Rollbar, Harness bar, and 7 point harnesses in the CS

I too found it strange that the bar only appears to mount to two places on the floor of the car. A roll cage should have additional bracing front and rear should it not? Mount to the bulkheand and then triangulate to the front of the car. A two point mount with crappy allen heads seems very strange and out of place on a $200k car. And they scratched the **** out of his floor when installing.

 

Just read the price too, almost $5K USD, for a glorified harness bar and harnesses? My Sparco 5 point FIA spec harnesses and bar (before I ran the full cage) cost me less than $2K AUD installed - around $1600 USD. My full cage - FIA spec, log booked, engineering certificate etc cost less than this unit. You guys in the 'States sure get cheap cars, but boy do you get reamed when it comes to any fabrication/engineering work!!

 

agree my omp challenge cage was $2,500

 

I thought it would be good to correct some mis-information that has been brought forth in several remarks made regarding the DMC Roll Bar System for the 360/430 and CS cars.

In posts made here , there was a concern that this is some sort of " Show Bar " and even the word " Dangerous " was used in reference to it . Well , I can assure you it is anything but that . After careful study of the Actual Factory competition bar , it's size , material make-up , location within the cockpit and most of all , it's attachment points , we arrived at the Design seen here. This was, and is , no quick , "Thing to hang your harnesses on " . Phrases like " Boy Racer " and " Crappy Allen Heads " simply have no application where this piece of equipment is concerned. For instance , the Factory Competition Bar uses 8 fasteners total to attach it to the chassis at four points ; the DMC unit utilizes 18 fasteners total to attach it at four points . The Button Head Socket Cap screws (BHSC) refered to have a tensile rating of ( no less than ) 145,000 psi. and a shear rating of over 48,000 psi . These fasteners can be found holding together critical components on cars today from Formula 1 on down .

In regards to it's compatibility w/ the HANS safety device and the credibility of the Teamtech harnesses utilized ; we use Curt Tucker's product for a reason and it's not cost - they are probably the most expensive harnesses out there . We have used these harness systems with the HANS device for over 15 years in all the Race Cars ( more than 30 ) we have both built and fielded ,with 100% positive feedback . Teamtech uses the highest grade materials , and is one of the ( few ) suppliers approved for NASCAR; He even holds the patent for the sternum strap style specifically called for by NASCAR . For individuals who intend to wear a HANS device, we supply a 3-2-3 shoulder belt designed expressly for that use - No Charge.

The base plates that anchor this unit are not " Sheet Metal " , they are 3/16" 4130 plate (which is 50% thicker than FIA or SFI standard requirements) , CNC cut and finished with a radius profiled edge , then CNC bent in a Press Brake. Some of the finest TIG welding you will see comes straight out of this shop , anyone who knows our product will verify this . This Roll Bar is indeed designed to provide support in a catasrophic event , yet like the limitations of any 4-Point roll bar , is not meant to rival or replace the safety of a complete , properly engineered and installed 6 or 8 point Roll Cage that includes door bars and a windshield halo built for competition ; we designed it as per the request of our customer , Kevin Marshall , as a safety enhancement because he is serious about his personal safety in regards to track days. Nothing more , nothing less.

In terms of this products' integrity , I'll put it up with the best of them and stand behind it , as I do all our products , and will happily refund anyone not satisfied that they got full value for what they spent , period. A quick call to anyone who sells our products should answer any questions about quality concerns. Kip @ Farnbacher-Loles Motorsports, (203) 798-2929. Todd @ Evolution Motorsports , (480) 317-9911.
Parris @ Silicon Valley Motorcars , (800) 721-8629 . John @ ForcedFed Engineering , (925) 371-2288 . Beau @ SRM Performance , (415) 454-7682.

As with anything new , I expect individuals to express their opinion , and I realise that our products are not for everyone . I would encourage those who are considering a modification such as this , to give themselves an education , and then go forward with that newfound knowledge and use it along with their budget to decide what's right for them . I have included a Picture for clarification of the attachment points , for anyone interested. Sincerely , Jim Dunford .
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I think I got a pretty good education and here is what it has taught me about race safety. This is a much better view you have given us. The first pics look to be a 2 point bar. I now see the 4 points that
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Jim
Great info, but you still haven't addressed the issue of the mounting points used. You draw a lot of references to Nascar, but what standards is the bar engineered to comply with and does it have certification as such?
It's a really classy looking product, but for the price, should include all of the above and more IMO. There were no aspersions cast upon the Teamtech harnesses that I could see, just issues about the mounting points, general design, fasteners (which you have answered) and cost. FWIW if safety was such a priority that HANS and Teamtech harnesses were considered a must, then I would be using a proper cage, not the glorified rollover bar shown here. Correct me if I am wrong, but from what I know of the 360, none of the mounting points you have used are actual reinforced chassis points. This is the greatest criticism I feel you should be addressing. Look forward to your response and appreciate your professionalism in dealing with the questions.

