Mounting a harness in a Miata?

[Roadster]

I picked up a pair of Corbeau Forzas today and I have a new Sparco 3 in. 5 point harness (wrap around). I'm ordering a harness bar from Bethania in a couple days, but the thing I can't figure out is how people mount the lap portion in a Miata.

G-Force sells these: http://store.summitracing.com/partdetail.asp?autofilter=1&part=GFR%2D107W&N=700+400988+4294844539+115&autoview=sku. I thought about using those and the eye hooks that they also sell and bolting it to the floor.

How does everybody else do it?

[Redraceface]

First let me ask you, why do you want a 5 point harness for your Miata?

[simontibbett]

You know what I have now lol.

But for those that don't mine are to the floor (stock mount locations)

[N3v]

on the drivers side, the left lap belt mount goes into the stock 17mm seatbelt bolt, the right one goes into the 5th seat mounting bolt.

[Redraceface]

The reason I ask is very important, if you’re not going to use the car for track use I would not recommend using a harness, and if you are going to use one, you really should be aware of the hazards of using one. However the mounting of your lap belt are very important, you need to be sure that the belts will load your body at the correct points if (God forbid) you’re in a crash.
Also, if you crash your body will be restrained, but your head will not, you run a serious risk of what we in my field call a basilar skull fracture, which will cause instant death.

[simontibbett]

on the drivers side, the left lap belt mount goes into the stock 17mm seatbelt bolt, the right one goes into the 5th seat mounting bolt.

The what??...

[simontibbett]

The reason I ask is very important, if you’re not going to use the car for track use I would not recommend using a harness, and if you are going to use one, you really should be aware of the hazards of using one. However the mounting of your lap belt are very important, you need to be sure that the belts will load your body at the correct points if (God forbid) you’re in a crash.
Also, if you crash your body will be restrained, but your head will not you run a serious risk of what we in my field call a basilar skull fracture, which will cause instant death.

I usually write something like this in every harness thread lol, props. OP is smart though and I believe will be doing some track events.

[N3v]

makes sense to me, but i'm also kinda wasted.

ok ok ok, let me try this again. the lap belt part of the harness. its gonna have two uh, thingies on it, metal tabs that you put bolts through. unbolt the big seatbelt bolt on the left side, stick the tab onto the bolt, then put it back on. then do the same, except on that 5th seat bolt, the only bolt that isn't on the floor.

[Redraceface]

I usually write something like this in every harness thread lol, props. OP is smart though and I believe will be doing some track events.

Yeah, it’s how I make my living, and I cannot help but offer my expertise when I see this subject come up.

[Roadster]

It's going to be driven mostly on the track and only occasionally to meets and such.

I wasn't really planning on using the 5th strap, just the normal four. Going to Summit this weekend to get the mounting tabs for the lap portion of it. The harness didnt come with them. :)

[Redraceface]

I would advise using the 5th strap it will help you to not slide under the belts and hold them in the right place, in fact it may sound like it would hurt, but you should have it come from directly under your butt.

[simontibbett]

Yeah uthe the ball strap Tommy, I don't want you to be hurt.

[Redraceface]

If you need a HANS devise I can help you get everything set up.

[Jack-MX5ATLanta.com]

What's the head fracture thing you talk about? Just a recoil impact?

[Otto]

What's the head fracture thing you talk about? Just a recoil impact?
like he said, the body stops, but the head and neck keep moving, and it snaps like a whip, cracking the base of the skull or its surrounding bones. doesnt mean instant death, but death is common

http://en.wikipedia.org/wiki/Basilar_skull_fracture

[Redraceface]

What's the head fracture thing you talk about? Just a recoil impact?

The Basilar skull fracture is, or was (sense the wide use of the HANS) the leading cause of death in the racing world in fact a very dear friend of mine Dino Cresentini died last year from the injury. How the injury occurs is very simple the harness in a race car is intended to restrain the body, and to load the body at certain points whilst in a crash however the head is not, unless of course you’re using a HANS devise. It’s not the speed that causes the injury it is in fact how fast (as a matter of time) the car stops, I could go into all the physics, but I would rather not it’s a lot of information, but if you are wanting to know more I’ve written an article for Victory Lane magazine, but anything by Dr. John Melvin, Or Dr. Bob Hubbard would be much better than what I’ve could ever hope to write. In fact I could get Bob’s Thesis on the matter if you’d like.

[Redraceface]

What's the head fracture thing you talk about? Just a recoil impact?

It's Not recoil, We've found that the injury occurs very early in the crash almost at the very beginning when the head goes up, at that point the fracture happens, and the main artery then becomes severed then the victim bleeds to death right there on the spot. We once thought it was a chest injury because the victims would bleed from there mouth, but after looking at data very closely we (and it's very obvious) noticed that the head extended far beyond the point of which it should.

