| Author | Comment | ||
|---|---|---|---|
dmark1 |
Hans Device and Formula Mazda Shoulder Harness Problem |
Lead | |
|
I am having an issue with my Hans device that I recently purchased and would like to ask everyone out there it they may have come up with a alternative fix.
The attach points for the shoulder harnesses are about 8 inches apart on the Standard FM and the Hans device requires that they be within 3 inches for optimum
protection. Since the interior portion of the attach points for the harnesses are not on the frame, it does not seem that moving them in would result in the
necessary protection for the harnesses. Has anyone ever moved the harness attach points in, and if so, how did you do so without compromising the strength? If
not, is everyone merely cinching them tight on the Hans at their present location and hoping that they do not slide off during the race? Any suggestions?
|
|||
NSXted |
belt spacing options | ||
|
Some guys worry about that, many others don't. I personally do, but we don't have enough crash test dummies to do justice to proper field testing, so
everyone is free to speculate endlessly.
There are ways to move those hardpoints; the permanent fix is to weld in new bungs (Moses Smith made some) at the correct spacing; but you have to take out the fuel cell. In the meantime, you can use carabiners (real, as in load bearing) to keep the belts at the proper spacing. I have some photos of what they look like, but the old links don't work, so give me a day to get around to getting them into photobucket. Check this discussion; http://formulamazdaforum.yuku.com/topic/854/t/Belts-for-HANS.html?page=1
Ted FM #13
Shoe String Racing |
|||
Shawn Westerhoff |
Belt Spacing | ||
|
I agree with you Ted, they should be professionally relocated but I have not done so. I think Derry has done it, mine seem to be very secure but I can
envision them rolling off at the wrong time. Is the HANS a 30 degree?
Take out the cell for sure anytime you weld around the cell, or you will end up with a new one like me! I guess weep holes in the bottom of the cell are not such a good idea. |
|||
chris sj ca |
HANS Issue | ||
|
I had the same issue. The FM was designed > 20 years ago when the best known placement for shoulder straps was "straight back". Thus the 8"
separation. New learning (FIA) later showed that shoulder mounts should be closer together. The HANS instructions cover that in detail. The seating geometry
on our FM (if we apply the 90's learning to the 80's design) should have shoulder mounts more like 2-3" apart. But this is impractical given the
space frame design on our cars. The current post location is a intersection point of 3 major members, and to move them would relocate them to an unreinforrced
frame member. Moses had designed bar that would bolt in to the existing mounts and provide 2 new ones. Technically (by FIA rules not SCCA) anytime the belt
mounts are moved within a chassis, the car needs some testing and blessing from the cars manufacturer. I suppose that means that some engineer will run it
through some stress simulation computer model. So, this quickly get too complicated for the amateur.
Putting all the engineering aside, I called HANS. They told me that in my scenaerio (8" separation on a legacy chassis design with no way to move) the best known practice is to cross the belt behind the shoulders. Left strap to right mount, Right strap to left mount. More angle than specification is preferred over "straight back". At the time, they had several NASCAR teams running in that configuration. At first I even questioned this, but I have ran that way with swivel shoulder mounts and the belt are very well aligned over the HANS, tighten very well, and I'm very satisfied with the official recommendation from HANS. Check the shoulder mounts on the new Pro FM and you'll see they are now conforming to the new FIA standards. We just have a legacy design and need to adapt the best way we can. One day, I'll probably get questioned by a track official and have to explain why my belts are crossed. I'll conclude by saying that I'm 5'8" and 140#. I'm one of the few "other" FM drivers that have observed an issue with the alignment of belts over the HANS. I should also mention that I use the FIA approved 2" shoulder straps, not the wider 3" shoulder straps. So, I have less tolerance for misalignment than someone with the 3" webbing. |
|||
NSXted |
Carabiners for HANS belt spacing | ||
As I mentioned above, I decrease the spread of my shoulder belts with climbing carabiners from REI. They are 3" wide (inside to inside). SCCA techs
have not commented, so apparently they think they're fine.
Ted FM #13
Shoe String Racing |
|||
pgannon |
|||
|
My team simply took a heavy piece of angle iron and drilled two holes corresponding to the factory belt mounting points. The belts were mounted to two more
holes that were drilled about 3 inches apart on the other flange of the piece of angle iron. This worked well. ( and is probably more aesthetically pleasing to
a tech inspector than Ted's carabiners ??)
|
|||