adding a top tether to passenger side 3rd row Suburban

Hodadical

New member
Preface:
So as many of you already know, one of the disappointing features found in fullsize SUVs (Suburban, Tahoe, Yukon, etc) is often a single top tether in the 3rd row... usually to be shared by the drivers and center seat leaving the passenger side without top tether. Why the car manufactors do this to the SUV they market to large families, I have no idea.

My wife and I, both being adamently against giving into the minivan, recently traded in our Subaru Tribeca on the much larger '09 Chevy Suburban (captains chairs) with the notion of maximum comfort in the SUV platform. We have 3 kids, ages 2,2,5 all in FF carseats. We had been riding the 2yr olds in the 3rd row and the 5 yr old in the middle row as 3-wide did not work well in the Tribeca and had planned on keeping this configuration in the Suburban getting the more spacious captians chairs leading to the easier to access 3rd row. But then discovered the 1 top tether in the 3rd row limitation found in this class of vehicle.

So I went back to consult my car seat manuals. The younger two ride in Recaro ProRides (FF) while the older in Recaro ProSport (5pt harnessed configuration). If I read correctly, the manfactor states only when used with a locking belt is the top tether optional (for LATCH and non-locking, its required). And wouldn't it happen, while the Suburban uses locking shoulder belts in the 2nd row, the 3rd uses a locking plate style belt meaning top tethering is a must.

Background:
Let me preface this with I am by no means an expert in the field nor hold any safety certifications. I do have a fairly extensive automotive hobbiest background and have spent considerable time modifying vehicles in pursuit of my hobby. I have skills in metal work, fabrication, and have built safety systems such as roll cages and 5-pt harnesses for adults previously. I'm not advocating anything in this post, just simply sharing a personal experience... anymore more you take from this is at your own perial.

Now, I've seen the posts warning against sharing anchors as well as those that say using cargo anchors is a death sentence... I've also seen posts pointing people to the E-Z-On mounts as viable alternatives, though this has always sat uncomfortable with me. Though I don't dispute their hardware is rated sufficiently, there is so much variability and vagueness in the mounting location, I fail to see how an E-Z-On bolt/washer sandwiched between some sheet metal is generally any better (though no doubt when attached to a structural location of the vehicle, this product completely lives up to the task)

Solution:
I had a couple of Britax Connector/D-ring straps left over from when we RF'd the girls. We used these to girth hitch around structural members of the 1st row seats and provide a top tether point when they were rear facing since most US cars do not have tether anchors behind the 1st row. I first sat out to find something similar for the Suburban's 3rd row seat that I could lash this to, but alas there was none easily accessed out of the lower rear of the seat.

Then I looked to the structural cleats the removable rear seat attached to. However, realestate was tight and there wasn't sufficent room to girth hitch the bulky webbing to and not intefer with the seat latching. Then what I noticed was the cleat the seat attached to was removable with two substainal bolts. So what decided on, was removing the cleat and passing the eye of the webbing through it before bolting it back down. This would give a lower profile than the girth hitch. Furthurmore, I used some tape to fold over the eyelet of the webbing in half and give an even more minimal profile. Now the wedding could be slid to the side and not interfer whatsoever with the seat latching.

What I'm left with is a tether mount for the passenger side seat that is in almost identical alignment with the factory one on the drivers seat. I've used components all properly rated for safety and the attachment point isn't dependent on sheet metal, but rather a structural element of the car (what holds the seat in place).

.
.
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So at this point, flame suit on, I'll open it up for comments/critisms. Acceptable solution to providing an additional top tether point to the 3rd row of a Suburban/Tahoe/Yukon or not? Just looking for personal opinions, not a binding certification. Good idea or not? Better to have this configuration than locking-plate style lapbelt only? or unsafe enough you'd change the vehicle or carseat to avoid not needing have multiple top tethers in the 3rd row?


Thanks,
 

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monstah

New member
My first observation is that you used a component designed and tested merely for rebound control. Very different than what happens to a forward facing car seat. It probably hasn't been tested this way. (If it has, it either failed so that's why it isn't suggested or it passed but Britax is keeping it's lips sealed. Who knows.)

Unfortunately, the school bus will be here any minute so I have to stop here but at least you get a bump from me.
 

nannykates

New member
I guess I would just put a child in each captains chair and one 3rd row to use the factory anchors or, better yet, rearface the twins and eliminate the necessity of 3 anchors.
 