 

ARGH!!! Damn site destroyed my post.


Anyway, your upper bar above the shoulders is going to fold like a pretzel if hit fore/aft or the down arrow shapped bars I have x'ed in blue will drive right through the harnes bar and pull the unsupported b-pillers into each other as the rollhoop colapses. Your way you have supported the harness bar but nothing else. I'll assume you have solid mounting locations to the chassis and not sheetmetal. This thread could go on forever....

The way I have redrawn it is traditional and this way for a reason. The Yellow diagonal can be one like shown or X'ed for max strength and tie into a single node at the mounting foot and a single node with the rolloverhoop and rear support bar also in yellow. This design supports the rollover bar over the driver head and supports the rollover hoop in the fore/aft direction. The green harness bar should be straight or if it interes with the seat curve in one piece mandrel bent and semi custom weled to accomodate different sized drivers from proper HANS positioning which is more than just using a teamtech harness. REmove the blue x'd out bars. Do an FEA on my design and yours and you will see what happens. Math is a really good starting point. 30 years of emperically doing something and 100% satisfied testimonal mean nothing. Data and crash testing is what keeps you alive. That's what SAE, those GM race engineers like Gideon, all that crash testing on the Delphi and Wayne State crash sleds, Scroth etc... do. These guys have the data. Dead guys don't complain.

The shear and tensile of the bolts is metalurgy and not in dispute. If you have a thin bolt with this metalugy it will break under light loads. A thick one will not. Think thin piece of paper = small diameter bolt thick piece of same kind paper = thicker bolt. You get it now? Your bolts look too small in diameter but I have not done the math to prove it.

I don't know how many guys are using Teamtech in Nascar but there are sure plenty using Scroth and some using the scroth 4 belt shoulderbelts which your belt keepers on the harness bar can interfere. I am pretty knowledgeable on head and neck restraints and I do not think HANS recommends sternum straps with HANS and for sure many sanctioning bodies forbid sternum strap use. Further to my knowledge HANS has never been crash tested with such straps with a SAE paper to judge its effectiveness and those straps violate SCCA single release rules for another thing. I know teamtech feels good on your body and holds the HANS nicely and may even prevent HANS pop-out on crashing because in a static state it feels so good. But tests and real world data during the violence of a crash is what counts.

 

Hello Stephen S. and thankyou for your kind words and also your concerns about the Roll Bar unit. The question about the attachment points is well founded...no doubt we've all hear the horror story about " the fellow who flipped his car , only to have his roll-bar punch through the floor and as a result , then broke his neck ". It has happened . I must be honest , in the 25 years I have been building cars , I have witnessed many terrible accidents ending in the loss of life at the race track. I am fortunate and probably lucky to be able to say , none of those were our cars . These are good reasons to be critical of anything regarded as Safety equipment - This unit being no exception.

I studied this car in our shop for about a week before we really started to build - and what I found during that time created the path to what we created as this product ; The major structural members through the center of the car (as with most cars ) are what we call the rocker panels , which span the car longitudinally connecting the front door hinge upright/a-pillar to the rear door jamb/ B -pillar and rear bulkhead. In this case , for those who may be unaware , they are cold formed from a heavy ( 3.5 mm ) aluminum sheet into a modified ' box ' section that is then welded into the intersection of the central crossmember and forward rear monocoque sections.

Without turning this into a ' Do it yourself roll bar forum ' - We found that the area just forward of this intersection would be a desirable spot to anchor the formed base plates of the main hoop. The base material has plenty of substance for the relative loads , yet would have reasonable energy absorbing properties with sufficient tear-out resistance , considering those plates are formed with three different planes of attachment and a total of seven fasteners per . I've not seen any other bolt-in units realizing these properties ; it makes producing the product consistantly more difficult , and hence , costly.

