Introduction: DIY LATCH System Retrofit

Picture of DIY LATCH System Retrofit

Cars made after 2002 have a LATCH (Lower Anchors and Tethers for CHildren) system in place from the factory, but there aren't any kits available to retrofit older cars. My car, a 1960 Ford Fairlane 500, didn't even come with seat belts, so I decided to custom fabricate a LATCH system of my own to enable the safe transport of my daughter while avoiding the expense and hassle of getting seatbelts put in.

Step 1: Buy Hardware

Picture of Buy Hardware

2 x 1/2" thick, x 6" eye bolt w/nut zinc plated
2 x 1/2" nuts zinc plated
2 x Carabiners (locking ones are probably overkill, but get good quality ones that latch into a hook system when closed)
4 x 1/2" lock washers zinc plated
4 x 1/2" cut washers zinc plated

(image shows disassembled parts on left and assembled version on right. The washers will go on either side of the sheetmetal of the car.

Step 2: Make the Holes

Picture of Make the Holes

Remove the lower seat cushion and check the floorpan for mounting locations. The bolts need to be accessible from between the upper and lower seat cushions. My floopan had a handy design stamped into it, marking a good spot to place the bolts, roughly 1/3 away from each other and the sides of the car.

With the upper seat cushion still in place, position the eyebolts so that they are flush against the bottom of the cushion and mark the area that the base touches.

Once the positions are marked, use a punch or drill to make a pair of holes about 1/2" in diameter. While this shouldn't be a problem in most cars, you should check to make sure there are no fuel lines, brake lines, or electrical wires located on the other side of the sheetmetal where you intend to place the hole.

Step 3: Secure the Bolts

Picture of Secure the Bolts

Begin by placing the nut, lock washer and cut washer onto the eyebolt, and then place it into the hole. Using the nut, adjust the depth of the eyebolt so that it sits behind the upper cushion. You don't want to be able to see it without pushing on the cushion and you don't want it sticking out at all.

Once you have the depth set, climb under the car to place the remaining nuts and washers onto the opposite end of the eyebolt. Be sure to put the cut washer on first, followed by the lock washer and finally the nut.

Step 4: Modifying Car Seat LATCH Belt

Picture of Modifying Car Seat LATCH Belt

Because the 1/2" eyebolt is significantly thicker than the bars used in factory LATCH systems, the existing latch connectors will not work. Simply slide a carabiner through the loop in the belt. Be sure to only use climbing or safety grade 'biners. I find that this step is a big improvement to the original system, and is more robust in addition to being easier to deal with.

Step 5: Install the Car Seat.

Picture of Install the Car Seat.

The final step is to install the car seat by hooking the LATCH system into your new retrofitted attachment points.


jjackson64 (author)2016-06-18

I know this topic is like forever old, but I am just finding it.

My professional experience (30 years) is in the auto industry. All of the people who are questioning the strength of this set up have never held the thin little manufacturer installed loop of wire metal car seat latch point in their hand.

The factory stuff is so thin (remember he had to add a carabiner because the original hook wouldn't open far enough to latch) that if you took the two bolts out of the factory piece you can bend the hooks with your bare hands.

I have used the same two eye hooks he used on my motorcycle trailer and they did not bend with a 600lb motorcycle pulling a side load during a impact.

The washers used are plenty big enough.

I think consumers believe the car makers use high grade titanium and carbon fiber to mount car seat latches in their vehicles. The reality is, they are doing their best to make it thin and light as possible to save weight and money. The factory hooks can probably hold double the weight needed.

The set up he has here would hold 10x what he would need. Those old cars used REAL METAL when they were made, he wouldn't have any issues.

Nice Job sir!

torklugnutz (author)2016-01-15

Here are the two alternatives you have with an antique car that didn't come with any seat belts.: bolting in aftermarket seat belts or making a latch point for the car seat. The keychain carabiners pictured were placeholders so I could photograph the project. They were replaced with load rated carabiners for actual use.
In the final analysis, antique cars are inherently dangerous, lacking even modest passenger safety consideration in their design. This addition enables these cars to transport car seat passengers with equal safety as the seat belted passengers. Which is to say, marginal at best. From the greater perspective of impact designed and tested autos.

