RX-Ben

I did a search, but there seems to be nothing conclusive on the proper way to install a harness/seat setup.

1. Stock seat mounting studs do not seem ideal as there is not metal reinforcement. Is this correct?

2. If the above is true, mounting lap belts to the brackets attached to the stock seat studs seems like a bad idea. As does mounting a seat.

3. If the above are true, then is the solution to weld in some sheet metal to the bottom of the car, then use bolts with backing plates for seat mounts, and backing plates with eyelets for lap and anti-sub anchors? I saw this here recently, in a re-build where the previous shop simply attached the seat to the stock floor.

4. What thickness sheet metal is appropriate for the above? Stainless seems like a good choice as it is exposed to the elements.

Thanks.

2000BSME

I can't remember exactly, I think it was Breyton-Kraus?? who makes some s.s. links for the sub and lap belts that hook up to the seat belt anchor points, and for the over the shoulder straps you'll need that cross bar, unless you have an eye attached to a rollbar like I have.

Don't overthink it.

2000BSME

oh, btw, you wouldn't 'weld' a plate to the balsa wood and floorplate sandwich, you'd put plates on both the bottom and top, and further the 'sandwich' of it all.

I don't have any reservations about my stock seat mounting in my vette, btw.

AU N EGL

Bray-kraus does make the anchor points for harness.

brkntrxn

What car? C5, C5Z, C6, C6Z?


-Kevin

Zenak

check out the section on this here:

http://forums.corvetteforum.com/auto...e-learned.html

RX-Ben

Thanks guys - the car is a c5

Obviously I wouldn't be welding to fiberglass and balsa. The sheet metal would span the composite floorboards and attach to the metal on either side.

Zenak - Yes, I read it before posting which helped inform my post. It is a great resource and I refer to it regularly.

You said that the seat rail mounts were possibly not safe but thought that your harness mounts were adequate to hold you if the seat mounts failed. Which implies that any harness setup that mounts to the stock seat studs is a bad idea. So I'm trying to find out a better way.

fatbillybob

Ben,

As designed seat is safe and there is metal strap under balsa floor as reinforcement for seat anchor. Seatbelt is on seat so those anchors are engineered for full average body weight and force generated. Best 6pt harness is to be attached to rollcage. Once you dual use a car then all bets off and you are guessing based on forum opinions and what others do. So do you own homework. That said many use braykrause things to attach 6pts to the seat mounting studs and use race seat like sparco evo. As a general rule of thumb don't mount your seatbelts/harness to anything that would not support the full weight of your car on your floor jack. So even with a big washer on a steel pan car (or the balsa floor of vette) I would not mount my sub straps. Many do it however at great peril. Do the breykrause thing it is a compromise but a decent design for the laps and the subs and you'll need a harness bar for the shoulders.

Bill Dearborn

On the C5 the inner side of the seat belt is fastened to the seat frame and the force from the frame is transmitted to that bolt in the floor. The outside belt mount is to the frame. One thing we know about those mounting points is they have been tested to meet federal safety standards. The BK harness adapters use the same mounting points so if they are installed correctly then they should be safe. On the C6 both ends of the lap belt are fastened to the seat frame and that has also passed crash tests.

One thing you need to take into consideration is how you fasten your new harnesses to the mounting points. You don't want anything twisted or bent. The belt pull should be perpendicular to the mount/mounting bolt.

Bill

RX-Ben

Thanks guys. Good to get this info.

I went w/the BK lap mounts (which use the stock holes) and will fab up a bar to span my seat mounts, in the proper location, for the anti-sub belts. I don't understand the need for lift-point stiffness on an anti-sub belt. If properly installed, it is only keeping the locking device/other belts in place. It is not preventing forward movement (unless in a highly reclined seat).

I'll use the stock mounting points for the seat, harness bar for the shoulder straps.