Next came the rear shoulder/hoop brace decisions ; we bantered about the many positives and negatives of upper vs. shoulder support of the hoop - the classic being diagonal uprights as illustrated in Fatbillybob's post w/ pic. The reason , among others , that we did not go with simple uprights is the same reason that the factory did not - Clearance. If you try to route that way you find out quickly that you interfere with the seat back reclining ; the headrest is more of an imposition than it looks at that angle. ' The Factory bar uses a shoulder support ', I said to myself , I'll use the same attachment point at the rear bulkhead, but I'll span the two points with an 1.50" 4130 harness tube like we do in the FIA touring car cages and add two upright diagonals as well to help dissipate for/aft and diagonal inputs. The Attachment points used are anchoring into the same spot as the factory bar and duplicating the two bolt arrangement at the flange. The formed , heavy wall cross section monocoque in the rear bulkhead transfers the load straight into the engine bay castings. For an aluminum tub , it's really quite a structure. I toured the factory in Modena in 2000 and witnessed the 360s' chassis going together on the line and I can only say it was something to see. If you can ever go to see these cars being built, you simply must. I am going back in October and more eager than ever to see the Production line w/ all the new cars!

The tubing we use for the main hoop is 1-5/8" x .095" wall 1020 cold roll DOM.
I bend and fit every piece myself and I weld every one personally.
This is not a MIG welded OMP deal here. ( With all due respect to OMP; It's a very high quality part as far as mass-produced products go.)

One thing to remember about engineering for impacts vs. engineering for loads , for simple input loads ( chassis torsional and beam ) , we strive for stiffness , and for impact loads we strive for energy absorbing with a degree of plastic deformation - stretching and bending .

Stephen , At the point that this unit becomes useful in a crash , I agree , I would rather have a fully installed cage , but the world is full of comprimises and this case is one; Our customer drives this car on the roads and as an investment thought it not wise to cobble it up permanently with a cage . Life is full of choices, and that's what makes it so great. I was told that it was a needed product so we built it. At least those who currently own one are happy. I guess you just can't please all of 'em , all the time! I hope that I have answered all of your questions . Ciao , Jim Dunford.

 

Thanks Jim. As you have noted the opportunity for rear bracing, as is traditional, is limited. There is no question as to the quality of the workmanship, the welds look superb, but as I stated initially, this is more about show than go. The factory bar is the same, particularly with the mid engine, bracing must come from the front of the car to stop the bar from folding over. Unfortunately this does affect ingress and egress from the car. A compromise would be bolt in front hoops and low mounted, removable side braces, to minimise impact on street usage. The cage pictured below, was originally designed with these issues in mind. It has now been pulled out and upgraded to a fully welded version.
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lucky i subscribe to posts; here's your original post

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Here is the message that has just been posted:
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I think I got a pretty good education and here is what it has taught me about race safety. This is a much better view you have given us. The first pics look to be a 2 point bar. I now see the 4 points that's much better but still for a professional your design staff needs help! It is well known in your industry that triangulation = strength. You fail to triangulate the upper half of the bar from driver shoulders to top of head. That thing will fold like a pretzel. Your 2 center bars with my blue "x's" in there is not triangulation. These do absolutely nothing. Your bar will fold in a fore/aft hit. Your roof structure will punch right through the unsupported harness bar. In a top to bottom hit as in roll-over you have made an extreme arrow pushing right down on the center of the harnessbar which will pull in the unsupported b-piller tubes = ouch. Also your harness bar is not one piece bent on a bender but weld connected which makes it weaker you did this so that it would be weaker than the connection to the 3rd and 4th point, I understand. But there is a better more conventional way.

You would have had a better design if you take out the bar I X'ed out in blue. Then add in the long yellow bar to form a single node for strength right at the mounting foot. Then you add the 2 yellow side bars to roll hoop to support the roll hoop in roll-over and in fore/aft hits. Note that the drivers side two yellow bars end in a single node for strength.
Finally you can add the green mandrel bent harness bar at any level required by the size of your diver. This way you can have a semi custom 4 pt bar and be custom compatible with required harness bar shoulder height for the customer's HANS. You may have a bit more weight with this set-up but you can compensate for that by downsizing the harness bar and keeping the other bars larger which will still be safe. You see HANS compatibility is not just what harness you use but includes more than I can say in just this thread with things like vertical position of the harness bar relative to the driver not the seat holes.

The harness keepers you have are O.K. but they will interfere if your customer one day goes to the dual 4 belt HANS specific harness. This is not an unreasonable thing for someone to buy who spends $250K on a car.
Driver's should also be aware that their body may not be compatible with the OEM seat due to such issues as departure angles of belts to seat to your body.

