phoenix7

it should be called the hurleysurf roll bar.

RX-Heven

iTrader: (1)

Yes and no.

Whereas in this case, the main hoop does tie into the shoulder belt attachment point to prevent movement of the bar, the design as was only provided very minimal support with the given tab, no matter what the strength of the seatbelt attachment point was. The bar was still capable of folding forward or rearward over itself at the seat belt point, ripping from the seatbelt point and pivoting at its base forward or rearward and finally, buckling sideways from lateral loads.

The diagonal brace in particular, and to a lesser degree the harness bars, help prevent the sideways buckling from lateral loads and reduces the likelihood of the bar folding rearward or forward over itself at its highest support point; in this case, at the seatbelt attachment point. The door bars help strengthen the position of support at the seatbelt attachment point helping to provide MORE support against the main hoop pivoting forward or rearward at its base. Notice they also meet up with the harness bar on the main hoop. The door bars also improve the stiffness of the chassis, especially in the vert since there is no roof to provide any support.

While this is not an ideal setup for racing, my car is a street car (sort of), and my goal was to:
1. Maintain normal operation of the top.
2. Add a diagonal support bar with an integrated harness bar.
3. Add some unobtrusive door bars that will help secure the main hoop.
4. Gusset the tab that attaches to the seatbelt support.
5. Maintain clearance around my head.

I know the pics make it look like the bars are right next to my head but in fact there is ample clearance, even with a helmet on and padding on the bars. The seat is all the way back and I do not drive with it that way.

There is only a **** hairs clearance between the targa top when it folds down and the drivers harness bar.

If I was to do it again and did not already have the main hoop from Kirk Racing, I would start with a custom main hoop and secure it to the floor several inches back from its current position. This would make the main hoop more perpendicular to the ground.

I've been trying to get Attila to post more pics of his bar for years now. Still waiting.
He has told he has to remove the targa top to put the top down.
FWIW, his car has been my inspiration all these long years, even preceding this forum.

lov-2-rev

iTrader: (87)

OK I lied. I couldn't let this rest for the night just yet.

Rx-Heaven-- Very good point about the entire bar pivoting forward on the floor. Makes the door bar idea much more desirable.
So in your opinion, the seatbelt tabs are inadiquite, even if the anchor points of the body are sound...... interesting. In what way did you gusset them?

As for my goals, I would have to agree with 1,2 and 5. If I use the Kirk bar, I will also plan on gussetting (or boxing with a bolt access hole) the seatbelt anchor tabs. If I can find a way around using door bars, I would like to for easier access.

Going back to my idea of a full width harness bar and such. I made a quick visual aid. This is what I came up with in a few minutes time. (don't laugh, I know it's crude)
(Disregard the copper as it is just there to hold everything in place.)




If the black legs were to intersect the harness bar at the same point, do you guys think something along these lines is viable? Perhapse anchoring at the floor behind the seats on either side of the tunnel, or on top of the chassis brace behind the seats?

Black91n/a

There'll be very minimal support there due to the very small angle between the main hoop and the other supports.

You can do a full width harness bar behind the diagonal brace, a number of roll bars do that, it's not really needed to tie them together, but if you want you can put in a little bit of tube there to bridge the gap.

phoenix7

ask www.awrracing.com if they make anything for the vert.

nitronatefc

iTrader: (2)

Anybody have the bar from Sneed Speed Shop? It is supposed to allow for full seat travel. I am 6' 3" and have my seat slid back all the way, then tilted back as far as I can in my vert. I still don't like the idea of having to remove the targa every time you drop the top with all these bars. I also was hoping to put a subwoofer in the spare tire area, but the Sneed bar won't allow that either. Here is a link:

http://www.sneedspeedshop.com/store/...idProduct=1074

I not the biggest fan of how a roll bar looks on our verts. I'm also not big on cages in street cars. What percentage of the time will you have a helmet on while street driving? Suppose you crash, and knock yourself out on the bar. Then during the crash, the bar fails and folds at the seat belt mounting bolt like we all dread. Now you are unconcious and unable to "pull a hurley" so your head cheese-graters the pavement. I ain't goin out like that yo....

hurleysurf24

iTrader: (3)

yay i have a rollbar named after me

lov-2-rev

iTrader: (87)

Here's a pic from their website for quick reference.


Nice bar but I agree, not having complete top opperation isn't an option. That is why a modified single hoop design like Rx-Heaven's is what I'm going for.

You're right, no one will be wearing a helmet during street driving. But personally, I'd rather knock myself out on a padded bar during a crash then to have no bar at all. Hurleysurf was very lucky, but what's to say you dont knock yourself out on any number of other things in an accident (i.e.- windshield frame, door edge, seatbelt anchor, etc...). Then you are upside down and unconscious without the protection of a framework above you. Seams like a no brainer to me (pardon the pun). The point of this thread has morphed to coming up with a design that is FUNCTIONAL and won't collapse during an accident, but still allows for complete roof opperation. That way, even if you are unconscious, the bar and harness system protects you; And you can still "flip the lid" for a sunday drive without issue.

