Quote:
Originally Posted by eggman51
Still not sure I understand the relationship between seat type and safety - I must be missing something (not being sarcastic there) - I just don't understand how fixed back vs reclining has anything to do with safety?
In the linked thread above, the angle on the shoulder straps would not conform to best practices for mounting a harness. The shoulder straps should be flat, or angled down up to 25 degrees, but not angled up.
The seats in the M - lovely for spirited road driving - are not usable with a harness because of the fixed headrest (and they do not have a hole for anti-sub straps, so afaik can only be used safely with the Schroth ASM capable 4 point belts). However, they should still follow the guidelines for mounting positions and angles.
I notice the owner of that car said he would use the 4 point harness for Autocross, and the 3 point belt for track and daily driving. Not sure I understand why unless it's a governing body / approval issue.
This is what I am planning to do, and appears to be how Vanne mounted his shoulder straps behind the fixed back racing seat. I just ordered the parts for this from HMS...
Totally open to the idea that I may be missing something, this is safety so I am not wanting to mess about, but I can't get a roll bar into the car yet. However, I don't see the relationship between racing seats, 6 point harnesses, and factory roll hoops being less safe than factory seats, 3 point belts, and factory roll hoops.
Cheers,
Eamonn
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The M sport seats definitely cannot be used with harnesses, including Quick Fits since the headrest is integrated. The shoulder belts might slip off regardless of the angle which you install them.
And regarding the link I posted, I was not suggesting by any means that's a good setup. I was merely showing you the seat I was considering since the fitment was spot on. Therefore I posted the picture of the eyebolts showing how I would address the deficiencies in that other setup.
Regarding fixed vs reclining, fixed back seats have high side bolsters so it's not meant to be used in conjunction with a factory 3-point setup as the lap belt would never get tight around your legs. For a track-only car ditching the 3-points is fine but strapping into a 5/6-point every time you're on public roads can be a hassle. Yes you can retain the factory 3 points but you still have the issue of the lap belts not securing you. Personal preference but not something I want to deal with (read not a safety decision but matter of convenience for me).
Reclining seats don't have this issue but most reclining seats also don't have the hole on the seat bottom to run a 5/6 point, usually limited to 4-points. 4-points are generally at disadvantage because you run risk of submarining so that's why they're only allowed at low speed events like auto-x, unless you find a harness that has anti-submarining (ASM) tech. The harness I linked not only has ASM features but is compatible with HANS and both FIA / FMVSS 209 certified (so should be good for road courses).
Separately during rollover, [the theory is] a fixed back seat will not give meaning the driver will stay upright if secured via harness. That's why a roll bar is crucial since you don't want the roof to collapse on you. Ironically if what I'm contemplating above "works", roadster owners wouldn't have to worry about this as the roll hoops would suffice for rollover protection.
FYI I am by no means a safety expert so you should do your own due diligence but this is what I gathered when I researched the issue for my previous track car (and ultimately settled on "half" cage, fixed back and 6 points with HANS).
So to recap, for my proposed setup, I *think* it checks all the boxes with respect to "street friendly", ASM, HANS, and rollover protection. A fixed back, aftermarket rollbar and 6 points would probably be safer but its not the direction I want to take the car in. Been there done that and I'm looking for something milder, easier on my wallet, and street friendly.
Picture below is my old coupe for reference...