Roll bar / harness bar question
 

I am going to install a roll bar and 5 point harnesses. I see that some roll bars have an integrated harness bar. Others do not.

My question is, do I need this harness bar?

Seems like I do to prevent the harness from compressing occupants in a frontal collision.

Do harness guides in the seat serve this same purpose?

I have a line on a roll bar without harness bar at a good price.

Chuck

If you want to anchor harness's to your roll cage, you need a bar that is approximately equal in height to your shoulder height. I think the PCA clubracing rules allow no more then 40 degrees of deflection to be conforming. Certain rigid race seats (Recaro, Sparco) have additional support within them to resist the crushing that can happen as the seat in compressed but these should not be relied as the harness fulcrum. Most of these harness bars are also integrated with seat supports for protection in rear crashes. If your doing any type of track driving, they are a good idea. The AutoPower bar in mine allows me to remove the harness setup when not in use, freeing up the backseat to my kids. http://www.pelicanparts.com/ultimate...ploads/bar.jpg


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8 9 9 1 1, The last of the line.

[This message has been edited by 89911 (edited 10-16-2001).]

You want a rollbar or cage that allows you to do a "wraparound" mounting of the shoulder harness. See photo.

http://www.pelicanparts.com/ultimate...ds/rollbar.jpg

89 911, how is your harness bar mounted? I have an Autopower roll bar, but it doesn't have any obvious mounting points for a harness bar, and the guy at I/O Port very rudely told me that you have to order the bar with it installed. Is it a bolt-in bar?

Thanks

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David Schultz
1973 911T 2.7
http://home.earthlink.net/~kineticdg/Porsche1.htm

Yes, it has to be ordered with the harness bar bolt in tabs. The diagonal piece bolts in. Heres a diagram: http://www.daveturner.com/autopower/rollbar.html

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8 9 9 1 1, The last of the line.

It wouldn't be very difficult for a good weldor to add tabs to your roll bar to accomodate a removable harness bar like the autopower setup. If you want a welded in harness bar it is even simpler. I can do it for you if you're in Vermont... A short length of cold rolled mild steel seamless DOM tubing, an angle grinder and a MIG or TIG welder is all you need. Not that I'm the world's best fabricator, but that is pretty simple stuff. The tricky part is getting the bends right and this has few (or no) bends, depending on how you do it.

As I'm sure others have mentioned, the harness bar gives a closer place to mount your harnesses. In a collision the straps stretch and the longer they are the more material available to stretch. You do not want to have any elongation when you crash - the steering wheel isn't that far from where you're sitting!

If you mount the shoulder straps at an extreme an angle some places won't even allow you on the track. The height of the mounting bar is important to prevent spinal compression in a crash.

The openings in a race seat do nothing to prevent this compression, they're just a convenience to get the shoulder straps at the area of your shoulders.

Do you need it - no. Do you want it - yes! Can you add one after you buy the rollbar - absolutely.

Charlie

Sounds like the best solution is to get a rollbar with harness bar, and not screw around with it. That link provided has good prices on Autopower.

Thanks for the input.

Don't forget to add in the cost of freight shipping if you're not in the local area. From CA to VT it adds up to over $100 extra. At that point you are in the price range of having one custom fabricated locally.

In my opinion, the biggest advantage to having a roll bar or cage custom built is that they fit your vehicle perfectly. The commecial roll bars will save your neck but they often sacrifice the shell to do so. The closer you get the roll cage/bar structure to the sheetmetal the less deformation you are likely to have in an incident.

I rolled a rally car once (about two years ago) that was relatively easy to fix and did not sustain any significant chassis damage because the roll cage fit so tightly to the shell. Try that with your average autopower bar some time (but be prepared to junk the car afterwards).

Cheers,
Charlie

I installed my Autopower bar myself and if fit perfectly. I have used Dave Turner Motorsport also and they have a good organization. AutoPower have built 10's of 1000's of bars for Porsche. I think I would trust them more then some guy with a mig welder and steel who had done a few. At a DE I went to at Mid-Ohio, they had driver training cars there for their school. Must of been 30 cars all with Autopower Bars installed. The shipping price to the best of my knowledge was less then $50 to Pittsburgh from CA.

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8 9 9 1 1, The last of the line.

[This message has been edited by 89911 (edited 10-17-2001).]

89911,

I do not tend to agree with that line of reasoning - it is much like saying "I'd rather have a Ford Taurus than a Porsche 911 because they build more of them, therefore they must be really good. I see a lot more of them on the road too so that proves they're better".

<sarcasm mode off>

Honestly, how many real race cars have you seen with an Autopower or Kirkey cages? Probably not many. A few weekend warrior types possibly, but my experience is that the professionals tend to have custom fabricated cages.

Even me, with a cheap VW rally car had a cage that cost half as mush as the car. I *personally* would not skimp on safety. I've seen the world from upside down in a car and I'll tell you a well built roll cage or bar is worth a lot.

To clarify there is noting wrong with a well built, custom fabricated cage or roll bar. My belief is that you can get one hand built for not a whole lot more money than the mail order mass produced units.

I understand that lots of people may disagree, this is just my opinion.

Charlie
aka "some guy with a mig welder"

Sorry, I didn't realize these were for "real" race cars. I was under the misconception that these were for DE's a few weekends out of the year. But, Hey, if you want to lay down a grand or two for a completely welded in roll cage, go ahead. Good luck if you ever want to sell your car again. Why not throw in the halon fire system, removable steering wheel, and window netting also! I also don't follow yourreasoning that Autopower make "cheap" cages? Maybe there are so many of them because they are a good value. They are SCCA aproved and made of the same steel you would make them of. The reason I bought mine was that a majority of the club racers I would see at DE's had these installed. It had nothing to do with price. The fitment of my bar is flush with all the dimensions of my car. Don't knock a well made product that is a good value unless you have proof otherwise.

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8 9 9 1 1, The last of the line.

[This message has been edited by 89911 (edited 10-17-2001).]

89911,

I NEVER ONCE said Autopower rollbars are cheap. NOT ONCE. What I did say is that custom fabrication is a reasonable alternative.

I feel it is important for others to realize that there are other alternatives other than pre-fabricated roll bars (or cages). Custom fabrication is one of them.

I believe that any race car is a "real race car" by virtue of the fact that you can crash it or roll it and do bodily injury to the occupants. Whether you do a single DE a year in your street car or you get paid a salary to race, you are at a very high risk of crashing and the safety system (roll bar or cage included) are a very important part of keeping you safe and alive.

The reference to professional racers was just to suggest that people who do this for a living most likely do not choose custom fabrication because it is a substandard choice.

If you want to continue this drop me an e-mail (csprigg@hotmail.com) and we can hash it out privately through e-mail - or the phone instead of wasting bandwidth here.

Cheers,
Charlie

PS. I am having a custom fabricated, removable roll cage installed in my 911 by a professional rally car cage builder for less money than an Autopower rollbar.