Hans Devices and DE
#61
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Originally Posted by Geo
3) I prefer a seat that won't deform and stay deformed.
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Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
Larry Herman
2016 Ford Transit Connect Titanium LWB
2018 Tesla Model 3 - Electricity can be fun!
Retired Club Racer & National PCA Instructor
Past Flames:
1994 RS America Club Racer
2004 GT3 Track Car
1984 911 Carrera Club Racer
1974 914/4 2.0 Track Car
CLICK HERE to see some of my ancient racing videos.
#62
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Originally Posted by Dan Gallagher
Do people ever sell used hans devices, and how much would they go for?
#63
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Originally Posted by Geo
Juan, this is purely my opinion....
I still wouldn't want the back brace. I bought an FIA homologated seat specifically because I wouldn't be required to use the brace (of any sort).
I still wouldn't want the back brace. I bought an FIA homologated seat specifically because I wouldn't be required to use the brace (of any sort).
The PCA appears to have a different take (a bit confusing to read):
http://www.pca.org/pca/clubrace/docs/pca_rules_2005.pdf
25. All cars will be equipped with a seat back brace except as provided in Safety Rule 26 below. Said device will mount securely to the roll cage/bar and will rest firmly against the back of the seat. The portion that contacts the seat will be a minimum of twelve (12) square inches and larger is suggested.
The seat construction must be compatible with the seat back brace and not pose a hazard to the driver. The seat back brace for composite seats must have a minimum of thirty (30) square inches contacting the seat back, and must have 0.5” to 2” of high density foam padding between the brace
and the seat back. The seat back brace cannot be bolted to a composite seat.
26. If the seat is within 3” of the firewall, a seat back brace is not needed but the area between the seat and firewall should be padded with high density foam. A seat back brace is not required in cars equipped with a current FIA approved seat and seat mount. Installation of a new FIA approved seat
requires concurrent installation of a new seat mount and new seat rails, if seat rails are used. The seat mount and seat rails must be sold by the seat manufacturer for installation with the specific seat selected. The chassis mounting points for the seat must be reinforced and in good condition. The
seat must be replaced after 5 years from the date of manufacture if not used with a seat back brace.
BTW, the high density foam also has a Snell certification #....45.2 IIRC. Similar to 45.1 rollbar padding.
#64
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Originally Posted by Larry Herman
George, don't you think that point is moot? If you have to replace your helmet and belts when you have a big impact (provided you didn't write off the car
), don't you think that you would have to replace the seat as well? How could you be sure that it maintained it's structural integrity?
![Mad](https://rennlist.com/forums/images/smilies/mad.gif)
I think that he is worried about the seat deforming during the accident (e.g., squeezing you like a taco) and remaining deformed after the accident (e.g., keeping you squeezed like a taco). I have heard conflicting advice about the Kirkey aluminum seat I just bought, with some telling me that they would only consider fiberglass for this reason.
I am sure he will correct me if my assumption regarding his intent is incorrect.
TD
#66
Race Director
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Originally Posted by Larry Herman
George, don't you think that point is moot? If you have to replace your helmet and belts when you have a big impact (provided you didn't write off the car
), don't you think that you would have to replace the seat as well? How could you be sure that it maintained it's structural integrity?
![Mad](https://rennlist.com/forums/images/smilies/mad.gif)
#67
Race Director
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Originally Posted by ltc
George,
The PCA appears to have a different take (a bit confusing to read):
http://www.pca.org/pca/clubrace/docs/pca_rules_2005.pdf
The PCA appears to have a different take (a bit confusing to read):
http://www.pca.org/pca/clubrace/docs/pca_rules_2005.pdf
#68
Race Director
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Originally Posted by TD in DC
Larry,
I think that he is worried about the seat deforming during the accident (e.g., squeezing you like a taco) and remaining deformed after the accident (e.g., keeping you squeezed like a taco). I have heard conflicting advice about the Kirkey aluminum seat I just bought, with some telling me that they would only consider fiberglass for this reason.
I am sure he will correct me if my assumption regarding his intent is incorrect.
TD
I think that he is worried about the seat deforming during the accident (e.g., squeezing you like a taco) and remaining deformed after the accident (e.g., keeping you squeezed like a taco). I have heard conflicting advice about the Kirkey aluminum seat I just bought, with some telling me that they would only consider fiberglass for this reason.
I am sure he will correct me if my assumption regarding his intent is incorrect.
