scotts300

iTrader: (46)

Are those seats WAY moved up? I thought the bar was supposed to be nearly against the seat backs...

Z3305

These should give you a better idea. The Sparco bar is in line with the rear of the bulkhead the rear speakers fit into. Also, my seats are in driving position in the photos, I'm 6'.

Stack

The driver must be really short or something ... one of the mods listed is a "short hub" for the steering wheel. Not exactly sure what that is, but I can imagine LOL.

Z3305 ... thanks for those pics.... the mounting shots are perfect! (more on that later)

Can you take a picture from inside the car of you seated? The lighting prevents a good view of where the bar is. Also, one with the seat reclined if possible.

Z3305

Stack- this is sort of what you just asked for. Imagine a driver in the seat As far as the seats fully-reclined goes, the space between the seat headrest and the bar would be the width of the speaker bulkhead, 'bout 6-8" I'd say.

Stack

Thanks for all the pics Z33 (though I'd still like to see one of you seated and reclined all the way to the bulkhead, preferably at the angle looking through the rear hatch)

But honestly, that point is kind of moot looking at the mounting point picture:


Why... WHY would they build this so it's "removable"? They introduced at least two new points of potential failure.

1st... the bolt: Is that allen head bolt a Grade 8 bolt? Can it be double-nutted to prevent it vibrating loose? Can it be tightened enough to prevent excess movement between the parts?

2nd... and this is what really concerns me... the tab mount. This, in my opinion, is why this type of bar needs support struts. You've got a lot of deflection and leverage against this tab if it were to experience an impact. Due to driver heights, seats variations, and most importantly the "depth" of this bar's offset design, there will be lots of force applied downward against those tabs possibly (probably IMO) causing them to bend downward.

3rd... the weld: why do it this way? Why not simply weld it to the attachment plate just like it is?! While you'd still have deflection issues, you'd at least be asking the b-pillar, weld, and bolt to take the force instead of the "b-pillar, weld, bolt, tab, and bolt" to do it.

4th (added)... is that mounting plate tight against the b-pillar? On third or fourth look, it seems that it is not... so you're already looking at the bar rotating until the bracket stops on the b-piller (probably going through the plastic in the process.) This is bad enough in and of itself since it adds accelerative force to all the above mentioned weak points.

The old saying applies here: A chain is only as strong as its weakest link... and IMO there are too many links in this chain.

One reason they may have done it this way is the same reason I'm asking about the additional photos of the reclined seat. They may have been trying to create clearance for a helmeted head. Which is fine and all, but if by doing so you've compromised the bar's effectiveness... what's the point?

Billhyco

iTrader: (14)

If you go with a Kirk roll bar, I have the rear plastic trim pieces that you will need and are already cut out. When I installed the roll bar I got an extra set of trim pieces and kept my OEM ones in storage. If you want the cut out ones just PM me. You can have them for free if you just pay the shipping.

Z3305

Stack- Thanks for a very thorough evaluation of the Sparco bar. I'm not an engineer (but I suspect you may be) so I can't really speak to some of your concerns. I do know the bar is what's described by Sparco as .120 walled steel and it's mig welded. The bolts you mentioned are grade 8 and everything is highly torqued and checked several times a year. You wondered in your post if the bar is tight on the B-pillar. Whoa. It's tighter than a gnat's a** stretched over a rain barrel. I'm pretty committed to safety myself and no small part of my motivation in getting Sparco's product was based on the fact that they're a responsible company who have been around a long time. Since they make numerous bars that have vertical supports and certainly could have for our cars I'm counting on the fact they've thought this through. Maybe that's naive, I don't know. I don't think this bar replaces or is necessarily better than a roll bar. But it's possible to have a poorly done local install on a well-made roll bar,so I guess installation is everything. I still think I've improved the car for the track over the single shoulder harness.

kuah@splparts.com

iTrader: (10)

A harness is something you wear, and to that point, driver comfort and ease of use are all points to consider, not just a safety rating.

This is a harness bar, not part of a cage or chassis reinforcement brace. The harness bar only sees forces exerted by the harness, and it only has to be engineered to take that amount of load. The bending moment on the tab is small given the angle of the belt, only a very small portion of the load creates a torque on the tab. And the shear strength of the bolt is at least on the order of a few thousands pounds of force, which is more than adequate for the loads involved.

Stack

In fact, I'm not an engineer (wouldn't that be nice!) ... but I've seen all too often products being "designed to sell, not to work", even from reputable companies (not just in the motorsports industry.)

BUT I'm not even saying "don't use this bar" or "this bar will definitely fail on you" ... I'm saying that I personally would not use it for the reasons I've stated above.

As far as improving the car for track use ... I cannot disagree with you on that point. You have, I'm sure, made the car easier to drive at speed. You've also secured yourself so you're not constantly trying to hold yourself in place, reducing the fatigue factor. Problem is... by improving the car, and by extension your abilities... you've also increased your risk level by being able to drive to car closer to its limits. Your next step (if you havne't already taken it) is to add r-compound tires to the mix, now that you'll be over-driving your street tires. Which will increase your speed and risk level that much more.

Granted, it's a conservative approach to track safety, and not everyone will see it the way I do.

Kuah... you wrote: This is a harness bar, not part of a cage or chassis reinforcement brace. The harness bar only sees forces exerted by the harness, and it only has to be engineered to take that amount of load. The bending moment on the tab is small given the angle of the belt, only a very small portion of the load creates a torque on the tab.

That's all well and good ... assuming that tab has been tested for those loads. Bolts can be tested and graded, as stated before, I'm not overly concerned with that. But a metal tab, oriented in the weakest way (with relation to the force that will be applied to it with this design) just seems like a bad idea. Hopefully I'm very wrong in the event someone has to test it out.

Does Sparco even sell this bar anymore for the 350Z? the website has it listed where you can add to a cart, but no information page. If you look at the picture they have shown on the site (I guess it's for the impreza), the mounting bracket is much simpler, and it has down struts.

http://www.sparcousa.com/harness_bars.asp