Question about seat belt mounting

[xxobuick]

The rule book states that the hardware that the seat belts be mounted to, be pulling in a direct line of pull.  Also that the Lap belts be pulling a straight line from 45-80 degree angle from horizontal.  My question is that I have a main seat belt mounting bar right behind the seat, about 6" behind.  I was wanting to know if it is legal to weld tubes in perpendicular to that seat belt mounting tube for mounting the eyelet bolts for the seat belts.  Here are some photos of what I want to know is legal mounting.





Here is a side view




Any Imput?

[NathanStewart]

Looks okay to me.  The likelihood of two good strong welds breaking and allowing those perpindicular tubes to pull out isn't likely but what if you machined those eyebolt tubes to have a bigger end on the backside of the tube?  Basically make the ends of the eyebolt tubes bigger than the hole in the cross bar so there's absolutely no way they could ever pull out. 

Be doubly sure that your shoulder belt attachment points jive with the manufacturers recommendations for the h&n restraint device you're using.  Most h&n restraint devices want the shoulder belt to be mounted higher up than the SCTA had previously specified for many years.  A shoulder belt that's mounted higher up helps to limit forward movement whereas a belt that comes up and over your should and then mounts somewhere below your shoulder does a good job of keeping your butt in the seat and restraining you vertically but allows for more forward movement which decreases the efficiency of your h&n restraint device.

FYI when I do a new car inspection I usually ask to see the instructions for the h&n device before evaulating their belt mounting position so it'd be a good idea to keep a copy in your log book. 

[Tman]

FYI when I do a new car inspection I usually ask to see the instructions for the h&n device before evaulating their belt mounting position so it'd be a good idea to keep a copy in your log book. 

Great tip Nate, thanks!

[xxobuick]

I will take photos of the driver in the seat with belts and hans device installed to show if it is the correct height.  The rule book states 2-4" below shoulder for the shoulder belt mounting.  We have it at 2.5".  Should that be altered if the hans device states something different, and is out of the 2-4" SCTA Spec?

[NathanStewart]

What year rule book are you looking at?  Since 2012 the drawings have said "see manufacturer's specificiations" which is in reference to "... shoulder harnesses shall be installed... in compliance with the helmet support system requirements... special consideration must be given to the shoulder belt interaction with the HANS type device, SFI 38.1".  This is in bold caps on page 29 of the 2012 rule book.

[Nick Flores]

He's reading the 2013 rule book.

[NathanStewart]

Rules change.  Maybe he's remembering what it used to say.  What I wrote is what it says now.

[trimmers]

While the text reads the same in the 2012 and 2013 rule books, the 2013 drawing (on page 31) has changed again.  The drawing now has no reference to "See manufacturer's specifications".  Figures 5 and 6 (upright positions) show "0 to -20 (-10 optimum) from horizontal", and Figure 7 (recumbent position) shows "2" Maximum (minimum?) 4" Maximum below shoulders".  So, if the H&N mfr. recommends that the harnesses attach points should be higher up, then the drawings would appear to contradict the text.

[NathanStewart]

Gah, that's not good.  Sorry didn't have my '13 book. The written word is what's correct and apparently the diagram is wrong.

[NathanStewart]

Okay, I see what happened.  SFI recently released a really great seat belt mounting guide that has some excellent details on exactly they should be setup.  Some of the details like belt angles were put into the diagram in the rule book.  I'm guessing that the 2-4" call out for the lay down position was carried over from the old diagram because the SFI guide doesn't show a lay down position.  The thing you've got to remember is that the wording and the diagrams go together.  You still have to mount your shoulder belts in compliance with the head and neck restraint device manufacturer's recommendations. 

If you're following the 2-4" guideline then I'd be led to believe that you have a lay down seat position, yes?  If so, you should be using a HNR device that's acceptable for that position and then follow the manufacturer's guidelines on how to setup the shoulder belts.