5 Point Harness

Reverb · Post by **Reverb** » Wed Feb 07, 2007 12:48 am

Has anybody installed a 5 point harness using a Manx style Stainless Steel roll bar? If so, how (where) do you attach the shoulder belts? Only thing I can think of is having a bar tig welded to the roll bar. But this would probably discolor the finish on the stainless. I`m also worried about rear seat access. I don`t absolutely need a 5 point harness, but my seats (like these

have the provisions for them. Any ideas?

Jon · Post by **Jon** » Wed Feb 07, 2007 3:03 pm

check out "Crow Enterprizes" at least you will see how far below your shoulder blades the straps must be. Don't have stainless but: I had a cross bar welded on the roll bar to anchor my belts. High enough to get your legs under, for those who rather ride in the rear. http://www.crowenterprizes.com/installation.asp

Tom-Kathleen · Post by **Tom-Kathleen** » Wed Feb 07, 2007 11:13 pm

I was trying to find a picture to show this, but I couldn't, so I will try to explain it. Some of the people in the fast & the furious crowd have also wanted 4 & 5 point belt systems. They have no normal place to mount the shoulder harnesses , same as you. So, they make up a bolt in, "U" shaped cross bar that runs behind the seats (at the proper height) between the door posts. The "U" would be upside down if you were standing above the car from the front, and parallel to the ground. This way the "U" is compressed, if the seatbelts were in a crash. You could do the same thing with a bolt on connection to the Manx roll bar, giving mounting points for the shoulder harnesses. Tell me if doesn't make sense, and I will try to expain it another way. I have seen this, and it works. Tom

fubar · Post by **fubar** » Thu Feb 08, 2007 4:47 am

If you do tig a cross bar in be sure to pre stress the floor mounts a good .060" at least because of shrinkage. You can pickle paste the welds to get the color out with acid or pollish with a rouge weal.

Gene-C · Post by **Gene-C** » Thu Feb 08, 2007 7:37 am

I just attached the shoulder harness to the Floor pan behind the seat with a std seat belt eye bolt and then run them over the seats, under the head rest on my beard seats or through them . It works great Gene C #729

Carltons · Post by **Carltons** » Thu Feb 08, 2007 4:43 pm

Sorry all, but I have to be Mr. Negativity. Disclaimer: Im not a structual engineer, or restraing system designer, I just want to be as safe as possible for my passenger(s) and myself. The point of a 4, or 5 point system is to have you securely in your seat and the support structure takes the load not you. That means that you have all points hard mounted. Attaching them to a roll bar that is only attached to fiberglass is not really a safe move. Granted being in a Fiberglass tub is not really safe in an accident is either. Also, when I talked with Crow. mounting the shoulder straps to the floor is an option, but If you are hit hard enough (say from the rear) the shoulder straps will compress your spine as your body moves forward, resulting in not good things. That?s why they recommend a cross bar at the correct height. If your intent is "added protection" then install them as correctly as possible. If your intent is the "fast and the furious look" go for it, but realize that the restraint system is not working to its potential. Might be actually detrimental to its function and your safety. Only the lap portion will be doing its job and what's the good of that. All of this gets multiplied (most likely exponentially) increased in the event of an accident with two people in the buggy. So in short don?t let you safety gear kill you. I went with Beard seats Crow 5 point restraints and the best "complete" roll cage I could come up with. My system is far from Ideal, but I tried to think of as many possibilities as possible, but still keeping asthetics, comfort in mind and safety at a premium. Carlton

