Miata Door bars

 Looking for feedback from people who have or have had door bars in their NA NB's. 
 

My '96 Miata track car only gets driven to and from events. Blackbird Fabworx rollbar and Kirkey road race seat installed. I see the bolt-in door bars on the market are purely for chassis rigidity and not for side impact safety but I'm wondering just how worth it they are on track. It looks like the HD bars are really the only option in stock at the moment. Not planning to go full cage as this will be a Time Trial car at most. 

Seems like some people took issue with the way they were anchored at the front, into the floor pan. Anyone experiment with alternative ways to anchor the bars at the front? Anything else I should be thinking about before pulling the trigger on a set? 

Subscribed because I have the same interest as well.

I had a one from Blackbird that was tied to their rollbar and connected to the A-pillar instead of the floor which is a more rigid spot compared to Hard Dog one. While it helped with stiffness it was pretty intrusive cabin space-wise. 

Have you driven a car with them installed yet?  Personally I find them really intrusive into the space where my knee and left foot want to go, and they raise concerns about injuries during side impacts.  Not a fan.

I will third the comment about intrusion. That's the primary reason we never added them to our product catalog.

+3 on intrusion.

Without gutting the doors, just about any bar in that area is going to take up a lot of space.  I have seen some that run very low along the sill, but I wonder how much they actually contribute to rigidity.  I would start with frame rails and seam welding the door openings.  The seam welding is pretty easy and quick, and made more of a difference than I would have expected.

All that said, our NA is a TT/HPDE car, and I eventually caged it.  Even though I'm not doing W2W, anything can happen, and you're still on track with other cars.  Not only do I feel much better about the total safety package, but the difference in driving dynamics due to the increased chassis stiffness was well worth it.

What are you actually looking to accomplish?

If it's rigidity, I'd look for a set of frog arms. Likely a similar increase in rigidity w/o becoming an interior hazard

Sounds like a no to the bars so far. My only interest in them was for chassis stiffness to inspire a little more confidence in the corners. I was originally looking at the DIYroadster bars due to being set lower in the car but they're out of stock. 
 

Seam welding is an appealing alternative, other than the fact that I'm not equipped to do it and would have to figure that out locally. 
 

I would love to have it caged but the cost is restrictive for me at the moment. I live in a condo, no room for a truck/trailer and I often drive from CT to NJMP, sometimes further making a full cage kind of  impossible. I mean, I guess I could be that guy on the highway in a helmet and Hans lol. 

Seam welding is definitely the first step if you're looking for rigidity in that area. And hey, for the price of getting someone to do it you can buy your own welder :) A spot welder actually works really well for the door opening and they're fairly small.

An alternative is a butterfly brace, especially if you put a flat panel over it for improved aero.

I will add this as some may find it useful:

Once upon a time we were going run the Datsun at a tarmac rally; which meant (for us) keeping the door windows. We added on door bar at the sill (required) for the other door bars we simply hammered out a pocket in the door for the bar to partially tuck into. Basically the 1.5" door bar would only protrude into the cockpit by 3/4" of an inch. Note you could only roll the drivers side window up and down with the door open.

Much like Rodan I'm a fan of full cage for Time Trials/HPDE but I get it's not the most practical. I street drove my Showroom Stock Miata; I am small so there wasn't the issue of my head connecting with the cage.  If I had to pick a compromise I'd either beef up the drivers door using panels with flared holes welded into the door or run a diagonal from the hoop  to the floor that at least added some additional protection my torso. 

Or you could put a full cage in it and wear an open face helmet on the road trip.

One possibility that would require some custom fabrication, but could help fore-aft rigidity is a removable petty bar.  You'd have to check the rules for whatever organization you're running, and you couldn't run a passenger with it, but it should be possible to build it to be easily removable for street driving.  I'm not sure how much it would actually contribute, though...

Another thing I thought about at one time was a bolt in bar that ties the windshield header to the roll bar.  Again, may not contribute much, probably no better than bolting on a stock hard top, but it would be easy to take out for street driving.

