1 2
NickD
NickD PowerDork
8/6/19 9:06 a.m.

So, I installed a Blackbird Fabworx GT3 rollbar in my Miata a few years ago, and from what I can tell, it does not have the integrated harness bar.

Mine is the purple one:

And this is a random one I found on the internet when I searched Blackbird Fabworx harness bar:

For the record, I did not spec this rollbar, or I would have spec'd a harness bar just in case. But someone had ordered the bar in that purple (and clearly without a harness bar) and then backed out on the deal and I snatched it up for cheap. And it hasn't been an issue because I've been running stock seats and seatbelts. But now the car has gotten much faster and I'm flopping around in the cabin and am looking at seats and harnesses. Blackbird doesn't really have a website, and I tried e-mailing them but got a response that they are going to be out of the office for a while and will answer back then. So, in the meantime, does anyone know if there is a bolt in harness bar that plays nice with the Blackbird Fabworx bar?

bmw88rider
bmw88rider SuperDork
8/6/19 9:27 a.m.

I don't know about the attach points on the GT3 bar but I wonder if the hard dog one will work. It's just a bolt in one. Seems like the GT3 one is weld in only. I just added the Hard Dog one if you need/want installed pics. 

Dusterbd13-michael
Dusterbd13-michael MegaDork
8/6/19 9:30 a.m.

How much room behind the seat to the main hoop do you have? Like, put a stick on the backside of the hoop and does it hit your seats? 

Im working on a bolt in solution to this problem at the momentwith a duece. I have an idea for mine that may work for you

NickD
NickD PowerDork
8/6/19 10:08 a.m.

In reply to bmw88rider :

Where does the Hard Dog one bolt to? Under the stock seatbelt tower bolts, I'm guessing. I'm wondering if the Hard Dog might be the trick. 

bmw88rider
bmw88rider SuperDork
8/6/19 11:34 a.m.

 

Yeah, a few pictures for you to see. It's totally separate from the rollbar except the 1 small tie in

bmw88rider
bmw88rider SuperDork
8/6/19 11:35 a.m.

NickD
NickD PowerDork
8/6/19 2:36 p.m.

So, got a reply back from Moty at Blackbird and he said that all of their bars have been built with integrated harness bars standard for "many years now." Am I supposed to use that cross bar on the lower legs to loop the harness around then?

djsilver
djsilver Reader
8/6/19 3:57 p.m.
NickD said:

So, got a reply back from Moty at Blackbird and he said that all of their bars have been built with integrated harness bars standard for "many years now." Am I supposed to use that cross bar on the lower legs to loop the harness around then?

Yes.  Some are straight like that and some are curved to make room for the seats, and depending on where the upright lands on the floor.

tomtomgt356
tomtomgt356 Reader
8/6/19 4:05 p.m.

Yes, that is the harness bar.

BoxheadTim
BoxheadTim MegaDork
8/6/19 4:23 p.m.

In reply to djsilver :

As someone who's owned a couple of Moti's GT3 bars, yes, that's the harness bar below the cross brace.

NickD
NickD PowerDork
8/6/19 6:18 p.m.

Oh, okay. So, plot twist: I'm dumb. Whoops.

Is there a 4 (or 5)-point harness we particularly like that will work with this style harness bar? I'd heard things about the Schroth Rallye 4, but that seems to have metal eyelets on the end of the shoulder straps to bolt to something, instead of the ends you just wrap around the bar

adam525i
adam525i Reader
8/6/19 9:25 p.m.

Are you trying to use harnesses with your stock seats? The Schroth Rallye won't work with a stock Miata bucket and they don't have a quick fit pro (which works with a hans device which is a good idea) for the car either. This thread talks about installing harnesses with stock Miata seats and is worth a read through (it's mostly about sub belt routing but touches on the shoulder belt issues) - https://grassrootsmotorsports.com/forum/grm/harnesses-with-stock-seats/119168/page1/ 

The proper way to do this is likely with some different seats with shoulder belt pass throughs if you want to use harnesses in the car (go with an SFI 16.1 5 point minimum). I'm working through all of this in my E28 right now (roll bar, fia seats, 5 point harnesses and a hans). 

Adam

NickD
NickD PowerDork
8/7/19 5:27 a.m.

In reply to adam525i :

No, I'm planning on replacing the stock driver's seat with a seat that'll hold me in place better and is designed for harnesses. Most likely I will be going with the Car Make Corn's bucket seat. https://www.cornsusa.com/product-page/corn-s-original-v3-bucket-seat. Passenger side, I'm just leaving with stock seat and seat belt, because I never have passengers when I'm driving the car hard.

z31maniac
z31maniac MegaDork
8/7/19 7:03 a.m.
NickD said:

In reply to adam525i :

No, I'm planning on replacing the stock driver's seat with a seat that'll hold me in place better and is designed for harnesses. Most likely I will be going with the Car Make Corn's bucket seat. https://www.cornsusa.com/product-page/corn-s-original-v3-bucket-seat. Passenger side, I'm just leaving with stock seat and seat belt, because I never have passengers when I'm driving the car hard.

Keep in mind if you ever do a track day/HPDE, most organizations require the passenger to have the same safety equipment as the driver. 

tomtomgt356
tomtomgt356 Reader
8/7/19 7:04 a.m.

Get a 5 or 6 point harness. The only 4-point you should consider is the Schroth ASM 4-point Anti-Submarine Harness. The issue with most 4-point harnesses is that the shoulder belts are pulling up on the lap belt with nothing counteracting that force. In an accident, the lap belt pulls up and you submarine under the lap belt. This puts all of the forces fo the accident on your midsection and organs instead of on your pelvis where it should be. 

