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View Full Version : 4 point seat belts


Mthrizzel
Tue, Jan-11-2005, 04:12:34 PM
hey

i have a set of four point sparco seat belts and i was woundering what the best way of mounting them would be

thanks brett

Tpb31
Tue, Jan-11-2005, 04:44:13 PM
do you have a roll cage/bar or harness bar?

Eric1855
Tue, Jan-11-2005, 05:35:37 PM
Without a roll cage or at least a roll bar they are very dangerous for everyday driving use.

Sirius
Tue, Jan-11-2005, 06:40:03 PM
What about thoes harnesses that bolt to the bottom of the seat, then either use the existing rear seat buckles as the upper support?

Blue///M3
Tue, Jan-11-2005, 07:06:40 PM
What about thoes harnesses that bolt to the bottom of the seat, then either use the existing rear seat buckles as the upper support?
I brought that up at my last DE with my instructor and he said they aren't nearly as safe. Something about the way the forces are generated in an accident will cause the seat to buckle and won't protect the occupants. Plus they are a 2in wide belt which is OK for the street but not sufficient for a track car, especially if you have a head/neck restraint.

Eric1855
Tue, Jan-11-2005, 07:13:16 PM
What about thoes harnesses that bolt to the bottom of the seat, then either use the existing rear seat buckles as the upper support?

Still dangerous.

The 3-point (OEM Seatbelt style) are designed to restrict longitudinal movement, while allowing lateral movement. However, a 4-point restricts both. Why is this bad?

When you roll your car, with a 3-point are able you move out of the way when the roof crushes in. However, with a 4-point, you are restricted that movement and your head and spine become the roll protection and your roof crushes right in on you. Hence why you need rollover protection with a 4-point.

Also, on the 4-point harnesses. They need to be mounted to a harness bar that is located behind the seat. They are designed for mounting 180-degrees off the shoulders, or flat back. If you mount them at a sharp angle over the top of the seat, say to the rear seat belt lower mount points the shoulder braces put undue strain on your spine. In a normal collision when your body moves forwards, the shoulder straps force your back down compressing your spine, also very bad.

Basically, in a daily driven street car they are completely unnecessary.

Sirius
Tue, Jan-11-2005, 08:02:18 PM
Ahhh. Thanks. My car came with a 4 point belt in it, but I removed most of it, but I can still hook it up. I did once and just took a spin around the block, and it was kind of uncoftorable.. although the support it gave me around corners was awesome. :D

Eric1855
Tue, Jan-11-2005, 08:43:36 PM
I use my Schroth ONLY when I am racing AutoX, all other times its tucked under my front seat.

beguile
Tue, Jan-11-2005, 09:00:01 PM
Eric1855, you have no idea how many times I've warned people on these forums about have racing harnesses with a rollcage, but for some reason, they don't listen to me. I'm glad to see people are listening to you. Good info. Perhaps we should make this thread sticky (since this question comes up so often).

Eric1855
Tue, Jan-11-2005, 09:02:51 PM
Eric1855, you have no idea how many times I've warned people on these forums about have racing harnesses with a rollcage, but for some reason, they don't listen to me. I'm glad to see people are listening to you. Good info. Perhaps we should make this thread sticky (since this question comes up so often).

I deal with it all the time locally with car clubs, web boards and many of our SCCA members. No one ever REALLY listens, but I feel I should at least throw the facts out there. I can't even count the number of totally stock cars I see on a regular basis just rolling down the highway with their Pep Boys or AutoZone harnesses completely oblivious to the danger it puts them in.

Blue///M3
Tue, Jan-11-2005, 09:19:46 PM
I vote for a sticky. Maybe a move to the racing/DE forum too.

Sirius
Tue, Jan-11-2005, 11:43:28 PM
This would be more appropriate in the track section.

GiveMeAnM3
Wed, Jan-12-2005, 12:53:43 AM
I deal with it all the time locally with car clubs, web boards and many of our SCCA members. No one ever REALLY listens, but I feel I should at least throw the facts out there. I can't even count the number of totally stock cars I see on a regular basis just rolling down the highway with their Pep Boys or AutoZone harnesses completely oblivious to the danger it puts them in.

I understand the logic behind why they are unsafe in the event of an accident. I was allowed to drive my instructors car (with racing seats and 5-point harness, and harness bar) and the support it gives is great (as in not having to hang onto the steering wheel for life) and makes DE's much more enjoyable. I just had the factory seat belts in my previous car and it sucked. Felt like I was going to bend the steering shaft!

So, to summarize, if I go out and buy those Schroth harnesses, they will provide more support and reduce driver fatigue for Auto-x and DE's, but if I roll-over or get into an accident, I may cause more injuries to myself versus if I were using the regular 3-point factory seatbelt? Just gotta figure out if it's worth it then...

(These will NOT be used for street use, just DE's and Auto-x)

Eric1855
Wed, Jan-12-2005, 12:59:01 AM
I understand the logic behind why they are unsafe in the event of an accident. I was allowed to drive my instructors car (with racing seats and 5-point harness, and harness bar) and the support it gives is great (as in not having to hang onto the steering wheel for life) and makes DE's much more enjoyable. I just had the factory seat belts in my previous car and it sucked. Felt like I was going to bend the steering shaft!

