Door Opening "X" Bars as Side Protection

[lateapex911]

I couldn't agree more. I'm not sure what the logic is with limiting the number of roll cage attachment points. It only seems to limit safety by reducing load paths.

One benefit is that spending mega bucks on dampers is pointless, as the chassis is an undamped spring of sorts....

[rsportvolvo]

One benefit is that spending mega bucks on dampers is pointless, as the chassis is an undamped spring of sorts....

Very true about the chassis is an undamped spring. That is why so much time is spent by top teams making the chassis stiff. Having a stiff chassis will allow you to reap the benefits of a better damper, not to mention a more consistent handling car.

[lateapex911]

Very true about the chassis is an undamped spring. That is why so much time and money is spent by top teams making the chassis stiff. Having a stiff chassis will allow you to spend a bazillion dollars on better dampers, that raises the bar for everyone.

Fixed that for you.

Few realize that the limits to the cage are actually one of the brilliant parts of the IT ruleset. We get into arguments about remote res. dampers, and those against cry foul that allowing such things will increase the cost by huge margins. Well, it COULD increase the cost, just like paying somebody $100 an hour to lick the undercoating off the car, but with a 2 adjustment limit, and an undamped chassis, the gains will be debateable, at best, and the actual costs difference to a high end non remote res. damper is rather non existant, anyway.

That's why I resist allowances that increase cage connection points.

[Knestis]

...particularly since it's possible to build a pretty substantial cage inside of the points already allowed - more substantial than most IT racers currently build.

One area where I think we can do a better job in this respect is not listing cars so light that there exists an inducement to skimp on cage structure in the name of weight. A large portion of the amount that Pablo the Golf is overweight is in optional cage tubes. I didn't worry about that because (a) I'm kind of a safety geek, and (b) because our focus was endurance racing, but I've had conversations with other MkIII owners - and others - who talked about "minimal cages" when talking about meeting weight.

If it gets that close, the car in question might be better placed a class lower at a higher minimum weight.

K

[lateapex911]

......agreed!

But, two monsters rear their heads there.

1- If that class is ITC, many will resist building because of lack of competition in their area, or perceived "extinction" issues, and...
2- Determining what a car CAN get down to, and finding the "break" point on that weight.

#1 is tricky because we are making it heavy to increase safety, ease of building and therefor popularity, but the questionable class placement kills it on the last point. Certainly it's a method worthy of implementation for the upper classes.

[Greg Amy]

Back to the original point, I've gotten word of another failure of a pure-X design. Same situation, where there was a single-diagonal-with-braces design, and it failed in the same manner: the single tube failed in tension. Welds were all good.

Fortunately, this last time was also to the passenger side; it didn't fail as far into the car as Richie's did, but the potential was still there.

I am now completely opposed to the approval of "X" bars, when they are designed such that there is a single tube across the door with two tubes welded to it to form that "X". It is now my opinion that there be an area of AT LEAST two whole tubes between the main the front legs of the cage, in order to resist vehicle intrusion and subsequent driver injury. I originally supported this "X" when it came up last year, but incidents this year have changed that. I plan to send a letter to the CRB, with photos, requesting the rule be changed.

If you already have this in your car - and, for reference, I did in the NX and the Miata - my recommendation is to add a horizontal tube at the bottom of your "X". - GA

[seckerich]

My suggestion for modification to the X bar rule would be to require the joint be gusseted. Minimum of 4" gussett on 3 sides. Would have the same structural area as a solid tube. Two solid tubes (high and low bent in arcs) plated in the middle just seperate and open like a shark mouth. It still comes down to surface area connected in the middle.

[Andy Bettencourt]

Back to the original point, I've gotten word of another failure of a pure-X design. Same situation, where there was a single-diagonal-with-braces design, and it failed in the same manner: the single tube failed in tension. Welds were all good.

Example. Glass if from side mirror.