370Z Harness Bar

BGTV8 · 09-22-2010, 05:21 AM

Folks

I now have a harness bar fitted to my car. I have included 3 photo's of the bar showing:

002 - the detail of how the bar is fitted to the body, using the upper B-pillar OEM seat belt pivot bolt, braced back to the lateral bodywork brace
004 - showing the harness shoulder straps looped over the harness bar
006 - showing the harness retaining fixtures to stop the harness moving laterally - these are sized for a 3" harness

I have not shown any detail of the laps belts. On the outside of the seat, an eye-bolt has replaced the 7/16" UNF bolt that locates the seat belt tensioner to the base of the B-pillar and the lap harness has been clipped into this eye-bolt. This requires a 19mm hole in the plastic trim at the base of the B-pillar (a 19mm blanking plug in grey plastic is available from any auto accessory store to dress the hole when you eventually sell your car). On the transmission tunnel side of the seat, a 1/2" hole has been drilled thru the tunnel with a 50mm x 75mm 4mm thick anodised steel plate on the underside of the car and the eye-bolt tightened thru it. There was no other option to adequately (from an engineering perspective) fit the eye-bolt which needs to take a load of 100kg (ie: my bodyweight) when being decelerated by up to 8G, as the rear seat slider bolts are not 7/16" UNF threaded (they are metric and we could not source metric eye-bolts). It will be necessary to remove the eye-bolt prior to vehicle sale and replace it with a plain black headed 7/17" UNF bolt prior to sale.

The bar was engineered by TrackArt Fabrications in Bayswater North (Melbourne, Australia) and they have made a jig and can supply these bars to order. Contact Andrew on +61 416 1310. They are located at Factory 13, 6-7 Nicole Close, Bayswater North, Vic 3153 and they can be found at http://www.trackart.com.au/home.htm

Express Parcel post to the USA is around US$140-160 - speak to Trackart for pricing on the harness bar. For supply into the USA, please note that these devices are supplied as-is, for off road use only. Installation will be at the purchasers risk.

The jig has been built symmetrically, with LHD and RHD vehicles in mind.

RB

theDreamer · 09-22-2010, 07:48 AM

Looks really good.

Mozen · 09-22-2010, 10:28 AM

that is very nice, i just got the Amuse bar after being told its adjustable so i could rotate the two holes down to be safe to mount a harness on for the driver...and i cant.

Does this bar obscure the view through the rear view mirror?

BGTV8 · 09-22-2010, 02:44 PM

Rear vision is unchanged

Mike · 09-22-2010, 02:53 PM

do you think any of these adapters would work instead of drilling through the trans tunnel?
CDOC - Sports Car & Road Race Supply - 800.915.2362 - Mounting Hardware

BGTV8 · 09-22-2010, 04:51 PM

Quote:

Originally Posted by Mike

do you think any of these adapters would work instead of drilling through the trans tunnel?
CDOC - Sports Car & Road Race Supply - 800.915.2362 - Mounting Hardware

I had quite a discussion with Brenton (the principal of Meridian Motorsport) who by the way is a mechanical engineer by trade and a long time racer in Sports/1300 (C and D Sports Racing is the clostest US equivalent) and a guy whose professional opinion I respect.

His view is that the shock loads in an accident imply a 100kg load (eg: me and my fat arse) at 8G (on the basis that a greater than 8g load will rupture my aorta or spleen which is a bit terminal

) is sufficient to bend anything that is indirectly attached, or attached in a manner that permits a bending load moment - either as a straight pull or as a twisting/rotational moment). If you exploit one of the options shown in the website reference, you will certainly have a bending or twisting moment of some kind.

The only option I can now see (having pondered on this some overnight) is that it might be possible to fabricate something out of RHS (rectangular hollow section if you are not familair with the term) that can be bolted to the floor using the two bolts that fix the rear of the seat runners to the floor, and then to fix a pair of eye-bolts to the RHS. The minimum requirement would be 3mm wall-thickness mild steel and I suspect that you would need at least 40mm RHS to get sufficient clearance.