As to the button cap screws you are quoting the metalurgy. Take one of those bolts and make them infinately thin and the metalurgy you speak of is the same but I can snap it with my finger. Take that sheer number that is in PSI. One that is 4mm will sheer easier than one that is 10mm. Fastener selection take into account such things as total energy found my multiple calculation one of which is MV2 and perhaps I am wrong but those bolts "look "undersized. Additionally cap head look nice but do not have that strength of a similar sized and similar grade hexbolt but they look cool and work if you have done the math .

I do not know what Teamtech does but 100% satifaction testimonals mean nothing. Scroth for example actually crash tests and the rest follow established protocal in harness design hashed out by the likes of SAE those GM race engineer guys (Gideon) and the like. Teamtech is the only maker who has all the fancy pads or as you say the patented sternum strap which may or maynot have had extensive testing. However, sternum straps in general are not allowed by most sanctioning bodies due to such issues as hanging yourself on them in a crash and single release rules. AS to the 30 years of experience...IMO then your design should be much better than what I suggest as a complete lay person in 5 minutes. I know there is at least one engineer on Fchat that can do an FEA and lets let the math prove who is right after all I'm just a club racer and you are a pro. Maybe those aftermarket unsupported roll hoops like I see on Miatas are all you need I'm no engineer.
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Hey Stephen - Is that your 550 pictured ? If so , Kudos to you ..... I spied the photo in your Profile and you've got that thing just flat working! The footprint of the outside tires is superb ! Does'nt look like that 550 has much of a problem with push! Looks a bit like my 250 S.Kart on the big track here at Infinion ( Sears Point ) - Hooked Up.

I 've done so many of the dual duty cages and like the way your original went , so many end up being pulled after a season or two , to be replaced with a ' Real roll cage ' I can't ever seem to get newbies to just do it right the first time , and instead they do it twice. Some things never change ! Anyway , good chatting with you and point taken. Where in Aus. are you located ? I usually visit in December , Fly in to Sydney , we hire a car and drive north up to the McLean River Valley for a visit and sometimes up to Lura in the Blue Mountains . I've been to a track around there , I think it's called Willowbrook ? Lots of Bikes when I was there. Somewhere north of Sydney as I recall. Drop me a line , I'd love to see that Maranello! Time for bed ,Ciao , Jim.

 

excellent thread , BTW

 

Yes Tony , I could not agree more , there is value in this exchange . I can always see value in intellegent dialogue ( and grammar! ) even if I am in defense mode mostly. Jim.

 

Yup SCCA thought of that. When you don't have the ability to do the math you go with what is standard in the industry. Page 145 of the SCCA GCR says the tube for the wimpiest class "showroom stock" is 0.120 wall DOM for the weight of the 360/430 and the tube you are using. Also, there is no difference between a MIG or a TIG weld as far as strength and durability. A MIG weld can be done just as well as a TIG and many manufacturers such as OMP use the MIG process. IN fact GM uses the MIG process on Aluminium in the new ZO6! The problem with MIG is that a rookie can hide weak welds through poor penatration because the MIG spits out weld wire like toothpaste and can sit on a joint instead of penetrate into it. With a TIG you joints either are good or they fail miserably so you can't cheat with a TIG. And for show there is nothing better than a nice TIG weld looking like a row of dimes. For those who do not understand welding always buy TIG products because it is more likely to be done correctly.

And yes dual use compromises are always an issue. I understand your points and your compromises. The real problem is when customers do not understand the compromises and get hurt thinking they are just as protected as M. Schumacher because their car has a hoop and a HANS. SAfety is an extremely complicated issue. It is easier to make a full out safe racecar than it is to make a safe dual use car. After you have seen a few friends pile up luckly with only pride in the hospital you rethink your own safety systems at the speeds we move. Bad things happen when you loose it at 150mph. Your system is either up to it or you'll find out the hard way.

 

Which system is truly safer? If safety is the only concern. Would a five point harness with a rollbar be safer than a three point lapbelt? I have been told that a harness is unsafe for street use. Which one is true?

 

A legendary hijack! Did you read this thread in detail?

