Roll bar per the SCCA TT rules

So I'm building out my Prelude for Level 2 safety. That means a 4 point roll bar.

The thing is, this will still be a street car and the kids really enjoy riding in it. Which means is like to keep the back seat at last partially functional.

In particular, I was looking at the rule that says the main hoop only has to be 15" wide. That would allow me to put a roll bar behind me, but still keep the car a 3 seater (for 2 kids).

The rules do say that it's desirable but not required that the main hoop span the width of the cockpit. 

Do you think I'd catch any flak in tech? I figure there's almost zero chance of having a passenger on track (most tracks don't allow them) so it's not like I'm leaving a passenger out to dry.

Had anyone else done this? Just curious to hear thoughts.

One issue is once you put a harness bar behind the drivers seat, back seat passengers no longer have a soft seat to impact in a crash, just a steel tube.    And the main hoop down tube towards the center of the car is another impact point.

Masher_Mfg said:

One issue is once you put a harness bar behind the drivers seat, back seat passengers no longer have a soft seat to impact in a crash, just a steel tube.    And the main hoop down tube towards the center of the car is another impact point.

That's why I was thinking of just doing a half width roll bar, which would just be behind the driver. Then the passenger side would remain clear.

The only concern I would have with a half width roll bar is that it assumes that you won't find yourself in a position where you have to crawl out of the right side of the car.  It's difficult to do that if the right side of the roof is crushed down.

Philosophically, once you ball up to that point, you would have been better off with a cage anyway.

BA5 said:

That's why I was thinking of just doing a half width roll bar, which would just be behind the driver. Then the passenger side would remain clear.

 

Do the rear seats have shoulder belts or just lap?  If just lap, the right rear passenger can flail around contacting the down bar towards the center of the car.

As for 4 point, is this 2 main hoop uprights + 2 back stays or 2 main hoop uprights + halo and 2 down bars from halo to front floor but no back stays?  

I'm surprised a 15" wide bar is legal, that doesn't offer much protection and besides, cars tend to flatten the A pillars in a rollover not the center of the roof so if the design does not have front bars, it does not do a lot. 

From the day and long since banned in drag racing.

The One Lap CRX has a roll bar/cage that has a removable center section.  It was originally just a bar, w/o the front half -- and the goal was to allow the center section to be removed for transits.

Has never failed tech, SCCA or otherwise.

Center is a full diagonal from top corner behind the driver to bottom plate by the passenger footwell.  Harness bar is only on the drivers side.  Each joint looks like the pic below.  The bolt holes in the tube ends have small tubing welded inside for clamping strength.

I would not be putting my kids anywhere near a steel bar.  Bodies and seatbelts stretch more than you think in an accident. I learned a lot about this through my son's car accident.

I'd also want many inches and a fixed seat between my cranium and the rollbar.  IMO steel rollbars aren't safe on the street without a helmet, even with dual-density padding.

Yeah I think once you put a roll bar in a car the rear seats are no longer useable.   Unless the rear seat occupants are wearing full harness and helmet and the cage is designed such that the rear seats are accounted for as occupied spaces in the cage design.   

Sure you can have the kids jungle gym their way back there but you have to acknowledge the risk you are creating.  Not just for accident safety but also post accident egress.  Coupes require consideration of quick rear occupant egress that is basically impossible with any type of roll bar structure in place.  

You can reduce the risk but if ability to have the kids enjoy the ride is an important part of the vehicles operation and ownership I think you should strongly consider staying in classes that keep you at SL1. 

As someone who builds rollbars and rollcages, here’s my take. When someone contacts me about fabricating either in their car, one of my first questions is whether the car will be driven on the street other than back and forth to an event. If the answer is “yes” as in it’s a street car first and an occasional track toy, I WILL NOT install a cage in it. If they want just a rollbar, then I ask if anyone WILL EVER be in the back seat, if the answer is “yes”, then I won’t take the job. I don’t need the liability of someone hitting their head on a piece of steel tubing, I couldn’t live with myself if someone were to get hurt by striking themselves on something I built. At the track you have a helmet protecting your head and you’re strapped in. On the street, should someone get involved in an unfortunate accident and strike their head, even with SFI padding, it will likely be life changing. That goes for rear seat passengers as well because the down bars would also be to both sides.