Pixelated

Moderator - CPST Instructor
A D-ring, as you've used, is not rated to withstand the forces that will be applied to it in a crash. I couldn't say if it would rip apart immediately and then you'd have your tether anchor flying around your vehicle as a wicked projectile, or if it might have some benefit. I just don't know but it is not approved for use how you've done it.

Given that you do have three factory installed and tested tether anchor points I would absolutely use those. Inconvenient? Possibly. But safe. Even safer would be to rear face the younger kids. Alternately, how close is your oldest to using a booster (and therefore eliminating the need for one tether anchor)?
 

canadiangie

New member
Hi and welcome,

You aren't the first person to rig up d-ring connector straps thinking that if its good enough for rear facing its good enough for forward facing.

Unfortunately, d-rings are meant to work towards the end of the crash sequence, when crash forces are coming down -- not at the beginning of the crash sequence (ie: forward facing) when crash forces are at their highest. Who knows what could happen. Also, maybe GM knows something about the structural integrity of the 3rd row making one tether anchor the max that can be there. Again, who knows.

You have enough factory installed tether anchors to transport your kids safely. Just use them. Really.


Also, there are SUV's that can accomodate 3 seats across the 2nd row, and/or offer more than one tether anchor in the 3rd row.

Two tether anchors in the 3rd with optional 2nd row captains chair = new body style Durango.

Total of six tether anchors (and four sets of LATCH) with wide 2nd row suitable for just about any 3 across = Pilot.


I have three kids and rock a Pilot because six tether anchors makes me swoon. :D



Eta: your 3rd row belts do lock. They lock at the latchplate, and also lock at the shoulder upon impact. We don't have Recaro up here and so I can't comment on what the Recaro manual says, but wanted to mention that your 3rd row belts would be considered a locking belt, generally speaking. All that to say top tethering is very important, and I support your efforts to top tether, but not in the way you're doing so now (ie: rigged up with D-rings).
 

Hodadical

New member
My first observation is that you used a component designed and tested merely for rebound control. Very different than what happens to a forward facing car seat.

I understand what you are saying, it is certainly "intended" or "marketed" by Britax to use with RF installations, but not "designed" or "test" for this application... i'm not so sure. the strap is sewn with a label stating it comforms to CMVSS/FMVSS 213 & 302 standards. If I understand these standards enough, they state minimal breaking strengths for all webbing attachement components, regardless of installation configuration. Now I haven't read the testing procedures outlined enough to know if the testing would be preformed in any or all scenerios in order to meet compliance or not.

I do agree with you the forces are certainly different with the rebound control in RF vs the more direct load in FF, though. But I'm not sure that precludes this component from being within those tolerances.

better yet, rearface the twins and eliminate the necessity of 3 anchors.

agreed this would be better and eliminate the need (for now). but at some point, they will out grow the weigh limits for RF leading me back to this same problem.

A D-ring, as you've used, is not rated to withstand the forces that will be applied to it in a crash.

Are you sure? While tensile strength is not published, the component says it conforms to CMVSS/FMVSS 213 which state "The webbing of belts provided with a child restraint system and used to attach the system to the vehicle or to restrain the child within the system shall— (a) Have a minimum breaking strength for new webbing of not less than 15,000 N"

Alternately, how close is your oldest to using a booster (and therefore eliminating the need for one tether anchor)?

She's not ready yet. Though its seems uneasy moving one out of 5-pt harness early only because of necessitary for a tether anchor for the other.

Hi and welcome,
You aren't the first person to rig up d-ring connector straps thinking that if its good enough for rear facing its good enough for forward facing.

Well, I hope you see I'm trying to approach this from an factual/epherical point of view, not simply just a gut feeling "its good enough".

Unfortunately, d-rings are meant to work towards the end of the crash sequence, when crash forces are coming down -- not at the beginning of the crash sequence (ie: forward facing) when crash forces are at their highest. Who knows what could happen.

See my notes above. are you saying the strap doesn't meet the 15,000N outlined in CMVSS/FMVSS 213? or are you saying a FF crash will generate in excess of 15,000N while RF would not?