Any decent belt should be able to wrap around the harness bar. If it comes with bolt in bracket, make sure there is an adjustable buckle on that end as well. If there is, unthread the belt and wrap it around the bar instead of the bolt in bracket.

Here is a good article from an awesome car magazine on harnesses that shows how to wrap them.

https://grassrootsmotorsports.com/articles/strap-how-properly-install-racing-harness/

NickD
NickD PowerDork
8/7/19 7:07 a.m.
z31maniac said:
NickD said:

In reply to adam525i :

No, I'm planning on replacing the stock driver's seat with a seat that'll hold me in place better and is designed for harnesses. Most likely I will be going with the Car Make Corn's bucket seat. https://www.cornsusa.com/product-page/corn-s-original-v3-bucket-seat. Passenger side, I'm just leaving with stock seat and seat belt, because I never have passengers when I'm driving the car hard.

Keep in mind if you ever do a track day/HPDE, most organizations require the passenger to have the same safety equipment as the driver. 

Thank you for the info. Not planning on any HPDEs though. Not really any tracks near me except for the Glen and from what I am reading, they are really picky on the convertible rules. And BMWCCA (which I'm a member of) just straight up bans any and all convertibles at the Glen no matter the safety equipment installed. This is primarily just an autocross car and I run at the local private country club race track in their time trial series, which doesn't allow passengers.

adam525i
adam525i Reader
8/7/19 7:17 a.m.

Keep driving a few hours to your friendly neighbors to the north and do a school with the BMW CCA at Mosport, your roll bar will be fine up here and you'll have a blast (and your Freedom dollars go pretty far up here). They will give you dirty looks for having harnesses without a Hans though and the equal seats/restraints thing is also in the rules. The seats you linked to look pretty nice.

Adam

NickD
NickD PowerDork
8/7/19 9:36 a.m.
tomtomgt356 said:

Get a 5 or 6 point harness. The only 4-point you should consider is the Schroth ASM 4-point Anti-Submarine Harness. The issue with most 4-point harnesses is that the shoulder belts are pulling up on the lap belt with nothing counteracting that force. In an accident, the lap belt pulls up and you submarine under the lap belt. This puts all of the forces fo the accident on your midsection and organs instead of on your pelvis where it should be. 

Any decent belt should be able to wrap around the harness bar. If it comes with bolt in bracket, make sure there is an adjustable buckle on that end as well. If there is, unthread the belt and wrap it around the bar instead of the bolt in bracket.

Here is a good article from an awesome car magazine on harnesses that shows how to wrap them.

https://grassrootsmotorsports.com/articles/strap-how-properly-install-racing-harness/

So, if I were to get say these G-Force 5-point cam-lock harnesses, instead of putting a bolt through the tabs for the shoulder belts, I would just wrap the belt around the harness bar and through the bracket as described in the GRM article and then be done with it? And then the lap belts go to the stock seat belt lower attachment points, and I drill a hole in the floor plan and put a plate and a washer and a bolt for the center strap, obviously.

Dusterbd13-michael
Dusterbd13-michael MegaDork
8/7/19 9:39 a.m.

Pretty much!

Only thing that i would do differently:

1. Mount inboard lapbelt to trans tunnel with a large backing plate instead of the factory seat rail mounted location

2. Drill a hole in the seat pan, sandwich it with large washers, and bolt the sub strap to it. That way it stays in adjustment when the seat moves.

EvanB
EvanB MegaDork
8/7/19 9:43 a.m.

In reply to Dusterbd13-michael :

He has an early Miata so the lap belt already bolts to the trans tunnel. I'm not sure when they switched but I think it was around 94-95?

NickD
NickD PowerDork
8/7/19 9:53 a.m.

In reply to Dusterbd13-michael :

My seat belt receiver mounts to the tunnel already. I think that the early cars were like that and then later they mounted the receiver to the seat rail. And I most likely will be mounting the seat in a fixed position, because I am driving it 98% of the time and I have the seat all the way back (I'm 6'3") all the time.

tomtomgt356
tomtomgt356 Reader
8/7/19 9:54 a.m.

In reply to NickD :

Nick, I have the 6-point version of that harness in my track Miata and that is exactly what I did. I think I used 1/4" plate for the sub belt backing plate, but it's been a while since I installed it. The belt mounting ends are swapable. Consider using an eye bolt and snap hook for the sub belt. Makes it easier to install and remove for adjustment with the seat in place.

https://www.amazon.com/G-Force-107H-Wide-Snap-Hook/dp/B000CMJEIK

https://www.amazon.com/G-Force-109H-22mm-Eyebolt-Washer/dp/B001CQ0XN0

NickD
NickD PowerDork
8/7/19 1:06 p.m.

Now I just realized that the seat that I want is out of stock. So now I'm waiting for an answer on when it will be back in stock roughly.

z31maniac
z31maniac MegaDork
8/7/19 1:36 p.m.

Just now clicked the link...........those are, ahem, expensive!

NickD
NickD PowerDork
8/7/19 2:47 p.m.

In reply to z31maniac :

Yeah, they aren't cheap, but they are designed specifically to work with Miatas (seemed like, from what I've read a lot of seats are too wide or end up sitting higher than stock) and seem less likely to destroy my spine on street use than, say, the Kirkey or Ultrashields

1 2
Our Preferred Partners
sjlc9gZJcdT5zGbgMgbFoaQPsTNcvqZLhdlWCWlxqaFsu08iLhYGdnbtUMVD2KsR