Seat Belt Extenders for Rear Seats?

[David 90274]

I'm looking for seat belt extenders for the rear seats of my wife's Model 3. My twins are in booster seats and it is very difficult to buckle the existing belts with booster seats in place. I tried these extenders from Amazon but they seem to be the wrong size:

https://smile.amazon.com/gp/product/B0797NDG48/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

The width of the "tongue" of the extender and the size of the hole in the tongue (sorry if this is starting to sound a little risque) are the same as the existing Model 3 tongue. The extender will lock into the existing buckle in the car. However, the tongue of the car's belt will not lock into the extender's buckle. The Model 3 tongue is much shorter than the tongue on the extender.

Anyone found an extender that works in the rear seats? I tried a forum search but didn't see any relevant threads.

 

[JCLeonard]

Try this thread..
2018 Tesla Model 3 "Oreo" Build Thread

Tons of other great info in there, too.

 

[David 90274]

Try this thread..
2018 Tesla Model 3 "Oreo" Build Thread

Tons of other great info in there, too.

Thanks. As you said, some interesting info in there on booster seats as well as the extenders. The reviews on Amazon for the extenders he is using are not great (2.2 stars, not latching consistently for several people) but they might be worth a try.

 

[BeetFarmer]

These did not work for the rear seats. Worked fine on MS rear seats but not the 3. They depress the release button when fully seated so they won't stay in. Just in case you run across them.
https://www.amazon.com/dp/B0777PJFKW/ref=cm_sw_r_cp_apa_nzUmBbWGSERZ5

 

[Lloyd]

You are not allowed in California to use extenders for any child or infant car seats. My daughter sold them and is certified in training installers. If you go to any police department they will show you how to install your car seats properly!

 

[RDaneel]

I also got ones on Amazon that failed to work. I bout some from Seatbelt Extender Pros (same company that made the ones on Amazon) and they are merely acceptable. They sometimes need to be tried about 4-5 times to actually latch. Better than nothing, but I going to call and complain. Also, I had to buy these direct and not on Amazon, as this model was not available on the Zon.

 

[mynameisjim]

I bought a unit from seat belt extender pros through amazon and it had trouble latching like some reported (20% latch rate). They replaced it with another style at no cost including shipping, which was nice.

The replacement works better (95% latch rate) but not perfect.

The fix was removing a little plastic from the side of the extender with a knife, that makes it latch every time.

 

[Max*]

You are not allowed in California to use extenders for any child or infant car seats. My daughter sold them and is certified in training installers. If you go to any police department they will show you how to install your car seats properly!

I'm pretty sure it's not just a CA thing.

Typical seat belt extenders change the geometry of where the seatbelt is placed. The seatbelt for a child should be placed across the lap, not the abdomen -- in case of impact, if the seatbelt is across the abdomen it can cause serious internal injuries.

In addition, it creates a 2nd point of failure. And (all? most?) seat belt extenders are not crash tested with car seats/boosters.

With that being said, it's a pain in the ass finding a booster seat that's narrow enough to work. We're going through the same thing now.

 

[David 90274]

You are not allowed in California to use extenders for any child or infant car seats. My daughter sold them and is certified in training installers. If you go to any police department they will show you how to install your car seats properly!

It is not a question of learning "how to install your car seats properly!", it is more a matter of finding a booster seat that works well with the Model 3. Bear in mind that booster seats are not like infant child seats. Most of them are only secured with the same seat belt as the child so the booster tends to move around quite a bit every time your child gets into or out of the car. That can make buckling the belt very challenging, particularly if you have a protective cover under the booster to protect the car (which can get in the way of the recessed buckle and allow the booster to move around even more when unbuckled).

Since my original post I did find a different booster seat that attaches to the car using the LATCH mounts, which definitely helps with buckling and just seems safer in general. The booster still shifts a bit but far less. It also means I don't need to worry about the buckling the seat belt when the boosters are not in use. I'd rather not have those things flying around the car in an accident.