I have roughed up a "drawing" (I am not a draughtsman, so it is "Very" rough) to try to convey what I mean. This would certainly permit you to avoid drilling the bodywork or plastic trim, and could be an option.

My drawing shows the eye-bolts mounted inboard of the seat rail mounting bolts, and option would be to mount them outboard, but you would want to ensure that there was space betwen the tunnel and the drivers door sill to make the mounting wide enough to provide sufficient material to generate the required strength to resist the loads implied in an accident, and that is not my forte.

If you have a local machine shop (or maybe one of the suppliers on the forum may pick this up), you should be able to get some calculations done on the amount of material around the eye-bolt that is required and then determine whether the approach I've outlined might work. For me, I'd be a tad concerned that the options shown on the website reference could resist the sorts of twisting/bending loads implied in a big shunt .... and having been thru a 130mph hit into an armco barrier in my race car 10 years ago, having belts that are solid and secure is for me, a priority. I have even re-engineered my race car to make the should belts as short as I can to avoid belt stretch providing too much freedom in an accident ..... a "big shunt" certainly gives you motivation in this regard !!!

Rgds

RB

BGTV8 · 09-23-2010, 02:57 AM

As a follow-on to my earlier post, I have had another look at the URL reference posted by Mike (specifically the Rennline Driver Side Harness Mount - I don;t thonk any of the others are applicable), and the mounting hardware may just work. The key will be for the chosen components to be mounted such that any load is a straight pull - that implies that the components need to point towards the front of the car, not the rear.

If there is space for them to be mounted in such a manner, with the seat positioned normally, then it will all work, but if not (i.e. clearance dictates that the only way these can be fitted is if the tongue that the harness clips into is pointing to the rear of the car), then I can't see how you can avoid the potential for the belts to become loose as the fixture is moved by the very large loads that exist during a big accident.

spearfish25 · 09-23-2010, 07:32 AM

The 8G estimate seems very low. F-16 fighter planes pull a constant 12Gs and the pilots have no vascular injuries...they just pass out if not wearing G-suits. In a sudden, frontal collision, depending on your speed, I'd expect something between 30-60Gs for a 30mph head-on collision. This however would be incredibly transient which is why people can survive these accidents.

Also, as one increases the number of mounting points to the car, the required load-bearing capacity of each mounting point, for the same maximal collision load, becomes less as well.

My concern with these modifications is that people will replace their well-engineered seat belts from Nissan with aftermarket, 'these look like they can bolt-on here' harness bars and then be in big big trouble when a serious accident occurs. You may be fine for the small accidents, but the big time crash may turn a poorly thought out harness bar into a bent coat hanger with you landing 3 turns further up the track.

BGTV8 · 09-23-2010, 02:56 PM

Whiich is exactly why a mechanical engineer did the load calc's - and yes, you are correct about spike loads, but the Monash University Road Safety Research Unit her in Melbourne are world leaders in accident analysis - Victoria was the first state globally to introduce mandatory fitment and wearing of seat belts and this is a subject very well understood around here.

F16 pilots are usually a lot younger but more importantly, a lot fitter than me, and the conventional wisdom is that a susutained load (greater than 80 millseconds) of 8G will prove fatal to 75% of the normal driving population.

Yes, spike loads of 30-80G can be tolerated by the human body, even in old farts like me, but not for much more than 5-16 milliseconds according to the folk at Monash Uni.

Not wanting to divert from the original post, though .... I will simply say that a full harness wil always be better in any sort of accident on a track than a lap-sash harness, and the bar I;ve fitted is well able to absorb the energy/loads involved.

ALso why I hav ebeen at pains to make sure that fixtures for lap belts are similarly attached to points in the bodyshell that are engineered for the loads.

As I said, these are all installed at the owners risk .. 'nuff said.

RB

phelan · 09-23-2010, 05:05 PM

Quote:

Originally Posted by Mozen

that is very nice, i just got the Amuse bar after being told its adjustable so i could rotate the two holes down to be safe to mount a harness on for the driver...and i cant.

Does this bar obscure the view through the rear view mirror?

umm....can you clarify the amuse bar issue you're having? kinda curious on that.