Lets face it, driving a convertible is inherently dangerous, more so then driving a vehicle with an enclosed cabin. We all accept that fact every time we go out, turn the key and pull out of the drive. But regardless of weather you are 6'6" or 5'1", a little extra protection in a convertible is a good idea. Period, amen.

lov-2-rev

iTrader: (87)

True enough, but my thought was to allow for more passanger seat movment. Having the diagonal brace on the same plain as the hoop limits the seat from sliding back and reclining. Although it probably is the only viable option.

Dude, you're an inspiration to us all

Bronze MFP

I don't know if any of you have hit your head on a "padded" bar before, but it hurts almost as much as no padding. In a bad accident, even a padded bar can give you a concussion or kill you. For a street car, if there is any remote possibility of you hitting your head on the bar, I wouldnt go for that design.

One question for lov-2-rev, when you say you want functionality of the top, would you be opposed to the idea of having to take the targa section out every time you put your top down? For a roll bar in the vert to even have the possibility of rear legs, I don't see it happening with the targa piece still attached.

Black91n/a

If you have the diagonal in the right place it'll cross behind the seat lower than the harness bar so it won't limit the seat travel as much.

phoenix7

hell, take the targa part off when you go anywhere. The top frame should help with the rollover too.

lov-2-rev

iTrader: (87)

Gotcha.

as for the question from Bronze:
I am opposed to removing the targa top everytime I open the roof. My spare tire is relocated to my trunk and there is a subwoofer being mounted into the origional spare tire well cover. No room to stash the targa in the car really. So then my only option would be to take the targa off and leave it at home. Not very convienent if I want to go topless while on a cruise somewhere. No, the targa needs to be able to stay on the top when folded down.

Phoenix- Have you ever seen the frame of the vert top? It isn't all that beefy. Won't provide any real support in the event of a roll over.

Bronze MFP

Ah i gotcha. my radio doesnt even work, and the spare tire is in my storage shed. plenty of space for me. But with trunk space at a premium, i see where you're coming from though. nothing else is fitting in that trunk with the targa in it.
how about an outer cage? one that runs from the trunk, over the top and to the windshield? yeah nevermind, i'll go sit in a corner now...

jackhild59

iTrader: (7)

Juiceh

iTrader: (4)

No. I was talking about the top of the main hoop collapsing in a rollover situation. The diagonal bar to the top of the hoop helps reinforce it to reduce the hoop collapsing.

I was wondering about this as well.

phoenix7

i was looking at porsche Boxster rollbars. I was gonna post last night but my wife shut the computer down before I could.


look into it though.

lov-2-rev

iTrader: (87)

^ Damn womanfolk runnin' our lives for us. My wife does it to me too. haha

Funny you mention it though. I was following a Mini Cooper convertible yesterday and thought the same thing. The double arch design is less obtrusive visually, but I wonder how solid they are. I'm gessing they are more for style then for protection.
I then thought about two individual cages similar to those used in 50's and 60's era rail jobs, but ruled that out because of how close you are to the bars.

The brainstorming continues..........

phoenix7

seriously, look up porsche boxster roll bars, it's not the same design as you're sescribing but it looks like it might save your head.

hurleysurf24

iTrader: (3)

Getting a concussion is much better then becoming decapitated or scraping your head against the asphalt until the contents of your head leak out on to the road. Your chances of hitting the bar in such a manner are slim to none, as when you get into a frontal are sideway collision, the car stops but your body continues to move forward. Even if you somehow manage to hit someone while going 50mph in reverse ... the bar SHOULD still be high enough to prevent you from hitting it. After all the point of a roll bar is to protect you .. and if itsnt atleast 3" higher then your head, then it becomes worthless and sholdnt be installed to begin with.

If anyone can see this one you may be interested .. I use to have pictures of the car with the top down, but they took it down.

lov-2-rev

iTrader: (87)

No, you and I are on the same page. It is 2 head hoops instead of a single hoop bar. I know exactly what you are talking about. But the fact that the main/lower structure is triangulated, is intreeging(spelling?). If one was to design something similar, that also attaches to the seatbelt anchor points, it would reduce or eliminate the bar structure from hinging at the floor. Then just beef the hell out of the hoops and tie into a full width harness bar.......... I think we're onto something here...........

hurleysurf24

iTrader: (3)

i like that design .. and think it shld work very well.

lov-2-rev

iTrader: (87)

Hurleysurf24-- It is tough to see but I think it is a variation of what Phoenix and I are talking about.

**Goes back to scrap bin for more wire**

Black91n/a

I don't like the design because in a rollover the forces will likely cause the middle to collapse inward/downward. A single hoop will protect you better.

lov-2-rev

iTrader: (87)

Once again, pardon the crudeness.

The lower tape pieces represent gussets. The upper tabs represent seatbelt anchor points.

The rear bar would double as the harness bar and anchor just in front of the top motors. The hoop braces should transfer downward force to the rear legs.
I suppose additional legs could be put in between the inboard part of the hoops to the floor or something. That would prevent the center section from colapsing. Just a thought.