Cusco vs BD Bar

[Mr nanotech]

Hi there! First off I have to send a big thank you to all the help you guys have given me in regards to previous posts here. You've given me a lot of help and it's much appreciated
Down to business though, I'm looking for a roll bar and currently have my eye on a decently priced Cusco 4 point half cage. This is one with the bars going right down behind the seats and bolting to the floor rather than the seatbelt towers. It's advertised on this forum on the for sale and I've already PM'd (working out logistics). Anyway I'm just curious about what the go is on these bars. I've been searching the interwebs and so far I've turned up nothing.
Initially I had my eye on the BD and Hardog bars. BD especially, but it's so hard to find a second hand and the prices for new are fairly high. I'm not saying I'm trying to cheap this out but I have a pretty good deal on the Cusco but before I hand of valuable moneys, I just want some specs.

First off, I'm curious if it will give satisfactory roll over protection in an accident and if there is any danger of head hitting the bars (as they seem to run up the sides of the seats rather than behind; or so photos lead me to believe).
The next question is if these bars bind the car together a little more like the BD's do, giving a slightly more rigid ride as both sides of the car are held together firmer (ie: how a roof could use the b-pillars to bind the middle of a car together).

The next question though, I'm not sure if this will graze my hard top or not, i've messaged the seller about it.
But first and foremost, safety comes first. Will this be adequate protection in a worst case scenario? How will this hold up against a BD bar?

[RG.net]

The Cusco rollbar you are looking at, was actually my first rollbar. It would provide adequate roll over protection, and it did stiffen up the chassis signifigantly.

The bars sit behind the seats, unless you haven't got a seat belt on, you shouldn't be able to hit your head on them at all.

back when I had it, I tryed my friends hardtop on my car, and the rollbar did clear it.

I prefer how the Cusco is mounted as opposed to the BD's personally, but each to their own.

Hope this helps.

[Mr nanotech]

Thanks heaps! Deal is now going ahead. Yeah I was concerned about clearance but it's good to know I can safely use my hardtop without grazing the middle out lol. I get a lot of use out of the hardtop since I have friends in Footscray etc.. It's suicide having a softtop out there!

So now I can sleep safely knowing I'm safe

[Mr nanotech]

If anyone else has anything to say regarding the Cusco, please do share!

[xhonda_boy]

You will lose about 1-3 inches of seat travel.

[Mr nanotech]

That... Is significant! However this car doesn't have the backing cross brace. here is a link http://i798.photobucket.com/albums/yy26 ... G_0102.jpg
Hmm... Well being a shortass this isn't so bad But that is a lot of seat travel

[RG.net]

You will lose about 1-3 inches of seat travel.

That depends more on the seat though John, when I installed this bar for the new owner (Module then bought this car later on) we figured out a way to reduce the lost seat travel.

You'll be right!

[deviant]

This is quite a hard thread to answer without potentially upsetting the owner or damaging the sale...

What do you want to achieve with installing a roll bar? Style or substance?

Unfortunately the bar you have shown can not be CAMS approved and in my opinion would offer very little roll over protection.

[Mr Morlock]

The roll bar thing probably has much more to do with style apart from track drivers who are in a different environment to road conditions. Mazda still does not fit a safety approved roll bar presumably because it is not considered necessary. You will not get any data or testing from roll bar makers- they simply do not have the resources to prove the value of them for road conditions. Anectdotal evidence is more belief than evidential / proof. The vast majority of MX5's have no roll bars. BD s/be able to answer some questions and one might expect that these are well made and engineered and presumably still locally made?

I think buying one is a personal choice though I am not sure if Vicroads have any regs on construction or certification. I imagine that you would also have to advise the insurance co of the fitment of a bar

[hks_kansei]

Vicroads do have a listing on suitable rollover types and styles, cant remember the publication number, but it's on their website.

as for the Cusco, personally, I wouldn't trust it, it's much thinner steel than the BD or MX5+ (BD is 3inch tubes, I think cusco is 2.25 from memory?), and from memory it doesnt have a diagonal brace on the main hoop, and the rear stays are bolted to the main hoop.

the lack of a diagonal brace means no triangles, so an already weaker structure.
and the bolted rear stays have an inherent weakness that all the stress would be put on a single bolt, whereas a welded bar has the stress dissipated around the welds. (plus CAMS manual does not allow either of these)

do bear in mind though all that is my own opinion.