JulieC56 (author)torklugnutz2016-01-15

I have a third alternative, don't transport the child in this vehicle. Children have no say in these situations and it's our jobs as adults to make sure they are safe.
Above all else (even though safety is #1), this is illegal. Possibly even child endangerment.

It was not tested by either car seat companies or the car company, therefore will void any warranty on the car seat.

torklugnutz (author)2016-01-15

I have never seen a seatbelt welded to a car frame. Replacement car seat lap belts are bolted through the chassis, with a big washer on the back side. The keychain carabiners in the photos are placeholders and listed as such. They were replaced with rated equipment.

The safety concerns surrounding antique motoring are myriad. Was eventually involved in a t-bone accident in this car. These old cars simply crumple up like cans on impact.

cyrusz (author)2012-07-19

This is really great, I love how they sit down below the seat, can passengers in the rear feel them much when sitting on them? I found this looking for latches for my 2001 ford. I do overhead hoisting and rigging and I have several of those eyes in my tool box at work i will grab, the best part is even the True Value ones are graded so they are approved for a load such as this.

So many of you are just so blindly negative, you dont seem to realize the load characteristics of this situation the system is as strong as the waskist link, a 300# test eyelet x2, but the 1" webbing on the child's seat is only about 125# also keep in mind that in a collision not only will the lets say 50# object not apply 100% force on those connections but the job of the webbing is to deform and absorb the pressure before it even gets to the eyelets. So lets say under speed that 50# becomes 500# (which is double the load of the belts the kid is in already) but the belts dont take 500# they stretch and slow the load.

We can go in to some deep physics here but the point is with auto manufacturers is most of this is a "good enough" approach, do you think they really run load from each angle on each bolt in the car, they just bump it up a grade and good enough, these bolts if anything will be the only thing that hold up in an accident.

This is still better than my original solution, So according to all of the folks who think the OEM components are infallible, I say in the 60's no belts means they designed the car to be safe without them right???

jclements6 (author)2012-04-18

I think a lot of people are forgetting that even if you installed seat belts into a classic car, your options for mounting the seat belts are about the same as what was shown here: Drill through sheet metal and hope for the best. Having said that, I would agree with some of the concern that this isn't as safe as possible. Were it up to me, I would make three considerable modifications to this system.

First, I would install a mounting plate to the underside of the vehicle. This is the same thing that they did on old cars for seats (and later on, seat belts). Get a super heavy gauge piece of steel, and weld it to the spot you're going to anchor the bolts. The piece should be as large as will fit, so that the force of an impact is distributed over a lot of space.

Second, I would use larger washers made of heavier duty steel. The Home Depot specials in this instructable just seem far too small to do any real good in the event of a catastrophic crash.

Lastly, I would use high grade steel eyelets with the eye welded together. This would ensure that the eyelets aren't unbent and release the car seat.

(I would also be sure that my carabiner is the heavy duty climbing grade. The one used in the photos looks more like the keychain grade ones I have lying around the house.)

Now, given those changes, I would be more than comfortable with having this system in my own 1960 vehicle. Why? Because first, it's as safe as you can get in that kind of car. Even seatbelts would have to be a custom install like that. Also, if there's a wreck big enough to dismount that system and mom and dad were in the car, that kid's an orphan anyways. The cars of that era were tanks. Sheet metal was several times thicker than what you might have on your 2012 Kia. There are no crumple zones or collapsing steering columns. My point is that in an accident, if you're hitting a newer car, they're going to take the brunt of the impact as your sturdy heavy steel on a boilerplate thick frame vehicle plows through their tissue thin steel and plastic unibody car. Any accident resulting in enough force applied to dislodge this system had at least one fatality associated with it. I'd just about guarantee it.

