Seatbelt Extenders for Child Seats

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Does anybody know if seatbelt extenders are safe for use with child car seats? We've got a long drive to Devon with a fourteen month old. His seat sits nicely on the back seat of my car, but the seatbelt clip is about 8" shy of reaching the buckle. If ever he's in my car he sits in the front, which isn't ideal as it makes using the passenger door mirror difficult.

Nothing particularly odd or unique about the seat!
 
Been doing a little bit of reading and I understand they're illegal and unsafe!

Thought perhaps a new, longer seatbelt buckle would be better? That way I could unbolt the old one (think it's just a 17mm nut holding it in place) and replace with a longer one, so there's no 'extension' piece involved.

 
I thought it might be because my car is older and child seats have got larger/bulkier, however it seems to be a problem on a number of cars as we've found with our relatives.

In the end, I bought one of those longer buckles (the woven type) and replaced with with the original buckle. It bolts straight into place and means there's no additional junctions/connections.

Having read further into it, I'm not sure the extenders are illegal or not. Their use for seats isn't advised, as they seem to be aimed at those whose body size does not allow them to use a 'normal sized' belt.
 
This is a subject close to my heart! First of all, is this your Peugeot 406 we're talking about? (And a rear-facing child seat)? When cars are type approved, there's a "gaberit" (a sort of representation of a "worst case" child seat), that the manufacturer needs to be able to accommodate. It could be that the 406 pre-dates that requirement though.

Secondly, is the belt too short, even with the seat fully back and fully down? That would be unusual! We managed OK with the front seat in Mrs. Avocet's old 405 and her Xantia - the latter being pretty much the same animal as the 406, in that respect, I think? You need to really shove the child seat into the seat foam, and get the belt as tight as possible. I used to kneel on the child seat when fitting it. On my old Alfa 164, which had electric seats, I used to put the seat fully back and down, then when the child seat was in, move it up a bit to take out the last of the slack, so that the belt was good and tight round it.

No, seat belt extenders aren't "legal". The legal requirement is in the Construction & Use regs and requires the belt to comply with either an old British standard, or ECE Reg 16 or EU Directive 76/114. A belt assembly with an extender in it, won't comply with any of those, because a belt with n extender, just wouldn't meet those requirements. That doesn't mean it is necessarily unsafe, but yes, technically illegal. The chances of prosecution, are, of course, minimal.

Does your 406 have seat belt reminders? If so, the switch for those, is usually built into the buckle, so if you remove the old buckle, that might become a problem. Also, does it have seat belt pre-tensioners? (They usually do if the seating position has an airbag). If so, that's often part of the buckle assembly too, so for those reasons, it's not a great idea to take off the original buckle.

Another problem, is that some tongues "feel" like they clip into some buckles, but might pull out early in a crash. Amazingly, there's no requirement for one manufacturer's tongue not to fit into another manufacturer's buckle. Many don't, of course, but of the ones that do "click", it's not always guaranteed that they will be fully engaged.

The other problem, (when not using the child seat), is that the extended buckle then comes "round the corner" of the person wearing it. Ideally, you want there to ONLY be webbing in contact with the wearer. Any hard parts, can cause injuries to the wearer. Rally harnesses, with the big buckle in the centre of the abdomen, usually have a big, padded piece between the wearer and the hard parts of the buckle.
 
This is a subject close to my heart! First of all, is this your Peugeot 406 we're talking about? (And a rear-facing child seat)? When cars are type approved, there's a "gaberit" (a sort of representation of a "worst case" child seat), that the manufacturer needs to be able to accommodate. It could be that the 406 pre-dates that requirement though.

Secondly, is the belt too short, even with the seat fully back and fully down? That would be unusual! We managed OK with the front seat in Mrs. Avocet's old 405 and her Xantia - the latter being pretty much the same animal as the 406, in that respect, I think? You need to really shove the child seat into the seat foam, and get the belt as tight as possible. I used to kneel on the child seat when fitting it. On my old Alfa 164, which had electric seats, I used to put the seat fully back and down, then when the child seat was in, move it up a bit to take out the last of the slack, so that the belt was good and tight round it.