I think the central answers to your question are:

a) Max safety comes with a full 5/6 point harness and a full roll cage and a hans.
b) A harness/hans with a hoop as per this thread *may* offer more safety than a 3 point seat belt, but it depends on your point of view.
c) certainly one should not fit harnesses without some sort of roll bar. The reason for the 3 point design and the fact that you can't get the factory 4 point belts in the US, is that they allow you to move sideways in the event of a roof failure and hopefully avoid a broken neck/spine in the event of a roll over.

My opinion on b) is that its an interesting option for a road car. The problem of a) is that you can't drive it without a helment since your head will likely impact the side bars at the top in a big accident on the road.

 

Dan , your points are really well put. The objectives for all of the street cars that we build units for ( from stock H.P. cars to turbocharged stuff with 800 plus.) , can vary , depending on the owner , but we insist that without fail the unit be designed to not allow the driver/passengers head to be able to come in contact w/ the unit as designed/installed. We know going in that many of our units will see 100,000 miles of service on the highways and in the canyons....They don't all live only on the track. Knowing full well that we are exposing our Company to the Liabilities that this scenario can create , we do all we can in the design process to eliminate that possibility. We believe we have done all we can do to design the 360/430 unit to avoid this concern , short of placing the bar so far back it becomes of questionable use. Some comments from the owners of recently installed units may help shed some light as far as this unit goes. Please also note that the pricing on this unit as originally posted here on FerrariChat WAS incorrect ( in error , it included the install time we charged here !), MSRP is in fact , $ 3865.00 + shipping and install extra.Thanks , Jim Dunford.

 

At track days we have now got the situation where street cars on R spec rubber are approaching Porsche Cup car lap times (with competative racers). As a result our State advisory committee is now looking at mandatory FIA compliant roll bars for cars quicker than a target lap time at each track. Many clubs are already imposing harness requirements and all clubs require roll cages to be used in conjunction with slick shod cars.The number of destroyed cars I have seen over the last 12 months of track days, one where the driver concerned was airlifted from the track, has made me realise, track work without a full cage and harness is a risky proposition.

 

A little off subject , but , with the advent of 'open track' popularity widening , it's really no surprise to us that the frequency of single car incidents at the race track has been steadily on the rise in the last few years . If you consider the horsepower averages on the most recent crop of performance OEM cars , combined with the currently available tires and dampers , your upper cabin 'Tuned' car can generate well over 1 G of lateral load with simple bolt-ons. Many weekend warriors don't drive at these limits often enough to gain the required finess and car control needed when the occasional , big inputs required to save cars headed the wrong way at high speed are called for.

Being located at Infineon Raceway in N. California , and being here year-round , we see a lot of crashed cars come in on the 'Hook' . I always appreciate being able to view the damage produced as a result of these ' incidents' ( NOT that I like to see destroyed hardware ) and often will take a minute to talk to the drivers ...if possible , and get their story. IMO , most of them appear to be cases of the car simply being ahead-of-the-driver. Track days @ Infineon now require at least shoulder and lap belts , a battery cut-out and a fire extinguisher in car for all the modified cars .

The average performance car available today , is admittedly more powerful and quicker responding than ever before.

The average Human today is only marginally more responsive and probably no more powerful than was 20 years ago....

So does this phenomenon seem so surprising ? Just an observation. Now back to the regularly scheduled thread.

 

Well I completely agree with all these last three posts. The reall problem as I see it is the hi horsepower to weight ration of the new cars with complete disregard for the effects of their mass and energy hitting a cement wall. I think Marshall thinks I'm a pro as something automotive but I am not. I'm just a garage rat with lots of greesy fingernails around Ferraris and racing one wheel to wheel and doing DE's too. I weld/have tube benders/lathe/mill/full service lift/O-scopes etc.. and have built my own racecar safety sytem but I am no pro and I am still learning. I have seen too many bad things happen and I feel my personal price for the sport is to be as safe as possible and that means for me only all the stuff from scroth quad shoulder belts to full containment seats and firesystems. As I got faster I started to scare myself. At the speeds I travel a blown wheel bearing or a nascar lovetap into the wall would definately leave a mark.

I am sorry to be hyper critical of the product in question as my english is not very polite. But if I raised some hackles and got some people to think at least it was worth it if it prevents some injury. There are amazing small details that could kill you like simply failing to properly wrap the tails of your harness on the harnessbar which I see time and again which is often missed by DE club's tech sessions. It is important to you and your family and the rest of us who love the sport to do your best to stay alive and live to track another day. Look at our Fchat brethern who died last year. Perhaps just a bit more forethought would have prevented the death of 2 good people.