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Myth: A rock-solid, shake-the-car installation is not ideal.

Extend2Fit RF seatbelt extendIs it bad or wrong to install your carseat so tightly that you shake the whole car when you’re testing to make sure it doesn’t move more than 1″ from side-to-side and front-to-back? That question comes up over and over again so we wanted to really explore the issue – look at the facts, talk to carseat engineers who know more than we do 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 lower LATCH belt webbing 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?

Survey says…. No! (with a few exceptions)

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 weight x speed equation that we use to teach parents and caregivers how much restraining force is estimated to keep their child restrained in a crash? Guess what? Your carseat is designed to withstand 1200 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.

Base installation technique

We know that the tighter you can couple the carseat to the vehicle, the better. This is why rigid LATCH/ISOFIX attachments are so beneficial. On the flip side – the difference between a carseat installed rock-solid (with seatbelt or flexible LATCH attachments) and a carseat installed acceptably with just a little bit of movement at the beltpath, in a crash, is negligible. Don’t convince yourself that a rock-solid install is going to keep that seat from moving during a moderate to severe crash – but it’s certainly better than starting out in a crash with a loose installation!

However, there could be cases where too tight is possible. If you’re using an add-on mechanical advantage (something like a MightyTite device) and you’re going overboard with it, you could potentially damage something. If you’re installing a carseat that has an integrated mechanical advantage system like a Britax seat with ClickTight, or Chicco NextFit with SuperCinch on the LATCH strap, you need to follow the manufacturer’s directions and guidance.

With typical carseats, if you can use a few tricks or installation techniques and achieve a really solid installation, that’s great. But 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. For the record, in my vehicle with stiff leather seats, I almost always need to put a knee in a forward-facing carseat to get an acceptable install. Occasionally I need to put a knee in the seat AND use the reclining seatback trick. These are easy things for me to do quickly and it sure beats wrestling with an install for 20 minutes. To clarify, I don’t always need to put my knee in a forward-facing carseat – but when I do, I certainly don’t feel like I’m doing something wrong.

Ultimately, you always want to read and follow the carseat manufacturer’s recommendations. There are situations where getting the seatbelt too tight will prevent you from closing a lockoff (or a Britax ClickTight compartment) or perhaps a lockoff will pop open 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 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 and you may need to lighten up a little on your regular installation technique.

Bottom line: Unless there is some compelling reason not to, get the carseat as tight as you can with *reasonable effort* but don’t feel guilty if you can’t 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 reasonable effort. 🙂