how we build cages the right way.

[roco]

made this little write up for a irish site here. thaught you guys might like it and add to it, this is only a rough write up and there are alot of other important points in cage building, but this is some of the things people should look for when buying or geting a cage built. too many shody cages being built, this is not an advertisement just information. and the cage built below is for local competition and built to those regs.

copyd accross...........

This thread is basicaly to show that our cages are built right. using the right tools and the right method, going off homolagated FIA design.

first of all, all roll cages must be mandrell bent. our bender and tools are the industry standard in roll cage and space frame fabrication and used the world over by some of the best race teams and custom car builders. this makes sure that the bend is uniform, no ripples or kinks, and no flatening on the outside of the bend.

cages must comply to certain design regs depending on the motorsport.
and must be of a homolagated design, or go through an independant engineers assesment.

joints in the cage must be profiled joints, this means the joint must be cut or notched to fit arround the adjoining tube. no but joints of any kind are used.

we take great pride in our fabrication and our cages, and all roll cages are welded properly and welded all the way around the profiled joints. not just welded on the underside, or half moon welds.

floor plates are regulation 3mm plate, theyre made to fit each car, and welded to diffrent planes on the car, ie, floor, sill, pillar etc.

Because we bend and fab our cages in house, we make each cage to suit each indevidual car, no mass produced bad fitting cages. we build some of the tightest fitting cages bar none, our cages follow the lines and main frame of the car as close as possible, and in most cases the cage can be welded to the chassis in muliple places giving maximum driver space minimum intrusion into the cockpit and driver view. also stiffening the chassis even further.

all in all thats how all top motorsport cages are built or should be built.
like said before i take pride in my work and thats what makes the diffrence in
a good product or service or a great product or service.


below are some pictures of a cage i built this week and you will notice some of the points i made above regarding the building and fabrication. the pics of the cage are taken in raw metal so no defects in either metal or welding are hidden with paint. all bends and plates can be clearly seen.

http://i38.tinypic.com/2l9p2df.jpg

http://i33.tinypic.com/118lqvq.jpg

http://i37.tinypic.com/29izjq.jpg

http://i33.tinypic.com/fw4z6s.jpg

http://i37.tinypic.com/9r674l.jpg

http://i34.tinypic.com/aau3xg.jpg

http://i38.tinypic.com/2r7szk2.jpg

http://i34.tinypic.com/2a5gqxe.jpg

http://i36.tinypic.com/21k038m.jpg

http://i35.tinypic.com/dvo5cp.jpg

http://i37.tinypic.com/m9m7o4.jpg

http://i33.tinypic.com/34o68gh.jpg

http://i35.tinypic.com/2uyqex0.jpg

http://i33.tinypic.com/xen5zt.jpg

http://i37.tinypic.com/335borb.jpg

[drift213]

grat job wish you was around los angeles area ill would of have gotten one for my silvia

[anotherblusi]

How were you able to complete the welds on the corners of the main hoop and roof cross?

[roco]

grat job wish you was around los angeles area ill would of have gotten one for my silvia

there are some amazing cage builders in LA. depends what area your in. and some of them far better than me.

@anotherbluesi; theres three diffrent ways to do this properly,

1: chop the roof off. not what alot of people want to do but it is the best way.
and usualy used for serious race cars.

2: cut small holes in the floor and drop the cage. down, this doesnt weaken the structure if done properly as most people think as you are replacing it with 6x6 3mm floor plates.

3: build steel floor boxes instead of plates, and have the top plate removable
so you can drop the cage into the box which gives you 3-4inces to play with.

either one will do but if done wrong can be worse than not welding the cage all around. the floor plates must be as strong as the cage you build.

[S14_Kouki]

I spy something wrong with your cage. It is very BAD to weld all that into the bend of the main hoop iv told ppl this before. When you bend the pipe it stretches the metal so it is alot weaker in the bend and should not be welded on.

[TIG]

Nice to see a thread on properly built cages. I have seen many cages so poorly done that I question how they passed tech. Great work.

[TIG]

I spy something wrong with your cage. It is very BAD to weld all that into the bend of the main hoop iv told ppl this before. When you bend the pipe it stretches the metal so it is alot weaker in the bend and should not be welded on.

