Roll Cage material clarification

[timmmy]

Hi All,

Hope you had a great Christmas and New Year

I need some advice about roll cages. Even though I intend to compete in my miata again this year I am presently building another car (actually been doing this for a while now but am getting somewhere finally), and I need to clarify roll cage material specs, as well as pick your brains about classification outside of COM.

The car is to be a replica of the 1988 IMSA/ Trans Am winning Audi Type 44. Basically its an 87 Audi 5000 turbo quattro thats heavilly messed with. Although I am still trying to figure out if I am going to make it a wide body which would push me from SPA to PA.



Heres my first question...

1) Roll cage material - I have my cage mocked up in 1" conduit right now (pic below) and I went and met with my cage builder today to discuss getting the real tubing bent upI > need to figure out what material to use. In reviewing the SCCA rule book I ahve the following information.

Over 2500Lbs 1.5 x .120 DOM/Seamless/Alloy, 1.625x0.120 DOM/Seamless/Alloy or 1.75 x 0.95 DOM/Seamless/Alloy

The target weight for this thing is about 2700 lbs without fuel or driver, amd I intend to use Chromoly Alloy for the cage. Right now I am thinking 1.75x.095, however the bend radii are larger so I may need to drop to 1.5 x .120. Any recommendations?



next question...

2. SCCA and other clssifications - As I am building this thing, I want to ensure it can be used in other competition. Anyone got any Idea what SCCA / other classes of racing this thing might be eligable for? and how I find out? - here's the basics of the car specs.

1988 Audi 5000 Turbo Quattro. Totally gutted (SPA) wiht 8 pt cage (2 seats so no petty bar)
Suspension - Coilovers and adjustable bilestiens or Konis (bilies for now). custom front lower control arms, camber / castor adjustment plates.
Brakes - Porsche 996TT (big Red) calipers up front on floaring hat S8 330mm rotors. Rear brakes 1991 200Q vented disks and calipers. Converted to Tilton dual maste cyl and vacuum from original hydraulic assist setup. note Power steering also converted to electric PS from original hydraulic.
Drivetrain - stock AWD rear and 016 gearbox, front diff replaced with LSD, mid and rear diffs are pnuematic clokable. Aluminum Flywheel with custom stage IV clutch.
Motor - Initially - built 5 cyl, with ported and matched head and sport cam. custom inlet and exhaust manifolds. big hybrid turbo and intercooler with SEM fuel injection system (034EFI). Motor should be making approx 300+WHP. Later (if I like the car on teh track) I will switch to a fully built out 7A 20V motor which should make upwards of 500WHP, or maybe a twin turbo audi V8..but thats much later.

Thats it. I plan to get this thing on the track later this year, certainly wont be ready before the first event, but maybe by August.

Thanks

Timmy (Haydn)

[offcamber09]

This won't answer much of your questions, but here's a start.

SCCA car class would be regional-only SPO. Basically a catch-all class for over 2.5L motored cars. Up until this past season there were no forced induction cars (other than DSR/CSR formula cars with bodies) legal for national competition. SCCA realized they were falling behind the curve as far as factory "tuner" cars are concerned so the SRT4 and WRX STI became legal in T2 (?) which is a very stock class.

As far as COM goes- I highly suggest the wide-body kit, thus moving to PA.

From 2005 SPA Champ ,

[timmmy]

Hey Scott,

Thanks for the info, it actually helps a lot as I couldnt find a competition SCCA class the car would fit in. Back in the motherland (UK) we used to have a class called classic thundersaloons which was perfect....

Ill keep looking here, its just a 'play' car anyway and I doubt I would ever wheel to wheel it as I dont have the balls for it ...... yet.

As for SPA vs PA, Given my current rate of progress, coupled with my driving ability I think youre championchip is safe for at least a couple of seasons even if I dont go wide body.

