Geo

2715 lbs with driver. Large driver.

Geo

Thanks!

Hehe. Especially since I'm certainly not built like a gymnist.

Seriously, this is a concern, mainly that I need to be able to get the hell out in a fire with a HANS.

Luke

O man, are you ever going to hate those door bars. hehe

Geo

Certainly not in a crash.

They will also yield the stiffest chassis structure.

Skip

I'll try to post some pics of my cage tonight - a little different in a few areas, especially the doors. But, we agree to disagree on that one, right? I have the pseudo-NASTICAR bars (non-parallel, not attached to sill, do not intrude door). I like the entry exit of mine - perfect considering the amount of high-side protection I got. Also, my cage goes a bit further back and has a removable rear crossbar (to carry groceries!... or, tires for non-trailered events.) Both driver and passenger got the NASTICAR treament, but I don't have that logitudinal bar low on the roll bar as you do - I might add that - looks smaHt!

One thing I do have, and requested, was a diagonal on the roof from passenger rear to driver front - gives me a little more if the car get slammed down on that corner from result of an end-over.

As I said, pics tonight.

Geo

Sure!

Thinking some more about it, perhaps if I were to do it again, I might tie the front of the cage to the firewall (still may do that, but I don't want my feet getting tangled up in it) and have the bar that is low rear to high front tie in where the bars to the firewall tie. I'd then add another bar from where the dash bar comes in to the door bars. That would make entry/exit a little better, but probably not stiffen the chassis quite as much.

Really looking forward to the pix Skip. I considered the overhead bar and want to put one in, but I'm too concerned about it being way too close to my head. If I can finalize the seat position with a little more head room, I will probably add one. That should really help with chassis stiffening as well.

RedRooster

Thanks for posting these Geo. I will be doing the same to my car over the winter. I hope you don't mind if I use some of your ideas. Gotta have the bar through the dash or over. My last car had the front cross bar under, way to close to the knees.

Some questions:
Why two low cross bars at the back connecting the low chassis weld point, would one not be enough?
Why three diagonal cross bars, the two intersecting and the rear most one?
Same for the side drive and passenger side protection, there are three bars there, do the diagonals increase the rigidity?
You have six "contact points" with the chassis, does adding another "contact" to the firewall from the forward down tubes put you over the limit for scca cage specs? (I though six was the limit).

tia,
Shaun.

jabbadeznuts

WOW!!

What are the specs on the cage? Tube type/thickness, etc.?

Geo

Of course not! Use whatever you think works for you.

I felt the same way. I have to make a template of the top of the dash to determine where exactly to run the dash bar. I'll be making both this week.

I'm not sure exactly which you are talking about.

The low one on the main hoop is there to prevent main hoop collapse (inward) in a side collision. The one just above the shock mounting points is to stiffen the chassis at the suspension mounting points.

Are these the two you are talking about?

BTW, these are the only two bars I would consider "optional" on this cage. Given that they only weigh between 5 and 10 pounds (closer to 5), I didn't even consider eliminating them.

Are you talking about the back or the doors?

In the back I have two cross bars. One is a required main hoop brace (from driver's head to passenger floor). The other is from passenger head to driver's shock mount. This one is to stiffen both the cage and the chassis. I had planned to X this, but decided against for two reasons. First, there are already so many tubes connected at the same point at driver's head that fitting yet another bar there was going to be a total bitch. Second, the main hoop braces (back to the shock mounts) are close enough to the main hoop that one bar will be enough.

Originally I planned only on the X brace. The X brace is the strongest, most rigid design. Many feel the NASCAR bars are safer, but basically all they do is give you working room. Their strength comes from mass. But, since they are bent tubes, the failure mode would be to bend until they they are a reflection of themselves inside the cockpit. For the X bars to fail, they would have to be literally ripped from the cage. For them to bend, the main cage would have to fail and/or the X bars to be stretched along their length - pretty tough to do.

The lower straight bar was added to the design after realizing there was more space below the X than I was comfortable with. It's there to prevent intrusion under the X.

I am allowed 8 points of contact - the 4 main points, the main hoop braces, and bars tied to the firewall. No other points allowed. We are allowed to attach as many bars as we like to the mounting plates (100" ^2 max). If I had a plasma cutter or metal cutting band saw, I would have cut the lower door bars to make a long contact patch on the mounting plates. This would have added considerable strength and rigidity, but in the end it didn't work out quite as I would have liked. I would also have liked the bottom of the X to connect in the corners of the main hoop and front downtubes where they connect with the lower door bar. The angles are so shallow that without a plasma cutter I could not cut the proper notch in those tubes.

As I said, if I were to do it again, I might try to plan on the connections to the firewall and tie the upper front X to the bar going to the firewall. I would not tie it to the middle of a bar with no other load path. I'm not 100% sure I'd do that because what I have now gives maximum support to both the front downtubes and to the dash bar. Since the dash bar will have bends on each end, I consider this support very important. Something to think about though. Also remember that there is a nasty mess in the driver's footwell to route those bars through.

Geo

1020 DOM mild steel, 1.500 x 0.120

My other option was 1.750 x 0.095. The 1.750 is stronger and lighter, but we already had a die for the 1.500 and the 1.500 can be bent around a tighter radius, making it easier to keep the cage tight to the coachwork.

Manning

Can we see some action shots of you getting in and out with your HANS and helmet?

Geo

It wouldn't be pretty.

Think of Pooh stuck in the honey jar.

Seriously though, it's no worse than high NASCAR bars. Don't forget I'll be using a NISsport quick release steering wheel hub. That will make things a little better.

Skip

Skip

Here it be:

from rear (shows removable cross-brace):


behind driver's seat:


behind passenger's seat:


driver's side from inside:


driver's side from outside:


passenger's side from inside:


passenger's side from outside:

Skip

driver's rear roof:


driver's front roof:


passenger's roof:


passenger's dash through and front base plate:


passenger's dash through and front base plate:


That's about it - these pictures and a few more are published here: http://www.tech-session.com/images/cage/