I usually agree with most of what you say, but there's a little more to it than that. While the main hoop may be slightly weaker around the bend because the material is stretched, what he is done is actually very strong. He has created a very rigid node for load transfer. If there is force exerted upon the top roof near the B-Pillar those compressive forces will be transferred down the diagonal, down the rear down tube, across the main hoop, and into the X-Bar in the roof.

The front down tubes are usually as far out to the edge as possible to accommodate driver space. If the front down tube is further out, and the rear down tubes are further inward the node will be offset causing there to be a place for shear.

In this case it is more than material strength but the position of nodes and load transfer.

[roco]

I spy something wrong with your cage. It is very BAD to weld all that into the bend of the main hoop iv told ppl this before. When you bend the pipe it stretches the metal so it is alot weaker in the bend and should not be welded on.


ive studied pictures of roll cages from the top race car builders and fabricators in the world, from race cars, to off road baja trucks, to space frame buggys and they all do it the same way. ive studdied all regulations and have never seen this. it does make some sense i supose. but like i said ive never herd it before?
its all about load transfer.

heres a pic of a ae86 from meridian motorsport, one of the top race car builders in australia.
http://www.mmsport.com.au/_images/bradsprintercage18.jpg

and a s13 from the same company,
http://www.mmsport.com.au/_images/p1010434.jpg

a roll cage from impact engineering in california. also a top company
http://www.impact-engineering.com/project/honda/image/civic_004.jpg

this is there 350 grand am touring car.
http://www.impact-engineering.com/project/nissan/image/nissan_005.jpg

this is a s13 cage from nickson motorsport in the uk, one of the most respected
fabricators around, building cars for le-mans, and porche, ferarri clubs etc.
http://i31.photobucket.com/albums/c363/fordescortmexico/DSCN17431853.jpg

thats just a few of many.

[roco]

I usually agree with most of what you say, but there's a little more to it than that. While the main hoop may be slightly weaker around the bend because the material is stretched, what he is done is actually very strong. He has created a very rigid node for load transfer. If there is force exerted upon the top roof near the B-Pillar those compressive forces will be transferred down the diagonal, down the rear down tube, across the main hoop, and into the X-Bar in the roof.

The front down tubes are usually as far out to the edge as possible to accommodate driver space. If the front down tube is further out, and the rear down tubes are further inward the node will be offset causing there to be a place for shear.

In this case it is more than material strength but the position of nodes and load transfer.

i couldnt have explained it any better. :bigok:

[S14_Kouki]

Yes that sounds good. Im just saying what I practice. Im sure its just fine for load transfer like you all are saying but im talking about for if you crash its already weak in that spot and you should not make it more weaker by welding on it. Theres a better chance of it sheering at that spot. Here is my cage I built ps sorry for the not so great mig

http://i58.photobucket.com/albums/g269/pandadrifter/IMG_0669.jpg

[TIG]

Yes that sounds good. Im just saying what I practice. Im sure its just fine for load transfer like you all are saying but im talking about for if you crash its already weak in that spot and you should not make it more weaker by welding on it. Theres a better chance of it sheering at that spot. Here is my cage I built ps sorry for the not so great mig

http://i58.photobucket.com/albums/g269/pandadrifter/IMG_0669.jpg

The load transfer I am referring to is in the event of a crash. The problem I see with your cage is that there are 3 independent nodes. You want to have as many tubes as possible going to a single node. The design you have actually has a much greater chance of shearing than the work posted by roco. The reason why you want to have the tubes going to a single node versus spread out is as I said stated earlier, load transfer. With three separate nodes the forces are not as spread out in the event of an impact. Instead they are pinpointed to where they are welded thus relying on material strength since the force be applied is not being dissipated over many tubes. Whereas, with a single node holding three tubes the impact forces are now spread across a much greater area, this lessens the forces applied.

To think of it in much more simplified terms, think of snow shoes. Snow shoes have quite a large area to displace the force applied (in this case the force exerted by gravity on the human body). This allows a person to walk on top of the snow because the forces are spread across a much greater area versus walking in regular shoes with a much smaller contact area.

Yes, the material is slightly weaker through the bend. However this is less of an issue with a single node holding several tubes because the forces will be distributed across those several tubes. Therefore, the force exerted on the bend will be less than that of three separate forces at three separate nodes that have nowhere to dissipate to.