I'm also still investigating the extenders since buckling the belt is still a bit of a nuisance. I can't find a specific California law that precludes using an extender for a child in a booster seat. If you could provide a reference, I'd appreciate it.

 

[David 90274]

I'm pretty sure it's not just a CA thing.

Typical seat belt extenders change the geometry of where the seatbelt is placed. The seatbelt for a child should be placed across the lap, not the abdomen -- in case of impact, if the seatbelt is across the abdomen it can cause serious internal injuries.

In addition, it creates a 2nd point of failure. And (all? most?) seat belt extenders are not crash tested with car seats/boosters.

With that being said, it's a pain in the ass finding a booster seat that's narrow enough to work. We're going through the same thing now.

I am still investigating the seat geometry issue. That is one reason that I initially bought the smaller extenders from my first post - it seemed like they would keep the lap belt where it needs to be - low and across the lap, just as you said. Since those didn't work I just ordered some slightly longer extenders but definitely plan to take a close look at where the belt sits when they are in use. Given the design of the booster, I don't think it will be an issue. The arms of the booster seem to prevent the belt from riding too high.

The "2nd point of failure" is a fair point, in theory, but as a practical matter as long as the extenders are well made and properly certified I think any potential trade-off is more than reasonable. Weight certainly wouldn't be the problem. My child plus their booster weighs far less than an average adult. Safety comes first but no reason you can't have reasonable levels of safety and convenience.

 

[Lloyd]

It is not a question of learning "how to install your car seats properly!", it is more a matter of finding a booster seat that works well with the Model 3. Bear in mind that booster seats are not like infant child seats. Most of them are only secured with the same seat belt as the child so the booster tends to move around quite a bit every time your child gets into or out of the car. That can make buckling the belt very challenging, particularly if you have a protective cover under the booster to protect the car (which can get in the way of the recessed buckle and allow the booster to move around even more when unbuckled).

Since my original post I did find a different booster seat that attaches to the car using the LATCH mounts, which definitely helps with buckling and just seems safer in general. The booster still shifts a bit but far less. It also means I don't need to worry about the buckling the seat belt when the boosters are not in use. I'd rather not have those things flying around the car in an accident.

I'm also still investigating the extenders since buckling the belt is still a bit of a nuisance. I can't find a specific California law that precludes using an extender for a child in a booster seat. If you could provide a reference, I'd appreciate it.

California defers proper installation to NHTSA www.seatcheck.org. You can go there. They also rate seats for ease of proper installation. Might be helpful for you. Also, checking, Booster seats are not supposed to be latched, they are only supposed to raise your child to the level that the seatbelt crosses their chest and neck at the appropriate level.

 

[Max*]

Also, checking, Booster seats are not supposed to be latched

You mean booster seats are not required to be latched, correct?

I don't see any regulations stating that a booster seat can't be latched (in addition to seat belt, obviously).

 

[Lloyd]

You mean booster seats are not required to be latched, correct?

I don't see any regulations stating that a booster seat can't be latched (in addition to seat belt, obviously).

I believe that is correct. Check the site I referenced.

 

[andremc]

Give the mifold a look. My 6 year old was having the same issue with buckling while in his booster. The mifold takes up less space, and makes snapping in a breeze. It did take him a day or two to get used to threwadjng the belt, but he likes it just fine now. His only complaints are a lack of cup holder and that it’s not as comfortable under his butt.

Basically, the mifold acts as a “reverse booster seat,” in that it pulls the seatbelt down to the child instead of propping the child up to the seat belt. It looks and feels secure when he’s in it, and we can now fit 3 people comfortably in the backseat (I have another kid in a full sized car seat).

Mifold website - Home

 

[Max*]

Give the mifold a look. My 6 year old was having the same issue with buckling while in his booster. The mifold takes up less space, and makes snapping in a breeze. It did take him a day or two to get used to threwadjng the belt, but he likes it just fine now. His only complaints are a lack of cup holder and that it’s not as comfortable under his butt.

Basically, the mifold acts as a “reverse booster seat,” in that it pulls the seatbelt down to the child instead of propping the child up to the seat belt. It looks and feels secure when he’s in it, and we can now fit 3 people comfortably in the backseat (I have another kid in a full sized car seat).