Over all though, this is a decent idea. With a little reworking, it could provide something that would at least allow the use of this car. I'm not saying that I'd drive the kids everywhere, every day in it, but it's a classic car. They get driven on Sunny Sundays and in parades.

An interesting video of just the type of thing you mention in your post: a collision of a 1959 Chevy Bel Air into a 2009 Chevy Malibu. The Bel Air takes a bigger beating than I would have ever guessed:

mackamitsu (author)2008-06-29

torklugnutz, Brilliant, all the materials you used are more then adequate. The only thing I can think of to reinforce the base would be to use 10G plates approx 4"x4" between the body steel and the fender washers. This will give you better spread of force on impact if you were ever in an accident. It will also distribute the load shift much better and put less stress on the body steel. Don't forget to check the biners for wear every couple of weeks, so they are always in good repair. You could put some teflon spacers in to minimize the contact points. Thats my 2 cents.

abudanger (author)mackamitsu2011-10-26

thinking of adding some latch points to the cargo area of my wagon. this is good info. def want to be safe, also want to be legal. thanks for the pointers.

mackamitsu (author)mackamitsu2008-06-29

before I forget, truck supply stores have better anchor eyebolts that would be the only thing I'd do different.

Darrin McNeice (author)2011-05-27

I did something similar to this on our Volvo 9 years ago. It came out a year or two before the latch system and I liked the idea of easy access. I used something like this - 1/2" Quick Link Chain Repair Link (see to attach a short lenght of chain, about 3 or 4 links, just enough to come out of the seat. I attached the repair link to the two inside seatbelt attachment points and then secured the seat to the chain. Once you ratchet the seat down, it did not move. I liked having my son in the center of the car, too.

derek244 (author)2010-05-12

I commend the author of this subject for doing this. Many of you are under the impression that car makers use some type of special metal in their brackets that withstand a million pounds of force. Others bash the author for putting his childs life in danger. Interesting. Do you all have your children riding in the absolute safest car? Are your car seats made out of some type of industructable material? Do you really think the amount of force required to completely sever the eyebolts will not have an effect on the other components in the car seat? I have made my own latch and tether brackets for my daughters Recaro child seat out of 1/4 inch steel and used the factory mounting points and grade 8 bolts in my 1970 Buick. There is no aftermarket kit available for us classic car owners, so we must use our common sense to make the trip safer for our loved ones. The forces required to cause thick metal brackets and high strength hardware to fail would mean the actual accident is extremely severe and not survivable regardless of safety equipment used. I drive a 2009 Honda Civic and have inspected the LATCH system on this car. It is much thinner and less substantial than this authors design. Now, I would reinforce the bolt mounting point a little more, but do you really know what it would require to rip the bolts, nuts, and washers completely through the floor?
The amount of technology in todays cars (crumple zones, SRS's, belt pretensioners, ABS systems, VSC systems, etc.) cannot be replicated and are much more of an issue in survivablity in a crash than this set-up will ever be. Loose and improperly installed car seats by parents far out weighs this type of modification. In 20 years we will wonder how we ever transported our loved ones in todays unsafe high tech cars and equipment.

Stickytack (author)derek2442011-02-03

It's not a matter of the car seat failing or the hardware used to mount it failing. It's a matter of whether or not the points where the anchors are installed are fully reinforced metal, that will prevent the washer from deforming the metal and pulling right through the drilled hole.

I would recommend more than just heavy duty washers. A 3" square of 1/8" thickness steel plate welded to the underside of the bodywork would be at least adequate to distribute the forces and prevent deformation of the anchor point holes in the event of a collision.

(I'd consider it to be over-engineered, but my child's safety is worth over-engineering.)

swissarmychainsaw (author)2009-07-01

I like this project, I even thought of doing myself. But I have some concerns. I get the feeling that "" is single! LOL Is this Mom approved?

