Harness Mounting Point
Discussion
Hello all,
First of all, great site, spent the last few days trawling through old posts and picked up an abundance of information.
I'm planning on doing some track days in the coming new year and have been prepping the car as such. The car will be kept primarely as a fast road car(odd weekend use only). The car is an E36 3.0l M3 Coupe. I'm currently in the process of fitting Recaro Pole Positions. Was not happy with the standard seats hold in the corners. I entend on using the standard 3-Point seat belt for road use and then fitting a harness for track days. I will not be fitting a cage.
Two questions. Is there need for a 6-Point Harness or will a 4-Point be sufficient?
Also where is a good mounting point for the shoulder straps? I hear that the shoulder straps should be kept between 0-20 degrees from the horizontal to prevent your spine getting crushed in a big accident. That rules out mounting them to the middle seat belt mounting point on the rear seat floor. I was thinking to weld in a bar between the tops of the rear suspension turrets and wrap the shoulder straps around that, with the rear seat uprights removed. This would also have the benifit of strengtening the chasis. Another option would be to just weld a bracket to the top of the rear drivers side suspension turret to put an eye bolt on to fix the shoulder straps to? Your thoughts please?
Thanks
First of all, great site, spent the last few days trawling through old posts and picked up an abundance of information.
I'm planning on doing some track days in the coming new year and have been prepping the car as such. The car will be kept primarely as a fast road car(odd weekend use only). The car is an E36 3.0l M3 Coupe. I'm currently in the process of fitting Recaro Pole Positions. Was not happy with the standard seats hold in the corners. I entend on using the standard 3-Point seat belt for road use and then fitting a harness for track days. I will not be fitting a cage.
Two questions. Is there need for a 6-Point Harness or will a 4-Point be sufficient?
Also where is a good mounting point for the shoulder straps? I hear that the shoulder straps should be kept between 0-20 degrees from the horizontal to prevent your spine getting crushed in a big accident. That rules out mounting them to the middle seat belt mounting point on the rear seat floor. I was thinking to weld in a bar between the tops of the rear suspension turrets and wrap the shoulder straps around that, with the rear seat uprights removed. This would also have the benifit of strengtening the chasis. Another option would be to just weld a bracket to the top of the rear drivers side suspension turret to put an eye bolt on to fix the shoulder straps to? Your thoughts please?
Thanks
Far from an expert but I would say that as well as keeping the line from you/your seat as nearly horizontal as possible you also want to keep the mounts in a straight line behind you (ie not twisting off to the left or right) so that any loads are applied straight ahead and as near to you as possible to minimise the length of webbing required (to reduce stretch).
The solutions you suggest sound eaither too long or not straight or both to be ideal.
You can achieve the horizontal routing by using a harness guide bar which would (probably I don't know the BMW) bolt to the B pillar and then leading down.
Alternatively something like a Brey Krause Harness Truss (which I use in a 911, don't know if its available for the BMW) will carry the harnesses in the right location right behind the front seats, so absolutely minimum length required: my harnesses have less then 10cm from shoulder to mount.
Finally if you were going to cage it then add a harness bar and Bob is your mother's brother.
Oh and I'd go 6 point if you can.
The solutions you suggest sound eaither too long or not straight or both to be ideal.
You can achieve the horizontal routing by using a harness guide bar which would (probably I don't know the BMW) bolt to the B pillar and then leading down.
Alternatively something like a Brey Krause Harness Truss (which I use in a 911, don't know if its available for the BMW) will carry the harnesses in the right location right behind the front seats, so absolutely minimum length required: my harnesses have less then 10cm from shoulder to mount.
Finally if you were going to cage it then add a harness bar and Bob is your mother's brother.
Oh and I'd go 6 point if you can.
Don't weld a bar between the suspension turrets and mount on that, as any impact which distorts a turret could tighten/loosen the harness with horrible consequences.
Harnesses and rigid seat without cage is a bad idea IMHO - if you roll and the roof gives way then you become a human roll bar. At least with 3-point belts you will get pushed/thrown away from the roof a bit.
If you want harnesses then do the job properly - spend the money on a cage (at least a half cage).
HTH
Harnesses and rigid seat without cage is a bad idea IMHO - if you roll and the roof gives way then you become a human roll bar. At least with 3-point belts you will get pushed/thrown away from the roof a bit.
If you want harnesses then do the job properly - spend the money on a cage (at least a half cage).
HTH
Nothing is ever as quiet as straight forward as one would imagine.
Interesting point there about 4-point harness and having no cage. I need the use of the back seats so a cage is not possible.
I might try a track day with the 3-point and see how it goes. Although this is not ideal after going to the trouble of fitting buckets. Still though will be better than a standard set-up.