As far as weakening an already "weakened" tube by welding on it, the same load principles apply. In roll cage design there are many load dimensions to account for, weld strength, material strength, and load transfer. A single node will rely on load transfer more than material strength in this case. Load transfer is by far the strongest method.

S14_Kouki, don't take this as a critique to you by any means. That is not my intention at all. This is more towards the general reading audience as some points of education.

:)

[S14_Kouki]

The load transfer I am referring to is in the event of a crash. The problem I see with your cage is that there are 3 independent nodes. You want to have as many tubes as possible going to a single node. The design you have actually has a much greater chance of shearing than the work posted by roco. The reason why you want to have the tubes going to a single node versus spread out is as I said stated earlier, load transfer. With three separate nodes the forces are not as spread out in the event of an impact. Instead they are pinpointed to where they are welded thus relying on material strength since the force be applied is not being dissipated over many tubes. Whereas, with a single node holding three tubes the impact forces are now spread across a much greater area, this lessens the forces applied.

To think of it in much more simplified terms, think of snow shoes. Snow shoes have quite a large area to displace the force applied (in this case the force exerted by gravity on the human body). This allows a person to walk on top of the snow because the forces are spread across a much greater area versus walking in regular shoes with a much smaller contact area.

Yes, the material is slightly weaker through the bend. However this is less of an issue with a single node holding several tubes because the forces will be distributed across those several tubes. Therefore, the force exerted on the bend will be less than that of three separate forces at three separate nodes that have nowhere to dissipate to.

As far as weakening an already "weakened" tube by welding on it, the same load principles apply. In roll cage design there are many load dimensions to account for, weld strength, material strength, and load transfer. A single node will rely on load transfer more than material strength in this case. Load transfer is by far the strongest method.

S14_Kouki, don't take this as a critique to you by any means. That is not my intention at all. This is more towards the general reading audience as some points of education.

:)

Yeah im not taking it in a bad way at all. I learded something new that will help me with my work in the future. I always thought of it in a different way. I figured that since I have three different points of contact that would spread the load transfer out greater. But now the truth as been told and its just more I know now thank you TIG and yes your cage is really nice roco dont get me wrong.

[mdcrose]

OP, nice looking cage!

I totally agree with you about striving to have the support members joiningg at as few nodes as possible. This will cause the forces on those support members to resolve into tension and compresses rather than shear. Also the outside of the tube is where the majority of the stretching takes place.

[Howard92884]

Fawking beautiful.

[96Turbo]

great cages, and good discussion on the load nodes. definitely learned something

can't wait till i need a cage!!! :bigok:

[fcdrifter20]

great cages, and good discussion on the load nodes. definitely learned something

can't wait till i need a cage!!! :bigok:


i have to agree. i thot the same as s14 kouki about the load tranfer at indpendent points. never thot it would tranfer load bettr if u combine them on one common location. thnx to roco and tig for teaching us all something new, and expaining it so clearly.

[burnsauto]

The load transfer I am referring to is in the event of a crash. The problem I see with your cage is that there are 3 independent nodes. You want to have as many tubes as possible going to a single node. The design you have actually has a much greater chance of shearing than the work posted by roco. The reason why you want to have the tubes going to a single node versus spread out is as I said stated earlier, load transfer. With three separate nodes the forces are not as spread out in the event of an impact. Instead they are pinpointed to where they are welded thus relying on material strength since the force be applied is not being dissipated over many tubes. Whereas, with a single node holding three tubes the impact forces are now spread across a much greater area, this lessens the forces applied.

To think of it in much more simplified terms, think of snow shoes. Snow shoes have quite a large area to displace the force applied (in this case the force exerted by gravity on the human body). This allows a person to walk on top of the snow because the forces are spread across a much greater area versus walking in regular shoes with a much smaller contact area.

Yes, the material is slightly weaker through the bend. However this is less of an issue with a single node holding several tubes because the forces will be distributed across those several tubes. Therefore, the force exerted on the bend will be less than that of three separate forces at three separate nodes that have nowhere to dissipate to.

As far as weakening an already "weakened" tube by welding on it, the same load principles apply. In roll cage design there are many load dimensions to account for, weld strength, material strength, and load transfer. A single node will rely on load transfer more than material strength in this case. Load transfer is by far the strongest method.

S14_Kouki, don't take this as a critique to you by any means. That is not my intention at all. This is more towards the general reading audience as some points of education.