TrackRat · 09-24-2010, 12:13 AM

Quote:

Originally Posted by BGTV8

As I said, these are all installed at the owners risk .. 'nuff said.

I sincerely hope everyone on here reads this last point over a few times before deciding to go with this product. Would love to see a picture of a professional harness setup with similar mounting points... although I doubt that will happen.

Mike · 09-24-2010, 03:46 AM

Quote:

Originally Posted by TrackRat

I sincerely hope everyone on here reads this last point over a few times before deciding to go with this product. Would love to see a picture of a professional harness setup with similar mounting points... although I doubt that will happen.

Actually, while the design is slightly different, it is anchored to the same mounting points as the Brey-Krause harness bar I had in my C6 corvette. I really don't see any problems with this design, and will probably be ordering it myself soon.

Mozen · 09-24-2010, 03:48 AM

Quote:

Originally Posted by phelan

umm....can you clarify the amuse bar issue you're having? kinda curious on that.

Yea sure. The strut bar is locked in place on each side by sitting on a flange, having another flange placed on the top and bolted into the car. There is then 2 bolts, 1 which has to go through the top flange, through the bar, and into the bottom flange, the other that goes through the bottom flange, through the bar, and into the top flange. They are in a X pattern.

Basicialy when you turn the eyelet holes on the bar around to be in place for the RHD side of the car the X holes line up and the eyelets face forward right at the seat. When you flip it for LHD, you cant get the X holes to align unless the eyelet holes are facing straight up.

Now you could, swap the top plates on each side, the ones that bolt into the car BUT they are side specific and dont sit right unless they are on their side. On top of that even if you do, you would still need to drill holes in the bottom plate ( the top plate has extra holes) to allow room for the bolt to now go though both.

I would post pics of what im talking about but im actually in the middle of getting everything together to go to XDC with Non Stop Tuning :P so need to finish getting stuff in the car and then get out the door. Ill thow some pics of what im talking about from the hotel tonight if i have time.

jay666 · 07-23-2011, 09:09 PM

Anyone know if Brenton from Meridian is on this forum? I have been waiting for an E-mail response from him for a while now. I want to buy this ASAP and I can't get a response.

Volcom370Z · 09-23-2011, 04:42 PM

Quote:

Originally Posted by spearfish25

The 8G estimate seems very low. F-16 fighter planes pull a constant 12Gs and the pilots have no vascular injuries...they just pass out if not wearing G-suits.

F-16s are 9G aircraft, and only in the proper configuration. You can youtube "G-LOC" to see what Gs can do to you in a sustained maneuver, but they are aren't hitting 12G... the on board computers prevent it. In a car accident however, you need to worry about the VERY high spikes in G load. A rapid (and brief) onset of 9G isn't a game ender... you MIGHT pass you (depending on the direction of pull), but the thing to be concerned with is the very high peak Gs experienced with a car crash. G forces that are perpendicular to the spine are much more survivable than those that are parallel to it.

Sorry to revive this thread... just thought I'd chime in.

09-22-2010, 07:48 AM	#2 (permalink)
theDreamer A True Z Fanatic Join Date: Feb 2009 Location: Texas Posts: 30,879 Drives: 370z Rep Power: 4210	Looks really good. __________________ theDreamer's Z // Fast Intentions // Uprev // GTM // HKS // TEIN theDreamer's Silvia // URAS // GREDDY Houston Zs // Facebook // Twitter // Instagram

09-22-2010, 10:28 AM	#3 (permalink)
Mozen Track Member Join Date: Jun 2010 Location: Newport News, VA Posts: 820 Drives: Nissan 370z PW M6 Rep Power: 18	that is very nice, i just got the Amuse bar after being told its adjustable so i could rotate the two holes down to be safe to mount a harness on for the driver...and i cant. Does this bar obscure the view through the rear view mirror? __________________ PW 370z \| AEM \| MISHIMOTO \| ARK PERFORMANCE \| WHITELINE \| NISMO \| STILLEN \| FORGESTAR \| BC RACING \| AMS \| NON STOP TUNING \| CARBONETICS LSD \| 4 Point DOM 1.75" SCCA Spec Roll Bar + Harness Bar CHECK OUT MY BUILD THREAD HERE

