I have finally made the decision to mount harnesses in my Z, but after extensive research I have a few questions I thought some of the more experienced racers could help with.

I am struggling with the mounting location for the inboard (driver's right side; passenger's left) lap belt and the anti-sub strap. For the inboard lap belt, I have the bolts and backing plates, I was just wondering what location is best since the general area is quite tight. At first I thought I could get away without drilling, but upon inspection I am not very convinced the seat mounting bolt can safely be used. Also, since I am mounting a 5 pt (will switch to 6pt eventually), I need to find the proper location for mounting the sub strap. In my research I found the thread with the sub strap mounted to a cross bar between the two rear seat mounting points, but again, this location is not optimal per Schroth's literature.

In summary:
1. What location is optimal for mounting the inboard lap belt?
2. What location is optimal for mounting a 5pt anti-sub strap?
(pics would be appreciated if possible)

Thanks!

 

I used the stock rear mounting points for the seat rails. I fabricated an L-shaped metal bracket to mount the harness. You'll need longer bolts to accomodate the L-bracket.

As far as the anti-submarine strap, I purchased 6-point harnesses so I can use the rear seat rail mounting points. You'll probably have to drill a hole on your floor to mount the strap for a 5-point.

 

You've got a roll cage, I hope?

 

Is the bracket below or above the seat rail? I ask because if below, I could see the L bracket and the anti sub bracket on the right side create an uneven mounting surface for the seat rail?

 

I originally purchased a harness bar, but have since reconsidered and am going with a cage. I am currently weighing my options (Kirk, Autopower, custom fabbed; not sure yet)

 

Good call. Better to not have a six/five point harness, unless you have a roll cage. Many people don't realize that, just wanted to make sure.

 

One advantage to consider in doing a custom cage is the seat mount. My T2 Z uses a custom BMF cage and MOMO Super Cup seat with specially built seat mount as well. As you discovered, the OEM inboard mount doesn't work well for the lap belts, so Cris Muller of BMF fabricated brackets to weld to the seat mount itself. These brackets are designed to run in double shear to run a bolt through. Same thing for the sub belt--a single point attachment welded to the floorpan was the safest and best solution. Sorry- no pics yet. There will be further details in the upcoming Spring '08 issue of Nissan Sport Magazine!

David Muramoto
Editor-in-chief
Nissan Sport Magazine

 

just completed my kirk rollbar install last weekend. did it myself and it wasn't to bad. keep in mind, the kirk is bolt in but the Autopower bar is weld in. it does take up some room on the pass seat but drivers seat is just fine unless your above average height. I am right at 6' and still sit comfortably while driving. at the track i will probably move the a little farther forward, so its not quite racing position.

what seats are you going with?

 

Absolutely, appreciate it.

 

This sounds very interesting. I'm not sure I understand the solution 100% from your description though. Do you mean that they welded a bracket to the seat mount, which in turn mounts to the lap belt? I assume then that the custom seat mount is welded and reinforced to the floorpan, correct? Please keep us posted as to progress!

 

Awesome! What solution did you go for mounting the inboard lap belts? Also, I tried searching through your posts, but didnt find and pictures of the installation. Did I miss them?

Regarding seats, again not 100% sure. I m going to go with something adjustable for traveling to and from events. I like the new Sparco Chronos, but Im not sure if they have an anti-sub slot. Any suggestions?

 

i REALLY need to post up some pictures...someone else was wanting them a short while ago. I don't have any actual install pictures but you can still see everything pretty well.

I like the Corbeau FX1 Pro but they aren't adjustable other then the sliders. My dad has them in his spec miata, nice seat for the money. His sub belts were actually mounted to the floor. We bought plates that bolt to the top and bottom side of the floor pan and eye bolts that the belts clip to. I think he bought it all together when he ordered the belts from www.apexperformance.com I want to say he got the G-Force 3" 6pt with the G lock. NICE belts too!!!

G/L!

 

Think of a custom seat mount, built of aluminum, in the shape of a square. This mount utilizes the OEM hardware to secure it to the floor. Allen-head bolts secure the seat from the side brackets. The double-shear seatbelt brackets are then TIG-welded to the bottom of the seat mount itself. Tested the seat mount and positioning this week and it was perfect!

 

Yes, definitely post some pictures. I would be very interested to see how it came together.

Regarding the FX1s, I have seen some threads lately about them being a bit high. Also, they are listed on Corbeau's site as being 5pt harness compatible. Would you happen to know if they are also compatible with 6pt harnesses?

 

I'm with you now, thanks for the explanation. I'm sure going this route helps with getting the seat positioning just perfect. Will look forward to progress updates!

 

If this is a street car, you're wasting your money.

If you want harnesses you need FIA sled-tested seats AND a roll bar. Having a roll bar in your car and driving around without a helmet is not always the smartest thing. Having a roll CAGE and driving around without a helmet is asking for brain damage.

Are your driving skills to the point where you're moving too much in your seats to increase your lap times?

 

i know for me its to the point that i am using the steering wheel more for a handle then its intended purpose. yes, i could increas lap times. or so i think

 

Last question first: Yes. If you cannot see the benefit of a harness and race seats in any car, I would respectfully disagree. I would confidently say that there are inherent gains that can be materialized through:
a)increased driver feedback
b)increased control, resulting in...
c)Driver Confidence

Furthermore, wouldn't you agree, that in racing of any form, even .05 seconds gained from even the smallest modification can be crucial? Maybe I am not at a level where this will make a difference to me yet, but still the point is made on a theoretical level, and when in doubt refer to the points above.

I am not wasting my money, IMO, for the aforementioned reasons. Again, the benefits are tangible in real world track/autox driving situations seen by many, surely short of "F1" status.

You second point is a good one. I have debated the matter and done my research, and found that there is a risk in running a 4pt roll bar without a helmet on the street. How I have rationalized this situation is through

a)ensuring the 4pt bar is positioned far enough behind the driver's position to ensure there will be no contact in the even of a collision.
b)To be thorough, pad the bar with approved foam
c)use an appropriate seat

The safety of this setup is, I agree, dependent on the rating of the seat purchased, but don't most specd Sparco seats fall into this category? Honest question for which I do not know an answer for in my research...I was under the impression that they do.

 

What was your conclusion to this?