a question on those 5 point shoulder straps

[Whaler]

Hi
I have mounted my lap belts and sub straps. 3 inch 5 pt RCI

Now I am sitting on how to mount the shoulder harnesses.

I have a round tube that is part of the upper frame behind the seats and aluminum bulkhead that runs across the car (picks up the body) I plan on using it as the attachment point
I am wondering if it's better to use 2 eyebolts 3/8" for each seat or 2 small 1 1/2"U-bolts 5/16".

Also can one use a single mount over each seat to attach two straps however centering over the seat?

I have the RCI attachment tabs which are tee shaped and would at least go thru a u-bolt where as the individual eyebolts still need some further method of attachment to the belt tab. Others like Simpson have a clasp like tee which can be clipped on and off.

Using the ubolts the attachment would not lie as flatly or as nice as eyebolts have the benefit of rotation to accomodate the tee tabs. The ubolys would house the tabs in a cocked like position as they would be mounted on the horizontal.

I am sitting on this until I am sure how to go about it and not drilling any bloody holes until then......Thanks

Tim

[Mr.Fixit]

The best way to mount the shoulder harness is to the rollbar with one of those nifty brackets made just for that. Otherwise, unless you're really short, the mounting point will be too low and the shoulder straps will stop forward body motion by compressing your spine.

[Whaler]

Hi
I thought about that as an easy $200 way out for my side but I still have the passenger side to worry about.
As for the mounting, yes there's an extensive thread on the location of the straps and safety.

shoulder belt mount location

thanks

Tim

[niles]

Wo sells the roll cross bar for a 2 in bar?
gn

[Whaler]

Hi Niles
Enzo has them in both 1 1/2 and 2 " for $175@ Finishline

scroll to the bottom of this linked page

http://www.cobraaccessories.com/f-catpg25D.htm

[niles]

Whaler:
Thanks for the input.
I also am at that point; and I read every post; and they were very interesting and though provoking. Many by very experienced and knowledgable engineers and NHRA people.

So the argument about 4 in low, to 4 in high etc; and the strong opinions and experiences made me think about it and pour a double.

Once the techies look at the car type, seat type/inclinataion, roll cage configuation; they arrive at "their Optimum solution" However, that is not universal. For instance a fuel dragster has a roll cage that surrounds the head and helmet, the driver is sitting on minimal padding and he's strapped in tighter that Dollie P. bra.
His best angles, impact body reaction is very different from a street Cobra; in addition the impact scenerio is vastly different(glancing rail impact-followed by a car break up and roll over.)

So the optimum dragster hearness angles(NHRA) may not be best suited for a Cobra.

Thinking more; what is the most likely impact; lost of control and side impact; belts are limited there. Head on with brakes locked; a likely scenerio. Thinking that one through and the observation that one is raised out of the seat typically upon impact. Street belts are not normally tightened beyond the comfort level. I recently heard of both occupants being ejected form a Cobra. It would seem that one should optimize the belt angles to keep one down and in. That would lead me toward a slightly higher lap belt angle and shoulder harnesses being 1 or 2 inches lower that the shoulders. I recognise that that will increase spine compression; but it will also reduce being lifted 6 to 12 inches out of the car during a roll over and receiving no benefit from the roll bar.

A disclaimer; these are my present thoughts; I would appreciate more technical and non-emotional discussion this very important subject. Unfortunately there is not a univeral solution because every impact probably has 4 or 5 variables that are collision unique. One trives for the solution that tips the odds toward you more often than not.

Still athinken!

gn

[Bob Putnam]

Niles,

I like someone who actually thinks things through!

There are so many variables involved it makes my head spin.

Not only do you have to figure the proportion of head-ons, side impact, rear impact and rollover - then add in any track use. Consider your personal driving style and history? Help!

I'm beginning to think I should dress like the Michelin man...

[Steve R]

Niles and Bob,
A friend brought to my attention that in the event someone rear- ended you, your head is going to bounce off the rollbar if your lucky. Have either of you given this any thought? we both have FIA type rollbars.
Steven
PS, I feel these discussions are very important. Even though they have been heated in the past, I have learned allot from them. THANKS!

[Whaler]

Hello All

yes good discussion and not a quick and easy solution

Before I had finshed reading Niles post I had to think of the poor bloke who was just killed 2 weekends ago at our airport.
He had been flying gliders for 8 years and was the pres of the local soaring assn. He had just bought himself a single place glider and was trying it out on a Sat morning.