Interesting point there about 4-point harness and having no cage. I need the use of the back seats so a cage is not possible.
I might try a track day with the 3-point and see how it goes. Although this is not ideal after going to the trouble of fitting buckets. Still though will be better than a standard set-up.
You could try a CG Lock. http://www.cg-lock.com/index.html
It does not add anything from a safety point of view but it will keep you pinned down tight so you can relax through the corners with non of the legs braced against the centre console lark...a relaxed / comfy driver is a safe driver!
It does not add anything from a safety point of view but it will keep you pinned down tight so you can relax through the corners with non of the legs braced against the centre console lark...a relaxed / comfy driver is a safe driver!
bb1 said:
Nothing is ever as quiet as straight forward as one would imagine.
Interesting point there about 4-point harness and having no cage. I need the use of the back seats so a cage is not possible.
I might try a track day with the 3-point and see how it goes. Although this is not ideal after going to the trouble of fitting buckets. Still though will be better than a standard set-up.
What about getting a cage with removeable rear diagonal? This was you can have the best of both worlds?Interesting point there about 4-point harness and having no cage. I need the use of the back seats so a cage is not possible.
I might try a track day with the 3-point and see how it goes. Although this is not ideal after going to the trouble of fitting buckets. Still though will be better than a standard set-up.
If you must have a harness then Id suggest that you dont worry about the angle as long as it is less that 45 degrees. Keep the webbing short as suggested and mount the straps to spreading plates welded to the vehicles body. I wouldnt entertain a harness bar for what should be obvious reasons, no a bar mounted between the rear suspension points for the same reasons. Personally Im not a fan of harness bars incorporated into rollover cages either: the safest place to mount is the body, because this is the location most likely to remain in position relative to the seat.
I realise that what I am proposing goes against as lot of forum wisdom (aka repeated myth); that doesnt make my advice poor though...
I realise that what I am proposing goes against as lot of forum wisdom (aka repeated myth); that doesnt make my advice poor though...
MINIrocket said:
What about getting a cage with removeable rear diagonal? This was you can have the best of both worlds?
I'd rule that out straight away. I wouldn't say the back seats would be to safe for a passenger with a cage built around them.I'll leave the cage until the car is retired to a full time track-toy.
I've ordered a CG-Lock anyway. Will give that a try and report back on its use. I've read up on them and they seem like a great little invention.
Also, it was mentioned above about mounting the Harness to the chassis somewhere and not a roll cage bar. IMO, if you have a decent proper cage fitted, it becomes part of the chassis and thus sufficient to mount a harness onto.
I saw this link in another bit of the forum...quite a bit in there about safe fitting and wearing of a harness: http://www.schrothracing.com/docs/Competition_Inst...
Might be worth seeing if you can get a copy of the blue book for harness / roll cage regs.
Might be worth seeing if you can get a copy of the blue book for harness / roll cage regs.
I'm happy to answer any Blue Book questions, if thatll help the OP. Theres a .pdf copy on a TVR speed championship site somewhere too, but I dont have the link to hand.
I have to strongly disagree that a six point bolt in cage becomes a part of the chassis: it is nothing of the sort. With regards to the integrity of mounting points: a laterally mounted bar is far more likely to be deformed in an accident (think about it, any side impact jeopardises its location and the risk is far greater with stupid harness bars) than a well chosen chassis mount.
I have to strongly disagree that a six point bolt in cage becomes a part of the chassis: it is nothing of the sort. With regards to the integrity of mounting points: a laterally mounted bar is far more likely to be deformed in an accident (think about it, any side impact jeopardises its location and the risk is far greater with stupid harness bars) than a well chosen chassis mount.
I aggee that finding somwhere on the chassis is fine. But my point about a proper cage becoming part of a chassis reffered to a full cage welded in, not a 6 point bolted in job.
After reading Schroth's guide above there it turns out that the seat I bought, Recaro Pole Position can have Harness fitted up to 45 degree from the horozontal, so I might get away with bolting one to the rear seat floor where the rear middle seatbelt latch normally resides.
I'll try a few track days with the CG-lock first anyway and see how I fair out.
Thanks for the input so far.
After reading Schroth's guide above there it turns out that the seat I bought, Recaro Pole Position can have Harness fitted up to 45 degree from the horozontal, so I might get away with bolting one to the rear seat floor where the rear middle seatbelt latch normally resides.
I'll try a few track days with the CG-lock first anyway and see how I fair out.
Thanks for the input so far.
bb1 said:
I aggee that finding somwhere on the chassis is fine. But my point about a proper cage becoming part of a chassis reffered to a full cage welded in, not a 6 point bolted in job.
After reading Schroth's guide above there it turns out that the seat I bought, Recaro Pole Position can have Harness fitted up to 45 degree from the horozontal, so I might get away with bolting one to the rear seat floor where the rear middle seatbelt latch normally resides.
