Thread: Seat & Seat Belt Mounts

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Food for thought.
In a crash the body will most likely leave the frame. Therefor . if you are held by the sdeat belt that is welded to the frame may not be a good idea.
May be that you want to stay with the body and have that protection around you rather than the body trying to go around you.

Use two, minimum 2" x 2" x 0.083" wall square tubing welded framerail to framerail to mount front and rear of seats. Make whatever provision you have to to clear transmission/driveshaft. Mount lap belts and crotch straps to rear crossmember. DO NOT mount shoulder belts to this crossmember. Shoulder belts must be anchored height of shoulders to prevent compression of spinal vertebrae on impact. Engineer the package so that the body and frame remain as a unit (translation: Use lots of bolts and nuts and big flat washers).

Evidence of my being uncomfortable with the fender washer approach, which had been suggested to me by a local guy, is me asking the question here. Regs, I share your concern about the forces involved and the strength of the floor, even with Core-Mat. IC2, I understand your "sandwich" approach and it sounds secure, but applying it to my glass body is a bit different. CCBob, your comment is one that really makes us think - this is a fiberglass car, so any crash of significance is going to put us in a world of hurt. Recall KennyD's pictures a few days back of the Willy's that broke up all around him. Tech, as usual you cut to the chase with specifics, which I expect are based on your understanding of the rule books for comp cars. While the body may be separating from the chassis in a wreck, your approach is to ensure that the part with the seats remains a unit, which makes sense to me.
I attached a picture from N&N's website showing the basic chassis - American Stamping rails with a round tube bracing section between, sort of a modified X-member with upper & lower sections. The upper section is at, or very close to contacting the bottom of the body - within 3/16" at the widest point in the area of the seats. Tomorrow I will spend some time laying under the car pondering the layout, and how best to anchor the seat bolts while keeping it presentable. The body is coming off very soon for final frame work, prep and paint, so the timing is not too bad.
Thanks to all who took time to respond.

I will agree with techinspector1 in asmuch the seatbelt should be mounted correctly for not only safety but also comfort. I find it difficult to understand why some people believe that in a crash, the body will seperate from the frame... If constructed correctly no car should fall apart like that... When building my Bucket I constructed a special crossmember with outriggers solely to mount seatbelts that when the body is fitted the seatbelt bolts pass through the floor into the crossmember mounts. The should height seatbelt mounts are welded into the heavy 3mm wall rollbar that is bolted directly to the chassis/frame. I personally find that the seatbelts in my bucket are far more comfortable than the stock belts in my BMW coupe, as they don't slide up my shoulder and cut into my neck.. As tech says..... use heaps of bolts / fasteners to attach that body....

This thread has made me look closer at the whole body/seat/seat belt mounting from a system approach rather than as individual components, which is the right thing to do. I will probably have more work to do than I had anticipated when I pull the body from the frame, but it will hopefully result in a safer overall approach.