No, seat belt extenders aren't "legal". The legal requirement is in the Construction & Use regs and requires the belt to comply with either an old British standard, or ECE Reg 16 or EU Directive 76/114. A belt assembly with an extender in it, won't comply with any of those, because a belt with n extender, just wouldn't meet those requirements. That doesn't mean it is necessarily unsafe, but yes, technically illegal. The chances of prosecution, are, of course, minimal.

Does your 406 have seat belt reminders? If so, the switch for those, is usually built into the buckle, so if you remove the old buckle, that might become a problem. Also, does it have seat belt pre-tensioners? (They usually do if the seating position has an airbag). If so, that's often part of the buckle assembly too, so for those reasons, it's not a great idea to take off the original buckle.

Another problem, is that some tongues "feel" like they clip into some buckles, but might pull out early in a crash. Amazingly, there's no requirement for one manufacturer's tongue not to fit into another manufacturer's buckle. Many don't, of course, but of the ones that do "click", it's not always guaranteed that they will be fully engaged.

The other problem, (when not using the child seat), is that the extended buckle then comes "round the corner" of the person wearing it. Ideally, you want there to ONLY be webbing in contact with the wearer. Any hard parts, can cause injuries to the wearer. Rally harnesses, with the big buckle in the centre of the abdomen, usually have a big, padded piece between the wearer and the hard parts of the buckle.

It was a very difficult few weeks deciding what to do! The wife has always had new cars and currently drives a new Focus (1.0 Eco Boost). My Peugeot 406 (yes same one as discussed in another thread, very closely related to your old Xantia!) is far roomier and better on fuel so we always take that for longer distance stuff. Plus I prefer driving it.... I just don't know why we couldn't get the car seat to fit. I really did push the seat down, but was about 2 or 3 inches away from the buckle and really had to pull to get it that close. The little ones seat is rear-facing and had been sat in the front with the air bag disabled, but I really wanted him in the back hence looking at ways of making it safe.

I bought a buckle made in the UK which conforms to a raft of safety specifications. I've plugged it in and pulled it, twisted it, pushed it, etc. etc. to try and alleviate some of my constant worry that it will un-buckle itself!

My 406 doesn't have the seat belt reminders (although there are three connector blocks underneath each front seat, probably for the air bags). The rear seats (where his child seat will be) have no wiring whatsoever. The buckle was removed with just one bolt. There are pre-tensioners on all seats yes, but so far as I know none of it is related to the buckle. The only bit of extra kit the original buckle is a spring and an elastic band connected to underside of the seat, so that when the seat is raised up, the buckle lies down out the way.

I probably should have said in my original post, but should anybody ever sit in the space his seat currently occupies, I will fit the original buckle back, which would then sit flush with the top of the seat.

Thanks for the knowledge on the laws, too. I struggled finding anything other than a few safety experts mention it being illegal.
 
It was a very difficult few weeks deciding what to do! The wife has always had new cars and currently drives a new Focus (1.0 Eco Boost). My Peugeot 406 (yes same one as discussed in another thread, very closely related to your old Xantia!) is far roomier and better on fuel so we always take that for longer distance stuff. Plus I prefer driving it.... I just don't know why we couldn't get the car seat to fit. I really did push the seat down, but was about 2 or 3 inches away from the buckle and really had to pull to get it that close. The little ones seat is rear-facing and had been sat in the front with the air bag disabled, but I really wanted him in the back hence looking at ways of making it safe.

I bought a buckle made in the UK which conforms to a raft of safety specifications. I've plugged it in and pulled it, twisted it, pushed it, etc. etc. to try and alleviate some of my constant worry that it will un-buckle itself!