:)

Do you have any suggestions for literature to look into when wanting more knowledge of cage design?

[96Turbo]

http://i37.tinypic.com/335borb.jpg

so how did you weld all the way around all the joints here roco? cut the roof, drop through the floor, or neither?

EDIT: this picture is beautiful by the way :bigok:

[s14_sr20_silvia]

I feel like I just learned more in the last 10 minutes than in any other day of my life.. my head hurts now... I'm going to take a nap.

[carps13guy]

solid job man. welds are top notch.

[roco]

ha ha, this is exactly what i wanted out of this thread. good constructive coversation and constructive points, and people learning more, like TIG said none of this is directed at any particular person or company, and not everything i say may be gospel, as im sure im wrong sometimes and appreciate constructive critisisim as it helps you in the long run.


thanks for the compliments guys, and thanks to TIG for explaining it properly.

@96turbo: this looks complicated but is actualy quiet simple. it depends on the customer prefrence but i havent had anybody let me cut there roof off yet so the method i mainly use is to drop the main hoop only. i cut two small holes under the main hoop legs, and basicaly i mock up the main hoop, front legs and top bar over the windshield, then tack them all in place, and tack down the front floor plates. i leave the main hoop plates loose under the hoop legs and when all is tacked and in the right position i remove the plates and drop the hoop only about 12'' or so, making it easy to accsess the whole joint. this drops the cage enough as i can also get to the front joints without cutting more floor. when the main cage structure is all welded i then hike the cage back up into position, weld up the hole in the floor, and re-position the floor plates, and weld the main cage in place tight to the chassis and completely welded. the rear stays and diagonal are then added from the rear and theres more than enough room to get a good weld. i have seen debates that this method weakens the floor, but there are only two very small holes which are then welded in, and then a much larger heavier guage plate is then welded over that area spreading the load, and in my cages i usualy try to weld more than one plate to multiple planes or load bearing points like sill's, chassis legs or pillars to spread the load even further. but like i said before if done wrong it can be worse than not welding the cage all around. the floor plates must be as strong as the cage you build. ive seen some nice cages welded to 2x3 light plate tack'd to the floor. in a hard impact it could just drive the cage through the floor and could be fatal. in some casess a bad cage would kill you quicker than no cage.

like i have seen stuff like this that just makes you cringe, there realy are some shady people out there.
http://www.buildcoolstuff.com/wordpress-car/wp-content/uploads/2009/01/img_2674.jpg

[roco]

this is some more usefull information about the roll cage point system,
im not sure if you use it over there in america, but here it is anyway.
this is a rough look at the Roll cage point system to help you choose which
roll cage is right for you. the image below highlights each different support bars added to gain greater structural integrity. which is right for you depends on the regulations of the motor sport discipline you are competing in or the stresses and demands you intend to put the cage and car through.

http://blog.edoperformance.com/wp-content/uploads/2009/07/062209_1118_NewCuscoRol17.jpg

there are alot more than 15 points but this is a rough guide to the structure of the point system. image thanks to cusco.

[orion::S14]

Looks great, thanks for sharing...

One note, regarding the Cusco chart pics...and your cage example: For it to be legal for SCCA, and many other sanctioning bodies in the US, you need a diagonal bar bracing the main hoop, on the same plane as the main hoop.

For example:

http://www.mazworx.com/images/products/detail_3018_s14_rollbar.JPG
(MazWorx u-weld kit)

...just something to note, since your rules are different than ours.

- Brian

[roco]

yes good point. thats why i havent gone too deep into metal types, sizes, or actual cage design as there diffrent for sanctioning bodys accross the world. like the cage above was built to our local motorsport regs and is bare minimum to pass those regs, but that may not be suitable for other motor sports. if your building a cage, you should decide which motorsport you wish to compete, sit down with your cage builder and follow the rules and regs of that sport appropriatly.

[240 GTR]

so, in order to fully weld all of the joints around the top of the main hoop, do you cut holes that are relatively the same diameter of the bars you are using in the floor?

also, what is the logic as far as dimensions of floor plates? is using plinth boxes a more ideal route than just using floor plates?

[MELLO*SOS]

Excellent looking welds and great discussions here.

Roco I'm sure you've already seen it, but you should check out race-dezert.com. Trophy truck and offroad racing forum with a great fab subforum. Tons of pics and some very competent fabricators there.

Keep it coming!