I'll try a few track days with the CG-lock first anyway and see how I fair out.
Thanks for the input so far.
It also depends where your shoulders are relative to the path the belts take through the seat harness cut outs. It will still be the case that either your shoulders (and spine) take the instantaneous vertical loading, or the seat back does. I don't fancy either personally. If you do go via the rear parcel shelf route, I'd fix them to the rear firewall and use eyebolts with a large retaining plate behind them to spread the load. If you mount the eye bolts vertically in the rear parcel shelf, the load is not being applied in the best direction. After reading Schroth's guide above there it turns out that the seat I bought, Recaro Pole Position can have Harness fitted up to 45 degree from the horozontal, so I might get away with bolting one to the rear seat floor where the rear middle seatbelt latch normally resides.
I'll try a few track days with the CG-lock first anyway and see how I fair out.
Thanks for the input so far.
Be wary of not using an anti-submarine strap. A guy racing a clio cup in 2007 was killed due to the '6th point' not being done up. If you're going to bother with a harness, do it properly. The argument about the roof caving in around you and a non bucket seat allowing you to 'move' isn't a plausible one in my eyes. The initial impact is the one which will fold in the roof, and you'll barely have any time to brace/move, etc. Get a basic cage (*with* a diagonal) if you're going down the cage route.
Another vote here for CG Lock - did my first track time with one installed recently and it really was excellent - no "bracing" going round corners needed, despite the inherent lack of support in the Alfa's front seats.
My intention with the Alfa is 4-5 track days/year, and I want to keep back seats and comfort getting to to and from track days, so I discounted stripped/caged/harness as OTT for what I will be doing.
ETA - From a laypersons perspective, installing a harness without a cage seems like going to a lot of hassle without any substantial safety advantages.
My intention with the Alfa is 4-5 track days/year, and I want to keep back seats and comfort getting to to and from track days, so I discounted stripped/caged/harness as OTT for what I will be doing.
ETA - From a laypersons perspective, installing a harness without a cage seems like going to a lot of hassle without any substantial safety advantages.
Edited by _Neal_ on Thursday 11th December 17:37
bb1 said:
I aggee that finding somwhere on the chassis is fine. But my point about a proper cage becoming part of a chassis reffered to a full cage welded in, not a 6 point bolted in job.
After reading Schroth's guide above there it turns out that the seat I bought, Recaro Pole Position can have Harness fitted up to 45 degree from the horozontal, so I might get away with bolting one to the rear seat floor where the rear middle seatbelt latch normally resides.
I'll try a few track days with the CG-lock first anyway and see how I fair out.
Thanks for the input so far.
As in just using the existing bolt holes to mount your new harness? I'm sure I have read that this is unwise but I cant find where I read it now..After reading Schroth's guide above there it turns out that the seat I bought, Recaro Pole Position can have Harness fitted up to 45 degree from the horozontal, so I might get away with bolting one to the rear seat floor where the rear middle seatbelt latch normally resides.
I'll try a few track days with the CG-lock first anyway and see how I fair out.
Thanks for the input so far.
_Neal_ said:
Another vote here for CG Lock - did my first track time with one installed recently and it really was excellent - no "bracing" going round corners needed, despite the inherent lack of support in the Alfa's front seats.
My intention with the Alfa is 4-5 track days/year, and I want to keep back seats and comfort getting to to and from track days, so I discounted stripped/caged/harness as OTT for what I will be doing.
ETA - From a laypersons perspective, installing a harness without a cage seems like going to a lot of hassle without any substantial safety advantages.
I have not used one but I think CG lock is the best solution if your using OE seats. I have never been a fan of a harness running under the headrest and off to the sides it always looks like it will slip off in a big smash. Not only that but with the amount of adjustment in the stock seats means you could never really be sure you are using the harness properly.My intention with the Alfa is 4-5 track days/year, and I want to keep back seats and comfort getting to to and from track days, so I discounted stripped/caged/harness as OTT for what I will be doing.
ETA - From a laypersons perspective, installing a harness without a cage seems like going to a lot of hassle without any substantial safety advantages.
Edited by _Neal_ on Thursday 11th December 17:37
Been looking at harnesses in my E36, and as I don't have a cage I came across this:
Sparco bar
Not cheap (around £300) but would do the job nicely, no?
Sparco bar
Not cheap (around £300) but would do the job nicely, no?
dan101smith said:
Been looking at harnesses in my E36, and as I don't have a cage I came across this:
Sparco bar
Not cheap (around £300) but would do the job nicely, no?
Hmm, that looks quiet interesting, but what does it attach on to?Sparco bar
Not cheap (around £300) but would do the job nicely, no?
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