Roll bar retaining soft top

[StuwieP]

Sorry for the vague title. Couldn't quite figure out how to describe it in a brief manner.

I've been speaking with David (Brown Davis) about a cage/bar to weld in to my NA. I'm working to build a track car but being a uni student can't afford a 2nd vehicle so it's also my DD. Comfort isn't a huge issue for me in terms of building the car. I ride bikes so I'm pretty much used to it.
Conventional wisdom seems to be cage = no soft top. The main issues I'm aware of is space lost (height and width) to the folding mechanism and the top won't fold back properly because of the rear stays, in addition to the a-pillar bar getting in the way of the latches.
A hard top would be $$ I'd rather spend on wheels, tyres, pads and lessons and running with the soft top removed for a year-round DD is asking for both trouble and pneumonia.

The long and short is I'm hoping that there is a volunteer with an NA and a hard top who could spare an hour of their day (any day) with David from Brown Davis and measurements could be taken to work out headroom, clearances etc. The general upside to this is that anyone else in the Melbourne area or willing to drive who is interested in a proper weld-in roll bar (main hoop to floor, proper diagonal etc, rather than just bolt-in-to-parcel-shelf style) and who wants their soft top for convenience could get a bar made for reduced price (R&D costs passed aorund and 'mass production' value)

Further, if anyone knows of any full cage (door bars, a-pillars, halo etc) design which maintains soft-top functionality, please let me know, I've been looking and I can only find the TR Lane cage. Given the option I'll take a full cage but as it stands it looks as though I'll have to settle for a bar until I can afford to get a hardtop from Dave (Lightyear) or I'll get very wet next time it rains.

Can you tell I still haven't made up my mind?

Cheers
Stu

[Hjt]

AGI all the way. Do a search for AGI half cage for pictures. There was a recent group buy.

If you local to Sydney you can view either. I have a half cage that doesnt fit a soft top and Yemmin has a soft top compatable version.

Pricing is similar to a brown Davis.

[StuwieP]

I'm a melbourne local, so with either postage or the drive up I doubt the pricing would be much different. The bars do look good though. Also, pretty muich settled on getting a 4 point bar rather than a cage (maybe some door bars).

Basically the questions I want answered by David are:
A) How much space is lost to the soft top compared to the hardtop (i.e. not compared to open roof, build as tall as necessary)?
B) How compromised will the safety of the bar be by maintaining the soft top? - will it cover shoulders / head sufficiently or will the bar be rendered essentially useless and take on the characteristics of a reinforced style bar.
C) If the answer to B is anything other than "minimally" is it worth spending the extra $ on a hardtop and removing the soft top? - this is more a question for myself, obviously nobody else can make that decision but the previous 2 questions ought to advise this choice.

The other option re measurements is that somebody trusts me with their hardtop for the day and I drop it off once David has done his thing.

Cheers
Stu

[Hjt]

I implore you to check out the AGI thread, it will answer all your questions. And FYI the bars plus interstate shipping worked out cheaper than other off the shelf bars.

[deviant]

If you are really keen on keeping the soft top then the roll bar will always be compromised by it, in particular width and height will be compromised.

You could make your own bikini top if you were really keen to save some money but that will carry all the same security and weather resistance as running with no roof.

Hard tops can be $800-$1500 but they do come up for under $500 if they are damaged. You would not be the first person to make one from paper mache and varnish it just so you can have one that goes around a cage.

If you are welding in the cage you dont particularly need to have the main hoop going to the floor. The modifications made will make the main hoop just as strong going to the front of the parcel shelf. The width of this main hoop will be compromised by fitting inside the seat belt towers...either way your seat belts will be rendered useless which becomes a road worth issue.

With the main hoop going to the floor you will also lose maybe upwards of 3 inches of space behind your seat, I hope you are really short!

Truthfully Stewie you either do one thing or the other with this stuff. You cant have a fully compliant cage, and be road legal, and retain interior space, and retain a soft top. You either go with the compromised set up of a road car with a soft top or you go the other way and pull the thing off the road and build a real cage for it.

