Harness mount points?

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Chrisnxl185

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Hey guys, just bought an 87 325is. It doesn't have airs bags so my parents said i could only buy it if i put in a 4 point harness. Now i'm trying to figure out where i should attach the harness in the back.
I haven't chosen a harness yet because i don't know if i want one or two mount points in the back.

First what is the minimum bolt thickness used for mounting a harness.

Does anyone know what these are and could they be used to mount a harness. A 5/16 bolt threads in. It could be reinforced too.


My other idea was fab up a bar that would mount on the upper rear seatbelt mounts.
 
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Big Daddy

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Why does your parents think a 4-point harness is going to offer any more protection than the standard lap/shoulder belt? A 4-point harness in a street car is going to get the attention of law enforcement any time you are stopped and they are going to assume you think you are a race car driver,so much for a warning! There is no added protection with the 4-point for street applications.
 
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Chrisnxl185

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i don't care about drawing attention from law enforcement, i don't speed.
And a 4 point is definitely safer than the stock seat belt. With a 3 point your upper body and head just move around strap. A 4 point holds your chest in place. If harnesses don't offer anymore protection why do race cars have them?
 
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Big Daddy

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Because they are in cars that required greater restraint due to lack of knee bolsters, dash boards etc. and there is the likely hood they will submarine if not restrained by the 4-point. Just because a race car has it does not make it safe for use in street/production vehicles, that is like comparing apples to watermelons. This is from the Biometerics of 4-Point Seat Belts:

While they show significant potential to reduce thoracic injury risk, there are still many issues to be resolved before 4-point belts can be considered for production vehicles. These issues include, among others, potential effects on hard and soft neck tissues, of interaction with inboard shoulder belts in farside impacts and potential effects on the fetus of latch/buckle junctions at the centerline of pregnant occupants. Work continues at Ford Motor Company to resolve these issues.
Click to expand...
 
E30m42cab

E30m42cab

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Who cares about your chest??? Seriously... it's your head and neck that you've got to worry about. When you hit something head on, your body will be stationary, and your head will still want to keep going. Race car drivers wear the HANS device. You may do more damage to yourself with a 4 point than a regular 3 point. Do your homework properly on this, or better yet, make your parents do the homework! Either that, get an E36.

THERE IS NO BENIFIT OF A 4 POINT HARNESS. THEY ARE NOT SAFE FOR THE STREET. PERIOD.
 
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Big Daddy

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I guess if you are going to install a child safety seat as your driver's seat than you could use the 4-point. Seems like you tend to ignore good advice! child safety seats lean back and the child is too small for a 3-point, or why do they only use a child safety seat until 8yrs of age than graduate to a 3-point? (by the way a child safety seat is a FIVE point system)

I would not mount a seat belt to that spot welded bracket, seat belts use high strength reinforced mounting plates, bolts, and washers.
 
echothreezero

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Go to an engineering shop that specialises in motorsport applications. not only will they sell you the harness and install it correctly, but they may be useful in convincing your parents it is an unecessary expense.

If you need to ask the question, it is not a job to do yourself.
 
E30m42cab

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So, when your cellphone falls behind your braked peday, or when you carpet rides up between the gas pedal and the brake pedal, or when the peice of trim above your knees falls out of it's lower bracket, or when a garbage bag gets caught on your windshield wiper, how the hell are you going to lean forward at a seconds notice to fix the little problem?? And have fun changing the radio station or putting a CD in. If you want to rice it up, don't tell us your parents told you to do it. If you're wearing the harness loose enough to do all that stuff, you're not wearing it properly at all. You gunna install 4points for all your passengers too?
 
Doughnut

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E30m42cab said:
You gunna install 4points for all your passengers too?
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I feel sorry for this guy now [xx(]

But seriously, My girlfriend would get in the car. . . And promptly get back out in laughter if she saw that I'd installed a 4 point harness in the front seats of my e30, LOL!!