[ls1_miata]

Here is a good guide for installing a harness. An improperly installed harness is less safe than a factory 3-point.

Start at page 20.
http://www.schrothracing.com/docs/Competition_Instructions.pdf

[simontibbett]

If you need a HANS devise I can help you get everything set up.

Do you all sell HANS devices? I need one.

[Redraceface]

Yes we Do, we also are one of two company's that develop it.

[simontibbett]

PM'ed

[Doppelgänger]

The Basilar skull fracture is, or was (sense the wide use of the HANS) the leading cause of death in the racing world in fact a very dear friend of mine Dino Cresentini died last year from the injury. How the injury occurs is very simple the harness in a race car is intended to restrain the body, and to load the body at certain points whilst in a crash however the head is not, unless of course you’re using a HANS devise. It’s not the speed that causes the injury it is in fact how fast (as a matter of time) the car stops, I could go into all the physics, but I would rather not it’s a lot of information, but if you are wanting to know more I’ve written an article for Victory Lane magazine, but anything by Dr. John Melvin, Or Dr. Bob Hubbard would be much better than what I’ve could ever hope to write. In fact I could get Bob’s Thesis on the matter if you’d like.


I have my bottom belts mounted with eye-bolts to the front seat mounts, should straps to a harness bar and the lap belts to the rear seat anchors. I also don't have an airbag and hate how unsecure I feel with a stock seatbelt. Eventhough I do wear it everytime I get into my car, I also wear mine fairly tight.

What I don't get is that both a stock belt and a harness keep your body as still as possible, so how does wearing a harness properly increase the likelyhood of a skull fracture, especially with newer cars having the pre-tensioner mechanism that actually makes the belt a good bit tighter at the moment of impact? I'd guess a skull fracture can just as easily happen with a stock 3-point belt, but the fact the anyone on a track is most likely to have a harness kinda takes away from even thinking about that type of injury when wearing a 3-point belt. I guess what i'm saying is that if a large number of people were to be using stock-type seatbelts for racing, it would be just as likely to suffer a skull fracture from a hard impact.

[simontibbett]

I have my bottom belts mounted with eye-bolts to the front seat mounts, should straps to a harness bar and the lap belts to the rear seat anchors. I also don't have an airbag and hate how unsecure I feel with a stock seatbelt. Eventhough I do wear it everytime I get into my car, I also wear mine fairly tight.

What I don't get is that both a stock belt and a harness keep your body as still as possible, so how does wearing a harness properly increase the likelyhood of a skull fracture, especially with newer cars having the pre-tensioner mechanism that actually makes the belt a good bit tighter at the moment of impact? I'd guess a skull fracture can just as easily happen with a stock 3-point belt, but the fact the anyone on a track is most likely to have a harness kinda takes away from even thinking about that type of injury when wearing a 3-point belt. I guess what i'm saying is that if a large number of people were to be using stock-type seatbelts for racing, it would be just as likely to suffer a skull fracture from a hard impact.

Are we speaking of hitting your head? Or causing a neck injury?

[Otto]

stock 3 points still have plenty of upper torso and shoulder movement no matter how tight you get them compared to a proper race harness

[Doppelgänger]

Are we speaking of hitting your head? Or causing a neck injury?
Basilar skull fracture. As for whackin' your head..what makes a 3 point safer than..lets say... a 6-point that's properly installed and properly worn?

[simontibbett]

Not sure..

I know a harness can cause neck injury a lot easier, especially worn very tight, as well as in a rollover without proper rollover protection a harness is worse to have.

[Doppelgänger]

Not sure..

I know a harness can cause neck injury a lot easier, especially worn very tight, as well as in a rollover without proper rollover protection a harness is worse to have.
Well, in my specific case ,I do have rollover protection. I unfortunatly, tested this theory in my 96 when I rolled it wearing a properly installed 4-point harness and had a HDHCSD bar. I walked away without even a bump/cut/scrape..nothing. Oh and when I saiy I wear my fairly tight, I should really say fit and snug. Now, when I go to the track, that's when I wear it tight.

[simontibbett]

Well you are very lucky not getting hurt with a little 4 point..lol

[simontibbett]

BTW what kind of 4 point was it?

[Doppelgänger]

Well, the 4-point was properly mounted to the seat anchors, I had it properly adjusted to sit across my hips and pulling down...about a 45* angle down and back, and had the shoulder harnesses back to a harness bar. It was a old Scroth belt from someones old race car...but it worked...and not just by luck.

[Redraceface]

4 point harnesses are very competent for roll overs.

[Redraceface]

gee, did I just chime in the like captain obvious, or what?

[Doppelgänger]

nah.. not really.