My 406 doesn't have the seat belt reminders (although there are three connector blocks underneath each front seat, probably for the air bags). The rear seats (where his child seat will be) have no wiring whatsoever. The buckle was removed with just one bolt. There are pre-tensioners on all seats yes, but so far as I know none of it is related to the buckle. The only bit of extra kit the original buckle is a spring and an elastic band connected to underside of the seat, so that when the seat is raised up, the buckle lies down out the way.

I probably should have said in my original post, but should anybody ever sit in the space his seat currently occupies, I will fit the original buckle back, which would then sit flush with the top of the seat.

Thanks for the knowledge on the laws, too. I struggled finding anything other than a few safety experts mention it being illegal.

It would really be unusual for a car (of any age) to have belt pre-tensioners on the rear seats. I'd be amazed if the 406 did. There's a chance it won't have them on the front, in fact, but usually, cars with airbags do have them. Usually, the pretensioner acts on the buckle assembly (because that way, it can tension both the lap and the shoulder belt at the same time). Usually, the buckle is bolted to an assembly that has a tube in it (which contains a powerful spring, held closed with wire). There's an explosive charge round the wire, so that when the crash is detected, it detonates, the explosive, which breaks the wire, and the spring then pulls the buckle back towards its anchorage, a couple of inches to pull the belt tight. There's often a slot in one end for a wee "flag" that pops out once detonated, so you know the unit has been fired.


You can just see the wire, disappearing into its tube in the photo.

With the buckle, the best thing would be to get a decent pair of verniers and compare the tongue on the original belt, with the tongue on the extender. If the measurements (width, depth, thickness, size of hole in each) are pretty much identical, then there's a good chance the buckles and tongues are compatible. One thing they really hate, is being "bent", so if the new buckle is trying to "go round a corner" of the child seat base when in use, that's potentially very dangerous. They can't cope with much side load, as they're only really designed to see a load in a straight line, pulling the tongue out of the buckle.

One other thought that crossed my mind for the front seat; does the car have a height adjuster for the shoulder belt? If so, you might get another few inches of webbing by altering the height of the height adjuster?
 
Ah, that clears it up! Yes the front seats have those -- I think the cylinders are hidden behind a bit of trim next to the rail (I've definitely seen them under there). It has front and side airbags, too.

I actually - naively - thought a pre-tensioner was just the mechanism of pulling a belt quickly and it locking to prevent a passenger being thrown forward in a crash. In that case, I can confirm the rear seats do not have pre-tensioners.

The new, longer buckle I have fitted emerges from the seat at the same angle and position as the original buckles, only they now reach the belt/tongue. It is completely free of any obstruction and does not make contact with the seat. Just for clarify, when I say "buckle" the only part I've replaced is the one I share a link to in post #2.

The rear belts are coiled up into the backs of the seats, so there is no option to adjust the height unfortunately. I think this is part of the reason why the seat belts are just that bit too short.


Thanks for all the contribution to this
 
The pre-tensioner does pull the belt tighter, immediately before a crash. The intention is to "buy you time" and reduce the shock loads into your body. Pulling something tighter to achieve that, sounds counter-intuitive, but it works like this:

Imagine the crash. At time "t=0" the car's front bumper makes initial contact with whatever it hits. Then at (say) t=5 (milliseconds), the bumper has deformed and the front crash structure has started to make contact, so the car starts to slow down. However, the occupants are still travelling at the same speed, sliding across the seat, towards their seat belts. Another few milliseconds into the crash, the car (which was doing (say) 30, might now be doing (say) 28, but the occupants are still doing 30, and are just starting to take up the slack in the belts.

And so it goes on. So what really happens, is that the car might take (say) 200 milliseconds to come to a complete stop from 30, but the occupants don't get as long to come to a stop, because they were "flying" for some of the time that the car was slowing down. So the occupants might only get (say) 175 milliseconds to get down from 30 to zero. That puts bigger loads into the occupants from the belts. The pre-tensioners take the slack out of the belts and "buy" you another (say) 10 milliseconds in which to slow down - which lowers the loads on you.

I'm struggling to see how you managed to attach the new buckle to the seat, though? Did you unbolt the pre-tensioner assembly and just bolt it on to the bracket on the seat that the pre-tensioner assembly used to attach to?
 
