Myth: A rock-solid, shake-the-car installation is not ideal and you could break your carseat or damage the seatbelt.
Is it bad or wrong to install your car seat so tightly that you shake the whole car when you’re testing to make sure it’s tight? That question comes up frequently so we wanted to explore the issue – look at the facts, talk to carseat engineers, and set the record straight once and for all.
First, a little background info – when carseats are crash tested in a lab, the tension on the belt webbing has to measure between 53.5 N (newtons) and 67 N. That tension is measured by a load cell device placed on the webbing. This is done to maintain repeatability between tests. The tension range was chosen because it represents the average tightness achieved by parents in the field.
In the real world, no one expects parents and caregivers to measure the tension on the seatbelt or LATCH strap that is securing their carseat. CPS Technicians are taught that a carseat is properly installed if it moves less than 1” from side-to-side and front-to-back when you check for tightness at the beltpath.
But is it possible to install your carseat too tightly? To the point of it being a detriment instead of a benefit?
In most cases, there is no such thing as too tight – only too loose. If you’re just using typical human strength and maybe a few installation tricks like getting behind a rear-facing carseat or using the reclining seatback trick, you do not have to worry about getting the seatbelt or LATCH strap too tight. Carseats and seatbelts are not delicate objects that are going to be compromised by a really tight installation.
Remember the <not technically accurate but simple concept used to make a point> weight x speed equation that we use to teach parents and caregivers how much restraining force is needed to keep their child restrained in a crash? Guess what? Your carseat is designed to withstand 1,200 lbs. of force or more in a crash! And the seatbelts and retractors in your vehicle are designed to restrain a 200 lb. adult in a 35 mph crash. That’s 7,000 lbs. of restraining force! Even an Olympic weightlifter cannot install a carseat with 1200 lbs. of force so don’t worry that your tight installation is somehow going to hurt your carseat or your vehicle.
FACT: The tighter you can couple the carseat to the vehicle, the better. This is why rigid LATCH/ISOFIX attachments are so beneficial!
However, there could be cases where too tight is possible. If you’re installing a carseat that has an integrated mechanical advantage feature – like a Britax with ClickTight, Graco with SnugLock, or Chicco with SuperCinch, you need to follow the manufacturer’s directions and guidance for proper installation.
For carseats that don’t have a built-in mechanical advantage, if you can use a few tricks or installation techniques and achieve a really solid installation, that’s great. However, if you’re fighting with the install and the best you can achieve is just a little bit of side-to-side or front-to-back movement and it’s not more than 1″ of movement, that’s perfectly okay too. It’s not always possible to get a rock-solid install but if you can – there is certainly nothing bad or wrong with that.
One of my vehicles has very stiff leather seats, and I almost always need to put a knee in a forward-facing carseat to get an acceptable install. Occasionally I will need to put a knee in the carseat AND also use the reclining seatback trick. These are easy things I can do quickly and it sure beats wrestling with a challenging installation for 20 minutes.
Ultimately, you always want to read and follow the carseat manufacturer’s recommendations. There are situations where getting the seatbelt (or LATCH strap) too tight will prevent you from closing a lockoff (or a Britax ClickTight compartment) because there is too much tension on the belt.
There are also situations where a LATCH belt with hook connectors is so tight that you can’t get enough slack in the belt to loosen it when you have to take it out. Tip: if this happens on a vehicle seat that reclines – recline the vehicle seat back then apply downward pressure to the carseat or base and that should introduce enough slack to allow you to loosen the LATCH belt.
Obviously, in these cases, you have a compelling circumstance (key words) and you may need to lighten up a little on your regular installation technique.
Bottom line: Unless there is some compelling reason not to, install the carseat as tight as you can with reasonable effort (more key words) but don’t feel guilty if you cannot get it rock-solid. On the flip side, it’s not bad or wrong if you can get that sucker installed like it’s part of the car with a reasonable amount of effort. 🙂
We’re going to say that this Myth is PLAUSIBLE simply because there are many seats on the market that have some sort of integrated mechanical advantage and if you go overboard while also using a mechanical advantage that could potentially (yet another key word) create issues.
For seats that lack a mechanical advantage feature, this myth is definitely BUSTED.
As a tech, there have been a few seats that have come in (RFOs really) that took several of us to get out because they’d been installed too tightly by an over-enthusiastic dad who generally was using LAs AND the seatbelt over top of that.
@Emma – yes, this can definitely be an issue with hook-style LATCH connectors. It’s one of the main reasons that CPSTs, and many parents, prefer the nicer, push-on lower anchor connectors. They make UNinstalling the seat or base sooooo much easier! In 20+ years, I have never had to cut a LATCH strap to get it off the lower anchor bars but I’ve come *real close* a few times. The struggle is real! Lol.
Does the same principle apply to tethers?
Hi Diane – that’s a great question! I don’t think it’s as important for a tether strap to be guitar-string-tight but it can’t hurt either *as long as you do it AFTER your forward-facing seat is installed* (with either seatbelt or lower anchors). You definitely don’t want a loose tether strap but it’s not critical for it to be super tight either. Just wait until after the seat is installed properly to pull the tether strap tight. If you tighten it before you tighten the seatbelt or latch strap – it could impede your installation. HTH!
Thank you for this!
When telling someone I was able to get my Nextfit installed with LATCH with virtually no side to side movement, they were telling me that an inch of movement side to side was beneficial to help avoid whiplash.
Any information on why this would be false?
Hi Emily, to help avoid whiplash??? Really??? How is that even possible? Do they understand what whiplash is? This well-intentioned person clearly has no idea what they are talking about so I would just leave it alone. Or you could politely disagree and then ask them to prove whatever they’re claiming is true. That puts the burden of proof on them to find supporting evidence for their ridiculous claim. You could also tell them to call Chicco for clarification. HTH! Good luck!