[TIG]

also, what is the logic as far as dimensions of floor plates? is using plinth boxes a more ideal route than just using floor plates?

Sizes of the floor plates is sometimes depends on the class and the sanctioning body. Some have requirements you have to stay within, others do not.

As far as plinth boxes, I prefer floor plates over plinth boxes unless I need one to get over a frame rail or something to get a tight fit.

Roco, hope you don't mind me answering these questions as well. :)

[roco]

no by all means Tig work away, thats what i want other members to contribute there knowlage and experience, as i found when i was learning you could get more info on NASA space station than you could Roll Cages. lol :D

@240gtr. yes i cut holes slightly bigger than the diameter of the main hoop tube. so the tube will drop through the floor leaving enough space.

and i agree with Tig i prefer floor plates over box's. no major reason just personal prefrence.

even though this thread explains roughly how roll cages should be built there is still alot more to it, and i wouldnt advise any beginer fabricator or welder to try build one on the fly as unlike many things you may not get a second chance.

[S14_Kouki]

my mounting plates are 6x6 and I used .080 thick material

[soon2bs13]

this thread is full of win!!

i have learned a lot tonight.

[TIG]

my mounting plates are 6x6 and I used .080 thick material

Just an FYI, all sanctioning bodies I have come across (SCCA/Redline/NASA) require 3/16" floor plates. Your regulations may be different though.

[S14_Kouki]

Just an FYI, all sanctioning bodies I have come across (SCCA/Redline/NASA) require 3/16" floor plates. Your regulations may be different though.

I built my cage for SCCA and the rules as of 2 years ago were .080 welded and 3/16 bolted

[TIG]

I built my cage for SCCA and the rules as of 2 years ago were .080 welded and 3/16 bolted

Ah yeah, I remember back then. I forgot about that! I swear rules change bi-annually.

[S14_Kouki]

Ah yeah, I remember back then. I forgot about that! I swear rules change bi-annually.

Dame I need to get another 240 so I can build a up to date cage and start drifting in competition.

[g6civcx]

Do you have any comments about the S&W rollcages? They don't have a main hoop diagonal. Instead, they have two braces that go from the main hoop to the transmission hump.

http://www.swracecars.com/store/images/cart/CAGEnewHC.JPG

[g6civcx]

Any thoughts?

[Jonnie Fraz]

Please correct me if I am wrong, but almost all the specs I have read require a diagonal or an X-brace. The pic you posted the upper half of the main hoop is not braced and is subject to failure.
I stand corrected....the wording in the SCCA 2009 rulebook says "It is suggested that roll bars include a transverse brace from the bottom of the hoop on one side to the top of the hoop on the other side."

[g6civcx]

almost all the specs I have read require a diagonal or an X-brace

This is my experience as well.

The pic you posted the upper half of the main hoop is not braced

I also agree.

is subject to failure.

I am not sure about this. The transmission hump is the strongest part of the car. This is why S&W designs their cage like this.

Can anyone comment?

[Jonnie Fraz]

I am not sure about this. The transmission hump is the strongest part of the car. This is why S&W designs their cage like this.

Can anyone comment?

I am not saying the trans hump would fail...The main hoop above the bracing, since it does not go to the top corner of the hoop. Granted it would take a massive impact to crush that hoop above the harness bar.
Truly I have seen some janky shit pass tech...but it is like buying a helmet. Do you need an $800.00 helmet...depends on what you are putting in it.

[g6civcx]

I am not saying the trans hump would fail...The main hoop above the bracing, since it does not go to the top corner of the hoop. Granted it would take a massive impact to crush that hoop above the harness bar.
Truly I have seen some janky shit pass tech...but it is like buying a helmet. Do you need an $800.00 helmet...depends on what you are putting in it.

I'm not asking about passing tech inspection.

I'm asking experienced cage builders about their opinion about the safety of the S&W design.

[TIG]

I'm not asking about passing tech inspection.

I'm asking experienced cage builders about their opinion about the safety of the S&W design.

I prefer and uninterrupted diagonal bar in the main hoop.

[g6civcx]

I also heard talk of a diagonal from the main hoop to the opposite corner across the passenger seat is acceptable as well.

Also the main hoop to the opposite corner on the rear strut tower.

[Jonnie Fraz]

I'm not asking about passing tech inspection.

