Spifz

Here are some pics of my cage install. Designed for strengthening the car, safety, and pass ing EMRA / FIA / SCCA tech (NHRA only good as a 5-point; I believe the roof bars would have to be out at the top corners of the main/front hoops to be certifiable, but since I'm not slicking it, I won't pass 10.00 and probably can't quite hit 135mph, so I don't need more than a 5.) The main hoop and T-top bars are 1.750 x .134, the front hoop is 1.750 x .120. I wanted it to be out of the way as much as possible, and not block much 'stoplight visibility' out the windshield (tall guys will know what I'm talking about.)

xpndbl3

iTrader: (5)

why did you run the halo bars down the middle and not on the outside edge of the t-tops near the roof edges for more strength? I've never seen them run down the middle instead of the outside edges.

nelapse

iTrader: (17)

Probably so he could still have 100% T-Top functionality.

Spifz

I would argue that they are stronger (for torsional rigidity purposes) where they are in my design, but the big reason was that I think it looks dumb to have the T-tops out and have bars in the way.

Sonix

iTrader: (1)

Can you get a shot of that third picture with a bit better backlighting? Looks like you welded it to the roof? I just want a better view there.

Is that allowed? To run your bars in the center there?

You've really got those squashed up there, think you can still get your headliner back in? And other panels?

5678TA

i highly doubt a headliner is on the agenda.. or any interior panels for that matter.. btw, that is a good idea.. i have a 10pt in my car and the bars that run along side the edge of the t-top is a pain.. if i was any taller, i would be smacking my head like its the cool thing to do..

good job..

AlkyIROC

I don't see a door bar. Without at least a driver side door bar, that roll bar/cage design is only good to 11.49. What about any rear bars? The 5(6) points of a legal roll bar are 2 for the main hoop, 2 rear bars and the one or two door bars.

As mentioned above, without a full halo bar (and door bars), that cage design won't allow you to go past 10.00. When you build a full cage to NHRA/IHRA specs, the main tubes only need to be 1-5/8". I don't know the requirements of those other sanctioning bodies. That's a lot of extra weight using 1-3/4" tubes.

My car has a full cage a t-tops. I can still remove my t-tops without any problems but they only come out when I'm working on the car and need a little more room.

Comp788

Most sanctioning bodies other then NHRA for some reason like 1 3/4" DOM tubing. Never understood why but they do. I remember going to El Mirage and being shocked how many of the cars were built using the larger tubing.

but I have to call BS on "I would argue that they are stronger where they are in my design"

I will agree that it "I think it looks dumb to have the T-tops out and have bars in the way." as well but when you start needing a cage in a car with a sunroof or T-top sacrifices have to be made.

Especially if you need it for protection!

Spifz

Thanks for the 'good job' 5678TA and I'll try to get a better picture up for you Sonix.

I have rear bars installed, but you can only barely see one in the one pic. I haven't finished the work yet, so no door bars yet.
I will be able to put the back seat area plastic trim back in, and the sail panel trim. I will make a panel that covers the under side of the bars up through the middle, and covers for where the front hoop goes along the roof and a pillar.

With the center tubes welded to the factory T-top structure, the result acts more like a beam. Instead of the body twisting action putting 'bending' stress on the joints where the roof bars connect to the front and rear hoop, it is trying to compress and stretch the bars in the center. I didn't bother to model it in Solidworks, but it seems like you would have to build a big gusset to achieve the same effect on outside mounted bars as I achieved in the middle.

ZONES89RS

iTrader: (2)

Hmmm.....looks awsome, i love to see different work like that, but i myself have a T top 95 Z daily driver, my 89 RS is a hard top so structural integrity is less of an issue, its the toy so i guess thats just how i roll.

Stephen

iTrader: (12)

Great design! If I had t-tops, I'd go that way too. At 6'5", my head wouldn't appreciate a standard cage design, but the doctor's wallets would!

CG_1985_Z28

cool design, looks great!

Fromaster

does anyone know the measurement of the top of the main hoop to the bottom of the bars? im gona start installing my cage after waiting for 3, long, aggravating months for the snow to melt....

Spifz

From Competition Engineering for their main hoop:
Mine is cut to about 36.5" from bottom of the tube, where it hits the mounting plate, to the very top of the hoop, but mine is recessed into the factory metal. If you want to put a headliner back in, you will probably want to make it shorter, but that is easy enough to do

Ucantcme57

Did you tack that to the car at the top of the windshield? I had a-pillar and roof bars welded below the t-top bottom bar so that I could pull the handle out, as well as I want to tape off the top bar and sand it down to bare metal the length of the t-top and polish to a shiny luster and clear the heck out of it, so everyone will see when the tops are off, but they are so tight that it is very hard to see with the tops on, they just look like a thick bottom t-top..