TD
And for anyone who doesn't believe you can come partially out of your seat (mostly to the sides), you need to look at a lot of crash tests and read first-hand accounts. It's quite possible.
#69
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Originally Posted by TD in DC
Earlier today, I almost pulled the trigger on an ISAAC until . . . I started thinking about the new less expensive model. Here is what bugs me. Almost all of the ISAAC marketing is based on touting the benefits of using a shock absorber system to allow movement at slow speeds but prevent movement at high speed. This makes intuitive sense to me. The new less expensive model relies on straps, and yet ISAAC claims it protects nearly as well. What gives? Doesn't this undercut much of the primary marketing materials? Also, if injury does not occur until 900, the expensive ISAAC permits 200 and the introductory permits 400, why wouldn't you always get the inexpensive strapped model since it, in theory, would permit greater range of movement and, presumably, more protection for lateral impacts. Yet, if you are considering a strap design, the R3 seems like a better choice AND is approved by a lot of the sanctioning bodies. Plus, you can take the R3 with you from car to car. ARRGGHHHH.
#70
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Todd;
The basic difference in the HANS/Isaac Link, and the Isaac "hydraulic" is that the former do allow a set range of motion before activation. In theory, they are designed to take up before a dangerous level of head exention is attained. The Full Isaac system reduces head travel very quickly, and therefore by reducing the time frame of unrestricted travel, theorectially offers an advantage in reduced overall head/neck loads. Whether the loads attained by the "semi-active" strap devices (the fast stop at the end of the tether) are low enough to be considered "safe" falls pray to many variables, but suffice it to say that they reduce these stresses to an accepted level, far more than having nothing.
The HANS is indeed quite dependant on good system architecture. The layout of belt angles and such is rather specific, and therefore can be rather diffcult to properly render in anything less than a full blown track car. The Isaac does seem to offer a distinct advantage here. I STILL am not quite able to get past my ambivalence towards exactly HOW the Isaac utilizes the belts, but I feel it does indeed offer distinct advantages in versatility.
To those looking at Kirkey road race seats, I would advise against it. Sorry Todd! Unless they have changed very recently - which I am unaware of - they have one key fault that makes them difficult if not impossible to install correctly. They only offer a 20 degree layback design for their road race seats, and in my experience this simply does not work. If you tip the seat back to get a good base angle for torso retention, and proper headroom, you can't reach the wheel. If you tip it up to reach the wheel, you lose headroom and the seat base goes horizontal (dangerous!). I have had no luck using these seats in sedans, in their standard form.
Too bad, because I bought an RR Deluxe for myself before I found this out. I spent many hours hacking away at my car trying to configure the thing. It was a disaster. I could reach the wheel, but only by fabricating a 2" extended hub! I had to cut out all the stock floor bracing and redo it to lower the seat. I had enough headroom (barely), but the seat base was FLAT. I found myself not being able to see out of the rear mirror... when I realized I was sliding out of the seat!!!!
I offered to drive up and help Kirkey solve this problem, but they did not take me up on it even though they said they had no road race expertise.
I solved the problem by cutting my seat and reworking the back-to-base angles. Ironically, it ended up at exactly the industry standard 10 degrees!!
Now... it works perfectly...
Wish I'd known about Ultrashield before I bought a seat!
The basic difference in the HANS/Isaac Link, and the Isaac "hydraulic" is that the former do allow a set range of motion before activation. In theory, they are designed to take up before a dangerous level of head exention is attained. The Full Isaac system reduces head travel very quickly, and therefore by reducing the time frame of unrestricted travel, theorectially offers an advantage in reduced overall head/neck loads. Whether the loads attained by the "semi-active" strap devices (the fast stop at the end of the tether) are low enough to be considered "safe" falls pray to many variables, but suffice it to say that they reduce these stresses to an accepted level, far more than having nothing.
The HANS is indeed quite dependant on good system architecture. The layout of belt angles and such is rather specific, and therefore can be rather diffcult to properly render in anything less than a full blown track car. The Isaac does seem to offer a distinct advantage here. I STILL am not quite able to get past my ambivalence towards exactly HOW the Isaac utilizes the belts, but I feel it does indeed offer distinct advantages in versatility.
To those looking at Kirkey road race seats, I would advise against it. Sorry Todd! Unless they have changed very recently - which I am unaware of - they have one key fault that makes them difficult if not impossible to install correctly. They only offer a 20 degree layback design for their road race seats, and in my experience this simply does not work. If you tip the seat back to get a good base angle for torso retention, and proper headroom, you can't reach the wheel. If you tip it up to reach the wheel, you lose headroom and the seat base goes horizontal (dangerous!). I have had no luck using these seats in sedans, in their standard form.