So, to summarize, if I go out and buy those Schroth harnesses, they will provide more support and reduce driver fatigue for Auto-x and DE's, but if I roll-over or get into an accident, I may cause more injuries to myself versus if I were using the regular 3-point factory seatbelt? Just gotta figure out if it's worth it then...

(These will NOT be used for street use, just DE's and Auto-x)

Yes that is true. I use mine for AutoX only, not HPDE's. I figure that there is little to no chance of a roll over in AutoX, however, in a HPDE or a lapping day there is a much larger chance of a rollover. I wouldn't use a 4 or 5 point harness without roll protection. But that is just me, perhaps a bit over protective,but better safe than sorry.

M3BlackPearl
Wed, Jan-12-2005, 08:57:13 AM
Wow... HOnestly, I can say I had no clue about the Dangers of 4 or 5 point belt system. I shall promptly remove. (Bolted into the bottom of the seats...) Ugh. heh. I vote for Sticky...
Thanks...
^_^

glenspeed
Wed, Jan-12-2005, 02:38:26 PM
I agree completely. I had the 4 point Sabelt in my old 328is only for autocrossing, but when I went to the track, I used regular seat belts!

Now they are sitting in my closet and will stay there unless I get a roll bar for the M3.

I like my head and spine the way they are!

Blue///M3
Wed, Jan-12-2005, 04:36:01 PM
I'm planning on 4 or 5 point belts in the near future but I am also planning on installing the autopower roll bar before my next HPDE. Until then, 3pt is where I'll stay.

Fly'n DuthhMan
Fri, Jan-14-2005, 12:05:08 AM
You're in luck, just happened to see this thread while I have the carpet and passenger seat out of my car. I took some pics so you can see how I have mine mounted.

These are 6point Schroth Profi III that are test for use with airbags.

Fly'n DuthhMan
Fri, Jan-14-2005, 12:20:49 AM
This little BMW specific aftermarket part from Brey Krause is kind of trick so it gets it's own post.

The rest of the post us unrelated to the picture below.

I run like this every day. I don't even have working stock seat belts.

Harnesses in my opnion are better than stock seat belts when used properly. I won't use them without an anti-submarine strap, just because I think that is the most important part of a harness. The strap helps locate the rest of the harness properly also.

These belts from Schroth have special feature built into the starp of each passengers shoulder harness that further help reduce submarining.

Submarining is the term used to describe what happens in a front or rear collision when the force of the impact tries to squeeze you body out under the lap belt. Basically the inertia from your legs mass pulls your torse out under the lap belt and underneath the dash. Anit-submarine straps and the "ASM" feature on the shoulder harness help reduce this.

Read more here http://www.schroth.com/english/container_english.htm

Having said all that, it is really a safety system, and for maximum protection a rollbar, helmet, and race seats that are SECURELY mounted are the best. A sturdy race seat will do a lot to keep your body off the door in a roll over or side impact, etc, etc.

Lets look at this from a different perspective, regardless of what you think of this equipment can do during an impact, one thing I know for sure is that harnesses keep your butt in the seat giving you better control of the car under high cornering loads. You'll spend less effort fighting to stay in the seat and more on where the car is headed. That makes harnesses a type of active safety device that can PREVENT a collision. (Passive safety devices being those that reduce injury once a wreck is imminent.

Fly'n DuthhMan
Fri, Jan-14-2005, 12:34:37 AM
Here are some pictures of my buddies crashed Audi after he took a non-existant exit road on a decreasing radius turn on HWY 150 near Ojai/Pine Mountain. The car had Sparco race seats and harnesses, no rollbar.

They left the road at about 40mph, you can see the drop. Both were uninjured and able to walk several miles to get cell service to call a tow truck.

Hooligan317
Fri, Jan-14-2005, 10:00:45 PM
I use my Schroth ONLY when I am racing AutoX, all other times its tucked under my front seat.

Schroth is a great alternative to a full roll cage, works well for track use and then stows away nicely.

Beowoulf
Sat, Jan-15-2005, 10:36:03 AM
I know there is an after market piece that you can use with regular 3 point belts to lock them to give you more support so you don't have to hang on to the wheel gut I can't remember the name.

You can also try this little trick. Move your seat back from the ideal driving position. Pull on the shoulder belt quickly so it locks and hold it there while you move your seat forward to make things nice and tight. You can still slide out of the way if you roll the car but it gives you a little more support to haelp stabilize you in the seat on the track.

GiveMeAnM3
Sat, Jan-15-2005, 04:04:49 PM
I know there is an after market piece that you can use with regular 3 point belts to lock them to give you more support so you don't have to hang on to the wheel gut I can't remember the name.


You mean this:
http://www.chasecam.com/cg-lock.htm

Beowoulf
Sat, Jan-15-2005, 07:46:25 PM
That's it.

shim
Sun, Jan-16-2005, 07:49:07 AM
You mean this:
http://www.chasecam.com/cg-lock.htm

i've mentioned that in some other threads about harnesses. i've been wondering if anyone's used the cg-lock and if it was helpful?

ShaunATL
Thu, Jan-20-2005, 01:37:31 AM
I spoke with one of the local Porsche racers about this (he actually sells the cg-lock in his store) and he said it's a total waste of money assuming you're using the "move the seat back" trick that Alex posted above. He said it accomplishes the exact same thing and nothing more, but that it would be worth it if someone didn't know to lock themselves in tight with the seat move.