I have a fabricator to build me a custom rollbar, but I need some info first... can anyone tell me

- suggested (required) tubing diameter / wall thickness? I'm interested in chromoly only.

- preferred rear mounting points? The Kirk mounts in the jack storage bins. The M2 mounts on the shock towers. My fabricator suggests mounting to the floor, on either side of the spare tire (roughly). Any pros/cons to any of these?

I'm sure there are specifications and regulations out there for SCCA or other governing bodies, but I can't track em down.

Thanks

 

...oh, and if it matters, this is for road racing specifically, looking to the future of perhaps needing to pass SCCA regulations.

 

well you need to do some researching on scaa regulation rollcage specifications. Find out what is required and what needs to be done to make it regulation. Also, your fabricator should know some of this.........if he's really a fabricator that does this a lot at least.....

 

i dont belive scca allows chromoly.. thats what ive heard from some of my customers who run scca, i belive scca website is scca.org

Michael

 

The kirk does mount in the bins, but thats an option. You can order it to mount in the bins or on the floor behind the seats.

Check this thread out. It explains clearance issues with the kirk bar.

https://www.rx7club.com/showthread.p...ht=kirk+racing

It only costs about $350, so it might be cheaper to buy the kirk bar instead of custom fabbing one. And with this bar, you know it meets regulataions.

 

If the "fabricator" does not already know this stuff, find someone else. Seriously. This is literally a life or death matter and it requires an experienced person to do the job.

To answer your question: go to scca.org and order the General Competition Regulations (GCR). Read Section 18, in particular. It will give you the basics, but the fabricator *must* have a personal knowledge of what will fly with the local tech inspectors in your region. You can also read my article on roll cages in the March issue of Driving Sports magazine. I'll send you a copy if you email me your address.

Some free advice: stop everything, attend some races, see what it's all about and where you will fit in (classes), meet some drivers, ask who built their cages, etc. Considering that you didn't know where to find the regs, I can only presume you have no track experience whatsoever. Go take some driving schools before you commit a penny to car preparation. You might find that the experience is not all you dreamed it would be, or that the expense is not worth it. Perhaps you will decide to get a cheaper car to start off in (Pro 7 or Spec Miata) and learn the ropes. In what class do you expect the 3rd gen to run? ITE?

All I'm saying is look before you leap.

 

if you want chromemoly... you gotta tig it! I don't think you will get good enough penetration if you try to mig or stick weld which might fail under stress. if your "fabricator" can't do a decent job at tig welding, find someone else which can!

 

No, it's just that they did away with the potential weight savings, so the double or triple cost is not worth it. Chromemoly (4130) tubing is stronger than mild steel for a given size/thickness/weight, but very, very expensive. In the past you could use a thinner wall 4130 tubing to achieve equal strength as 1020 steel. However, (1) it made racing more expensive as the weight savings cost a lot of money and (2) people were lying about the material to get the weight savings (by using thinner wall 1020 and passing it off as 4130), but at the risk of their lives. So, now, the tubing thickness is the same for either material and there is almost no benefit to paying the high cost of 4130. Not only does the material cost more, but it must be properly stress relieved (normalized) so that the welds don't crack. This usually means TIG welding by an expert fabricator, rather than MIG welding my almost any half-decent weldor.

 

Thanks for the advice guys. The shop who can build the bar for me works exclusively with chromoly. Their primary business is building tubular race car chassis. He builds a lot of roll bars and cages, but not for SCCA.

And Blake, your advice is sound. I have been driving DE events and my primary purpose in getting a bar is for personal peace of mind, safety, facilitating a harness...
My question is based on knowing enough to know that perhaps someday I might want to race SCCA and that they have specific regulations that I would like to not violate with a rollbar that has been permanently welded in my car.

So... given the fact that the GCR is not freely/readily available and assuming we have some SCCA racers on this forum, I thought here would be a good sounding board so I didn't make a mistake going with the wrong bar.

The class in which a 3rd gen might run I suppose would be a good topic for another thread as its not my primary concern at this time

 

You need at least 6 points of contact with the frame/body. You should be at least .125 wall and 2in od. Every cage design will be different but the objective is the same.

Adam

 

1) 3rd gens do not run in any of the SCCA IT classes. At least not in anything that resembles a stock car (think tube frame). In anything near stock form, they can only compete in Solo-I and Solo-II.

2) You will not get a definitive answer from this forum, For example, the 2in OD requirement mentioned above is not necessarily true (hint: it depends on the roll-bar design). Contact the local SCCA folks and talk to thiir head tech inspector directly. That is the best way of getting correct answers.

-bill

 

In Solo-I, you are classed according to autocross modifications. Downpipe = ASP...

The FD used to be in GT something or other when it is was a showroom stock car.

You can run whatever you want in SPO today, but then you might as well be at a track day with unlimited passing because there will be some tube-frame beast lapping your slow a$$.

I had a custom bar done for my car a few weeks ago. PM me for more info, I don't want to get all worked up about why I sold my bolt-in and paid a hefty sum to get a bar done right the second time (sigh, I hate when I have to re-buy something because I didn't know enough about purchasing it the first time). I use my FD for HPDE and have decided I'm not an autocrosser, so I'm going to time-trial to maintain my Mazda Motorsports membership.

I would advice you find another fabricator that knows SCCA regulations. They will be using both the Solo-I and Club Racing GCR to design the bar, and EXPERIENCE SPEAKS VOLUMES! I know that folks have had cages designed by non-SCCA shops that were failed and had to be redone from scratch.