Cheers

[therooster]

I think that in the SCCA your car would be at ITE car, another catch all regional class. The difference is you car would be a modified TUB car as opposed to a purpose built TUBE frame car. You would have to meet some requirements such as meeting the rules of sanctioning body (old SCCA Trans AM) and run DOT tires. More fun in my opinion.

Either way your cage would pass as far as tubing from what I read.

Chris A.

[gread]

BMWCCA has been in discussion with upgrading cars over 2800# to go to 1.75 x .120 tubing for their rollcages. SCCA is also looking into upgrading material for rollcages due to the higher speeds being encountered with the upgrades in rubber and power. I would stick to 1.75 x .095 DOM minimum tubing as your main safety cage material with a fair amount of gusseting. Tubing gets most of its bending rigidity from O.D. and around your body I suggest not skimping for radius near the car body. If your going all-out race, strength is better than visual appeal. Also make sure the cage tie ins pick-up the subframe points wherever possible and try to keep the drivers door bar up and away from your head as much as possible. Just my $.02

[jlwhorf]

NASCAR mandates 1.75 X 0.095 DOM tubing for the main cage. If you are going for safety, install NASCAR style door bars for the driver (4 parallel horizontal bars with 4" long vertical bar connecting them). It may be more difficult to get in and out of, but is much safer if you have a side collision.

Jonathan
900 Monte Carlo PA

[offcamber09]

"Thundersaloons"...I love that.

I should have added that my lead-sled's cage is 1.75x.120 DOM.

There is likely to be more competition in SPA than PA. I was joking in my previous post- the more the better. There are much faster SPA cars than mine lurking out there.

[timmmy]

Hi All, and many thanks for the great input.

I was originally planning on the 1.75 x 0.095" and it sounds like I should stick with that, dont think I want to go up to .120 everywhere, althouhg I may do the main hoop and front bars in that as they have the bends adn would be tough to change out later. the streight parts can always be upgraded later if the SCCA change thier regs.

Ill look into the ITE class and see if I can make this thing applicable just in case. I have been scouring the web for the old specs for the Trans AM cars, not had much luck yet, although I have a lot of good photos as reference so I am basically copying all that to a point.

Another question for you all though...... I am tying the cage into boththe front and rear turrets with diagonals in as many places as seems feasable. My question is can I tie the cage into the body elsewhere with gussets. I would like to tie into the window pillrs, B pillar and a few other places in teh same way rally cars and touring cars do....or is this a no-no in the US?

here is a shot of a new BMW cage - notice A) the wierd and huge gussets up front...but also the gussets at the B Pilalr and the seam welds to the A Pillars



im trying to find better shots....

Scott, out of interest what does your mustang weigh in race trim?

[offcamber09]

Mustang = 3050# full of fluids and minus driver. 340 hp at the crank.

[christine]

Another question for you all though...... I am tying the cage into boththe front and rear turrets with diagonals in as many places as seems feasable. My question is can I tie the cage into the body elsewhere with gussets. I would like to tie into the window pillrs, B pillar and a few other places in teh same way rally cars and touring cars do....or is this a no-no in the US?

You want to be very careful about where and how you attach the cage. Cages have been protested and disqualified over attachment points.

You can get an online copy of SCCA's GCR (General Competition Rules) and other info here:
http://www.scca.org/Club/Index.asp?IdS= ... &x=030|057&~=
They have diagrams and specific info regarding cages. You might also consider posting on the IT forums:
http://itforum.improvedtouring.com/forums/index.php
I know that some SCCA techs like Dick Patullo hang around there.

Christine

[kfoote]

The COM rules for tubing size and diameter are for roll bars, not for full cages. My reccommendation for tubing size on the cage you are constructing would be to SCCA specs. One little tidbit about the SCCA cage rules: You have to use the same tubing size throughout the cage. For SPo (and COM PA) you don't have to worry about the number of chassis attachment points, as long as it meets the minimum.

Any car with an E46 BMW Motorsports chassis would be a PA car. If you'd like one, I know where you can get one. That design isn't exactly new, it's been used since 2000.