In reply to Rodan :

I've had the same thought about tying a roll bar to the windshield header. I suspect it would be fairly effective, as you can see them move independently and there's a lot of leverage up there to close the box instead of down near the floor. You could copy the Caterham style of arcing center bars to keep some head clearance.

In reply to Keith Tanner :

I had similar thoughts a while back after seeing this BBFW 'street cage':

Without the door bars, it would be an interesting alternative for a dual duty car, but probably wouldn't meet the requirements of many race orgs.  Ultimately it became moot for me when I decided our car would be a dedicated track car.

calteg said:

What are you actually looking to accomplish?

If it's rigidity, I'd look for a set of frog arms. Likely a similar increase in rigidity w/o becoming an interior hazard

I'll go the exact opposite. I saw no difference with frog arms at the track and took them back off and sold them. Even on 800/500 spring rates and RComps. 

Although to be fair, my car had a roll bar and Flyin' Miata frame rail reinforcements with the butterfly brace. The frame rail + butterfly brace was HUGELY noticeable increase on a floppy NA. 

In reply to Rodan :

Moti (Blackbird) has a history with Sevens so I'm not surprised he's tried it :) That's pretty much what I was thinking, but I'd tie it into the header without the down bars. For a "street bar" I'd probably also make it compatible with a soft top if I could. I'll bet you could install a hardtop on that with bolt-on brackets.

Moti's work has definitely been a major inspiration for the door bars and custom half cage street/track idea. I emailed him to inquire about custom bolt-in door bars as I heard he'd been working on them a few years ago. I'll update this when he gets back to me on the status of those.
 

Taking all this into consideration, I think my next move will be seam welding and cross bracing. As it turns out, a friend of mine is into welding on the side so this should be a fun thing to tackle sometime  over the weekend. 
 

And now I'm looking at cages :) Things escalate rapidly in this hobby... HD bolt-in SM cage is actually sort of in my budget. I've heard mixed things regarding the safety of those vs a custom welded in cage for W2W racing. Maybe it would do the job as a mostly HPDE car though? 

I have no concerns about the safety of the HD cage - it's a well-known and proven item from a very well established builder, but it's not as sexy as some of the fabrication flex from a custom builder. The biggest problem with it is the front bars are more intrusive than a tightly fit welded cage so you end up with a bar closer to your ankle than is ideal.

But a cage really does make a big difference in day to day useabiliry. The top bars are close to your head and the car becomes smaller inside. Ideally you'd also combine it with a proper seat and harnesses. It's a big step. 

In reply to Keith Tanner :

Thanks, Keith -- good to hear the HD cage gets your seal of approval.  It's probably the way I'll end up going despite the cramped floor area. I see they sell a street cage as well but talk about bar intrusion. I'm not sure I could live with that.  The SM cage is definitely a big step but I've got the Kirkey / IO port brace and 6 point harnesses in already.

I'll stick with welding and bracing this season. The cage will be a good winter project. 
 

So that settles it. Nixing the door bars 

If you buy a MIG welder to do the seam welding, you're almost halfway to having the tools you need to build your own cage... 

I had a HD bar in the Targa Miata for years. It would be called a street cage now. I think the front half could be improved for driver clearance but there would definitely be an increase in both cost and install difficulty. They've been crashed enough that I think it's a well-proven design, just not as roomy as some. I could put you in touch with the Lemons scrutineer if you'd like, he'll have Opinions on both the HD cages and the various Californian cage builders.

As a mid-point between an artisan cage and the bolt-in HD unit, Miatacage sells tubing kits. You need to do the final fitting so it's more involved, but if you're willing to do the sweating without having to do the engineering they're a good option. It's about the same price as the HD but you'll end up with a roomier cockpit.

If you do go for a HD cage, get the one that welds together instead of the bolt together option. It still bolts into the car, but the front and rear halfs have to be welded in situ. I don't even know if Tom still sells the full bolt-in version.