LATCH limits (child weight only)

broxbourneDELETE · Feb 14, 2007

How can a vehicle specify a max child weight for LATCH if the weight of the seat alone is variable? A seat can weigh anywhere between 5 - 25#. How can the LATCH distinguish the seat from the child? All of it is going pull against the LATCH in the event of a crash. The vehicle manufacturers have assumed an *average* weight for the seat itself. Maybe I'm missing something, but I don't think so ... Does anyone else find this remarkable?

The LATCH anchor is welded onto the carframe. The most likely point of LATCH failure is at that weld junction. Anyone testing the weld must definitely need to know the total weight.

http://www.saferidenews.com/pdfs/LATCHApp_B_pg105.pdf

--Charlene
Mom of 2 boys, 3yo and 11mo

Splash · Feb 14, 2007

Anchors are not required to pass dynamic crash tests, only pull tests. It is very likely that individual manufacturers crash test their anchors at higher levels, but of course that is not going to be released.

The pull test equates to roughly 65 pounds, if memory serves me correctly. And that is a fairly conservative estimate. To get the 48 pound lower limit, they assumed the weight of a high weight harness seat (remember, anything that doesn't harness beyond 48 pounds doesn't matter) and applied that to the limits. I shipped two Boulevards yesterday, and their shipping weight, with box, was just under 22 pounds each. It's a pretty big and heavy duty box, too.

Subaru specifies that you may use lower anchors up to 60 pounds. Subaru gets their anchors from the same place everyone else gets them. So... 48 pounds is pretty conservative and unlikely to fail at that point. However, we do what we're told

I prefer a seatbelt install if all other factors are equal.

AdventureMom · Feb 14, 2007

Others may know more about this, but I had the same question a month or so ago... I think they probably take into account a standard seat weight - probably 10-15lbs? What issue is with all the higher-weight seats like the Regent that weigh much more. I think that NHTSA is trying to address the LATCH limit issue and come up with a more standardized system - that was addressed briefly in my CPS tech course. I did notice in our course when we were installing seats that the LATCH anchors are different from car to car, with Ford having very beefy-looking anchors. We usually use the belt anyway in our own car - it's easier to us now that we know what we're doing

broxbourneDELETE · Feb 14, 2007

Splash said:
Anchors are not required to pass dynamic crash tests, only pull tests.

LATCH anchors are not req'd to pass any crash test? OMG, really? I have done loads of mechanical testing in my life and my response is still OMG!

The pull test equates to roughly 65 pounds, if memory serves me correctly.

Can anyone possibly point me to the test method for this 65# test? I really want to see it. This standardized weight seems absurdly low. The front of a real Hummer has an anchor from which you can winch up the entire vehicle! (I am not doubting you Splash on weigt, but I wonder how "Failure" is defined in their method)

Subaru specifies that you may use lower anchors up to 60 pounds. Subaru gets their anchors from the same place everyone else gets them.

The LATCH is probably only as good as the weld. If they all really come from the same place, the quality of the weld, and how they define "Failure" is what would make the difference.

I prefer a seatbelt install if all other factors are equal.

Yes I do too now. Yesterday I posted some q's on seatbelt webbing but I think I would prefer the risk I perceive associated with that better now until know more about the minimum test method requirements for LATCH.

Splash · Feb 14, 2007

They don't necessarily fail at 65 pounds, they just stop testing at 65 pounds. When LATCH first debuted in the US, there was no reason to go above 65 pounds because there were very few seats that went above 40 pounds.

Actually, if you look through the private chat forum, and find something titled "Chat transcript" I think there is some more info in there.

southpawboston · Feb 14, 2007

http://www.car-seat.org/showpost.php?p=86060&postcount=2

broxbourneDELETE · Feb 15, 2007

The most information on LATCH testing starts around S8 (p.834) and goes to the end of the document. I am not sure the aforementioned 65# came from, but I skimmed FMVSS225 and saw numbers like 500N pre-tension; 11,000N within 24sec; 11,000N over 1 second; 8kN, 5kN static force and now I am feeling much better about LATCH usage vs seatbelt webbing.

http://www.carseat.org/Legal/FMVSS225.pdf

Regarding all those child weight limits published in SafeRideNews (40# Honda, 60# Subaru, etc), is there any document that shows Honda or Ford or GM making, or assenting to, those statements?

Patriot201 · Feb 15, 2007

It still makes me a bit angry that certain manufacturers (mainly Honda) don't make the LATCH weight limits public or even mention them at all. They also don't seem to have any staff who know anything about the LATCH weight limits.

If a parent didn't know to ask, how are they supposed to know that there even is a weight limit for the anchors? What if they assume that the anchors can be used indefinitely (or until the carseat manufacturer says)? Second, what if a parent didn't have access to the internet to find the information from SafeRideNews?

I know I need to let this go, but I somewhat resent that the internet is the only source of information regarding the LATCH weight limits and, even if you have access to the internet, it isn't easy to find that information.

I really wish that information was more accessible to the general public.

Patriot201 · Feb 15, 2007

broxbourne said:
Regarding all those child weight limits published in SafeRideNews (40# Honda, 60# Subaru, etc), is there any document that shows Honda or Ford or GM making, or assenting to, those statements?

Good question!!

LATCH limits (child weight only)

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