Here are my concerns:
1. Latch systems are tested. Is this? Any part of it?
2. Look at those "eye bolts" notice how it is essentially a piece of metal bent to a circle. On impact would they bend out and release the car seat? How about at least getting them welded shut. Tie a cider block to it and drop it off a parking garage. Where does it fail?
3. They make "body washers" for the bolts of the seat belt. They are huge washers meant to distribute force so the bolts won't rip out of the body of the car.
4. It's just hard for me to take this seriously when you say something like this: "safe transport of my daughter while avoiding the expense and hassle of getting seatbelts put in." Seatbelts might be more expensive than your lag bolts, but they go in *just as easy* as the work you put in for this.
5. Did you consider actually buying a *real* latch anchor and putting that in? At least that way you get a tested product, some some hardware store mish-mash.
Sorry to sound harsh, as I said I thought about doing this myself. My wife, rightly, thought I was a moron. It's our kid we are talking about here.

Ok OK that said I take my dog on my motorcycle. See, I *am* am moron, don't listen to me.

1. No. The products all have a certain load rating on their packaging, but I didn't do any math or computer modeling to figure out the failure points.
2. The eye bolts are quite thick, and while they aren't welded, I think the amount of force to distort them would probably turn a human baby into jello.
3. Washers are a good point. I think mine are good enough and that's what they had on the shelf at Home Depot. Bigger wouldn't hurt.
4. Hassle = damaging the period accuracy of the car interior. Expense is about $25 per seat plus installation. There are no such things as accurate rear belts for my car. They simply did not exist.
5. I did look at getting a factory LATCH kit, but the dealers don't sell them. The best I got was the top latch anchor point retrofit kit, which isn't useful.

PS. yes, it's mom approved, though she's not an engineer either.

Bottom line, it's an antique car and this is the best way to put a car seat in it. Aftermarket seat belt kits would bolt in in virtually the same way and be ugly.

Splaxx (author)torklugnutz2010-03-17

Its not so much the child becoming jello as much as the child being the force that will make the eye bolts jello. Your talking the child's weight multiplying by powers depending on the impact.  example: a child at 10lbs would require 300lbs of force to restrain the child at 30 mph. So how heavy is your child and how sure are you about the strength of the eye bolt.

classtopher (author)Splaxx2010-11-22

You need to know more than the speed of the car and weight of a child to measure the force. You need to know the deceleration and what distance the deceleration it is over OR you need to know the number of Gs. Looks like you are assuming 30Gs which is probably about right for most accidents but they certainly get worse that 30Gs.

Splaxx (author)classtopher2010-11-22

Yes, but I am generalizing a point. The other thing one should note is that the bolts are in the sheet metal not the frame. Another factor for fail. Sorry, neat Idea but not worth the risk of my or anyones progeny.

classtopher (author)2010-11-22

This is clearly a controversial topic and the standard disclaimer which applies to many instructables should apply here "dont try this at home". However, human progress has been due to people who "try things". I am not an expert in the physics of automobile crashes, but I do have a decent physics background. I think this is a very interesting instructable and thought I would take a swag at some of the basic physics involved. The previous disclaimer should apply to this analysis too. Aside from the question whether not to try such a thing, the controversy seems to surround the strength of the eyebolts and other hardware and if they would be strong enough to hold up in an accident. Many people have given their thoughts but not too many calculations in the comments, just gut feelings.

