Rollbar question

[WutApex]

I've recently been contemplating adding a roll bar in my car as this would allow me a secure method for adding a harness and race seat.

I've discussed a custom set-up with a couple local builders and this is the route I'll probably go, which will definitely prohibit any possibility of having a rear passenger since the rear supports will be tied in to the rear subframe in the trunk.

I'm still thinking about the MM bar w/removable harness bar for the rare times a passenger would ride in the back seat since the rear supports tie into the wheel wells instead of the trunk (yes, I know and understand the risks associated with it)

My salient question is: would it be wise to tie in the MM bar to the rear seat riser for additional rigidity? Has anyone does this? Any pics?

Separate question: can I use an aluminum race seat, i.e. Kirkey/Butler/Ultrashield without any rear support, i.e. harness bar w/seat back brace? Are they structurally strong enough to hold up in an accident only being bolted to the floor?

 

[wheelhopper]

Don't know about the aluminum seats. I do know that if you are serious enough to add a roll bar, you may as well have it done right and not worry about the rear seat. Chances are your suspension is not going to be friendly for taking a bunch of passengers around anyway, and when you do you may as well not have them bang their heads and knees into steel bars in an incident. One passenger at a time.

 

[suaveflooder]

^^^truth

 

[a1yola]

I have the Mm 4-pt rollbar with removable harness bar and welded-in cross bar. I got the removable harness bar for the same reason as you stated, for potential passengers. But to be honest with you, since I removed my stock seat belts (have to use harnesses all the time now) and have the welded-in cross bar, there's no chance of having passengers back there anyway. I should've went with a welded-in harness bar.

As for aluminum seats, I was talking to the guy that runs ioport racing here in northern California and he said you should use a seat back brace. Aluminum seats are constructed of pieces of metal welded together. In a high impact crash those welds breaking apart are a potential hazard. Better safe than sorry...they're less than $100!

 

[Sirl]

I also have the Autopower bolt in with removable Harness and Diagonal bars.

It has been a great compromise between street car and track car for the past 3-4 years. I have put my kid back there many times, to go to local shows and meets.

At this point its becoming more All Track, so, i'm on the verge of selling the bolt in and getting one welded in.

Point is, its hard when your car is a "tweener" In between track and street car. IMO, the autopower bolt in is the perfect mix, and suited me well.

Just my opinion, of course. Luckilly, never had to use it.

I would not use the Aluminum style seat without a back support. In a hard hit, I dont think it would hold up. Just my opinion, i've never used one.

 

[David Hester]

Couple of things. If you plan (or even if you don't plan right now) to run with NASA HPDE or SCCA PDX, go on line and look at their rules regarding rollbars. Both allow them in track day, and even some hillclimb classes, BUT if you install one, even if not required in your group. it must meet standards. Curved kickers used by NHRA are not allowed in NASA/SCCA. Ask before you spend your money. Fellow on FNSweet for Roushs, bought one "made from same tubing used in racing" that is worthless for NASA/SCCA. AutoPower has approved bars, as does Kirk Products.
Also with passengers (and yourself, of course), don't forget padding!

As far as back support, it is required with Aluminum seats, NASA and SCCA, and I would with FIA seat, too. Saw a Miata driver get beat to heck by his car when his approved FIA seat flexed enough to beat his head against his Petty bar and doorbars. He went off driver's right smacked wall, that was 2 hits to helmet-on impact and whiplash, then crossed track backwards and hit left side wall- 2 more hits to his head. Worker I talked to said he expected to find body parts when he looked in car, there was so much blood. Most was from his nose and lip. Moving on.
Supports are easy to make, or I/O Port has one pretty cheap. Watch some YouTube in car and watch some of the seat flex and belts slack with just 1- 1 1/2 G cornering. Imagine a 50-70 G crash. I always support seat to cage.
In the Fox car, I had a tube in a tube with several holes, so we could adjust seat for wife and I. Used stock seat rails with a couple of steel strips welded to mount seat bottom and a pull pin.

 

[David Hester]

Sirl
BTW I had a bolt in AutoPower cage that I welded up. SCCA GCR tells you what is acceptable- Removed one bolt at a time and filled in holes. Welded an extra "L" plate to main feet and then welded that to floor/sill. It was in the white Fox body we crashed tested. Could do the same with Rollbar, unless you are thinking about a cage.

 

[WutApex]

Kinda what I thought with the Alum seats....I've never seen any, in person or photos, without a rear support brace.

From what I've read, the footplates on the Autopower bar are a bit small. I think by the time I modify it (bigger footplates? / tie in to SFC / tie in to rear seat riser) that a custom bar would be better.