Mifold website - Home

Not crash test rated -- New booster substitute won't be rated

 

[andremc]

It wasn’t crash test rated by the IIHS because they didn’t consider it a true booster seat, not due to any functional deficiencies. It passed all the other regulatory requirements though, which was enough for me to have peace of mind. Well, that and seeing how the seatbelt sits on him and functions when braking compared to when he’s in his traditional booster.

If you don’t feel comfortable, that’s fine. Just know that it’s an option that has been deemed safe.

 

[Max*]

It wasn’t crash test rated by the IIHS because they didn’t consider it a true booster seat, not due to any functional deficiencies. It passed all the other regulatory requirements though, which was enough for me to have peace of mind. Well, that and seeing how the seatbelt sits on him and functions when braking compared to when he’s in his traditional booster.

If you don’t feel comfortable, that’s fine. Just know that it’s an option that has been deemed safe.

I never said it's "illegal" or not approved for use. Just saying that it's not crash test rated, mifold is fairly new, there's really not enough data to say how safe it is.

I'm not knocking your decision, but at the same time people buying it should be informed.

A crash test rated alternative is the bumble bum (it didn't do great, but at least it's rated so people know what they're getting into).

 

[David 90274]

California defers proper installation to NHTSA www.seatcheck.org. You can go there. They also rate seats for ease of proper installation. Might be helpful for you. Also, checking, Booster seats are not supposed to be latched, they are only supposed to raise your child to the level that the seatbelt crosses their chest and neck at the appropriate level.

Max already addressed the LATCH with booster seat question but here is a link to the booster seat in question in case anyone is curious (assuming TMC allows links like this):

https://smile.amazon.com/gp/product/B00AHVR7ZI/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

I had a look at the NHTSA site you indicated but didn't see any specific references to seat belt extenders. It does reiterate the same info that Max provided about how a seat belt is supposed to fit for proper function.

I know you mean well but trust me, the last thing I need is a link to another website with generalized info on car seats. Like many responsible fathers I did fairly extensive (perhaps even excessive) research on the subject. You initially indicated that California prohibits the use of seat belt extenders with all "child seats". I asked for a reference to that information. Answering with your link is kind of like handing me a library card when I ask about a specific quote from Scene I, Act III of The Taming of the Shrew.

 

[Max*]

Max already addressed the LATCH with booster seat question but here is a link to the booster seat in question in case anyone is curious (assuming TMC allows links like this):

https://smile.amazon.com/gp/product/B00AHVR7ZI/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

I had a look at the NHTSA site you indicated but didn't see any specific references to seat belt extenders. It does reiterate the same info that Max provided about how a seat belt is supposed to fit for proper function.

I know you mean well but trust me, the last thing I need is a link to another website with generalized info on car seats. Like many responsible fathers I did fairly extensive (perhaps even excessive) research on the subject. You initially indicated that California prohibits the use of seat belt extenders with all "child seats". I asked for a reference to that information. Answering with your link is kind of like handing me a library card when I ask about a specific quote from Scene I, Act III of The Taming of the Shrew.

We have 2 of those, they're great boosters.

In addition, the owners manual for that booster does NOT prohibit the use of seat belt extenders (it just doesn't talk about them at all). https://images-na.ssl-images-amazon.com/images/I/A18ABaP8SoS.pdf

But the Model 3 owners manual states "Warning: Do not use seat belt extenders on a seat belt that is being used to install a child safety seat or booster seat." Page28

 

[andremc]

I never said it's "illegal" or not approved for use. Just saying that it's not crash test rated, mifold is fairly new, there's really not enough data to say how safe it is.

I'm not knocking your decision, but at the same time people buying it should be informed.

A crash test rated alternative is the bumble bum (it didn't do great, but at least it's rated so people know what they're getting into).

Understood. However, simply posting, “not crash test rated,” without any additional context can also lead to someone being misinformed. That’s why I wanted to make sure to clarify why it wasn’t crash test rated.