Geo

1) I can't do anything about the steering column.

2) My beef with back breakers is that they are pointed at my spine. And the fact that IMHO a seat that is not rigidly mounted will transfer less energy to the driver in a crash.

TT Surgeon

I think the bottom line is that you have to take safety seriously, non-pca clubs are not as safe in my opinion, one group had the honor system for tech, there were a lot of dishnorable guys that day.
If a hans makes you feel safer get it. Years ago when I was class racing they had a rule about driveshaft safety loops. Well, I snapped a driveshaft at 137mph, that shaft would have decappitated me if not for that steel hoop as it easily ripped through the aluminum floor panels.
Safety first, I think I'll put the DAS bar in mine.

Geo

That's a pretty parochial statement.

Better than some perhaps, but not all.

RedlineMan

The problem is that in a rear hit, you would be utterly horrified how far back the seat will likely bend, how far up the seat back your body will travel, and how ultimately close your head will end up being to that roll hoop. It really CAN be that dangerous.

Of course it is a matter of degrees. If you are short and a long way from the hoop, if your seat is very stout in makeup and mount, and you don't get hit that hard, you might be fine. If any one of these go against you, you might get more than your bell rung!

It is NOT a universal problem, but it is DEFINITELY something you must take into account when making your decisions.

Phokaioglaukos

For Larry and other instructors who may spend as much time in other people's cars as their own at a DE, I can see that the HANS (Hubbard/Downing) is not attractive--it can only be in a properly prepared car. (There is a FIA spec sheet in Acrobat format HERE.) For my car, though, I can set up the HANS correctly, and I won't be riding in other people's cars for some years.

I note that only the HANS is FIA approved. It's also SFI 38.1 certified. The SFI web site seems to be down now, but it should come back up HERE .

I guess the whole HANS setup is more expensive than a R3, but it has been in the market longer and I can set my car to use it properly. Thoughts on how to go?

RedlineMan

First off, the early 944 seat mounting is really a joke; 4 little 6mm bolts into tin platforms with floating nuts. Most of the floating mount pockets have long since failed from metal fatigue all on their own with only street driving. My floor had actually collapsed and the seats sagged sideways!

Mounting a seat is a real brain teaser.

First you need the positioning worked out. On top of my list is getting leg room worked out first. Then see if you can get the arm reach down right from there. This is where the Kirkey road race seats fail because of what I offered before.

Once that is worked out, syou need to allow for some re-adjustment in your mounting design because invariably what you think works sitting still in the shop will prove less than optimal in battle. You'll need to give yourself the chance to alter the setup with clever design.

Next, the mounting. I like alloy seats because they offer lots of options for mounting. I use a side mounting method like below. You can either do sliders or solid mount. I make side plates and bolt through the side panel for a very solid mount. You can also make your mount flanges large for multiple holes to fine tune your seat setup (see above).

I have landed on the concept of first attaching the two seat rails together (if using sliders) with a piece of 1.5x.125 angle iron welded to the sliders front and rear to form a square. It can sometimes be easier to use seperate tabs for mounting each corner because welding a bar across the two sliders front and back makes it a little trickier to keep the sliders parallel to eachother so they will slide easilly.



Then, I make pieces that these two cross members will sit on/in. Whether you need more headroom governs whether I set inside these mount rails or on top of them (as pictured). These mount rails are made of the same angle iron, and run across the floor from side sill to tunnel and weld on both sides and also various spots across the floor pan. 944s & 928s require you to section around the e-brake mechanism, which requiures more work.

Nuts are welded on the back of these beams corresponding to holes in the seat rail crossmembers. I use minimum 8mm fasteners, often prefering 10mm for serious track cars.

This all makes for a fairly simple and very stout mounting system that is not horrendously difficult to render.

Here is one I did in a 911 to give you an idea of what the floor rail look like. The seat rails then sit on top of this.



Does any of this make ANY sense?

RedlineMan

I would say a MINIMUM of 10 degrees. Then, you can fiddle with how much thigh support you like. Some people like the seat snug under their thighs while other like some room there. If you recall, in previous safety threads I've mentioned seat base declination as an important part of any safety system in regards to hold the driver in -vs- what crash bio mechanics try to do, which is submarine you.

RedlineMan

I went with the HANS for the same reason, but I have come around to the point that I regard the Isaac as the best for versatile and simplified usage in recreational applications in a single car. For varied car usage, I think Larry made a good decision.

Sanjeevan

John, what are your thoughts on the lack of certification of any form with any of the isaac units.
Thanks
Jeeva

Phokaioglaukos

The Isaac web site does not describe mounting the unit to the car/seat, so far as I can see. Does the non-helmet end just attach to shoulder belts?

TT Surgeon

Parochial, maybe, but from the many non pca de's I've done that's the conclusion I find. You tend to see gigantic run groups; rag tag cars that I doubt were really 'teched'; same day run group promotions( noivice to intermed solo for ex); honor system teching; multiple off track excursions.....
I don't think they are all bad, pda runs a good one , but I think I'll stick with the pca events, jmo.

Geo

Gotcha. For some reason I didn't connect that you were talking about DE. I was thinking racing. Sorry.

ltc

The non helmet end merely rides on the belts on a roller/pin arrangement.
It is NOT firmly attached to the belts....this was discussed a year or so ago in a very long thread....I'll try and find it.
Here are a few pics:
http://www.isaacdirect.com/images/Pr...m/RearView.JPG
http://www.isaacdirect.com/images/Pr...em/IsoView.JPG

ltc

Here is one:
http://www.isaacdirect.com/images/Pr...k/SideView.jpg

ltc

FIA approval, along with SFI 38.1 approval would affect the design/operation/efficiency in what manner?
To me, these approvals/certifications mean absolutely nothing, especially given the history of the HANS and the FIA.