The human body can only withstand amount of G's (which are multiples of the acceleration due to gravity on Earth which is 9.81m/s2). The accident that killed Princess Dianna subjected her chest to 70Gs (according to PBS). Her car was going 80mph and essentially slammed into a concrete wall. Anything above 30 Gs is a VERY serious accident. Assume a head on collision in which the passengers are subjected to 50Gs. 50Gs (490m/s2) would be a passenger strapped into a car going 50mph hitting a concrete wall and the car and the car going from 50mph to 0 mph over approximately 3 feet (3.2 feet = one meter). That assumes the front of the car would crush 3 feet which is less true for older cars that do not collapse and absorb as much energy as newer cars) on impact. It also assumes the deceleration is constant over the 3 feet of deceleration. If a 40lb (18kg) human was strapped to a carseat and was subjected to 50Gs the resulting force on the human is 8899 Newtons (F=MA). Fasteners are rated according to mass (lbs) not force, however, to compute the force it is assumed that the "A" (acceleration) in "F=MA" is 9.81m/s2. So if a fastener is rated at 1000 lbs (453.6kg) the equivalent force would be 4449 Newtons. Assuming the force is distributed equally between the two anchor points, each anchor could be subjected to 4449 Newtons and combined 8899 Newtons and therefore the 50Gs. So one might decide to go with fasteners rated to 2000lbs for 100% margin. This is just a swag at the kind of calculations that one can make in convincing themselves that they should or should not do something like this. Or perhaps might influence your choice of fasteners. You should consider the same physics in deciding how the fasteners could be anchored to the car itself.

In full disclosure, I did something similar to my car. My child weighs 20lbs and all of the fasteners have 100% margin at 70Gs and I ran the normal lapbelt through the carseat too just to be safe.

As others have said, operating a vehicle alongside other vehicles is inherently dangerous and we take risks in most things we do. Slow down and drive defensively.

twistedsense (author)2010-08-03

This looks like a great idea and it retains the original look of the car. People don't understand what it's like to own a classic car like that. They just think you care more for the car than your daughter. But I know you wouldn't have bothered figuring out how to install her seat if that were true. I don't know why people are upset. Looking at what you've done and looking up the shear strength on the parts you've used I'd say you have more than covered your daughter's safety. From what I see the car seat or the car seats belts would fail before your eye bolts and carabiners would. Kudos to you and boo to the naysayers.

iamflashman (author)2010-06-11

First of all, nice article. I would just suggest that instead of regular eye bolts, you can purchase fully closed eye bolts at a tractor supply or fastenal. They support in excess of 1000 lbs depending on the size. They also are shouldered so they bolt directly to the floor and do not allow for the torque effect that you would have just bolting regular eye bolts down. Secondly, I have been reading the comments and find it amazing how all of these self professed experts have no idea what they are talking about. They talk about seat belt anchors like they are some magical thing that automobile manufacturers invented. I recently ordered a seat belt kit and the hardware provided for the anchors (and these are for an adult mind you) were grade 5 bolt 7/16" bolts. The anchor was merely a 3" grade 8 fender washer on the bottom of the floor pan. These kits meet all federal regulations and are no where near as strong as a good grade 8 closed eye bolt with a proper washer on the back side. I can promise you, none of the people commenting against your idea of ever worked on or installed any type of seat belts or bothered to do any research for themselves. Race car drivers count on the eye bolts I descrive above to save their life in a 100+ mph crash. These are full grown adults travelling at speeds you should never go with a child in the car!

hammer9876 (author)2010-03-28

Just curious. Is this still "Mom approved" after she reads the comments here?

I suppose this is better than no car seat - or seat belt - at all, but there are good carabiners used by climbers who bet their lives on the things and there are cheap carabines sold at big box stores which are to be used on nothing heavier than keys. 

Amir (author)2010-03-26

I feel the need to come to the author's defense after some of the comments I've read voicing concerns over the latest safety requirements issued by the Ministry of Truth.

I'm  not an engineer. But I do have some recent experience with 1/2 eye bolts.

I don't believe that any survivable vehicular crash could exert enough force to cause those bolts to fail, regardless of whether or not they're intended for such an application.