I understand the arguement of not being tested in this configuration and the concern that arises from that (if i could afford to do my own crash testing definitely find out, I would), but I don't see the arguement where the strap is grossly above its working limits in FF configuration while not so in RF. I totally acknowledge the force will be greater in FF, but if its still within working limits, whats the problem?

Also, maybe GM knows something about the structural integrity of the 3rd row making one tether anchor the max that can be there. Again, who knows.

possible? sure. but I highly doubt this is an engineering problem/limitation of the 3rd row itsself given it is designed to hold two full size adults in a frontal crash... and i'm sure there is some sort of testing involved in making sure its capable of doing that.

Eta: your 3rd row belts do lock. They lock at the latchplate, and also lock at the shoulder upon impact. We don't have Recaro up here and so I can't comment on what the Recaro manual says, but wanted to mention that your 3rd row belts would be considered a locking belt, generally speaking.

Thats good to know. I'll do some more reading. But if my seats are capable (according to the manf) of sustaining themselves in FF with just the lap/shoulder belt, that means only a very small portion of the forces would be transfered through to my top tether... and even in event of my top tether failing (minus flying shrapnel), the seat should perform just as it would without my addition.


Respectfully,
-R
 

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canadiangie

New member
None of us know. I don't, pp's don't, and you don't.

That's the problem with hypothesizing about these sorts of things, it still gets you no where, really.

The purpose of a tether strap is to reduce head excursion. Reducing head excursion means the child is less likely to strike the seat in front of them, or a side pillar, or whatever else is around them. The purpose of a d-ring strap is to slow or reduce rebound, but that's about it. Maybe it would also work to reduce head excursion, but I'm certainly not willing to bet my kid's adorable brain on it.

I have seen the Transport Canada research crash testing (google it, but get popcorn ready) and its down right astonishing to see how car seats behave under crash force in real vehicles. It's even more fascinating to see how much movement there is for the crash dummies. It's a humbling bit of footage, and it plays in my mind from time to time, especially when I see misuse. I'm rather convinced that people far underestimate the power of crash force.

Anyway, none of us can stop you from rigging your seat with a d-ring, but I'm guessing none of us are going to advocate that you do, and especially not when you have 3 factory installed and approved tether anchors.


Giving this more thought, what is the advantage of having your bigs in the 3rd row? I know GM prohibits the 2nd row captains chairs from being folded flat while driving, and prohibits the chairs from being tumbled forward while driving. Are you tumbling at your destination? Have you considered putting one child in the 3rd row in the middle? Shouldn't be too hard to access her. I worked in a 2013 Escalade a few weeks back and it's fairly roomy to get to the 3rd row between the captains chairs...
 

Keeanh

Well-known member
The very back cargo hooks of the Suburban used to be structural and could be used as tether anchors in earlier models. I can't say for certain if that applies to a model as late as 2009. I think you should start by finding out if those back anchors can still be used as tether anchors.
 

Hodadical

New member
Anyway, none of us can stop you from rigging your seat with a d-ring, but I'm guessing none of us are going to advocate that you do, and especially not when you have 3 factory installed and approved tether anchors.
Understood. I was hoping to have a discussion about "if you were going to" modify/add a top tether anchor, the safest, most logical, and thought out method for doing so and try to leave my circumstances out of it. As someone that's experienced working on cars, I don't subscribe to the notion there there is no safe way to go about this.

Giving this more thought, what is the advantage of having your bigs in the 3rd row?
Ability to access them in the 3rd row to buckle them in. Since none of my children are buckling themselves, they all require my assistance. If two carseats where in the 2nd row captains chairs rendering the unable to tumble, as a larger stature male that drives my kids to school everyday, I cannot fit between the back of the 1st row and upright 2nd row (remember, captains chairs don't slide front and back). getting in is the problem, once in, fitting between the captains chairs to access the 3rd row is no problem.

I know GM prohibits the 2nd row captains chairs from being folded flat while driving, and prohibits the chairs from being tumbled forward while driving. Are you tumbling at your destination?
Yes, but I had actually never heard of this restriction... especially folded flat, that makes no sense. I'll consult my owners manual in closer detail.
 

canadiangie

New member
Understood. I was hoping to have a discussion about "if you were going to" modify/add a top tether anchor, the safest, most logical, and thought out method for doing so and try to leave my circumstances out of it. As someone that's experienced working on cars, I don't subscribe to the notion there there is no safe way to go about this.


