Cage is finished

[dbsupra90]

looks good man.

i would have preferred swing outs, but thats just me. im not a little guy to be climbing in and out of a jungle gym.

i would also like to have some reward bars to tie in the back corners of the hatch. not really for safety per se, but would help to stiffen up that area.

130lbs isnt bad at all really. cm would have been less, but its also twice as much as ms.

good job overall!

 

[IJ.]

^ LOL @ "Jungle Gym" here for real Dave

Tim: My cage in the 240z saved my life and it was Migged

 

[blackout_89t]

Wow that looks great!
I would love to build a cage one day.

 

[Wiisass]

looks good man.

i would have preferred swing outs, but thats just me. im not a little guy to be climbing in and out of a jungle gym.

i would also like to have some reward bars to tie in the back corners of the hatch. not really for safety per se, but would help to stiffen up that area.

130lbs isnt bad at all really. cm would have been less, but its also twice as much as ms.

good job overall!

Swingouts are nice for cars that will see a lot of street time. I don't like them as much for race cars because they do compromise some of the strength of the door bar. And with x-bars, or NASCAR bars, required for pretty much everything, swingouts are a little harder to pull off. But I was just talking to someone about trying to figure out a way to make x-bar swingouts that would still be legal for competition.

I don't think anything in the back will do anything. The only loads that are coming in are from the shock/spring and the subframe. The subframe mounts are only about 4-6 inches behind where I put the bar between the two shock towers. So there are isn't much going on back there. I'm sure in a car without a cage, there is some flex back there due to the rest of the chassis twisting, but with the cage, it should reduce all of that.

And with the weight, if you look at most rulebooks now, you have to use the same size material whether it's mildsteel or chromoly. NASA and SCCA rulebooks now have both listed as the same thing. It seems that Chromoly is on it's way out for roll cage material. It's not really worth it anymore. You'll end up paying double to have a cage that might be a little stronger. But you also have the inherent problems with putting a chromoly cage in a car. Chromoly gets brittle around the weld area and without a heat treatment, this leaves a weak area right next to the weld. So a localized heat treat could solve this, but I'm sure that would add more overall cost to the roll cage. I had also heard that NASCAR is now only allowing mild steel for the construction of their chassis, I'm not sure if it's just for the Car of Tomorrow or if it has been that way for a while now.

Tim

 

[dbsupra90]

tim-

i understand your points, and taken. i was just saying some options and if it were for me the only things i might change.

the nhra rule book i have says ms needs to be 1 3/4" OD x 0.118 wall. cm needs to be 1 3/4 OD x 0.083 wall. this is for >10.00. <9.99 needs to step up to 1 5/8 OD.

i know this isnt for drag, just using this as reference since this is the only rule book i have. its always best to look at the rules of the governing body to make sure it is in spec. nothing worse than building a cage just to find out it isnt legal.

you may be right about the rear hatch section flex. just any open area like that i would like to be stiffened. you obviously have done your research, and i think your construction and fitment is very nice. i think it will work well, and hopefully never have to find out.

 

[Wiisass]

I keep forgetting about NHRA. For the stuff I do and the people I usually deal with it's NASA, SCCA, US Drift, FormulaD or D1 that they're worried about. But I think NHRA is the only rulebook that still gives you the benefit of weight savings if you use chromoly.

I'm a rule book nerd though. I spent a day going through the roll cage section of all the possible classes that most of my customers or I would be running cars in. Outlined all the major points in my logbook and then noted differences. So I like to think I'm pretty prepared and knowledgable. Until someone throws the NHRA curveball at me, I'm usually spot on.

Tim

 

[Supracentral]

The heavier the car, the more rigid the cage needs to be.

I'm not a fan of mild steel for a roll cage, especially in a car this heavy.

But the work does look top notch.

I'd suggest gussets in all the corners. Especially in the "halo". It will make the cage a lot stronger and a lot more rigid.

The MKIII is a VERY heavy car for the speeds it can attain.

 

[Wiisass]

I did use thicker tubing for this thing because of the weight. But in race weight, it's not too much heavier than a lot of things flying around out there on the track.

I will be gusseting the cage I am putting in my brother's supra. But I did not do it for this cage. It is an option I have available and he did not want them at this time.

 

[Clied]

nice... i like it

its cool....

 

[Tun_x]

Looks good .. Nhra might give you shit about the height of the door bars unless the guy driving is a midget .

 

[Termik]

Really good man! I planing this also.

 

[MK3Brent]

Looks good .. Nhra might give you shit about the height of the door bars unless the guy driving is a midget .

That's what I was thinking. hheheh,

 

[Wiisass]

Well it's not going to see any NHRA stuff, so I didn't read their rules or pay attention to it. But it is legal for every sanctioning body that it will be running with.

Tim

 

[MDCmotorsports]

MDC, any reason why you're not a fan of MIG welds, just out of curiousity. Is it just an appearance thing? I mean a proper MIG weld is just as strong as a TIG weld, the only bad part about mig welding is less control over the heat affected zone.

Tim,
You've just answered your own question.

Mild steel VS Mild steel?

MIG = TIG if both propperly performed.

4130 Chrome molly VS 4130 Chrome Molly

TIG > MIG. When Mig welding 4130, you'll actually get the 4130 too hot and the material will be fatigued (sp?) and brittle from the get go.

:-(

Failed 4130 cages FTL. :cry:

 

[Wiisass]

Oh ok, well then I agree. I would never MIG a 4130 cage, it's just asking for trouble. But also not heat treating a 4130 cage no matter what welding method is used is asking for trouble as well. Like you said with MIG you will heat the material too much and the area around the weld will become brittle. But this will also happen with TIG, but with TIG, the heat affected zone is much smaller. But heat treating is still necessary to make sure that the joints are strong. Otherwise you aren't gaining anything with chromoly. The joints will be weaker than if it were mild steel.

Tim