Orienting the belts/mounts is obviously important, but a much easier issue to handle vs. solid mounting points.

fatbillybob

most pros don't either. antisub belts do not prevent anti-submarining. They prevent the lap belt from moving and allows proper action of the rest of the harness and therefore prevent submarining. In other words the subs are not designed to grab you by the ***** in a crash though sometimes that can be the result.

A delta V 35mph federal crash test is about a 50G pulse. 45mph is a 70G pulse. It can be more or less depending on a bunch of other factors but this is reasonably acceptable. So if you weigh 225lbs that 11250 to 15750lbs on your harness system. Each belt gets different forces but if you just divide by 6 you get 2625lbs at the 70g number. 100g is surviveable seen in actual telemetry from many real race crashes like ralf schmachers at indy. So you see the weight of your car about 3000lbs is really a very reasonable thing to expect. So the guy that gets his nuts squashed has that happen because his harness lossens in a crash and the body moves too much too far. If you put a jack under your wifes sheetmetal floor pan and jack the car and get a couple inches of deformation no look how your retention just all goes to he!!.

RX-Ben

I have a hard time reconciling your first paragraph with your second.

This guide mentions the stresses that result in a crash, and you cannot simply divide by 6 to get the loads on each harness:
http://www.schrothracing.com/docs/Co...structions.pdf

Joe_Planet

The brey krause hardware sucks ***** because its for the stock seats and the harnesses would be improperly mounted. You sit on the harness and it crushes your *****.. not the ideal fitment. If you want to properly install a harness you have to put eye bolts through the chassis and install a proper seat to be effective AND safe.

fatbillybob

Yes I am being very conservative because I am not an engineer but I am a chicken. I took few compromises and I have my full containment seat attached to the cage not the chassis. Schroth are the best. I even went so far as to use the 4 shoulderbelt hans specific unit at big bucks. That is like an 8pt harness. The reasons are for another thread. Anyway, I have said nothing inconsistent. page 10 first line talks about antisub on 4pt belts and its action and how movement causes submarining. If your subs fail/loosen you got 4pt belts and you submarine. It is just a different way of saying what I said. Page 23 says minimum load at shoulder is 3240 about the weight of a car like c5. and 1650 at the subs. So if you do a proper 6pt with 2 proper distinct mounting points which will be very close to each other you get 3300lbs on the sub location again the mass of a C5 vette. Many many pros will just put a couple of big washers under a steel floor and mount subs and lapbelts. I see this all the time and amateurs diy'ers follow. So in the end my rude math is close. I'm way overbuilt exceeding schroths minimums and I have tested my safety gear unfortunately. I challenge anyone with a sheetmetal floor and just washer and eyehook anchors to strap in tight and lift their car on the washer with your cheapo harbor freight floor jack. The subs will loosen and you will be able to scoot your hips forward. That's submarining and that's how you get those graphic ball bag rip pictures that have gone around the internet.

John Shiels

I put large graded washers and eye bolts which are rated & Made in the USA from MSC. They show the strength of the eye-bolts at 3 pr 4 different angles of tension. I ran it buy a few people in the know who are engineers and one being here all the time. The opinion was by the time it all ripped out the belts will have done tons of damage to me amd I would have had other problems. If you have no cage, HANS and every other thing over designing the belt is really of no use.

AU N EGL

after my encounter with a wall at Road Atlanta many years ago, we took out the floor boards and put in sheet steel. not flexible or light. but much more protective.

RX-Ben

Thanks again for the responses guys, I appreciate it.

John - where did you mount the eye bolts and washers?

brkntrxn

RX-Ben,

In my C5Z06, I mounted by lap belt eye bolts just inside of of the rear seat rail mounting posts. I drilled holes through the floor and through the metal reinforcement strap under the car. In addition, I made some small metal plates to fit inside of the metal strap for a bit of extra material.

For the sub-belts, I mounted them on eye bolts on the frame of the Sparco seat mounts.

As mentioned above, unless you have a full cage and absolute correct placement of mounting points, everything is going to be a compromise. The best you can do is get as close to optimal as possible.





After snapping the pic, I ground down the excess bolt length sticking through the nut.









-Kevin