SKJP chat transcript/Radian clarrification?

Mommy2Five

New member
I just recently had time to read through the whole SKJP chat transcript, and I have questions!!

Question 1: Regarding this quote

crunchierthanthou -> Special Events - CEU Chat Session: is there a maximum amount over the top harness slot- more than just top of ears even with the top of the shell?

Carseatengr-> Special Events - CEU Chat Session: No maximum so long as the ears are not over the seat back height


!!!! So there is no maximum over the slot limit, up until the ears reach the seat shell???? My 7.5 y/o is even with the top slots, but has 5+ inches before her ears reach the shell. She could acceptably go 5 inches over the slots????? (referencer pic)


IMG_0002-5.jpg




Question 2: In reference to SKJP's allowance for changing out current chest clips

In the transcript Dave says
a wider one most likely would not affect the test results

but have they ok'd certain specific brands of clips? Or just the IMMI ones? (could I conceivably use the free Nautilus clips Graco sent me??)

Thanks for any insight that could be shared!
 
ADS

Wineaux

New member
Head/Ears over the top is one thing, but the never to be violated rule for straps are:
  • RF: At or below the shoulders.
  • FF: At or above the shoulders.

If the straps are at your DD's shoulders as seen in the picture provided, then she has outgrown the seat. Any seat.
 

Mommy2Five

New member
Head/Ears over the top is one thing, but the never to be violated rule for straps are:
  • RF: At or below the shoulders.
  • FF: At or above the shoulders.

If the straps are at your DD's shoulders as seen in the picture provided, then she has outgrown the seat. Any seat.


That was my understanding with other seats, but SKJP has indicated otherwise..... The Radian manual says 1" over is acceptable, but reading the transcript it seems that the engineer is saying even more is ok..?


Carseatengr -> Special Events - CEU Chat Session: The critical consideration is the angle of the shoulder belt relative to the spine. in the case of the Radian, given the occupant height limits, this angle will never become an issue. So in order to accommodate the very small percentage of occupants that fall into this limited category (shoulder slightly above the 5th harness slot yet not exceeding our height limit) we allow this belting configuration.

Carseatengr -> Special Events - CEU Chat Session: Also FYI we test with the H-III 10 yr old ATD weighted to 85 lbs using the NCAP sled pulse and see no adverse spinal loading

Thoughts?
 

scatterbunny

New member
Head/Ears over the top is one thing, but the never to be violated rule for straps are:
  • RF: At or below the shoulders.
  • FF: At or above the shoulders.

If the straps are at your DD's shoulders as seen in the picture provided, then she has outgrown the seat. Any seat.

This isn't the case with the Radian. ;) Which is why the cardinal rule for CPSTs is to RTFM. :p
 

scatterbunny

New member
Me, personally...I guess I'm okay going slightly over the top slots, but not 5+ inches. The risk is spinal compression, I don't know how common that risk is, but it sounds scary enough that I'm not willing to chance it with my own child. The rule not to use a FF seat with shoulders over the top slots has been in place for so long that I'd have to be convinced by much more than what I've heard so far to change my mind. The Radian's test results might not show excessive head excursion with the dummy's shoulders over the top slots, but does that dummy accurately measure risk of spinal compression from straps below the shoulders?
 

tanyaandallie

Senior Community Member
I agree with Jenny. SK says it's ok but I'm still not super comfy with it. Not sure I'd go 5 inches over even though they say it's fine.
 

ZephyrBlue

New member
How do they/can they measure spinal compression in a crash test dummy?

If SK is saying that 5+ inches is acceptable, for example, how can they verify that no spinal compression is happening?
 

carseatcoach

Carseat Crankypants
I'm fortunate that I expect my child to be eight-ish when she hits the top strap slots, and I'd be okay putting her in a good high-backed booster at that point. I don't think I'm going to be as anxious about measuring shoulders/slots every single time I strap her in as I would be with another seat, and I'm not going to have a booster overnighted the day her shoulders creep over the slots, but I don't think I'd be okay with 5" over.
 

CDNTech

Senior Community Member
Am I the only one that doesn't see 5+ inches in that picture? Honestly, it looks closer to 3 inches to me (tips of the ears to the top of the shell). Even 3 inches, though, would be too much to me. I'm comfortable with about an inch, but anymore than that and I'd be moving them to a different seat.
 

Defrost

Moderator - CPSTI Emeritus
I'd be okay with an inch over.

I found this while looking into a harness to replace a broken seatbelt (we've since decided against it.) It's an article about installing racing harnesses. I thought it was interesting, since I'd also read that spinal compression was more a concern for younger babies/children, but apparently it is for adults as well.

If the upper attachment point falls significantly below the driver's shoulder, then a spinal compression injury is likely to occur. In an accident situation, the shoulder belts pull down and back on the torso as they resist the forward motion of the driver. The resultant restraint force compresses the spinal column and will add to the stresses in the spine already caused by the
force of the crash impact.

Link to the entire article.
 

scatterbunny

New member
Thanks, Debbie! :thumbsup: I'd heard speculation that maybe spinal compression wasn't really a big issue the older a person was, and that's why it's okay for an older child to go a bit over the top slots. I was never comfortable with that idea, and that article just reinforces my feelings.
 

snowbird25ca

Moderator - CPST Instructor
How do they/can they measure spinal compression in a crash test dummy?

If SK is saying that 5+ inches is acceptable, for example, how can they verify that no spinal compression is happening?

In a different part of the chat Dave discussed a specific angle of the straps in relation to the horizontal plane and the child's shoulders. So there is some additional information in there. The other requirement, is that the child has to be under the overall stated height limit in order to use the seat over the top slots. I think this means most kids really won't exceed that top slot by much before hitting the overall height limit.

I'd be okay with an inch over.

I found this while looking into a harness to replace a broken seatbelt (we've since decided against it.) It's an article about installing racing harnesses. I thought it was interesting, since I'd also read that spinal compression was more a concern for younger babies/children, but apparently it is for adults as well.



Link to the entire article.

There's another article I read awhile ago that went into further detail and also talked about the angle of the harness in relation to the shoulders. It stated that the optimal level is as close to even with the shoulders as possible, just slightly below and slightly above being ok as well. It gave an angle on how far below was acceptable, I don't remember it for 100% sure, but I think it was a 5* angle allowed measured from horizontal of where the strap started to the top of the shoulder.

I'd be fine with using the seat slightly above the top slot given what I've read. I wouldn't go much over the top slot though.
 

Mommy2Five

New member
Thanks guys, interesting food for thought.

I have NO INTENT to use the seat like that, it's actually DSs seat and he'll be 7+ before he hits the top slots if he stays on the familial growth curve, I was just curious how others interpreted the engineers answers.
 

Wineaux

New member
Me? I'd stop using the seat when my DS's shoulders were either even with the straps, or his head was over the seat to the middle of his ears. The Radian would allow me to exceed that by a little bit, but as far as I'm concerned that little bit would just be the time it took me to research, find, and buy a new seat.
:twocents:
 

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