Half cage - Questions on safety

[Bodie217]

Hey guys, I'm transitioning my weekend/autoX 135i into more of a dedicated racer. My initial desire was to get a half cage, seats, and 6pt harnesses. I read various threads on these set ups, and almost every time I see someone talking about the dangers of having a 4-point half-cage in a roll-over situation. The fear is landing upside down and the roof caving in, and the half-cage not providing enough strength or headroom to keep your neck in 1 piece.

The other concern is an instructor refusing to ride passenger because of the 4-point cage, meaning my upcoming HPDE would be ruined.

My reason for wanting race seats is that the stock seats do not offer enough lateral bolstering, requiring more effort in high-G maneuvers. Also, after every track event, the outside of my right knee is heavily bruised from bracing against the center console.

Does anyone have a professional opinion on half-cages?

Thank you!

[lowside67]

I think this fear is unfounded. The (general) issue is with fixed back race buckets and no rollover protection because the seats do not collapse in the same way stock ones would.

However, a modern car has an incredibly strong A pillar and further, a properly designed 4 point bar should not move or deform whatsoever. So as long as you can apply the formula car style test where you compare an imaginary line from the top of the roll bar ("half cage") you are having built to the top of the hood area with the top of your head and are comfortable you are under it, I wouldn't lose a moment's sleep.

I also do not know that many organizations prohibit fixed backs with a half cage - I think it usually just without any rollover protection.

-Mark

[bbnks2]

Just put the seats in and drive it lol Skip the cage. It causes more liability than safety most of the time. Unless you are building for some specific racing class which has specific rules regarding seats/cages...

[Bodie217]

Originally Posted by bbnks2

Just put the seats in and drive it lol Skip the cage. It causes more liability than safety most of the time. Unless you are building for some specific racing class which has specific rules regarding seats/cages...

Good point... Where would you mount the shoulder harness straps?

[fe1rx]

Originally Posted by Bodie217

I read various threads on these set ups, and almost every time I see someone talking about the dangers of having a 4-point half-cage in a roll-over situation. The fear is landing upside down and the roof caving in, and the half-cage not providing enough strength or headroom to keep your neck in 1 piece.

It is hard to imagine how having the half-cage could be worse than no cage in this situation. It can't make the OE roof weaker.

I suggest checking with the oganizer rather than make any assumption about acceptibility.

As to your motivation for adding the half cage, seats and harnesses - makes perfect sense. Gives you somewhere to attach your harnsses and lets you use a HANS too. This is exactly why my car has a half cage, race seats and six-point harnesses.

Addressing your comfort and safety should be priority one and satisfying armchair critics should be priority zero.

[bbnks2]

Originally Posted by Bodie217

Good point... Where would you mount the shoulder harness straps?

A half cage (usually just a beefed up strap bar) is convenient but not necessary at all to run a harness... You can bolt the harness traps somewhere underneath the rear bench. Just gotta find a place that gives a decent angle.

[Mark Aubele]

Fixed back seats without a 4 point bar sketches me out. Anything as new as the 1 series has an incredibly strong roof structure, and honestly I'd rather roll a 1 series without a bar than a Fox body Mustang with one, but I think the four point makes mounting the harnesses easier and safer. Never liked having that much length in the shoulder belts going to the rear seat area (how most would mount them without a bar). We have an autopower in my wife's 135i, it is SCCA Level 4 TT legal (she hillclimbs the car), and pretty cheap. The other bars I have seen available for this chassis would not pass our tech, and are stupid expensive.

[crowtrobot]

I'm in a similar situation with my car; the sport seats do not offer enough lateral support as I've gained experience and gotten faster.

Supposedly, the Cobra Nogaro fixed back seats will be compatible with Schroth Quickfit harnesses, so you'll be able to have a 4-5pt harness without the need for a rollbar. The tradeoff is that the seats are not particularly cheap. The Quickfit Pro's allow for a HANS device and potential upgrade to an anti-sub strap.

The other issue is different rule sets for different clubs. I guess if you can find someone that lets you run your desired setup, just keep with them...

[The Wind Breezes]

Half cages are bad. Enjoy your harness while the A pillar crashes down and doesn't kill you but leaves you paralyzed. In other words, what's the point?

If you think you're moving around too much do the "seat belt trick". If you really need more gear, do it right. Full cage or no cage.

[Mark Aubele]

Originally Posted by The Wind Breezes

Half cages are bad. Enjoy your harness while the A pillar crashes down and doesn't kill you but leaves you paralyzed. In other words, what's the point?

Do you honestly think a four point with harnesses and fixed back seat is less safe than a bone stock car? Guys have been tracking/hillclimbing/etc with this setup for years and years.

Some organizations (such as the SCCA level 4 TT) require a bar, 5 or 6 point harness, fire extinguisher, suit, and gloves.

[fe1rx]

Originally Posted by The Wind Breezes

Half cages are bad. Enjoy your harness while the A pillar crashes down and doesn't kill you but leaves you paralyzed. In other words, what's the point?

Point to any evidence of this actually happening. Ever.

[fe1rx]

Originally Posted by The Wind Breezes

If you think you're moving around too much do the "seat belt trick". If you really need more gear, do it right. Full cage or no cage.

The seat belt trick is virtually useless, even with sport seats. A Schroth Harnessbelt is a better half measure, but it is still nowhere near the equal of a race seat and 5 or 6-point harness in terms of holding the driver in position.

As for full cages - these are useless on the street unless you drive around with a helmet on all the time.

Do it right is a great idea, but right for what?