Yerboogieman (author)2009-08-30

I remember our comet didn't have seatbelts. That thing was great. We were the second owners when the people traded it in the early 1990's. My dad was driving it and was at a stop sign and this old woman gets out of her car and tells my dad she had bought that car brand new with her husband.

joker402 (author)2008-09-05

My truck is grandfathered in with regards to having the kids in a booster (since in the back i only have lap belts). Might be a similar situation. FYI, this type of thing is often done in ORV's so kids can ride in them.

torklugnutz (author)2008-07-22

Rear facing vs. forward facing: Moot point. The carseat is forward facing. There is no other way to install it. The old infant seat was rear facing. In any case, it is outside the scope of this instructable to debate the merits of carseat design. I did install 2 sets of seatbelts in the front as originally available as options from Ford. They cost, I think, about $20. Installation was identical to this latch system and involved punching holes in the chassis to mount them to. Mounting to the car's frame would not be possible, because the frame does not cross at any point that would be practical to mount to, and punching holes into the frame would be quite difficult. To install the carseat, I used the included LATCH belt included with the seat. The infant seat, when I used it, I had in the front passenger seat, but because of the lack of shade and the inconvenience of blocking passenger access on that side of the car. A major hassle with a two door car.

torklugnutz (author)2008-07-22

How are seatbelts fastened to a car's chassis? They are fastened with bolts. It is the same basic thing as I have done here.

ajmcc (author)2008-05-06

Congratulations - having a latch connector is much safer than just using the lap belt system. I wish my older honda had that option. One question. Did you give any thought to using larger fender washers to back up the nuts? I am not so worried about the force during a collision. But the fatigue of the metal around the washers due to all the flexing of the long eyebolts. Thats alot of torque that could be translated through a small washer in to soft steel. PS - the upholestery in the car looks great and congrats looking out so well for your kids.

parkersmom120106 (author)ajmcc2008-07-22

Number 1, the latch is NOT safer than the seatbelt and it has a 40-48lb limit in most cars, the seatbelt does not. The latch was not designed to be safer than the seatbelt, it was designed to be easier to use (which IMO it is not). Not to mention that this rig up is not a latch system.

drsteevo (author)2008-06-29

This seems like a really bad idea, please reconsider your engineering. A washer and bolt through sheet metal seems to be your weakest point and it may not be as strong as you need -- why take a chance with your daughters life? How much trouble could it be to fabricate a backing bar? And why not use a locking carabiner?

bluemeow (author)2008-06-01

O-M-G... I don't even know what to say to this. Your daughter will be in my prayers. :-(

torklugnutz (author)bluemeow2008-06-01

Right, cause prayers work better than bolts? Hahaha. Give me a break. If you don't know what to say, why did you bother to leave a comment? You're an odd one.

Mommy_Jasmine (author)2008-05-31

How do you find this safe?? It is going against ALL of the seats instructions. I am sorry, but I do not think that there is any way I would EVER "rig" something to hold my childs car seat into my car. Also keep in mind that said car seat is supposed to keep your child safe, not just keep them from jumping around the car! Also IF you did in fact do your research you would also know that your 16 month old is MUCH safer RF! I would deffinatly do some more research. Please reconsider this & put your childs life first over your ever so precious car. What your car looks like with lap belts lying around should not matter. I would much rather my child be safe then to worry about lap belts lying around! say this is perfectly safe...right. small suggestion. Call or write to the Manufactorer of your seat & ask them. I can bet you they will tell you the same thing we are all telling you. Also make sure to describe in detail & send pictures. If they say it is safe then ok, but they will NOT tell you that. Please stop being so dumb & put your childs life over your cars beauty!

Retrofit seatbelts mount in the exact same manner as my "LATCH System". They come with a pair of bolts and washers that get installed into a punched out hole in the sheet metal. The only main difference is that I'm using a seat belt that comes attached to the car seat rather than one that is permanently attached to the chassis. When I say "rig" I mean "fabricate," not "put together with duct tape and coat hangers. If you don't like this project, don't do it. If you think it needs bigger washers, welded cross members or any of the other suggestions that will make it safer, knock yourself out. That's one of the great things about this hive mind we call the internet; one good idea often leads to another.