On a side note, a Google Image search for "PTG BMW M3" has a pic of me on the second page . I had thought that A-pillar cage design was used on the PTG E36 M3's as well, but that is not the case.

[timmmy]

This won't answer much of your questions, but here's a start.

SCCA car class would be regional-only SPO. Basically a catch-all class for over 2.5L motored cars. Up until this past season there were no forced induction cars (other than DSR/CSR formula cars with bodies) legal for national competition. SCCA realized they were falling behind the curve as far as factory "tuner" cars are concerned so the SRT4 and WRX STI became legal in T2 (?) which is a very stock class.

As far as COM goes- I highly suggest the wide-body kit, thus moving to PA.

From 2005 SPA Champ ,

Im having a hell of a time trying to find regs for SCCA SPO /SPU.....anyone got a valid link?

[timmmy]

Another question for you all though...... I am tying the cage into boththe front and rear turrets with diagonals in as many places as seems feasable. My question is can I tie the cage into the body elsewhere with gussets. I would like to tie into the window pillrs, B pillar and a few other places in teh same way rally cars and touring cars do....or is this a no-no in the US?

You want to be very careful about where and how you attach the cage. Cages have been protested and disqualified over attachment points.

You can get an online copy of SCCA's GCR (General Competition Rules) and other info here:
http://www.scca.org/Club/Index.asp?IdS= ... &x=030|057&~=
They have diagrams and specific info regarding cages. You might also consider posting on the IT forums:
http://itforum.improvedtouring.com/forums/index.php
I know that some SCCA techs like Dick Patullo hang around there.

Christine

Hi Christine,

Many thanks for the info. I looked into IT and I dont think this car fits there as there is a caviat about no turbocharged or supercharged cars in IT. I think Scott is right with the SPO but I am struggling to find the actual regs.

The cage plan right now is per SCCA GCR regs but the regs are not 100% supported by some of the cage images I am seeing. i.e. the regs say...(from touring category)

"B. It shall attach to the car at no more than eight (8) points,
with the forward section of the cage attaching to the front
bulkhead or front fender wells (see GCR Section 18.2.,
Figure 1)."

however I have seen several IT car cages that are tagged into teh A & B pillrs. As this car is to more of a track day car than an SCCA car (unless I can get it to comply with SPO once I find specs) I am thinking I will tie it in per the Eurpoean guidelines. Nice thing at this point is that I have some time up my sleeve as it will be weeks until teh basic cage install is done and I can add teh tie in gussets later if I decide to go that way.

Cheers

[timmmy]

The COM rules for tubing size and diameter are for roll bars, not for full cages. My reccommendation for tubing size on the cage you are constructing would be to SCCA specs. One little tidbit about the SCCA cage rules: You have to use the same tubing size throughout the cage. For SPo (and COM PA) you don't have to worry about the number of chassis attachment points, as long as it meets the minimum.

Any car with an E46 BMW Motorsports chassis would be a PA car. If you'd like one, I know where you can get one. That design isn't exactly new, it's been used since 2000.

On a side note, a Google Image search for "PTG BMW M3" has a pic of me on the second page . I had thought that A-pillar cage design was used on the PTG E36 M3's as well, but that is not the case.

Hi Kevin,

Thanks also for the valuable input. I think I am settled on 1.75 x 0.95 (may go a bit thicker dependant on whats available) Alloy throughout the cage. Youre comment about 8 points min is interesting, as per one of my other responses, I dont suppose you can point me in the right direction to find SPo Regs?

Haydn

[kfoote]

Hi Kevin,

Thanks also for the valuable input. I think I am settled on 1.75 x 0.95 (may go a bit thicker dependant on whats available) Alloy throughout the cage. Youre comment about 8 points min is interesting, as per one of my other responses, I dont suppose you can point me in the right direction to find SPo Regs?

Haydn

The SPO Cage regs fall in general under the "Production" section of the roll cage regs, section 18.6 of the GCR