Too bad, because I bought an RR Deluxe for myself before I found this out. I spent many hours hacking away at my car trying to configure the thing. It was a disaster. I could reach the wheel, but only by fabricating a 2" extended hub! I had to cut out all the stock floor bracing and redo it to lower the seat. I had enough headroom (barely), but the seat base was FLAT. I found myself not being able to see out of the rear mirror... when I realized I was sliding out of the seat!!!!
I offered to drive up and help Kirkey solve this problem, but they did not take me up on it even though they said they had no road race expertise.
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Wish I'd known about Ultrashield before I bought a seat!
#71
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Originally Posted by kurt M
2. Street driving with as roll bar or cage is less safe than not having one unless you have your helmet on.
#72
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John,
My Kirkey seat has yet to be installed (I was trying to get the 944 ready for a DE tomorrow, but it will not be ready). I can probably return it for an ultrashield. Which ultrashield did you get, and do you have any advice on how I should mount it in my '84 944? Is the mounting hardware fabbed, or is there something else I should buy.
TD
My Kirkey seat has yet to be installed (I was trying to get the 944 ready for a DE tomorrow, but it will not be ready). I can probably return it for an ultrashield. Which ultrashield did you get, and do you have any advice on how I should mount it in my '84 944? Is the mounting hardware fabbed, or is there something else I should buy.
TD
#74
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Geo,
I don't think the stick pointed at your spine with a back brace is any worse than the stick of the steering wheel pointed at your chest. In fact we are probably more likely to get hit by that than the back brace. Distribution of load is the key so if the PCA etc say 30 square inches 12 square inces of plate on the back brace pole or whatever there should be enough distribution. You can always have more square inches. Also, if a properly designed cage with seat bolted to cage and cage features like seat rails that go from the base up to the harness bar the seat can deform less under your conditions regardless if it is plastic or metal as it is supported along its entire length from seat leading edge to shoulders. Is your beef with back braces not really the concept of seat back bracing but really with the way back braces are made/installed today for non-pro racers as an "add on" device with zero testing?
I don't think the stick pointed at your spine with a back brace is any worse than the stick of the steering wheel pointed at your chest. In fact we are probably more likely to get hit by that than the back brace. Distribution of load is the key so if the PCA etc say 30 square inches 12 square inces of plate on the back brace pole or whatever there should be enough distribution. You can always have more square inches. Also, if a properly designed cage with seat bolted to cage and cage features like seat rails that go from the base up to the harness bar the seat can deform less under your conditions regardless if it is plastic or metal as it is supported along its entire length from seat leading edge to shoulders. Is your beef with back braces not really the concept of seat back bracing but really with the way back braces are made/installed today for non-pro racers as an "add on" device with zero testing?
#75
Race Car
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Originally Posted by kurt M
Street driving with as roll bar or cage is less safe than not having one unless you have your helmet on.
[...]
You are FAR more likely to have a multiple G impact than have any kind of compartment intrusion rollover. Period.
[...]
You are FAR more likely to have a multiple G impact than have any kind of compartment intrusion rollover. Period.
The often-repeated theory is that a high-density padded cage is more likely to injur the driver than the multiple unpadded steel components of the car itself. When I think of the rolled edge of the roof, the sharply angled steel of the A- and B-pillars, I wonder if this is true. Earlier in the thread, John made a point about flat versus rounded objects and their characteristics when you hit them, and it was part of a very intelligent and articulate post, but I wonder how likely it is that I'd make a nice, flat contact with my roof, A- or B-pillar, and -- regardless of the shape of the steel -- I think I'd still rather get hit by a bat covered with high-density padding than the un-padded steel that's there in a stock 20-30-year-old 911.
Some people cite the proximity of the cage as the hazard -- it's closer to the head than the steel pieces of the car. But John's post also talked about the danger of velocity achieved before impact: the whip action. A padded bar closer to my head is a potential hazard, certainly. But so is the unpadded steel that I'm going to hit with greater velocity with a few more inches of travel.
I bring this up not because I think I'm any kind of an expert on this. I'm not. In fact, I'm eager for people who know more than me to set me straight. But as a layman, I think that my cage is giving me a net gain in safety, in spite of some trade-offs. Am I wrong?