Cerb roll cage design

[Omerta]

I'm a couple of weeks away from handing my Cerb (LS powered Targa rally / road car in New Zealand) over to a specialist roll cage builder. The integral roll cage (which doesn't meet motorsport standards) has been removed to save weight and make room for a proper cage.

So a question for our engineers and racing experts - 4 of the 6 mounting points will be to the outrigger corners. Are they torsionally stiff enough relative to the main chassis to get any benefit from the cage? If not is it worth adding some bracing (more weight) between the outriggers and the main chassis? If so where?

For the main bar bracing, I'm thinking to run a "V" from the top corners down to the trans tunnel, and from there to each of the bottom corners. Kind of an X, centered on the tunnel.

[teamHOLDENracing]

Six mounting points does not sound enough....

Mine has ...

2 to the back of the chassis over the diff
2 further forwards, end of transmission tunnel
2 to rear corner of outriggers
2 each door bars down to outrigger
2 to outriggers in front of door openings
1 extension down to front corner of outrigger in front of drivers feet
2 down to transmission tunnel from cross member under dash

[teamHOLDENracing]

Pics here:

[Brummmie]

Seat belt mounts could be useful? You have the rear parcel shelf ones.

[Omerta]

Thanks Andy.
What does your shoulder harness attach to?

Brummie -

[teamHOLDENracing]

If you look at the second photo there is a bar which goes down to the diff cage. The same bar on the drivers side was drilled and a piece of solid bar, tapped at each end for the harness mounting eyes, welded in.

Edited by teamHOLDENracing on Thursday 12th February 10:20

[Redmist336]

Make sure you adhere to the stock cage as described in the MSNZ schedule. If not then you'll have to get an engineer cert showing loads. If you're also going moly might I suggest you get a signoff from Leon at MSNZ before you start to cut tube.
I'd also have a look at the modern WRC PBMS pillar design. It's certainly tonsionally stronger a standard cross pillar. The only special consideration you'll have with the Cerbera is attempting to tie it into the central ladder.

[Omerta]

Hi Daniel - still haunting the Cerb forum huh

Yes I'm familiar with the MANZ standards - Automotion in Levin did a beautiful job on the cage for our Targa 944 last month - they've done quite a few or the Bridgestone cars - so will be going to them for the Cerb too.

[Redmist336]

Don, still haunting, still dribbling, still procrastinating. Just spent 30k on a new gearbox for the Jimco, so just waiting for a deal on a car that I can throw an LS into.

[Redmist336]

By the way, don't let Leon hear you calling MSNZ (MotorSport NZ), MANZ (Motel association of NZ). I've accidentally done the same thing, and been reprimanded severely for my indiscretion.

[Omerta]

Oops... used to be MANZ though didn't it?

$30k

And I though $4.5 for the TKO was a lot!

[Redmist336]

30k, yep I know what you're thinking, cheap.. too cheap. I only bought the small Albins Sequential and got a deal on it as it's a cancelled order. Needed to be done as I just couldn't hold the Fortin transaxle together.
The Albins is rated at about 1000hp on road or 600hp off... and I'm pulling 519whp or just under 600hp... cutting it close? I just couldn't afford the big Albins.