I am thinking of making a bracket that has shoulder clips to hold the harness shoulder straps. Then attaching that to the back of the seat. Any other ideas?

 

yea, will it be stable though? casue the way our seats are designed is pretty hard to do a 4 pt harness but i mean nothing is impossible, would think bucket seats would be the best to jus switch out on, fia approved recaro pole postions or something, maybe teamrx8 would know a good idea with the stock seats

 

Do you know how much work it is to rewire the stupid seat belt and airbag sensors? I had thought about cuttings holes in the stock seats and then making fiberglass/carbon inserts to route the straps through. I am not intending these to provide any grip in a collision. The harness will be mounted to floor and rear passenger latch (on the rear deck) for the shoulder straps.

 

You guys need to remember anything less than following the manufactures instructions for mounting the belts can be very dangerous. While it may be OK for autox to mount a 5 point to the seat mounts or clip it to the rear seat belt/kid seat anchors you could get killed if you had a wreck at a track day with an install like that. I see guys all the time mount the shoulder straps down behind the seat to the back seat anchors, that is a good way to compress your spine and make sure you never walk again. If you do not have a roll bar to properly mount the harness to make sure you wear your stock seat belt. The harness is good to hold you in the seat but a half @ss mounting will only get your hurt.



Here is some good info: http://www.simpsonraceproducts.com/s...restraint_info

 

Apparently, I am not making my mounting idea very clear. Takata makes a harness that is designed to use the latch (for child seats) on the rear deck of the car as a mount for the shoulder harness portion of the 4 point harness. The rear deck latch is well within the 0-10 degrees angle to my shoulders (as specified). I am merely looking for a guide mount (to keep the shoulder straps in place) like what you would have when you use a racing bucket and the straps come through the holes. The floor is an excellent place to mount the lap portion of the harness (provided you have a proper anchor setup that can withstand the force that may potentially be applied). The concern with mounting the shoulder portion of the harness to the floor (which I am not doing) is that you could cause a compression fracture in your spine because the belt would be pulling your spine down in an accident instead of just keeping your shoulders securely attached to the seat back. Hopefully this helps.

 

That childseat attachment point you want to attach to is only rated to 5300N static strength vs. 13,345N for and adult upper body restraint on a passenger car. Passenger car harnesses are only designed for 25-30g impact which is about 55mph vs. a racing harness which is designed to withstand 55-60g's which gets you 70+mph crash capability.

So bottom line is a racing harness attached to the child seat isn't going to protect you for more than a 10-15g impact which equates to about 30mph. Not very safe IMO.

P.S. I do use upperbody restaints attached exactly this way for Solo, but would never even drive on the street this way. To many stupid people trying to occupy the same space as me on public roads.

 

Wow... great info.

Another idea that someone at my work brought up, was to make a harness bar that attaches at the top seat belt anchors on the doors. Make the bar removable so when you are not at the track, you can still have rear passengers. You could then put loops on the bar that would hold the shoulder harness from falling sideways. That is by far the best idea I have heard yet, as I don't really want a roll cage.

Shane

 

You can still use your idea with the baby seat mount to hold you in the seat. To be safe just wear your stock belt with it when on the track.

 

I'm not sure on the RX8, but in many applications it is ill advised to install 4, 5 or 6 point belts in a car without a cage, because if you have roof collapse (even partial) and are belted bolt upright...well, you get the picture.

If I'm running track events and am not going to install a cage, I'm also not installing racing restraints, so that I can bend/roll over to get out of the way of the roof, in case of collapse. For autocrossing, if you just want to be "locked down" in order to not have to exert energy bracing or holding yourself in position, I guess a set of shoulder belts makes sense, as the likelihood of a impact(s) great enough to seriously compress the roof line is nil.

 

Doing a simple 4-point harness attached to the rear seat anchor points is fine for autocross, but like everyone said that won't do for the track. I could see a (removable) harness bar setup with racing seats for the track if you just do track days or HPDE events. In a case like that, the chances of a serious accident are slim, and the chances of a roof-crushing rollover are virtually nil.

Now if I could just find an off-the-shelf harness bar for the 8 I'd be happy...

 

I used to think that....till I saw a really bad accident at a track day this summer. It involved a totalled NSX and Ferarri Stradale and one almost dead driver who needed 6-8 hrs of surgery to be put back together again

I decided that harnesses without roll cage was a no-no after that

 

That's too bad. Where did this happen?

 

roll overs etc happens in hpde-- No four point harness without a roll bar--AND you are better off with an open face helmet--better view and the airbag will not catch the chin bar.
Olddragger

 

I'll 3rd that about accidents - I saw the results of one this summer- Porsche spun, hit a barrier backwards then flipped OVER the barrier and landed upside down on the other side. Hanns device, roll bars and harnesses saved both the driver's and instructor's lives. Speed on the turn before terminal oversteer took over resulting in a spin into the grass that precipitated the rollover was likely 100+MPH. Life is short enough - don't try DIY harnesses.

 

If not for the fact that even the mazdaspeed roll cage basically eliminates the back seat and makes driving without a helmet a dangerous proposition, I would be all over the $685 price tag. I am going to take with G-Dimension and maybe Danstoy to see if they have any ideas.

MEh...

Thanks for all the replys guys. I appreciate your input and experience.