Could you mitigate any potential injury? Yes, you likely could with multiple layers of varying density padding, but all occupants would need to be properly belted in and not with stock seat belts. Their movement would need to be restricted as in 4-5 point harnesses. 

This is just how I run my shop and I have turned work away, but I can live with that. I just completed an NHRA-certified cage in an S197 Mustang. The owner wanted a 7.50 certified cage which requires a full “funny car style halo” around the driver and “X” bars in the door opening. He is building the car for Drag & Drive events which requires 4-5 days of driving from track to track. His last event covered 850 miles. I spoke with him at length and discussed the pitfalls of the 7.50 cert and driving the car on the street. After a bit, he agreed how dangerous it could be and came to the decision to build to the 8.50 rules instead. It’s still a full cage, but the interior cabin is big and with the bar so far away from his head and double padded, I agreed to build it. He signed a liability waiver/release and I did the car. I wasn’t happy in breaking my own rule, but there is no back seat, so no rear passengers and it gets trailered to most events. He is only doing 2 Drag & Drive events per year. 
 

Again, this is just my opinion, but a steel pipe to the head = coloring books for Christmas for the rest of your life(I didn’t make up the saying but I will use it in these type of discussions.

Thanks for all the responses.

Just as a reference, because I'm not sure it was clear what I was asking, but I was thinking of something like this:

Where the roll bar is just behind the driver's seat. It meets all the rules (except for the desirable to span the width of the cockpit sentence).

I feel like I've seen stuff like this before but couldn't find an example. 

Yes this is what I had pictured you doing.

Still not a good idea for rear seat passengers as arms will contact the back stays and legs will contact the down bar in the center of the car as they flail about in a crash.  It is very apparent you don't understand the dynamics of a crash / roll over.

You have 3 choices

No rear seat passengers ( and use a full width roll bar )

Get another car to race and use existing one as a street driver.

Take up golf ( Yes, I'm being abrasive and no I don't care. . . )

I feel like the price of proper safety is a back seat, and that seems like a fair price. A solution like this compromises both the function of the roll bar and the safety of anyone who has to sit next to it. Metal and skulls should not have a direct line of sight path to each other.

Something that hasn't directly been brought up yet.  There are 3 issues with intruding roll bar / cage installs

Steel is hard, tubing is round and street car belts only partly retain the occupants.

Car interiors ( modern day ) are covered with plastic and are some what compressible. The surfaces tend to be flat and will distribute impact loads over a larger area where as impacting a tube results in line contact.

I've thought about this as well. Personally, I would favor welding in some floor plates for a bolt-in rollbar from the likes of Kirk or Autopower. Then bolt the bar in for events and remove it for street driving. Sounds like a PITA but it's not really such a big deal.

Yeah, I thought about going the removable route as well.

Maybe I'll still do that, but at this point I designed a full width roll bar and am having that fabricated. I might make it removable but I'm leaning towards giving up the back seat.  I don't want to have to carry around a rule book and an engineering power point to explain it every time it gets questioned. :) 

I also asked the kids about it and they like riding in the car, but hate riding in the back seat (they are getting a bit big for it!) so I'm not losing anything they like anyways.

That said, it's an oddly written rule. Usually one avoids mixing hard requirements and 'desirables' when making engineering guidelines.

Maybe I missed it, why are you doing level 2 safety? It's pretty rare I see a slick top car with a roll bar in TT or HPDE unless it's for hill climb.

In reply to accordionfolder :

You are correct. I want to do Hill Climbs again.

In reply to BA5 :

Ah, that makes sense then!