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Yup, I saw that site a few years back. Some nice stuff, but it doesn't always relate back to rallying. Different needs I suppose.
Love the Primera by the way. 312 hp from a NA 2.0 litre engine!

Bob
 

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Discussion Starter · #3 ·
I really like this approach but when I try to sketch it up on a Manta after moving the seat, steering wheel and shifter it just doesn't seem to work.

-Travis
 

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Discussion Starter · #4 · (Edited)
Here is a QUICK sketch. You can see that once I move the seat back the entrance opening becomes much wider than I'd like.

Note that I've only drawn in part of one plane here.

The red is the main hoop and the upper yellow is the roof hoop.

-Travis
 

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Try running a vertical from the lower part of the front hoop (where it meets the floor), up to the center of the door opening, where the intersection from the rear diagonal hits the roof bar. This will shrink the door opening and add more pillar strength to the windshield area. I'm working on a wire model, will try to finish it by tomorrow so I can post photos.

Bob
 

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Hmm, I just ran out of wire too.... I'll get some more tomorrow, but I may have to attend a wake (friend's father died), so no guarantees of tomorrow. Coming along nicely however.

Yes, that bar is what I had in mind Travis. Also, I like adding a rocker panel bar (horizontal and welded directly to the rocker). This acts as a framerail, and lends a bit more stiffness than simply a crossed 'X', as well as providing side protection from a sliding impact (i.e., tree stumps and rocks prevalent on rallys).

Bob
 

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Discussion Starter · #8 ·
Here's a shot inside the dash of the WRC Focus that crashed in Germany a few months back. Nothing earth shattering but it shows triangulation of the dash bar and A-pillar support.

-Travis
 

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WOW!
Great drawing!
How about drawing up a cage for my GT while you're at it ,Travis.

Has anyone any experience with an Auto Power or Kirk cage kit? I've been told that it's almost easier starting from scratch.
Opinions?
James--racer wanabe
 

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My understanding is that the Kirk and AutoPower cages are both very similar, and based on older Showroom Stock designs. That is to say, they consume a lot of valuable space since they're configured to clearance all factory interior parts. I bent a new main hoop for Jim MacMahon's Opel GT racecar, as he bought the Kirk cage kit and the main hoop supplied was too close to his helmet. I made the new hoop a 'press fit' into the roof area, which gave Jim more head clearance.

Bob
 

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Discussion Starter · #11 ·
19693SGTEOPEL said:
how much of a cage do you need though?
Seeing as the WRC drivers do get hurt occasionally even with professionally designed and built cages I can't say that I want any less cage than they have. In fact I probably ought to have slightly more cage.

I suppose it depends on how much you value your arms, legs and.... life.

-Travis
 

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Depends on how extensive the cage is. I've made cages with 80 feet of tubing, and I've made cages with 150 feet of tubing. I think my tubing used was 1.2 lbs per foot?

Bob
 

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Discussion Starter · #14 ·
I'm not sure what you were using for tube but 1.5" x .095" 1020 DOM is 1.426 lb per foot.

213 lb for 150 ft. Ouch!

How's that wire frame coming Bob?

-Travis
 

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I was taking a guess, I couldn't actually recall the number. Yes, that was for 1.5" x .095" DOM. My friend's old circle track Ascona used about 130' or so of 1.75" x .095" tubing. The car weighed 1980 without driver, but the car was extensively gutted. I still think the weight of the cage was a secondary concern...the car handled quite well, and was predictable to tune. You could feel 1/2 psi of tire pressure change. So you could say the chassis was 'stiff'. And the car had been in numerous incidents that would have destroyed a car with a lesser cage. Only once did we have to make a new front hoop because it was bent.

Bob

Forgot to add, I didn't get to work on the wire frame becase of the wake I had to attend. Tonight I'd like to get in some more time on it, but I have a bunch of welding on some window bars for a friend's workshop. We'll see.
 

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Discussion Starter · #16 ·
An interesting idea but it's just not going to provide the strength or stiffness of a properly designed cage...

-Travis
 

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As promised, here's the wire model of a rollcage. Don't laugh too hard, it was a rush job!

Bob
 

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Side view of the same....
 

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And the rear view.
 

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Discussion Starter · #20 · (Edited)
Very cool Bob.

I came up with the same thing in the front. Three supports on each side going out to the frame rail above the crossmember mount as well the diagonals betweeen the bottom of the front hoop and the center of the dash bar. You may be able to run these slightly past center of the dash bar which would stiffen the bottom of the front hoop side to side.

I question the value of the second dash bar. It may add a bit more support to the front suspension crossmember but it can't be much.

I like what you've done with the roof. The extra support for the center of the windshield and rear window bar is great.

I wonder how much rigidity you're giving up for easier access in and out of the cage over a more conventional X bar setup...or even the modified X bar setup in my second sketch.

The rear looks pretty conventional. What part of the body are you picking up?

What do you think about a bar between the center of the dash bar and the center of the bar over the rear window? It seems it would add a good deal of rigidity to the front but I can't determine if it would be getting in the way all the time.

Great job with the model BTW.

-Travis
 
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