cage that was installed previously in the challenge cars. For a pro car it would have been done even more robust. However, rules dictate design and attachments as well so you have to be very careful. The rear roll hoop as well as the main structure was made of 1 3/4" 0.095" wall alloy 4130 and all heli-arc welded vs. MIG If the car was not so heavy, we would have gone down to 1.5"D 0.095T 4130. We typically do not use DOM as we can save weight and have better strength with 4130 chromolly