09-22-2010, 02:53 PM	#5 (permalink)
Mike The370Z.com Sponsor Join Date: Jun 2009 Location: Loganville, GA Posts: 5,944 Drives: 370z Rep Power: 2186	do you think any of these adapters would work instead of drilling through the trans tunnel? CDOC - Sports Car & Road Race Supply - 800.915.2362 - Mounting Hardware __________________ NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z Porsche: 93 968 / 23 Macan GTS / 93 968

09-23-2010, 02:57 AM	#7 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,513 Drives: 09 Nissan 370Z M6 Rep Power: 39973	As a follow-on to my earlier post, I have had another look at the URL reference posted by Mike (specifically the Rennline Driver Side Harness Mount - I don;t thonk any of the others are applicable), and the mounting hardware may just work. The key will be for the chosen components to be mounted such that any load is a straight pull - that implies that the components need to point towards the front of the car, not the rear. If there is space for them to be mounted in such a manner, with the seat positioned normally, then it will all work, but if not (i.e. clearance dictates that the only way these can be fitted is if the tongue that the harness clips into is pointing to the rear of the car), then I can't see how you can avoid the potential for the belts to become loose as the fixture is moved by the very large loads that exist during a big accident. Last edited by BGTV8; 09-23-2010 at 02:59 AM.

09-23-2010, 07:32 AM	#8 (permalink)
spearfish25 A True Z Fanatic Join Date: Mar 2009 Location: Naples, FL Posts: 4,117 Drives: to work Rep Power: 1856	The 8G estimate seems very low. F-16 fighter planes pull a constant 12Gs and the pilots have no vascular injuries...they just pass out if not wearing G-suits. In a sudden, frontal collision, depending on your speed, I'd expect something between 30-60Gs for a 30mph head-on collision. This however would be incredibly transient which is why people can survive these accidents. Also, as one increases the number of mounting points to the car, the required load-bearing capacity of each mounting point, for the same maximal collision load, becomes less as well. My concern with these modifications is that people will replace their well-engineered seat belts from Nissan with aftermarket, 'these look like they can bolt-on here' harness bars and then be in big big trouble when a serious accident occurs. You may be fine for the small accidents, but the big time crash may turn a poorly thought out harness bar into a bent coat hanger with you landing 3 turns further up the track. __________________ 2013 Cadillac V-Wagon, RIP Z Last edited by spearfish25; 09-23-2010 at 07:46 AM.

09-22-2010, 02:44 PM	#4 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,513 Drives: 09 Nissan 370Z M6 Rep Power: 39973	Rear vision is unchanged

09-23-2010, 02:56 PM	#9 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,513 Drives: 09 Nissan 370Z M6 Rep Power: 39973	Whiich is exactly why a mechanical engineer did the load calc's - and yes, you are correct about spike loads, but the Monash University Road Safety Research Unit her in Melbourne are world leaders in accident analysis - Victoria was the first state globally to introduce mandatory fitment and wearing of seat belts and this is a subject very well understood around here. F16 pilots are usually a lot younger but more importantly, a lot fitter than me, and the conventional wisdom is that a susutained load (greater than 80 millseconds) of 8G will prove fatal to 75% of the normal driving population. Yes, spike loads of 30-80G can be tolerated by the human body, even in old farts like me, but not for much more than 5-16 milliseconds according to the folk at Monash Uni. Not wanting to divert from the original post, though .... I will simply say that a full harness wil always be better in any sort of accident on a track than a lap-sash harness, and the bar I;ve fitted is well able to absorb the energy/loads involved. ALso why I hav ebeen at pains to make sure that fixtures for lap belts are similarly attached to points in the bodyshell that are engineered for the loads. As I said, these are all installed at the owners risk .. 'nuff said. RB

07-23-2011, 09:09 PM	#14 (permalink)
jay666 Base Member Join Date: Mar 2011 Location: Chicago, North Side Posts: 161 Drives: '09Nissan 370Z Nismo Rep Power: 14	Anyone know if Brenton from Meridian is on this forum? I have been waiting for an E-mail response from him for a while now. I want to buy this ASAP and I can't get a response.

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