Cams Cage Question

[PRO_32]

hey guys, I always find the motorsport section informative so I thought someone might have a quick answer to my Q.

I'm in the process of building my track 32, the car is currently with the cage builder we spent yesterday going through the design I wanted and what he wanted etc. I wanted the rear bars going from the main hoop diagnolly to the top of the rear strut towers, However today he tells me cams (spoke at length with offical over the phone) doesn't want the rear members from main hoop leaving cabin or on a diagnol. I'm sure I've seen it done like that a dozen times over.

Any help greatly appreciated.

I know more than likely the answer is in the cams manual, which I will go through online tonight.

Cheers

Andrew..

[phunky_monkey]

Hey Andrew, I had my CAMS approved cage built last year, and despite my bar not being a diagonal to the strut brace, we were at one point considering moving it there as I was having issues fitting into the car (couldn't get my seat far enough back). The cage builder I used gave no indication that this would be any issue and he is a member of the committee who deal with CAMS on this issue.

However the rule may have changed since then, so best to check in the manual.

[Merli]

Are you building the cage to a specific CAMS category?

That's the only reason I can think of, for not wanting to go from the main hoop through the rear firewall.

[PRO_32]

ok well shedule j 3.1.1 says that the must be confined between the 4 strut towers I could not

Find anything that states it cannot protrude past the rear firewall.

Now can't wait for cage to be finished jus wiring left then might

Actually be able to take it out!!

So I guess problem solved.

Cheers.

Andrew

[Merli]

No, that's from the general Schedule J...

Each CATEGORY of racing has its own little quirks and nuances.

e.g. Category 3J = (aka Improved Production or IPRA) is a popular racing category around the Skyline crew.

It contains the following paragraph:

14. SAFETY STRUCTURES

14.1 Roll over protection structures: Roll over protection structures must comply with Schedule J (refer “General Requirements for Cars and Drivers”). They must be constructed so that no parts of their structure extends outside the passenger compartment, nor penetrates any body panels except for holes drilled for attaching the cage to the vehicle. It is not permitted to fit additional bracing outside the passenger compartment, other than a strut tower brace as described in Article 9.7. It is permitted to attach parts of the safety cage to the interior of the passenger compartment, either by welding or bolting. The removal of the minimum amount of upholstery to assist the fitment of the safety cage members is permitted.

Link to all the specific racing categories:

http://www.camsmanual.com.au/02_race.asp#3rd

[BezerkR32]

mmmmmmmmmmm thats shit as you really want to pick up the suspension point if possible.

No, that's from the general Schedule J...

Each CATEGORY of racing has its own little quirks and nuances.

e.g. Category 3J = (aka Improved Production or IPRA) is a popular racing category around the Skyline crew.

It contains the following paragraph:

Link to all the specific racing categories:

http://www.camsmanual.com.au/02_race.asp#3rd

[Merli]

mmmmmmmmmmm thats shit as you really want to pick up the suspension point if possible.

I agree...

Apparently, this takes into account the crumple zones that are usually built into today's automobiles.

It was thought to be safer to allow the crumple zones to work first, and then rely on the cage to protect the driver.

Doesn't help if you're trying to improve the RIGIDITY of the car though

[unique1]

how about cutting the parcel shelf back half way and adding a new rear firewall behind the strut towers? that means the strut tops are now officially in the compartment area.

i also got a rollcage question i might add in here if the OP doesnt mind.....

im trying to get the front legs as close to the A pillars as possible, therefore the front legs joining onto the floor plates will end up on a slight angle to allow some room agianst the sill to get the welder in around the legs to complete the welds, is that ok or should they be perfectly vertical coming from the A pillar to the floor plate?

Edited April 1, 2009 by unique1

[Duncan]

yeah the 3D sports sedans regs also have specific additional requirements to watch out for.

re the floor plates and the cage being vertical, yes you should if at all possible because it will be stronger. generally you get the cage fairly close to the chasis and then weld metal plates between the 2 to support it in a few places, we used 3 plates per length we were supporting. Also keep in mind you have to go through the dash on a skyline because you are only allowed one bend in the front legs (where you leave the windscreen then head down to the floor.)

[PRO_32]

Thanks for the info guys, need to clarify That this car is being built mainly for sprinnts, khana's and trackdays not somuch ipra or sports sedans etc, so it would seem (based on the previous posts) I am less restricted with my cage design as to me it seems pretty important to pick up the rear towers.

I was thinking the same about the rear firewall/parcell shelf, I don't think it even needs to be there jus worried about stability in the rear window as it's jus lexen there may be too much movement there.

Also noticed that Duncan picked up the rear cradle mounting points with bars from the main hoop does the play a big role in rear end stability (is there an issue with deflection in suspension geometry through cradle movement????)

Cheers

Andrew

[Duncan]

yeah we don't have any hard data of course....but have a good look at the (lack of) reinforcement of the rear cradle mounting points andthink about all the forces pushed through it - power, turning, braking everything. THe additional tube to support the mounting points were minimal so we included them. As Stu said lots of people pick up the strut tops in the cage but they are only 2 of the 6 rear points on a gtr.

[Risking]

Pick up on everything you possibly can thats allowed in your categories rules.

People seem to get confused with log booking a car. You can't build a "cams" approved cage and get it log booked. It must be based on the outlines and tailored to suit the category you intend to log the car as.

a 3D sports sedan has a specific outline above the base design as does 3J IPRA etc etc etc.

You cant build a 3D category cage and log the car as a prod sports car. So build the cage according to the chosen category.

For alot of categories specific rules say you cant pick up suspension points not within the basic 6 point structure.For instance the rear cradle mounts and shock towers are two big ones.

Rear legs are not to protrude through the rear fire wall if one is fitted to the car. Which is why alot of cages go to the most structural part of the wheel arch. In a skyline you can get very close to the structural part of the rear shock tower without penetrating the fire wall anyways.

Of you can move the firewall to extend the "cabin" area IF your category allows it, I highly doubt thats the case in any production based category though.

[PRO_32]

Thanks for all your input guys, alot food for thought.

Will post some pics up with the final product hopefully before Easter, main hoop and seat mountings are all done now so I guess another week and I'll be able to start chucking on all the suspension bits and pieces .

Cheers

Andrew.