I'm asking experienced cage builders about their opinion about the safety of the S&W design.

OK are you asking about the design or about running a $249.95 EWS cage?

Here is my take I do not like the design...No diagonal in the main hoop.
Would I run a S&W cage...No Way! EWS is not up to spec for SCCA, Formula D, NASA, D1, ect...

[DALAZ_68]

this thread and its info is sticky worthy...

[g6civcx]

OK are you asking about the design or about running a $249.95 EWS cage?

Design. I already have the cage welded in. I'm considering adding a few more bars, including a diagonal.

Here is my take I do not like the design...No diagonal in the main hoop.

Point taken.

Would I run a S&W cage...No Way! EWS is not up to spec for SCCA, Formula D, NASA, D1, ect...

What is EWS?

[TIG]

I also heard talk of a diagonal from the main hoop to the opposite corner across the passenger seat is acceptable as well.

Also the main hoop to the opposite corner on the rear strut tower.

I still prefer running it from the driver roof to the floor. It makes a lot more sense that way in terms of triangulation to protect the driver. Running a diagonal downtube from the opposite corner is still acceptable.

What is EWS?

Electro Welded Seam tubing...similar to ERW (Electro Resistance Welded). DOM is the standard these days for roll cages.

[Jonnie Fraz]

Design. I already have the cage welded in. I'm considering adding a few more bars, including a diagonal.


Ok cool...I am realy glad you are not thinking of using the S&W cage.

There is a design on the first page that instead of using the diagonal from floor to the top of the hoop, they X the rear kickers.
http://i31.photobucket.com/albums/c363/fordescortmexico/DSCN17431853.jpg

[95KA-Turbo]

Would this door bar design be Formula D legal? I know their rules shows a bar that is completely diagonal but if this bar kept going forward and connected to the bar going through the dash (which the cage in the picture doesn't have) it would have the same connecting points.

http://www.izzyscustomcages.com/images/CustCars/240sx/P1010001.JPG

http://www.izzyscustomcages.com/images/CustCars/240sx/P9120063.JPG


I am fine with cutting up my door panels but I am trying to get a Formula D cage to work with all of the interior panels, and that design would make for minimal cutting.


I photoshopped this real quick:

http://i34.tinypic.com/dp7shv.jpg

[TIG]

I don't see how that door bar would be legal or safe. In the event of a side impact it would just bend in towards the driver and destroy the seat and likely injure the driver. The shortest distance between two points is a straight line. Extra material with extra bends means there's extra material that will bend in an impact.

My favorite door bar design is X or uninterrupted X.

Sorry if that wasn't very clear. I've been working on a lucubration on intake design all day and my mind has turned into mashed potatoes to say the least.

[95KA-Turbo]

Gotcha, I never though about the extra material having more room to move.

Can you post a picture to show the difference between the two different X bars?

[TIG]

Gotcha, I never though about the extra material having more room to move.

Can you post a picture to show the difference between the two different X bars?

Regular X:
http://jaffster.com/E46M3/3-23-08/main/p3230002.jpg
NOTE: The vertical bar is a jacking point.

Uninterrupted X:
http://www.motoiq.com/Portals/0/Magazine/Articles/Kojima/300ZXTT/part1/35.JPG

Notice how the uninterrupted X is two separate bars with a bend in the middle, where as a standard X requires one solid tube, then another tube cut in half and notched to fit around the other tube to form the X.

[theslows13]

excellent, excellent content here guys! i can say im proud to be on a forum that, unlike MANY others, provides real info, MATURE discussion/critique

please, carry on good sirs

[FullAutoLock]

Great thread!!!! A Def sticky IMO!

[g6civcx]

How about the rule that says any triangulation of the main hoop must provide the same protection to both front passengers?

It looks like just about every diagonal main provides more support for the driver side.

Any comments?

[95KA-Turbo]

Regular X:
http://jaffster.com/E46M3/3-23-08/main/p3230002.jpg
NOTE: The vertical bar is a jacking point.

Uninterrupted X:
http://www.motoiq.com/Portals/0/Magazine/Articles/Kojima/300ZXTT/part1/35.JPG

Notice how the uninterrupted X is two separate bars with a bend in the middle, where as a standard X requires one solid tube, then another tube cut in half and notched to fit around the other tube to form the X.

Wow, that uninterrupted X is amazing. Fuck doorpanels, haha.