Spifz

It is tacked to the top of the windshield ledge, and welded to the reinforcing plates along the A-pillar (the heavy stamped out pieces.)

Fromaster

ok, good im nbot going crazy, looks like im gona have to slice mmine to about 34" because i want to keep teh headliner, thanks for the help

GMan 3MT

iTrader: (4)

Looks gooe.

Coming from a road racing wannabe, here's my thoughts...

.134 wall? Max I've seen required for a camaro in SCCA/NASA is 1.750x.120
Welding to the body... Not allowed in some classes (along w/ seam welding)
I like the dual bars running in the center. On my gf's car, I'm planning on something like that in addition to the ones on the outside edges, and hopefully still retain the use of the t-tops. If you take an impact (upside down) on the top the the a-pillar, the hoop around the windshield isn't going to hold up very well.
Where did you run the horizontal cross bar in the front (hard to see anything in the pics)
Are your rear down bars straight or have a bend. If you're not going to be putting the rear seats back in, make em straight. (must be straight in SCCA/NASA)
Oh yeah, and if you havn't already, get some of that high density padding for yer heed!

Keep up the good work.

Here's my shameless plug for my tight cage...
http://www.fototime.com/inv/BF3FEEA31C743E2
CMC rules, no welding to the body... it doesn't say it can't touch the body

Spifz

Nice work on your cage GMan 3MT! As far as windshield hoop, I think it will be in trouble either way if you hit hard upside down on the corner. For our cars, with the windshield slope being what it is, FIA requires down bars from the windshield/a-pillar corner to keep it from smashing in on a roof impact. I bet a diagonal bar across the roof area would also help a lot, but some of that is just my guessing. Anybody have ideas about the 'no welding to the body' rules? There must be a good one, because I'm pretty convinced that I am picking up strength doing it.

GMan 3MT

iTrader: (4)

Thanks. That bar from the windshield/a-pillar corner down makes it an even bigger PITA to get in and out of. I left that one out of my original design, may put it in if we ever do a rallye in it (think Targa NewFoundland )
It's kinda stupid IMHO. Their reasoning is that the cage is built as a safty structure, not to reinforce the chassis. Yes, you are definetly picking up some torsional rigidity and overall strength by tying the body and cage together.

From the NASA CCR... "Chassis stiffening is a side benifit of a good roll cage system, but it is not the intent of these rules. Parts of the cage deemed by the Chief Scrutineer, to serve no practical purpose other than chassis stiffening may be considered in violation of the intent of these rules (Note: Some class rules allow for chassis stiffening)" CMC doesn't, I think AI does.

83 Crossfire TA

iTrader: (2)

Unless you’re planning on racing in a class that does not allow it, don’t worry about it, they’re just trying to prevent someone from getting an advantage from a stiffer chassis.

randy4762

Just a note about passing SCCA tech, the cage can only be attached at the
6 or 8 attachment points to the car. The way I get around this rule is to actually "jack" the tubes in tight with a porta power to the body all along the a-pillar. The cage will not pass tech if it even has a tac anywhere else!

SCCA specs DOM tubing because it is far superior to ERW used in other sanctioning bodies. 1.5" tubing is used below a certain weight, and 1.75 is used on the heavier cars.

It looks like your cage will be a strong one. Keep posting the pics as it comes along. I can't say enough about triangulation. That is where the strength of the cage comes from. I have some photos of SCCA style cages
I have done for Grand-Am cup cars if you want to see them. Grand Am cages are allowed all the attachment you wantto the body.

Randy

FSTFBDY

iTrader: (33)

post em up Id like to see em also.

Or e-mail em to me at chris @ cecoatings dot com

randy4762

Okay here's the photos. But before you curse me out, I know they are not
photos of an f-body cage. Just so you know I am a Chevy guy all the way.
Unfortunately that is not what always comes in the shop. Who could refuse the chance to do 3 cars like this for national recognition and a pro racing team to boot?
I would do the camaro cage similar to this because both cars have the laid back a-pillar and are short in the back with long door openings.

randy4762

here are the rest. In the last photo notice how rigid the chassis is by lifting the rear wheel. So the cage can serve two purposes, safety and rigidity if done properly.

FSTFBDY

iTrader: (33)

Looks Good !