[hks_kansei]

Hardtops don't give you any more usable space for a rollbar.
The area behind your head really only gives an extra 15mm of height, the rest of the space is further forward, which would mean placing the main hoop in front of your forehead.

[bruce]

Such a cage may attract Police attention, especially in Melbourne.

[StuwieP]

thanks deviant - that's the kind of information I'm looking for, even if i don't want to hear it it's also the sad realisation I'm coming to - like i said, looking more at a 4 point roll bar now rather than a full cage, just something a little more confidence inspiring (and legal) than a bolt-in attaching to the seatbelt towers (VIC regs say no to such things, rules out the off-the-shelf BD bar altogether).

I'm 5'10-11" and I've got a pair of bucket seats in the car and somehow came out with 10-15cm space behind the backrest. Ideally I'd be slightly further back but the OEM bolts prevent it. My shoulder is just above the door, the bottom of the seat is only about an inch (or less) off the floorpan. Still, not much headroom (surprise ) but plenty more than before.

hks, I'm under the impression that the folding mechanism of the soft top can force the bar to be narrower than ideal, rather than necessarily finding more headroom?

re the DIY hardtop, Dad's done some work with fibreglass (we're not exactly pro engineers) inc. his TA22's body panels so that could definitely be done. Maybe Lightyear could offer some tips?

bruce, not planning to do anything that'll land me in hot water re. roadworthy and the boys in blue - if it can't be done and stay on the road, it's off the table as an option. again, looking more at 4 point. As i write all this, I'm starting to think a bolt in (a la AGI - thanks hjt) is easiest in the short term, until I really get my act togther. Seems to be the natural direction of the advice you guys are giving me.

Thanks again.
Stu.

[Hjt]

A good bolt in roll bar is CAMS compliant so it should be good enough for your purposes. Mine has matching door bars. It's a half cage.

[StuwieP]

thats the AGI half cage in the thread you mentioned earlier? Hard to find the questions amindst the organisation. I'll try to get in touch with AGI, see how much it might cost all up. cheers

stu

[StuwieP]

thats the AGI half cage in the thread you mentioned earlier? Hard to find the questions amindst the organisation. I'll try to get in touch with AGI, see how much it might cost all up. cheers

stu

[hks_kansei]

hks, I'm under the impression that the folding mechanism of the soft top can force the bar to be narrower than ideal, rather than necessarily finding more headroom?

Ah, yes, the hardtop has a bit more room in that regard, but it's still only a small amount.

The top has humps at shoulder height to fit the side latches to, so it sits about the same as the softop frame.
The width at head height and higher is limited because it tapers inwards slightly.




Also, regarding the Vic rules for rollbars, make sure to look into it a bit further, I think the regs have changed in the past year or so.
(the rollbar guide I referred to when I bought my bar a few years back is no longer listed on the vicroads site as current)

[StuwieP]

yeah using the NCOP regs now which are as clear as mud, hence consulting with David on building the bar, and if they decide to change the regs in the future (which they surely will) I'd rather avoid things that could be considered unroadworthy.

[jorgan92]

Anything worth doing to your car in Victoria is illegal, most cops are a bit nicer on MX-5's than they would be say, a skyline. one the other day claimed my car was "the safest thing on the road" because of my roll bar

So don't worry too much about the rules, at the end of the day you can still get a defect for something 100% legal. Just make sure you can get it out if you need to, that's my advise.

[StuwieP]

at the moment I'm not serious (or financially secure) enough to get into full on racing, so probably not worth going the whole hog. again, consulting with David to figure out what is best to do for me, and to get certification for it. NCOP suggests exemptions for their regs could be granted by vicroads (not explicit but hopefully 'implied')

re the cops, i've nothing against them and i figure there's no point in being anything but polite. my car is hardly offensive (yet I'll have to work on that) and door/sill bars shouldn't attract much attention. a 4 point half is completely legal though, so, no trouble there.