Had been up flying after a towplane released him. Came in for his landing and had gotten screwed up somehow, either too fast, too low or too high, anyhow the instructor who was there also waived him off and told him to go around. Somehow without further radio contact he decided to crank it around and try something only he will ever be able to explain.
Unfortunately he ended up dragging a wingtip, then doing a cartwheel onto his nose on the tarmac.
Died instantly of major trauma to the head. 11:30 on a nice Saturday morning

Later the autopsy this week explained no medical conditions were found attributing to the accident ( some thought so as he was not responding to radio direction). *Not the first thing on my mind either, when the shi* hits the fan!......
The aircraft had a full harness restraint system meant to keep him in his seat.
Turns out he cracked his skull open on the bounce back off the airframe right behind his head.

So I relate that story and as Steve R relates....what about that Rollbar behind us??

The fact that many of us have the lowback buckets leaves us vulnerable to all kinds of neck and head trama, let alone spinal compression in some impacts.

Didn't we read about two guys last year out for their sunday drive losing their lives on a road collision last year. One or two of them had broken necks.

Headgear and collars next?

Anyhow we can only do our best when building these cars and I guess drive them as defensively and responsibly as we can.

Tim

[Richard Hudgins]

Hi Folks,

Once again a good discussion and one that all owners and drivers of these type of vehicles should pay attention to.

If you will go to JBL , The first photo is a JBL at the track.

You will notice that behind the drivers head is the crossbar/seatbelt mount that JBL uses for the Single bar. This bar mounts a head impact pad/restraint as well as the seatbelts.

Now, you all may notice that the impact pad is not installed. This is not good. In a rearward impact, not only would your head contact the alloy bar, but due to the large space between the head and the bar, you would hyper-extend your spinal column. (the pad is 8 inches thick and made from sorbathane)

The point that I am trying to make here is this:

No matter what you design as a safety measure or piece of equipment as part of a safety system, You have to get people to use the whole system.

On the cars that have the forward brace, it is very important that proper impact absorbing material be put in the areas where one may contact the bar in a accident. So far, I have had a hell of time getting folks to do this. Just like the pad on the crossbar.

The reason is always that they do not like the way they look.

I have the same problem with brake pads, the Polymatrix A pads are much better than the D's. But they make your wheels dirty. Therefore, customers would rather have clean wheels then great brakes.

Once again, vehicles are comprised of systems, The systems need to be complete to operate correctly.

[Bob Putnam]

A head "rest" is a good idea, although we've had few requests for same. This is the way we've done it on our track car, and I don't see a problem using it on a 427 either. It has about 1" of stiff, energy-absorbing foam:

[Mr.Fixit]

All in all, a Cobra is pretty safe for a motorcycle. Other than that I wholehartedly agree with Richard Hudgins on the topic of cobra safety

[niles]

Steve/ Bob, Richard/guys:

good discussions. Head protection is what got me going on this subject.
I have sat in the Cobra seats and noted the lack of support and protection.
I've researched their origin and I have it from good authority that ole CS, Mr's Austin and Cooper had emptied a keg of Bitters while discussing seats and in a heighten state of creativity sawed the barrel and half and then quartered it and said "slap a little vinyl on it and it will satisfy those Budweister swiling Americans"

My chassis has a dropped footbox and I have fitted a Miata seat; too high with the built in head rest.
Acura Integra seat and a Ford Escort barely fits widthwise; but are quite short and come up about even with the rear coaming.
I'm thinking of using this solution; without headrest; seat looks "reasonable stock" with the head rest installed; acceptable protection from the roll bar and rear whiplash.

At least that "today" solution.

gn

[Mike Braddock]

Sounds like a good solution Niles. What kind of roll bar(s) are you running? We went with dual roll hoops which allow us to use a pair of leftover Porsche 914 seats which fit very well and look right at home with the dual hoops. The dual hoops also give us a good location to which we can attach the shoulder harnesses as shown in the following photos:

http://www.pbase.com/mjb2/cobra_seatbelt_mounts

Much like Richard's solution but without the bar running between the seats. The high back seats give us peace of mind, as do the two hoops. The seat belt mounts were made out of Chevy 283 connecting rods with standard bearings. They fit the 2" tubing perfectly and the bearing material should be soft enough not to damage the coating on the hoops when the car is finished. Finally, the allow us to position the shoulder harnesses properly with respect to our shoulder height...

Mike

[niles]

Rhichard:
Ref the pic of the JBL cross bar; is it a alum. bar? machined to fit the bar x-section?
grover