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Seat belt (harness) swivel mounting not possible ?
drt - 11/1/16 at 11:27 PM

Dear all,

I bought some TRS 4 point harnesses,
They come with 7/16unf bolts and the holes on the belt fitting plates are 7/16unf as well ?
Normally belts require a top hat that allow these to swivel side to side ? And most of the times up and down as well ??
Or is it just me ?
any suggestions? please do... I'm not really keen on boring out the plates or using a smaller bolt



ste - 12/1/16 at 05:31 AM

send them back and buy the sparco ones


907 - 12/1/16 at 06:14 AM

I wouldn't have a problem with drilling the plates out to fit swivel washers myself,
in fact as I wanted my washers in stainless to match the chassis I made them to fit M12 bolts.
Drilled the Sabelt ends to suit.


Paul G


Ben_Copeland - 12/1/16 at 08:07 AM

Unfortunately thats what you get with cheap harnesses.


drt - 12/1/16 at 11:50 AM

yeah srr guys...
Still a student with limited resources :p
I thought this was the locost forum XD

drilling the plates it is


loggyboy - 12/1/16 at 12:07 PM

I've always thought TRS were a good brand?
My willans ones in my tin top have 1 point that is fixed bolted in a similar style (other 3 are through eyebolts), although no swivel is really necessary in my particular situation.


redturner - 12/1/16 at 02:28 PM

In my single seater all 6 mounting points are bolted solid, no need for swivels. I use Sparco harnesses and the holes are 3/8" which take a cap screw quite nicely.....


The Black Flash - 12/1/16 at 04:53 PM

Yeah, do you actually need them to swivel? Mine are on eyebolts but they can't really move anywhere as they go through holes in the seats anyway. KISS if possible I'd say.


redturner - 12/1/16 at 05:26 PM

quote:
Originally posted by The Black Flash
Yeah, do you actually need them to swivel? Mine are on eyebolts but they can't really move anywhere as they go through holes in the seats anyway. KISS if possible I'd say.
and if a time arrives when you might compete under MSA rules and have to wear a HANS device swivels will only assist in NOT keeping the straps in place.....


coozer - 12/1/16 at 05:29 PM

I used them in my car, got all the swivels, correct bolts and covers from a ford ka in the scrappy... Get two sets of front ones cause for some reason the bolts in the back do not have anything stamped on them...


minibull - 12/1/16 at 06:39 PM

Harnesses aren't supposed to swivel. In theory seat is in a fixed position, harness remains at same angle to seat at all times (usually passing through slots on seats). Swivel on seat belts is to allow change of belt angle when seat is moved fore and aft, or reclined. So if your seats are in a fixed position you don't need a swivel mounting. If you have seats on a slide just open up the holes to correct size for spacers.

[Edited on 12/1/16 by minibull]


redturner - 12/1/16 at 06:59 PM

Seriously, there is no way that I would drill the holes in a harness anchor, you would be weakening the area around the hole. Just bolt it solid.....


drt - 12/1/16 at 09:39 PM

I could agree on the top ones not swiveling,
but the bottom ones need to cope with different pelvis or stomach sizes XD
Its just the difference of a few degrees... belts need to be inline with the applied force.

The only option is to use a grade 10.9 or even 12.9 M8...
And have a top hat with just the 1.5mm wall :s

But then we're left with the enigma that TRS supplies 7/16 with the set in the first place.

I'll go search for a 7/16unf tap, or if anyone could sell me some threaded tubes that would be great

thanks guys


loggyboy - 12/1/16 at 09:52 PM

quote:
Originally posted by drt
I could agree on the top ones not swiveling,
but the bottom ones need to cope with different pelvis or stomach sizes XD
Its just the difference of a few degrees... belts need to be inline with the applied force.



Technically they dont. As in general harnesses are intended and set up to suit 1 person. In your situation your adapting a harness to suit a less specfic situation so will have to make compromises.


redturner - 12/1/16 at 10:20 PM

quote:
Originally posted by drt
I could agree on the top ones not swiveling,
but the bottom ones need to cope with different pelvis or stomach sizes XD
Its just the difference of a few degrees... belts need to be inline with the applied force.

The only option is to use a grade 10.9 or even 12.9 M8...
And have a top hat with just the 1.5mm wall :s

But then we're left with the enigma that TRS supplies 7/16 with the set in the first place.

I'll go search for a 7/16unf tap, or if anyone could sell me some threaded tubes that would be great

thanks guys
If you insist on having swivels, just use spacers with 3/8" x 12.9 cap screws. My Sparco belts came with 3/8" holes and no bolts and have never failed scrutineering either here or in France............


drt - 14/1/16 at 12:04 AM

yes indeed Loggyboy you are right ofc,
but it is 'car' use

Redturner, cap screw is the name of a bolt where the non-threaded shaft bit is the same diameter as the threads right ?


redturner - 14/1/16 at 08:48 AM

quote:
Originally posted by drt
yes indeed Loggyboy you are right ofc,
but it is 'car' use

Redturner, cap screw is the name of a bolt where the non-threaded shaft bit is the same diameter as the threads right ?

No, a cap screw is another name for what you might call an Allen bolt / screw, but they do have a plain shank unlike a set screw which has threads all the way down. You must not use these. Some bolts do have a slightly wasted shank. If you insist on having swivels why dont you get some waisted bolts of the correct size.....


cliftyhanger - 14/1/16 at 09:06 AM

Re the 7/16unf thread, that is universal across ALL production cars worldwide. (unless somebody has gone against that agreed convention)


redturner - 14/1/16 at 09:31 AM

I compete in France quite a lot and consequently I have to obey FIA rules and change my belts every 5 years. I always buy Sparco and they always have 3/8" /10mm holes and I always attach them solid. Whether our type of cars can be classed as production is another matter.....


drt - 14/1/16 at 01:18 PM

I did not foresee this thread getting this long :p

I would need a bolt where the shank is 7/16... as then you can tighten them without the bucle being crushed...
Or use extra nuts on a normal bolt ^^


redturner - 14/1/16 at 01:47 PM

quote:
Originally posted by drt
I did not foresee this thread getting this long :p

I would need a bolt where the shank is 7/16... as then you can tighten them without the bucle being crushed...
Or use extra nuts on a normal bolt ^^

Now even I am getting confused. Get a suitable bolt of length and thickness. place through the hole in the belt anchor and a suitable hole on the chassis. Place a suitable nyloc nut on and tighten up, you wont crush it.You dont need any more nuts.....

[Edited on 14/1/16 by redturner]