[GSXRJJordan]

Was browsing one of my other forums, SCCAForums, and came across this: The coolest cage design for a C6 Z06 (which is tough since it's aluminum frame/fiberglass body). Done completely in CAD, then CNC'd...

http://sccaforums.com/linkthru.aspx?url=http%3a%2f%2fforums.corvetteforu m.com%2fautocrossing-and-roadracing%2f2400350-pfadt-c6z-build-pictures.html

http://www.pfadtracing.com/photos/data/519/medium/Cage_Rendering_6.jpg

Look at the test fit!
http://www.pfadtracing.com/photos/data/519/medium/IMG_4831_1_.JPG

Anyway, impressive as hell... and yes, the supports all load the same point to minimize shear forces on the main hoop.

[Izzy's Cages]

Would this door bar design be Formula D legal? I know their rules shows a bar that is completely diagonal but if this bar kept going forward and connected to the bar going through the dash (which the cage in the picture doesn't have) it would have the same connecting points.

http://www.izzyscustomcages.com/images/CustCars/240sx/P1010001.JPG


Legal for Drift? Yes. But it wasn't built for it, so you have to be careful when looking to other builds for designs. It was built primarily as a street car and the occasional autocross. Never anything wheel to wheel or tandem.

The owner was easily 6'7" and wanted doorbars, but didn't want to climb over them as it was his daily, and didn't want to loose his armrests. He ran out of budget halfway through the build as he had just placed tar mat all over the interior before drop off, so a lot of the budget went to removing it in the pad areas. Unfortunately, I had to stop the build unfinished as it was.

There should have been another bar connecting the rear bend down to the hoop pad.

The downside of the double bend X bar... even when gusseted, is that there is also enough material in them to intrude into the cabin like a sharks mouth should there be a failure. I like them better than the traditional 3 bar X, but they aren't without cons.

[Soloman]

Awesome discussion guys!

So in all of your guys opinions what is the safest and most legal yet still somewhat daily drivable door bars? I am building an s13 coupe and am looking at getting the mazworx pre-fabricated cage that is D1 and SCCA legal.

[EchaKqulo]

This is a great thread, i have subscribed to it.

Adding to the all loads through the same point: When a load/bar is placed away from the junction point, there is an additional load that is been applied to the Junction point. There is a new bending moment apply to that point which is M=F*d where the M (moment), F (force/load) and D (distance) which that distance is the perpendicular distance form the bar axis, or load path, to the junction point. If that bar is placed on the Junction point that bending moment is GONE, since D becomes 0.

In the engineering area, cages "behave" like trusses and therefore the objective to a strong cage is to have as little as loads as possible so every time a bar is placed away from the Junction point there is an additional load that could have been eliminated thus applying more stress on the cage.

Great info Keep it going!!!

[Jonnie Fraz]

Legal for Drift? Yes. But it wasn't built for it, so you have to be careful when looking to other builds for designs. It was built primarily as a street car and the occasional autocross. Never anything wheel to wheel or tandem.


Quoted for truth! If you are looking to drift spend time looking at drift car cages, they will be very different than street cages or straight line stuff. Drift follows the SCCA rules pretty close, so if you are looking to do grip, you should also be alright for drift.

Izzy you do some very nice work!

[95KA-Turbo]

I've been trying to find nice looking drift car cages. It isn't an easy task, haha, most of the cars don't have well put together interiors.


I have no clue if this is a drift car but I like the way this looks. I don't have any other pictures though:

http://img.photobucket.com/albums/v347/nihon_jin/S14%20Cage/DSC00160.jpg

[roco]

wow theres been a good bit of discusion since i was on here last.
and alot of great points and tips.

@95katurbo: as roll cage design goes its not down to looks its about function, theres no point looking for a nice cage that looks the nuts but will colapse and kill you on impact, and like said before theres a big diffrence between a cage for the street and the track, in my honest opinion i dont think inferior cages for street should be built as it gives the driver a false sense of security, and the same for some track cages too, hence this thread.. all cages should be of homolagated design and be approved by a governing body, now saying that the propper built and design'd cages usually look the best.

[boostbyyou]

nice work!

[senger]

so im gonna have to bring up an old post. but im currently building a roll cage for an s13 hatch. and on the driver side, where all the fuse box shit and some other wiring are, do you need to relocate it? and to where?