[nderwater]

The only harness bars I've found for Miatas are made by Hard Dog - are there any other shops (jdm?) which sell these? Have any of you guys fabbed your own, or had one added to your rollbar?

Now that I'm living so close to Road Atlanta and Barber Motor sports Park, I'm itching to get back into running HPDE events like I used to run in my E30 BMW's. Tracking a convertible, though, has become a bigger expense than I expected - I've already purchased and installed a roll bar, but some local events require a harness bar and harnesses to pass tech. My helmet is expired, so I also need a new one of those. Add these expenses to the $400 entry cost of a typical weekend DE event, and I've spent almost half the purchase price of my car! And that's not even counting the extra maintenance work and professional inspection needed to get the car ready for the event.

Here are the rules for some local club's driving schools:
> Peachtree BMWCCA - Convertibles not allowed, even with roll cages
> SCCA - Convertibles must adhere to safety regs for the applicable race class
> AudiClub Cherokee - Convertibles require rollbars and harnesses
> Peachstate PCA - Convertibles require rollbars
> NASA Southeast - Convertibles require rollbars

For you guys who participate in HPDE's and other track events, what safety gear do you recommend installing, and where did you find the best deals?

 

[DRFT MX5]

I've found the NASA guidelines are the best to go by. If you have a Hard Dog Hardcore bar you should be fine. The real issue is having your helmeted head far enough below your bar. For most americans it takes an aftermarket seat. The cheapest and easiest to get low that I've seen is the ultra shield seats (which is what I'm buying). But be warned they arne't pretty.

 

[roadsternut]

Having a rhd car, luckily I can attach the harness in the manner recommended by the JAF; directly to the shelf with backing plates. Not sure you can do this on LHD cars though.

Most JDM harness bars are designed to tie into a roll bar.

Tuckin99 bar:

D-Technique bar:

Kyouei Sports bar:

 

[VtecMX5]

I was thinking about making one for my car.. wouldn't take much.. maybe like $20 in parts. Might get expensive if I wanted to powdercoat it, unless people wanted in on it.

 

[Matt [exz3owner]]

what rollbar do you have that doesn't already have a harness bar?

and who is JAF? no sanctioning body in the US would allow harnesses to be attached to sheetmetal...

 

[Greg G]

JAF: Japan Automobile Federation

 

[VtecMX5]

@ Thu Aug 24, 2006 6:27 am]what rollbar do you have that doesn't already have a harness bar?

You askin me matt? I have the Hard dog extreme, with single hoop. eventually i'll upgrade it after I get all my other projects completed, but for now I was thinking of making a harness bar, since mine doesn't have the ability to add one to the bar.

 

[nderwater]

i have the hdhcdd m2 - harness tabs, but no harness bar. the tabs are mounted low on the bar's uprights, which isn't exactly the best location to mount one strap, let alone both.

 

[roadsternut]

@ Thu Aug 24, 2006 2:27 pm]what rollbar do you have that doesn't already have a harness bar?

and who is JAF? no sanctioning body in the US would allow harnesses to be attached to sheetmetal...

Both of my last two roll bars, from Okuyama and D-Technique, didn't have a harness bar. The Japanese Automobile Federation is the body in Japan that administers motorsport, on behalf of the FIA. The JAF published specific advice on the old roadster website at http://www.printpia.co.jp/rashinban/, recommending for the Roadster, attachment of the shoulder straps to the unibody at the back of the shelf, and not to use the various harness bars in sale. I think this is to do with the fact that most of these harness bars don't meet FIA guidelines for harness attachment; firstly, there is the dubious dependance on a bar that can distort and bend in a side impact.

The FIA requirements for harness fitting is that the shoulder harness should be ideally 0-10 degree below deflection from the driver's shoulders, but no more than 35 degrees, to prevent unnecessary injury. Note how the D-tec bar is much higher than the Tuckin99 bar, putting less downward load on the driver's shoulders.

For some drivers in some seat configurations, you exceed or get very close to the limits.

As for attachment through the unibody (the "frame" of the car for monococques), the SCCA regs are pretty much the same as any other FIA snctioned regulation in this regard. While direct attachment to the rollbar or to the "frame" of the car is preferred, attachment to suitably reinforced other placess is acceptible.

You should read your own regs before making a sweeping statement :roll: :
http://www.scca.com/_FileLibrary/File/GCR2006.pdf

Each seat (lap) and shoulder belt of the harness (5, 6, or 7 points)
shall have an individual mounting point (i.e. 2 for seat belt and
2 for shoulder belt minimum). Six or seven point system antisubmarine
straps may share a mounting point with one or both
seat (lap) belt(s). The minimum acceptable bolts used in the
mounting of all belts and harnesses is SAE Grade 5. Where
possible, seat belt, shoulder harness, and anti submarine strap(s)
should be mounted to the roll structure or frame of the car.
Where this is not possible, large diameter mounting washers or
equivalent should be used to spread the load. Bolting through
aluminum floor panels, etc., is not acceptable.

This is what these parts are for :

Spreads the load, hence backing plates. The reason, I think, you can't fit these in Miatas is that the area used for the harness reinforcement plates is taken up by various screw down access panels for the fuel pump and tank senders. Probably not strong enough. But as I said, on the other side, for rhd cars, the metal work is planty strong enough.

 

[retrorocket]

Having a rhd car, luckily I can attach the harness in the manner recommended by the JAF; directly to the shelf with backing plates. Not sure you can do this on LHD cars though.

Most JDM harness bars are designed to tie into a roll bar.

Tuckin99 bar:

D-Technique bar:

Kyouei Sports bar:

... the tuckin99 and D-T bars look quite nice, Arrive and Club IGB also make similar ones

 

[roadsternut]

THe only good looking harness bars I've seen are tied straight into the rollbar, but just bolted in place.

 

[khorton]

Here's some I had fabbed up. Seamless tubing and collars from an industrial supply house. A local welding shop welded the collars to the tubing. The original owner had a Hard Dog Hardtop put in but specifically no harness bar, so I had to add it later.

 

[firedog25]

I was thinking about making one for my car.. wouldn't take much.. maybe like $20 in parts. Might get expensive if I wanted to powdercoat it, unless people wanted in on it.

Not really, I got my intake manifold, valve cover, and strut tower bar brackets powdercoated for $200 shipped from Ca. to NJ. and back again.