Any problems with using the stock 3-point seatbelt with the Autopower/MM bar?

Any big differences with the tube thickness? AP= 1-3/4" x .120 DOM, MM= 1-3/4" x 0.134" DOM

Both builders I spoke with mentioned tying in to the rear subframe in the trunk.
Is mounting to the wheel wells sufficient?

 

[David Hester]

LOL I sort of bounced around. Just tried to tidy up.

in order
1) yes go bigger
2)Not for most PDX/ HPDE, some Time Trials
3) Extra weight is your enemy.
4) Personal preference. Both have advantages.
Now back to my rambling.

Note thickness for rollbar vs roll cage is different.
One thing to think about ... thicker walled than required adds weight you don't need.....
You and builder will be interested in pages 28-34
http://scca.cdn.racersites.com/prod/assets/2012 TTR - All Levels_v3.pdf
Pages 10-118
for cages
http://scca.cdn.racersites.com/prod/assets/2012GCR-updatedAugustMobile.pdf
Both builders you mention know the requirements, as opposed to "tuner shops" that don't all seemed to worry about function over style.
As long as they know you are interested in road course over drag race bars, sounds like you are good to go.
Autopower tied into wheelwheels with their Fox body cages.- added bonus of giving some support, even without the cross bar wheel well to wheel well.
A/Sedan cage was built by SCCA/IMSA racer-builder Tommy Higgins and he tied to frame rails.
SCCA allows 144 sq in foot plates. Bigger than Autopower uses

 

[Sirl]

Thanks David,
Always appreciate your insight and wisdom.

 

[a1yola]

Kinda what I thought with the Alum seats....I've never seen any, in person or photos, without a rear support brace.

From what I've read, the footplates on the Autopower bar are a bit small. I think by the time I modify it (bigger footplates? / tie in to SFC / tie in to rear seat riser) that a custom bar would be better.

Any problems with using the stock 3-point seatbelt with the Autopower/MM bar?

Any big differences with the tube thickness? AP= 1-3/4" x .120 DOM, MM= 1-3/4" x 0.134" DOM

Both builders I spoke with mentioned tying in to the rear subframe in the trunk.
Is mounting to the wheel wells sufficient?

I once read that the stock 3-pt seat belts should NOT be used with any type of roll bar/roll cage. I forget the exact reason off the top of my head, but it's something about the design of stock belts vs harnesses. Stock belts allow the body to move a certain way during a roll over and harnesses are designed to move the body in another way. Harnesses are designed with the intention of a roll bar/roll cage being used.

 

[WutApex]

All these limitations (having to wear harness full time, no rear passengers, not drilling holes for tow hooks, no hitch for a trailer, etc) and the money involved (purchasing seat, harness, roll bar, back brace, etc) is really pushing me toward a cheap, already built, dedicated track car like a Miata (I'd still have to drive it w/full cage to & from the track).

I'm also looking at track-oriented WCM Ultralite/Birkin/Westfield/Locost type cars but I'm worried about reliability.

I guess I have to put some serious thought into what I want to do...the car is in too good of shape to turn into a dedicated track rat.

Thanks for the info guys - I appreciate it.

 

[wheelhopper]

^That is your best decision. I have many friends that took a street car and spent well over $10K to get a cage and seats custom installed. Then there was still work to do. I have seen track ready cars with cages many times in the $5K range. That is your best bet. All the expensive hard work is done. Just make sure it is built correctly. It does not have to be super pretty just strong.

 

[Sirl]

I couldnt agree more!!!

If I knew then what I know now... Things would be very different.

If you have the space to park a track car, go that route.

Keep your eyes on the NASA classifieds. Good cars come up all the time.

My buddy, Carmine, recently sold a track ready, 97 Cobra, and bought a full race version, both for around 5 grand.

 

[David Hester]

Yeah, live and learn. I went through 3 formula Vees, a formula ford, 2 Fox bodies I built and then the already built A/Sedan car before I bought a tube frame purpose built car. All fun, but buying a race proven car that someone else needs out from under is the best way to go, unless you just want to have fun with track days. you can do that with any car.

 

[gcassidy]

FWIW (and I know every situation is different), but I put in the A/P with removable diagonal and harness bar in 2002, and the only time I ever took it out was when I got it home.
"Here honey, look how easy this is to do!"

I never ended up taking anyone in the back seat, it's too hard to get there. We'ed always find another way to carry more than two people. :shrug:

 

[WutApex]

I know...I can count the number of times my kids rode in the car....a royal pita installing car seats. I think not having the option at all is what bothers me.