Roll cages - all alfa's

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kevin
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Roll cages - all alfa's

Post by kevin » Fri Dec 18, 2009 10:57 am

An interesting roll cage design on a 105 series, especially on A pillar .pics not good quality as from phone.
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MD
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Re: Roll cages - all alfa's

Post by MD » Fri Dec 18, 2009 2:48 pm

Kevin

Had a quick look at this design and posted some comments perhaps for the next one?

err.. sorry about the typo errors. :oops:

Whis = why
Rool = roll
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Re: Roll cages - all alfa's

Post by GTV27 » Fri Dec 18, 2009 6:44 pm

Yeah, I think interesting is a euphamism for wrong - creative sure, but not sound fundamental engineering. Its not hard - straight lines and triangulation. That would not pass muster here.

Shame to see so much effort and material being expended on so little actual protection.
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Re: Roll cages - all alfa's

Post by ALFA GTV6 GP » Fri Dec 18, 2009 10:12 pm

MD wrote:Kevin

Had a quick look at this design and posted some comments perhaps for the next one?

err.. sorry about the typo errors. :oops:

Whis = why
Rool = roll


MD

Nice points!

I thought you were taking the "whis out of the Sert Efrican accent in your description of the suspect "rool" cage. :D

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Re: Roll cages - all alfa's

Post by MD » Fri Dec 18, 2009 11:06 pm

Yeah John. "twas a bit rushed cause I had something else I wanted to do and I got caught up in the engineering and overlooked the friggin typos. :oops:

I figure lots of guys cruise in and out of this forum. Some are registered and some are not but I just felt that I wouldn't want people to just accept that cage set up and make one the same without seeing some discussion on it first. Hence my tcw.
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Re: Roll cages - all alfa's

Post by Mats » Sun Dec 20, 2009 4:16 am

There are a couple of points that are somewhat contradicted in the FIA rulebook though. "Helmet crucher" have max measurements and the upper side bar cannot sit higher then halfway up in the door (the actual projected hole). So they can seldom meet at the main hoop. Also, the rules force a second door bar, an X or similar. I just put a second bar in myself, as low as possible to make egress easier. Some rules stipulate maximum mounting points so the cross bar might not be allowed to weld or bolt to the tunnel.
The points where all the bars meet at the top of the main hoop look seriously stupid though as do the "A-pillar".

There is hopefully something going on here that we don't know about... :)
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Re: Roll cages - all alfa's

Post by PietereQ » Sun Dec 20, 2009 9:27 am

Yesterday I have finally appointed gtv6 for roll cage install in Febuary. The company did a roll cage for a hillclimb 75 before, so making a cage for mine shouldnt be a biggy. The cage on my gtv6 will be similar to the one they did before, exept for mine is gonna have tubes going to the shock towers:

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Re: Roll cages - all alfa's

Post by kevin » Sun Dec 20, 2009 10:27 am

MD,Mats thats exactly the comments I was looking for as there are many guys here in SA buliding cages with no clue as we are not really governed by anyone unless you are in our top level touring car racing where all the cages are made with the car in Europe.
Question about dash for side crush, is why do you need it if the bulk head is a strong enough section in itself just like the sill in the bottom caption. If the roll cage is connected on A pillar at top of bulk head then it will help transfer load.
I think this thread could help alot of new guys and existing to recheck there cages, I know mine is really bad hence starting again.
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Re: Roll cages - all alfa's

Post by MD » Sun Dec 20, 2009 2:50 pm

PietereQ

I think your proposed cage is much more orthodox and to the point. As with any cage it's a matter of small choices here and there which way you want to go so it becomes a personal outcome within reason. However on balance, that cage should do the job well enough without any changes.

Kevin,

SA seems to have plenty of good innovation happening with mechanical stuff and it doesn't quite ad up that they do not make good roll cages. Only based on what I have seen on some forums, the Dutch are great innovators and fabricators. The German stuff is more often than not way too tough. Then I suppose we get into regulations as Mats says .Like you guys ,our rules are very rubbery. Most of the cages that are prescribed here are too minimalist for my liking but if you deviate from the rule book, technically if you want it approved , you have to get a private engineer to certify it. I know calculations help but how you put your name to such a thing without testing the design to destruction beats me but that's bureaucracy for ya.

As for the dash bar, it works best if you triangulate through the firewall to the inside guard rails above the dampers but this can cause other engine fitting probelms. Personally, I like to also triangulate acrosss the firewall between A pillars for added leg protection if the engine gets pushed into the cabin but it's all weight so it's up to you.


The following pics are not of Alfas but the principles are the same.
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Re: Roll cages - all alfa's

Post by Mats » Mon Dec 21, 2009 3:14 am

The whole point of the cage is to keep the body as large as possible during an incident. A cross bar under the dash ties the two sides of the cage together in a section where the oly thing keeping it apart is the bar across the top of the windscreen. Very weak section indeed (looking at the roll cage as a separate unit), yes the firewall and windshield frame helps a lot but in a severe side crash the bar will be very welcome indeed. It also has some secondary benefits that you might not realize at first; You cab use it for mounting the steering and pedals and thus keeping those under good control in a crash (i.e. not coming further into the cabin). As for the solid feeling in the pedals, have a look at the firewall when someone is pushing the pedals and you will see why you also want the pedals to be solidly mounted in the cage rahter then the flimsy sheet metal...

The FIA technical rulebook is a great source for cage design, it's based on experience with real race crashes and therefore produce safe cages that are not too heavy. They also focus on stuff like getting out of the car quickly which can be a problem if you make the car as stiff as possible engineering wise (makes a spider-web in the door hole...). The rule book also have loads of sketches of both cages and specific parts like how pipes should meet and how to design removable bars, gussets and body tie-in points.
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Re: Roll cages - all alfa's

Post by kevin » Sat Apr 10, 2010 10:30 am

Some more cage design . Not 100 % correct according to FIA but alot better than my bolt in cage.
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Re: Roll cages - all alfa's

Post by MD » Sat Apr 10, 2010 2:31 pm

Kevin,

Good but not all is rosy. See comments.
In addition to the comments in the photo.The hipline of the main hoop has a bend in it without any horizontal control. If the car lands on its roof, I suggest the hoop will continue to bend outwards as there is "nothing"to prevent it from moving out the "B" pillar.

The two hipline bends need to be joined by a horizontal bar at least.

Finally, there is no apprent gusseting to the body work anywhere, A/B pillars,dashboard, etc. Doing that reduces body flex particularly if it is seam welded as well.
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Re: Roll cages - all alfa's

Post by kevin » Sun Apr 11, 2010 12:24 pm

Good comments. Im going to copy this cage with additional extras as you mentioned. Sketch them in. Im gonna post pics of the engine for this car under another thread. What do you think of fuel tank . Rules state it must be compartmentlised.
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Re: Roll cages - all alfa's

Post by LacUS » Thu Mar 17, 2011 1:07 pm

So guys, this is my rollcage.
The cage is made by FIA standards it can be homologated to race the car in any FIA race.

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Re: Roll cages - all alfa's

Post by la_strega_nera » Thu Mar 17, 2011 2:45 pm

Very nice, I'd add one more tube per side though - from the main hoop where the upper door bar hits, to the rear leg base (gives a load transfer path from the door bars to somehwere usefull).
I'd also add a bar accross the main hoop where that bend is half way up - stops the legs bowing out if you park ity on it's roof, and also helps stop it folding in if you get t-boned...
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