Think about it dude, the money you waste on a harness, is money you could spend on say. . A nice fuel pressure regulator for your poor old m20 or something.
 
echothreezero

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Dude if you're still reading this and the flaming hasn't scared you off you're doing well.

Welcome to the forum by the way!

All the above is well-meaning advice from guys who know their stuff. Don't rice up your e30. its not a race car its a very capable '80s sports sedan.

Forget the harnesses and do something that will actually make it a better car. The list is endless.
 
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Chrisnxl185

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first off i'm definitely not going to rice out this car.
I'm just going to improve the safety of this vehicle. And it doesn't matter that it's not a race car, every car should have four point seat belts. And if your going to tell me they don't improve safety or are dangerous, you better back it up with something.
A few articles i came across:
http://www.ncbi.nlm.nih.gov/pubmed/17311168
http://www.umtri.umich.edu/content.php?id=936
http://www.intellichoice.com/carBuying101/Seatbelts

so does anyone have any suggestions about installing harnesses. Looks like i'm going to fab up a harness bar.
 
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Chrisnxl185

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Doughnut said:
I feel sorry for this guy now [xx(]

But seriously, My girlfriend would get in the car. . . And promptly get back out in laughter if she saw that I'd installed a 4 point harness in the front seats of my e30, LOL!!
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haha i think this post is funny. did you really think your girlfriend's hypothetical reaction to a four point harness would deter me?

And no, i'm not installing 4 harnesses, haha the other passengers will be fine.
 
Doughnut

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Chrisnxl185 said:
And no, i'm not installing 4 harnesses, haha the other passengers will be fine.
Click to expand...
The first link you posted: mearly compares 4 point to 3 point seat belts and the article finishes in saying "risk of injury to a pregnant woman and her fetus in frontal crashes. The risk of fetal injury in pregnant occupants may be related to the location of the 4-point seat belt's buckle and latch junction at the centerline of the mother's abdomen."

The second link you posted: "issues include, among others, potential effects on hard and soft neck tissues, of interaction with inboard shoulder belts in farside impacts and potential effects on the fetus of latch/buckle junctions at the centerline of pregnant occupants."

And lastly, in the 3rd link you posted: The only info on 4 point harnesses (x4 and v4) Is about how Ford and its Volvo subsidiary are researching the use of the X4 and V4 style harness and mainly talks about how the 3 point belt is far superior to the old style lap sash belt.

Be sure to install the harness to your parents exact specifications and be happy knowing that your safer than everyone else with the standard 3 point style.















ffs.
 
Kirby

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I'm a little surprised at the flaming going on here. I don't consider this ricing the car. If I wear a 4 point harness when I autocross does that mean I am a ricer????

If you get a harness designed for the car, it will mount to factory locations, and include all the instructions necessary. Don't get a generic one - the manufacturers for these harnesses have engineered them correctly for you:

Specifically, you want the Schroth:
http://www.koperformance.com/BMW/in...nt_harness/schroth_rallye_4_point_harness.htm

Here is some installation info regarding the E46. Obviously the E30 is different. I think in the E30 you remove the existing seat belt bolts and bolt the harness in using them.

http://www.soloracer.com/e46rallye41.html


I don't think any of us here are automotive engineers qualified to state which is safer. But the Schroth is DOT approved for street use, so that's certainly more qualified than the comments I see above. Pay no attention to the flaming, the guys posting in this thread are usually very helpful and friendly.
 
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Chrisnxl185

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haha finally someone with some constructive feedback, thanks Kirby

Ya i was looking at those schroth harnesses. The only thing is, aren't the rear mounting points of the harness supposed to be approximately level with you shoulders? I suppose if the back of the seat was strong it would be okay to have the mounting points lower but my seat looks kinda flimsy.

On the Koperformance site they list a harness for e30 but i looked on Schroth's website and i couldn't find one for an e30. I wonder whats up with that
 
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