Thanks for the detailed description on how they work -- taught me something, which always makes for a good day! They do an incredibly important job by the sounds of it. The front seats definitely have this incorporated into them, but the rears do not. I've seen the whole assembly on a 406 being broken.

The child seat is going onto the back seat (where there are no pre-tensioners) so the only thing I removed was the original buckle assembly. This assembly consisted only of a buckle mounted onto a piece of angled steel which was then bolted to the body of the car. Once removed, I simply replaced it with the new buckle which emerges slightly higher out of the car seat.

I've attached a picture of the same assembly I removed. The spring pushes the buckles into an upright position when the seat is folded flat, but when you lift the seat up an elastic band (which you can see cut off in this picture) pulls the buckles flat so you can fold the rear seats over them.
 

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Are you sure you are fitting correctly , have fitted many child seats to many different cars and none have presented a problem , always lots of excess of belt length.
 
Are you sure you are fitting correctly , have fitted many child seats to many different cars and none have presented a problem , always lots of excess of belt length.

Yes we've tried many different methods. Thinking it was because the car is 22 years old, and perhaps seats have got bigger since then, we tried on modern cars and it was very tight. Some we just managed to fit others would not. I can't remember the model number but we found others struggling on forums.

We've followed all of the instructions about adjusting the position of the seat, plus pushing it down into the car's seat as much as we can while buckling up.

With the new longer buckle, there's still only a very little slack in the belt, but I can now buckle it in place and tighten everything up as we should.
 
Thanks for the detailed description on how they work -- taught me something, which always makes for a good day! They do an incredibly important job by the sounds of it. The front seats definitely have this incorporated into them, but the rears do not. I've seen the whole assembly on a 406 being broken.

The child seat is going onto the back seat (where there are no pre-tensioners) so the only thing I removed was the original buckle assembly. This assembly consisted only of a buckle mounted onto a piece of angled steel which was then bolted to the body of the car. Once removed, I simply replaced it with the new buckle which emerges slightly higher out of the car seat.

I've attached a picture of the same assembly I removed. The spring pushes the buckles into an upright position when the seat is folded flat, but when you lift the seat up an elastic band (which you can see cut off in this picture) pulls the buckles flat so you can fold the rear seats over them.

Ah! OK, I misunderstood. I thought that was your solution for when it was in the FRONT seat. Yes, if the buckle is compatible with the Peugeot tongue, you should be fine with what you have. Just be careful that when a "human" sits in that seating position, the longer wire on the buckle doesn't come round the corner of their pelvis and/or leave the buckle assembly in contact with the abdomen of the wearer. You really don't want anything "hard" feeding the loads into the wearer, only webbing.
 
Yes we've tried many different methods. Thinking it was because the car is 22 years old, and perhaps seats have got bigger since then, we tried on modern cars and it was very tight. Some we just managed to fit others would not. I can't remember the model number but we found others struggling on forums.

We've followed all of the instructions about adjusting the position of the seat, plus pushing it down into the car's seat as much as we can while buckling up.

With the new longer buckle, there's still only a very little slack in the belt, but I can now buckle it in place and tighten everything up as we should.
Usually only the lap restraint crosses the seat the diagonal passes behind the seat which mean you car seat must be bigger than a 25st occupant .?
 
Usually only the lap restraint crosses the seat the diagonal passes behind the seat which mean you car seat must be bigger than a 25st occupant .?

Yes that's right, lap restraint across the seat with the large belt wrapping around the back. Honestly we've really tried with it with all the logical ways and there's nothing we can do to get it to fit. The buckles in my car are recessed within the seat whereas on other cars they've been free on the seats in the back -- this would make a difference.

I suppose it depends how far the back of the seat extends outwards. It touches the back of the passenger seat which I don't imagine the belly of a 25 st. person would do, but of course they would be wider than the seat is deep. I don't know why it seems such an awkward seat but it is!
 
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