Roll cages - all alfa's

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Mats
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Re: Roll cages - all alfa's

Post by Mats » Thu Mar 24, 2011 4:41 am

A whole lot of tubing... :)

Didn't think you could get away with not having a tube across between the ends of the main hoop. This one should also be welded to the tunnel. A "dashboard tube" across the bottom of the windshield is also a good thing, especially if you tie in the steering column bracket.
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Re: Roll cages - all alfa's

Post by MD » Thu Mar 24, 2011 2:08 pm

I agree matts.

I would just like to ad this comment. For the life of me I cannot understand why it is a very common practice to fix the rear bars to a piece of flexible tin like the inner guards !!

The rear members should alway be fixed either to a reinforced damper tower or the rear spring base as I have show time and time again but the only guy listening is Kevin.
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Re: Roll cages - all alfa's

Post by LacUS » Fri Mar 25, 2011 10:33 am

Mats wrote:A whole lot of tubing... :)

Didn't think you could get away with not having a tube across between the ends of the main hoop. This one should also be welded to the tunnel. A "dashboard tube" across the bottom of the windshield is also a good thing, especially if you tie in the steering column bracket.

It's ok, but. The cage is made after FIA WRC standard.You can find the drawing for it and my cage is made like that.
The rear tubing stands on a reinforced stand also FIA standard.Thats why this cage is homologated. The only thing I agree, the under dash tube, but it would requier a new homologation proceedure, and thats an expensive thing I can say. :oops: Anyway thanks guys for your comments.
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Re: Roll cages - all alfa's

Post by Mats » Fri Mar 25, 2011 3:33 pm

MD wrote:I agree matts.

I would just like to ad this comment. For the life of me I cannot understand why it is a very common practice to fix the rear bars to a piece of flexible tin like the inner guards !!

The rear members should alway be fixed either to a reinforced damper tower or the rear spring base as I have show time and time again but the only guy listening is Kevin.
Because the cage has really only ONE function, to stay as large as possible inside the bodyshell in the event of a crash. That's the FIA priority.

Chassis stiffness is quite a long way down on the list.
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Re: Roll cages - all alfa's

Post by MD » Tue Mar 29, 2011 1:21 pm

Because the cage has really only ONE function, to stay as large as possible inside the bodyshell in the event of a crash. That's the FIA priority.
I got no problem with that at all. My take on it though is to do just that AND at the same time make the cage talk to the chassis. Why waste the opportunity so it does both?
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Re: Roll cages - all alfa's

Post by LacUS » Fri May 27, 2011 11:14 am

So I've got the paint job done. I like it very much. What do you think guys?


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Re: Roll cages - all alfa's

Post by fedezyl » Fri May 27, 2011 11:22 am

Not bad at all really! :D
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Re: Roll cages - all alfa's

Post by kevin » Fri May 27, 2011 1:31 pm

Looking good , now the work starts
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Re: Roll cages - all alfa's

Post by LacUS » Sat May 28, 2011 11:49 am

kevin wrote:Looking good , now the work starts

Yes, a whole lot of work :)
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Re: Roll cages - all alfa's

Post by kevin » Fri Aug 23, 2013 12:53 pm

Took some pics at Glenwood today at Zwartkops of a new GTV build . The roll cage look really good with the front engine bay bracing similar to that of oz touring car from a few years ago .
Great ideas .
MD thought you might like the front bracing .
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Re: Roll cages - all alfa's

Post by Mats » Fri Aug 23, 2013 1:16 pm

The main hoop looks well forward, i that the reason for that strangely positioned cross-tube/belt-tube?
I don't like tubes welded to the middle of tubes, it ruins the whole point of a space frame; to only connect tubes where other tubes connect, to create triangles. If you put a joint in the middle of a tube like that you make the cage weaker.
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Re: Roll cages - all alfa's

Post by kevin » Fri Aug 23, 2013 1:30 pm

Yeah the cross tube is for belts as they have a rule here of max 15 degrees for belt angle .
But technically speaking it should in that case strengthen that member because it reduces the L/R ratio because its at right angles . Just a thought. If the triangle don't intersect on the same plane then that's not great for load transfer like on the door area to the rear section on the b - pillar .
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Re: Roll cages - all alfa's

Post by Mats » Fri Aug 23, 2013 1:51 pm

Are you talking Euler?

If you get hit in the side it will move that crossbar over, bend both the rearward tubes and those will in turn pull/bend the main hoop.
Now, if you had followed FIA procedure the rearward bars would have been tied into the same point as the top door bar, the cross bar goes as far down as possible (tying into an existing joint) and the belt bar goes in the rear X where it can be in the perfect height and does the least damage...

If you get hit from behind or have a big off the rear bars will have no support other then the bending stiffnes of the main hoop (nothing really), had it been tied into the joint where the top door bar meets the main hoop it would load the door bar in a good load case and the main hoop would just be there to stabilize the load transfer (Euler again).

Now is the time to move those bars, that cage can (and should) be improved.
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Re: Roll cages - all alfa's

Post by kevin » Fri Aug 23, 2013 2:20 pm

To true . Was just thinking from one angle . If you roll I see your point totally .
My car I put the set belt brace on the back hoop . What you think of this ?
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Re: Roll cages - all alfa's

Post by Mats » Sat Aug 24, 2013 12:22 am

From a load-into-cage point of view it's fine, your weight is not going to generate nearly enough load to do any real damage to the cage and the tubes are very short and sturdy.
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
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-Strandberg.photography-

GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
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