Harness Crotch Mounting Points

[Jon_Bmw 13]

Yawn, another post about mounting harnesses, but I don't think this has been covered in that much detail(not that I could find anyway).

 

Basically you have to mount through the floor, fine.

 

I am going to use proper >40cm2 plate with a nut welded to the underside. Sandwich the floor between the eyelet (in cabin) and the plate/nut (under the floor). This is all fine according to the FIA/MSA website and the willans harness fitting guide agrees. It makes no specific mention of welding it to the floor, although I think I might from underneath.

 

The problem is the location of the mounting points;

 

The FSA/MSA and schrothracing.com all sugguest an angle like this:

 

http://msauk.org/uploadedfiles/msa_forms/b...tors_Safety.pdf

 

SEE PAGE 183!!!

 

SO pretty much straight down(or 20 degrees back) from the exit point of the 5 harness point on the seat ---- THIS IS WHERE I PRESUME IT IS THE EXIT POINT OF THE SEAT< RATHER THAN VERTICLY DOWN FROM THE BUCKLE AS THAT WOULD MEAN CUTTING FABRIC...

 

So then I think I will read what willians suggest to make sure its all the same, NOPE! It is different.

 

http://willans.com/index2.php?option=com_d...7&Itemid=30

 

Looking at the above link it wants you to put the crotch mounting points BEHIND the seat!

 

I presonally think the FIA method is better because the plate if close to vertically down is going to want to pull up where the design method is at its strongest. If you were to follow the Willians method the harness mounting point is going to be subject to greater back-to-front(of the car) motion which is likely to rip the bolt frontwards along the floorpan.

 

 

So if the 'experts' can't really agree, how they expect mear mortals to get it right is beyond me.

 

Last question following the FIA method I think I am right in saying that it is vertically down from the 5th buckle point on my Corbeau Forza seat rather than vertically down from the point where the aircraft buckle is.

 

 

Sorry for the long post.

 

Rest assured the mounting plates are proper sized ones, not the half sized ones that I have seen used in some 205's on this board.

 

Regards

 

Jon

[Tom Fenton 1,526]

In my track car we mounted them backwards as per the Willans info, its hard to decide which is better though, obviously more vertically down would hold you up if you rolled and were upside down, but pointing backwards is going to better hold you back in the event of a hard frontal shunt. I guess that really the lap straps do more of the work but I do feel more secure in a car with 6 pt belts as opposed to 3/4 pt.

[Jon_Bmw 13]

Thanks for the reply Tom.

 

In one respect I realise that I will be better off no matter where I put them(within reason) than if I was wearing just a 4 point harness. But seeing as there is little effort difference, it would be nice to get them in the right/best place first time. It seems so strange to me that there are two clearly different mounting points given by two 'sets' of experts.

 

On a side note as I have been meaning to ask, but struggled to find the appropriate place to ask, has the forum changed recently?

 

This is a screenshot I now get when opening a thread:

 

 

To get the responses I have to click the peoples names at the bottom! It never used to be like that. It makes scanning through threads very difficult. I suspect I have forked something up with the computer/internet.

 

Sorry about the poor grammar and spelling earlier, I was in a rush

[Anthony 1,000]

To get the responses I have to click the peoples names at the bottom! It never used to be like that. It makes scanning through threads very difficult. I suspect I have forked something up with the computer/internet.

Under the "Options" drop down box at the top right of the screen, you can choose the display mode - quite often it seems to get messed up if you click a link from Google that brings you to this forum. No idea why, but a single click and it's fixed again. Yours is set to "outline" whereas you want "standard"

 

Can't help with the harness question though.

[base-1 17]

TBH I don't think it matters a great deal. For reference, in my experience the crotch strap eyelets are fitted to the rear seat rail (just welded in)

 

Edit, bah slow

Edited July 23, 2009 by base-1

[oz. 2]

like wossitcalledsaid above ^ doubt it matters hugely but on the 106rallyeregister forum someone got a little heated at the idea of mounting the belt to the seat rail. I can't remember the argument but at the time it seemed that they had a valid point.

 

I think the FIA recomendations are better - vertical or 20deg back as any force occuring in a crash will be put on the shell wheras if you put the mounting point far back you will end up just putting unneccesary stress on the seat in a crash.

 

My personal preferances are to go with what FIA say as they have experience from the racing with loads of different brands.

[EdCherry 34 1 Cars]

Personally going to attach my crotch straps to the rear seat mount bar. If this fails then id be f***ed anyway since its CDS. Seen lots of different ways of mounting and prefer this one to be honest.

[base-1 17]

I doubt it makes any difference really, although I don't have any data or anything. The straps have to go forwards to the hole in the seat base anyway which has always seemed a little bit of a design flaw to me, but they need to cater for all shapes and sizes I guess. Would be interesting to know what the guy on the Rally Register said and his reasoning. Cars I've seen with them fitted to the seat rail had WRC spec seat rails, although I'm not sure if that's how the WRC cars had the fixings attached

[Jon_Bmw 13]

The straps have to go forwards to the hole in the seat base anyway which has always seemed a little bit of a design flaw to me

 

This is the annoying thing, the fabric just seems to be cut in the wrong place, forcing the belt to go forwards by maybe as much as 3 inches! Then the brilliance of a Corbeau Forza comes into play and the hole is directly above the seat frame!

 

In the end, I was getting bored and I just found some nice flat bit of floor to get the most contact point and drilled away. They are over 100mm apart which matches the regulations as well. It happens to be about 30 degree angle, but straight down or close was impossible.

 

Anthony, thanks for showing me the way, it must have been a google link stiching it up as I didn't change it.

Edited July 23, 2009 by Jon_Bmw

[philfingers 5]

Mine is wrapped arounf the rear seat rail, 20mm square section on reinforced plates all welded in. I choose to wrap it around then rail and use the adjuster buckles to adjust it rather than eyebolts, which would IMO need welding in, which I think weaken the rail a little at this point. The only issue is they're a real pain in the A*** to adjust. The rear rail isn't so far back, probably6" from the 5/6 pt exit in the seat and down at about 20deg. If the seat rail gets ripped out then i'll have other things to worry about!

 

Mine is wrapped arounf the rear seat rail, 20mm square section on reinforced plates all welded in. I choose to wrap it around then rail and use the adjuster buckles to adjust it rather than eyebolts, which would IMO need welding in, which I think weaken the rail a little at this point. The only issue is they're a real pain in the A*** to adjust. The rear rail isn't so far back, probably6" from the 5/6 pt exit in the seat and down at about 20deg. If the seat rail gets ripped out then i'll have other things to worry about!