The best method of "caging" a mk1..

[gldgti]

With cages and Cams, anyone can build a cage for a race car, but you need to use the correct "roll cage tube" (which many motor racing fools will tell you is very special). Consequently, cages don't come cheap because on a steel basis, the stuff is mighty expensive. Add to that the fact that to make a good cage, you need to be a decent welder, fabricator and have an idea about how these things are done - and it takes a lot of hours to do it right.

Once a cage is in and painted, its pretty hard to check that its made out of "roll cage tube" anyway, and I'm sure that there are plenty of cars out there that have cages made from other materials - but thats really besides the point I guess.

Save your money, forget the cage and get some good brakes or something.

[Peter Jones]

With cages and Cams, anyone can build a cage for a race car, but you need to use the correct "roll cage tube" (which many motor racing fools will tell you is very special).

Being a motor racing fool, I'll explain,

Normal round tube is made by taking a flat rectangular piece of steel and bending it into a round tube and welding the join together.

This creates a seam along the length of the pipe which is where the tube will split open in an impact.

Roll cages have to be made from seamless tube which is made in one piece without a seam, it's behaviour under deformation is much more predictable.

Along with making it out of the right stuff the cage dynamics are actually mathematically modelled and in some cases copies of the cage are made and destructively tested in a hydraulic jig.

[gldgti]

Yeah I know Pete, but you can still buy seamless tube/pipe that cams wont pass for a cage, because the paperwork isn't there for it, not for any technical reason.

You are not a motor racing fool - but I'm sure you'd agree, there are people in motor racing (as in anything) who are fools.

I don't doubt that mass produced cages for particular vehicles are researched and tested, but the majority of Sunday racers cars are definitely not - nor, do they really need to be, if the person that builds it has some experience and good common sense. I'd be very impressed if you could point me at someones car they've built where they did any kind of FEA or hand calcs on the cage in it.

[mikinoz]

Save your money, forget the cage and get some good brakes or something.

I think that is a great piece of advice mate.

I'd also check the regs in Transport Tas if you are proceeding as they have a few things to say about cages that you will need to comply with.

[straight_fresh]

European cage regs for road and race are very different to those here and there's a wide variety of quite acceptable (to Europe) bolt-in cages.

yeh but somehow i dont think the guys with chromed gearboxes and polished carb linkages are tremedously concerned with how theyre colour coded or equally chromed roll cage is going to perform when there car is upside down in a sand trap, if it ever made it within 50k's of a legitimate track meet.... he wants a show cage cos they look cool /

[JoshFair]

I'VE CREATED A MONSTER!! haha

[Volksee77]

I'm with you peter, as for the seamless tube which still won't pass for any techinical reason um yes there is, it is the carbon and iron content within the metal that is the reason they won't pass it because the higher the carbon and lower the steel content of the steel means the weaker it is mate (the cheapest stuff from india is the main culprit of this). The roll cage tube is all low carbon and must contain a certain percentage of Fe45 to ensure it is strong enough, which is why they charge more for it. CrMo is an entirely different price range though.

The little bit extra for the correct steel itself isn't as expensive as having 6 months off work while you recouperate in hospital because they cage did nothing or split and ended up in you!.

If you want a show cage then go for it at your own peril. Even when i have the front hoop out of my rally car to drive from my house to my workshop the police still pull it over at every chance they get for a scrutineering, make sure your car is perfect otherwise you may as well start lining up the RTA to have the defect stickers removed now

[Peter Jones]

So, back to the original question - The best method of caging a MK1 is to engage an automotive engineer who specialises in the design and manufacture of roll over protection systems.

I'm using Brown Davis, in fact the car is booked in for this Friday and yes, they will do all the calculations, build it out of the right materials and it will be fully CAMS compliant.

[MiKe1_golf]

all OP want's is a half cage that makes his mk1 look more agressive.

i'd be looking at the bolt in jobs from europe or the states if you can find them. getting an engineer to build some epic roll cage is going to cost thousands of dollars isn't what you need.

obviously you need to speek to your local road authority before spending a heap of coin on something that may only get you in trouble.

these types of half cages offer more than just looks too. the chassis stiffening will be very noticeable. for example we have a number of hilux utes at work. all the same year modet etc. but one of them has been built to mine specification which means revolving lights fancy reflective stickers aaaaand a 2 point roll bar. id drives like a road car the others are boats in comparison.

you can pick up a half cage for an s13 or 180sx pretty cheap.. around $400. it would be interesting to see if one of these could be modified to fit a mk1. would most likely involve a fair bit of fabrication to fit and may end up being an expensive exersise after all... and will it be able to pass road worthy? i dunno.

look on youtube at home made roll cages.. i remember watching a clip on there of a dude building a cage with a pipe bender some hole saws and a welder... looked pretty good in the end too. could be a fun way to learn to weld. but like people have said i wouldnt want to rely on a bodgy roll cage in an accident.

[MiKe1_golf]

here's a pic of an s13 half cage. would be interesting to measure one up.

[gldgti]

So, back to the original question - The best method of caging a MK1 is to engage an automotive engineer who specialises in the design and manufacture of roll over protection systems.

I'm using Brown Davis, in fact the car is booked in for this Friday and yes, they will do all the calculations, build it out of the right materials and it will be fully CAMS compliant.

Thats a big commitment Pete, I'm impressed.

I can see i've backed myself into a corner on the tubing material side of things, so I wont say anything else - but thanks for giving us all some good clarification Volksee77. It makes sense to me that it would be low carbon, when I've worked with it it does seem to be more ductile than most small diameter pipe (as opposed to tube) which I likely wrongfully assumed was down to a final stress relieving (heat treatment) after it is formed.

[Volksee77]

Josh, check out OMP in europe, they make FIA compliant steel cages that don't cost the earth. A 6 point basic steel cage costs around $800(not including postage) so i imagine a half cage would only set you back half that but the plus is it will look like a proper cage, bolt straight in and being it has 4 points it will begin to stiffen the car up (a 2 point will do squat).

[Peter Jones]

Josh, check out OMP in europe, they make FIA compliant steel cages that don't cost the earth. A 6 point basic steel cage costs around $800(not including postage) so i imagine a half cage would only set you back half that but the plus is it will look like a proper cage, bolt straight in and being it has 4 points it will begin to stiffen the car up (a 2 point will do squat).

Racer Industries import a lot of the OMP stuff here, might be worth giving them a call and see if they can get it in for you. Racer Industries

[GRN_VAGN]

http://www.hottuning.eu/?nav=products&subnav=view&product_id=324

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