But here is the thing, this is NOT a good idea! You are putting your childs LIFE at RISK! Do you not care or understand that you could KILL your child with this rigged LATCH set up? It blows my mind how you do not see this. I am telling you to call the maker of the seat & ask them what they think! You say that they are the same thing as the lap belts are, but they are NOT. The lap belt kits have been tested. They are rated to hold a car seat or an adult. The equipment you used to "rig" your anchors are NOT rated for this use. They are meant to do other things, not keep a child alive in a moving vehicle. Also AT least if you are going to keep this crazy system at least consider turning your 16 month old BACK RF. She is NOT safe either way, but she would at least maybe be a little better off if she were RF! Just do the research about it. It will show I am right.

Every day 118 or so people in America die in car accidents. By putting my daughter in the car, I'm risking her life. Statistically, riding in the car is the most dangerous thing that any of us do on a day to day basis. Rear facing car seat? That ended at 18 lbs, didn't it? She outgrew the infant seat some time ago. This seat does not have a rear facing installation option. The manufacturer probably wouldn't comment on my installation. They're already in a tenuous position of liability for selling car seats in the first place. What are they going to tell me over the phone? It's not like they're going to send out an engineer to inspect my install. What's the financial reason for them to do this? As I've said before, the way I have this set up uses the lap-belt included with the LATCH system on the car seat. What we're talking about is the anchor system, which apart from the carabiners is quite similar to what came with the retrofits I installed previously. This argument is academic and pointless. You have your opinion, I have mine. The end.

RF ending at 18 lbs...MAN are you WAY behind. My son is 20 months old & 25lbs AND he still rides RF, so no it does NOT end with the infant bucket OR at 18lbs. As a matter of fact the LAW is 1 year AND 20lbs.
However the AAP reccomends RF to the max limits of a converitble seat (RF & FF seat) which is usually 30-35lbs depending on the seat! Here are a couple of links about Extended RF!
Here is also a link to an album of older children RF!

As for what the manufactor can say over the phone is that it is NOT safe as it has not been tested. They are not likely to send someone to check your install, no, but they are likely to understand from the install that it is against their instructions & not tested. I just really can not see how you feel this is safe for your child. How can you think that a few bolts screwed into your vehicle frame with a few other bolts & washers, then to NOT use the correct LATCH hooks that came WITH the seat & use a climbing carribener to attach it to the "rigged" hooks is safe. Sorry I do not understand your logic. I just hope that your child does not get killed for your stupidity!

capeKO71 (author)2008-05-31

As a carseat tech, I ASK YOU PLEASE DON"T DO THIS!!!! This is dangerous beyond what you know. I understand you are trying to keep your kiddo safe - but in reality, you are using YOUR CHILD AS THE TEST DUMMY!!!! Carseats have recalls all the time, due to continual testing... you have no idea what this would do in a side impact, forward, or roll over scenario. DO you understand that in a 30mph cras, your child who weighs 30lbs will be the equivelant of 900lbs???? Are you really going to bet your childs life that your "do it yourself latch" will hold that carseat in? Please people... don't do this... in fact... flag this person to get this removed.

torklugnutz (author)capeKO712008-05-31

As a classic car tech, I assure you that this installation is at least as good as the accepted method for installing aftermarket seatbelts, but without the mess or fuss of lap belts cluttering up the back seat. If you don't like it, don't do it.

MD_Willington (author)2008-04-17

Hmm.. FYI not a street application...but we pretty much do the same thing for our demolition derby cars, we hold down 2 deep cycle 12V AG batteries in our cars pretty much the same way and they don't go flying, we also do the same for our fuel "cells" and they stay put... And we are in a continuous traffic accident for up to half an hour!