Ability to access them in the 3rd row to buckle them in. Since none of my children are buckling themselves, they all require my assistance. If two carseats where in the 2nd row captains chairs rendering the unable to tumble, as a larger stature male that drives my kids to school everyday, I cannot fit between the back of the 1st row and upright 2nd row (remember, captains chairs don't slide front and back). getting in is the problem, once in, fitting between the captains chairs to access the 3rd row is no problem.


Yes, but I had actually never heard of this restriction... especially folded flat, that makes no sense. I'll consult my owners manual in closer detail.

It's in your owners manual. The seats don't lock down when folded flat. Free to fly around in a rollover collision, etc. Must be returned to upright and locked into place before driving.


Right now you have a strap added to the very anchor that keeps the bench in place on that side. Lets pretend I think the d-ring will hold on impact (ie: not unstitch or otherwise break). Lets pretend it stays put and transfers crash force onto the anchor it is wrapped around. Are you 100% confident that that anchor will still be able to hold the bench in place when it is taking a *direct hit* of force from the d-ring? What if the d-ring actually holds and the crash force deforms the anchor just enough that the bench becomes unlatched on that side? What if the webbing of the d-ring interferes with the latch just enough to detach the bench? Too many what if's for this girl.

I can't get on board with a convo that centres around rigging up an 09 with three perfectly good tether anchors. I keep coming back to WHY is this even being discussed. Three kids, three tether anchors... that's pretty much your answer. :)
 
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canadiangie

New member
Serial posting... :eek:

A solution for the issue of fitting between the 2nd captains chair and front passenger seat is to move the front seat significantly forward and adjusted bolt upright. This creates more space than most people realize (it's tantamount to 'tumbling' your front seat out of the way) and should allow you to get back to the 3rd row with seats installed in both captains chairs.

I've been driving a full size SUV since 03 and I always keep my front passenger seat moved quite far forward (not so far forward that it obstructs my view or anything) M-F when it's just me driving. On weekends when we're all going out I wait until everyone is loaded up before adjusting the front seat back. Upon arrival it takes about ten seconds to slide the seat forward to give my girls more room to get out. They always load and exit from the passenger side.

Just a thought..
 

MommyShannon

New member
I agree with moving the front seat forward. It makes a HUGE difference in my van. I am not familiar with your vehicle. How deep is the trunk area? For max safety and the ability to buckle everyone, I'd try rf the 2 year olds in the 3rd row. I have my 11 month old in our van's 3rd row. I am 5'3" and can just kneel on the bumper and I can reach to buckle her in. I'm a little confused that you are so concerned with top tethers when the benefit is dwarfed by the loss of safety by ff. yes, eventually you would have 3 ff again, but rf until the idea age of 4 would pretty much guarantee your older child would be in a booster and you might even have a different vehicle. Alternately, you could just put 1 rf 3rd row, 1 rf 2nd row, and 1 ff 3rd row and tumble the 2nd row seat to climb in like you are now. Just put the ff in whichever position is allowed for the tether.
 

katymyers

Active member
I agree with moving the front seat forward. It makes a HUGE difference in my van. I am not familiar with your vehicle. How deep is the trunk area? For max safety and the ability to buckle everyone, I'd try rf the 2 year olds in the 3rd row. I have my 11 month old in our van's 3rd row. I am 5'3" and can just kneel on the bumper and I can reach to buckle her in. I'm a little confused that you are so concerned with top tethers when the benefit is dwarfed by the loss of safety by ff. yes, eventually you would have 3 ff again, but rf until the idea age of 4 would pretty much guarantee your older child would be in a booster and you might even have a different vehicle. Alternately, you could just put 1 rf 3rd row, 1 rf 2nd row, and 1 ff 3rd row and tumble the 2nd row seat to climb in like you are now. Just put the ff in whichever position is allowed for the tether.

I agree. With your oldest being 5 just rear face the toddlers for another year (or even two!) and at that point put the oldest in a booster. At that age most kids can buckle themselves with the seatbelt and you can put the younger two in the middle row. There are so many easy options to solve your problem, whether or not the tethers will fail is irrelevant you are doing something that hasn't been tested by your car manufacturer, your car seat manufacturer, or by the manufacturer of the d rings, that's using your children as crash test dummies and its irresponsible given all the other safe and test proven options.
 

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