newmanx59 · Post by **newmanx59** » Fri Feb 09, 2007 12:03 am

[QUOTE="carltons"]Sorry all, but I have to be Mr. Negativity. Disclaimer: Im not a structual engineer, or restraing system designer, I just want to be as safe as possible for my passenger(s) and myself. The point of a 4, or 5 point system is to have you securely in your seat and the support structure takes the load not you. That means that you have all points hard mounted. Attaching them to a roll bar that is only attached to fiberglass is not really a safe move. Granted being in a Fiberglass tub is not really safe in an accident is either. Also, when I talked with Crow. mounting the shoulder straps to the floor is an option, but If you are hit hard enough (say from the rear) the shoulder straps will compress your spine as your body moves forward, resulting in not good things. That?s why they recommend a cross bar at the correct height. If your intent is "added protection" then install them as correctly as possible. If your intent is the "fast and the furious look" go for it, but realize that the restraint system is not working to its potential. Might be actually detrimental to its function and your safety. Only the lap portion will be doing its job and what's the good of that. All of this gets multiplied (most likely exponentially) increased in the event of an accident with two people in the buggy. So in short don?t let you safety gear kill you. I went with Beard seats Crow 5 point restraints and the best "complete" roll cage I could come up with. My system is far from Ideal, but I tried to think of as many possibilities as possible, but still keeping asthetics, comfort in mind and safety at a premium. Carlton[/QUOTE] I concur, mounting the shoulder harnesses to the floor is not a good idea. A factory Manx roll bar is mounted to the frame in 2 places with 6 bolts thru the fiberglass in a shear application and fiberglasse is extremely strong in a shear application. I would be willing to bet by the time you managed to bend or pull the 2" stainless steel Manx rollbar from it's mountings with your body against the seatbelts during an accident, you wouldn't be in any shape to complain that it didn't do it's job.

shaihulud · Post by **shaihulud** » Fri Feb 09, 2007 9:03 am

I'm not an engineer, but here in Oz the Australian Design Rule (ADR) is that a seat belt mounting must be able to hold 14 times the weight of the passenger measured as a shock loading. Do the maths it's scary. Whatever you do make it very strongly. Also here the bolts that hold the seat belts must be high tensile 7/16 UNF only` (not a metric equivalent, 7/16 UNF only) and at least grade 8. It must be possible to fit and remove the seat belts using one spanner (wrench) only, so either the nut or the bolt must be welded to the frame. Also nylock nuts must be used and all body washers must be 200mm (4 inches) across and 4mm (1/8 inch) thick minimum of mild steel at least and fitted to both sides of the body. So. build it strong.

Jon · Post by **Jon** » Fri Feb 09, 2007 12:53 pm

Back to my first statement! mount it to a cross bar! Here's where the roll cage mounts thru the FGB and has a hard point to the frame. only three holes on each side to contend with.... Outside and Inside shots Take a look at the whole roll cage at: http://users.adelphia.net./~jpboyton/

fubar · Post by **fubar** » Fri Feb 09, 2007 4:45 pm

Also here the bolts that hold the seat belts must be high tensile 7/16 UNF only` (not a metric equivalent, 7/16 UNF only) and at least grade 8. It must be possible to fit and remove the seat belts using one spanner (wrench) only, so either the nut or the bolt must be welded to the frame. Also nylock nuts must be used and all body washers must be 200mm (4 inches) across and 4mm (1/8 inch) thick minimum of mild steel at least and fitted to both sides of the body. Now I have a question, wouldn't welding a high tensile bolt or nut change the tesile stregnth or temper? Or make it brittle if it cools too quickly? Or melt out the nylon locking jizz?

newmanx59 · Post by **newmanx59** » Sat Feb 10, 2007 3:09 am

[QUOTE="fubar"]Also here the bolts that hold the seat belts must be high tensile 7/16 UNF only` (not a metric equivalent, 7/16 UNF only) and at least grade 8. It must be possible to fit and remove the seat belts using one spanner (wrench) only, so either the nut or the bolt must be welded to the frame. Also nylock nuts must be used and all body washers must be 200mm (4 inches) across and 4mm (1/8 inch) thick minimum of mild steel at least and fitted to both sides of the body. Now I have a question, wouldn't welding a high tensile bolt or nut change the tesile stregnth or temper? Or make it brittle if it cools too quickly? Or melt out the nylon locking jizz?[/QUOTE] In a word, Yes, and not for the better. The welded in nuts will lose a considerable amount of strength. More then likely the large bolt size required is to compensate for the loss of strength in the nut due to welding. The correct way to do it would be to use a special "weld nut" that is actually spot welded inplace or to capture the nut.

shaihulud · Post by **shaihulud** » Sun Feb 11, 2007 2:14 am

Yes. fubar. But dem's de rulz.

fubar · Post by **fubar** » Sun Feb 11, 2007 8:22 am

Sounds like the same quality of people setting your auto standards are like what we have for building inspectors here in the NW. But I guess you have no choice but to work with them.

DIESELDOOG · Post by **DIESELDOOG** » Wed Feb 28, 2007 8:18 am

here is what your looking for. http://www.meyersmanx.com/forums/showth ... =seat+belt

Manx Club

5 Point Harness

5 Point Harness

belt attachments

Seat Belts