PS118 (author)2008-04-14

I think a lot of people are giving your idea an unfairly bad rap. In their defense, I guess it's understandable. You don't want some yard-monkey strapping his kid in with duct tape and string. On the other hand, listen up people, Detroit isn't into Voodoo! The same laws of physics and engineering design apply just as well in your own garage as in theirs. There's no reason a careful, well thought out, home design can't be just as strong (or stronger) than an assembly line one. It sounds like you've done your homework as to load ratings, etc, and even used aftermarket seatbelt kits as a model. That's good engineering. I had to retrofit my classic (fat-fendered Ford) with seatbelt kit, and the only two things I see different here are: 1) Your washer size may be too small. 2) They recommended punching the holes instead of drilling so the metal won't tear under stress. ("recommended" not "required") That aside, the only real criticism I could even make is that actual seatbelts would be more versitile (for example, taking friends for a ride, or when your kid grows out of that seat) and could be easily tucked in for showing. But that's a personal thing I guess.

Exocet (author)PS1182008-04-14

Of course Detroit, and other auto makers arent into voodoo. But there is a HUGE difference between this, and something that comes standard in new cars. Let me spell it out for everyone. T E S T I N G This is a child's life we are talking about. Not something to EVER even think about something silly like this.

PS118 (author)Exocet2008-04-14

Maybe that's what I'm having trouble seeing. All components have been load tested and mfg specs well exceed the demands. The method of installation has also been DOT tested and is the recommended way of installing aftrmarket seat belts (capable of restraining an adult, so again, well exceeding needs). The only testing that has not been performed is an overall integration test (crash test), which is totally unreasonable to expect with a 1960 Fairlane. It meets specs. Though for some I don't know if empirical soundness in the world will ever outweigh emotional response of "risking my child's life" with something you, yourself built.

willofgod (author)2008-04-14

The people giving this instructable bad comments are clearly not engineers. The bolts and 'biners are clearly WAY overkill for this application. The onlt questionable point of failure is the hole through the floorpan. I would suggest a bar on the underside that spanned across two mounting points for each eyebolt.

gog (author)2008-04-14

Great idea torklugnutz. I've thought about installing a seatbelt or two for the rear seat of my 1965 Scout a couple times, Currently friends do not want to ride in it due to the lack of belts and the height of the seat sticking out of the bed. Only mod I'd think of possibly doing is installing a plate between the two bolts on the underside of the car to tie them together, I could see it helping to strengthen the attachment so all the force doesnt end up on one side. I do have a lap belt for each of the front seats and they look factory.

Exocet (author)2008-04-14

I wouldn't trust my daughters life with this. And quite frankly, it shocks me that you or anyone else would. Flagging for a horrible, dangerous, and quite possibly life threatening idea.

jc817 (author)2008-04-13

I think its genius. Throw in a problem, some common sense, and a little hardware. I'd like someone here to actually figure out at what point those eye bolts would "deform" though. Preferably someone not ignorant enough to have said "Carabiners aren't designed to withstand thousands of pounds of force." I'd rather trust my safety to a bolt through the frame of a car, than a retrofit kit made in china anyway.

Kromtara (author)2008-04-13

Nice idea, but come on. In theory some things that should work, don't and vice versa. You don't know IF this is safe until you put it through some serious testing. If car manufacturers were confident a retro-fit system would be just as safe as a factory installed one - they'd offer it. And make money by over-charging for it too. You may as well have your daughter wear the attached outfit.

snowbird25ca (author)2008-04-12

Thanks, that's really interesting to know about the strength of this type carabiner. So you are probably right about the eyebolt being most likely to be the point of failure. For comparison, the entire LATCH system is tested at a minimum 15kN, the LATCH system is comprised of both the lower anchors and the top tether anchor. - which is yet another problem with this setup...

torklugnutz (author)2008-04-12

I'm curious about the roadside check comment too. They don't do those where I'm from, but I would have to imagine that I'd cruise right through due to the age of my car. This instructable isn't for people with cars made after 1965, or whenever lap belts became standard and it would be a lot of hassle for someone with a newer car to go to for a minor convenience. Doing an instructable on installing seat belts would be more or less the same as this, but with lower mounting holes and the ease of using hardware included in the seatbelt kit. I appreciate what you're saying and I think you're coming from the right place, but I also think you're looking at it as someone who owns a newer car and you might be overthinking things a bit.

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