THSCC Forums

Since it looks like I can't get an off the shelf roll bar to fit me in my NA miata I am looking at doing a custom roll bar. SCCA has too many rule books that all say slightly different things and don't specify exactly what applies. My car is almost exactly 2000lbs without fuel and I have enough easy weight left to remove that will offset the rollbar weight.

Is the correct guideline the 2014 GCR section 9.4? That would put me in the category :
1701 - 2699 lbs 1.500 x .095 or 1.625 x .080

Or is it the 2014 solo rulebook appendix C?
Over 1500 - 1.500 x 0.120 or 1.750 x 0.095

The 2014 solo rule book reads as being focused on solo II but makes no useful mention of solo I or solo II anywhere in the document.

Also, bethania garage goes out of their way to say that only their 1.75x.120 bars are solo I legal- I can't find any document that would require that tube thickness for my car, even looking through some of the older rule books.

My current plan is to build a bar with a mix of tube sizes and I want to know exactly what the requirements actually are.

If you're going to stay at under 2500lbs race weight 1.500 x .095 DOM is what you want.

That's easy enough.
This probably isn't new information for a lot of people on here but I thought it was interesting. I made a quick comparison of dom tubing weight per foot and then used an online calculator that approximate the relative strength. First number is weight, second number is the strength with higher being better:

1.625x .083 = 1.367 0.2
1.5x .095 = 1.426 0.19
1.75x.083 = 1.478 0.24
1.75 x .095 = 1.560 0.27
1.5x .120 = 1.769 0.23
1.75 x .120 = 2.089 0.33


1.75x.095 looks like a winner to me.

Looks heavy to me.

Solo I and II do not exist anymore in SCCA Solo speak. Solo (autocross) only.

See the Club Racing rules in the Time Trials area for a variety of rules:
http://www.scca.com/clubracing/content.cfm?cid=44472

and more specifically the Track Trials and Hillclimb link: http://scca.cdn.racersites.com/prod/ass ... _final.pdf

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Dick Rasmussen

FS 50 2018 Mustang GT

More rule books, thanks Dick. The TT and hillclimb book says: "Over 1500 lbs. 1.50 x .120 or 1.75x.095"

While the GCR says to refer to section 9.4 which allows for 1.5x.095. Regardless, I think 1.75x.095 is what I want.

Can we become a NASA club please?

I'm good with staying independent.

Means we still get to borrow from anybody's rulebook that we want to.

You should stay on the safe side. Go with solid round bar stock.

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2006 Civic Si - #24 HS for 2015

2005 GMC Sierra
1991 318is Garage Ornament

I went with a little more than a roll bar in 1.75x0.95

Very impressive, but not much room left for the subwoofers.

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Art McDonald
Premier Amateur #518
2008 Dishman Cup
Pivot Cone Snob

Rodney is a waxer (but in a good way)

Did I miss what holds up the A-pillars?

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Vincent Keene
'06 Ford Mustang GT (track rat)
'15 Dodge Charger R/T (yeah, it's got a HEMI!)
'07 Ford Fusion SE (205,000 miles and counting)
'98 Chevy Z-24 (retired)
'93 Acura Integra (Team SWB 24HOL Car)

Wishful thinking?

The setup is for HPDE and street driving. All of the off the shelf bolt in roll bars are positioned above and slightly in front of my head, which makes them super dangerous on the street when I don't have a helmet on. The main hoop is farther back such that even without belts on I can't make my head touch it.

Or what keeps those "wings" from coming in / folding over. I'm sure it's better protection than the door offered, but I wouldn't want to be in there when an SUV t-bones you.

You're saying because of the lack of a dash bar? The drivers side has a square tube running under the car that ties into the frame rails (and acts as the front seat mount reinforcement) which keep that mounting point from coming in. Dash bar + nascar bars would definitely be better but the point is not to build a caged car for wheel to wheel. I needed a custom fit roll bar to get on track at all (a harddog bar is literally above and in front of my head). Adding door bars lets me gut the factory doors which totals out to about 52lb - offsetting most of the weight of the entire setup.

The factory side impact protection is pretty sad piece of folded sheet metal attached to the inner door skin with a series of spot welds. Also, my car is no longer a rattling mess when I drive it, which is a nice bonus.

I'm with Ricky on this one, those side bars are welded to sheet metal at the bottom and have nothing holding them in place other than the main hoop at the rear. I would have skipped them.

Factory side impact protection inside the door isn't designed to stop whatever is hitting you from the side. It's intended, along with your door paneling, to give in and be soft enough when it hits you to move you sideways without breaking you too badly if whatever is hitting you gets between and A and B pillars.

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"Every ship is a minesweeper, once."