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I have a 1940 60 Series 4-door sedan, unfortunately I also have three year old so I need to install at least one seatbelt in the back to secure a child seat. (state laws do not exempt antiques from the child restraint requirements.) Will attaching a seat belt affect the original status of the vehicle? and does anyone have any advice on how to best attach it?

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If you look at the anchoring of current seat belts in vehicles they are attached to a fairly large backing plate that has rounded edges so if there is any pull on the plate they will not tear into the metal.

Years ago my Dad installed seat belts in a 59 Buick and drilled holes in the body and used very large (2+inch) diameter washers on both sides of the body with the installation bolts.

If I was doing it now I might use the washer solution if I might plan on removing the seat belts. If not, I would try to purchase the current threaded backing plate that is used in current vehicles. IMO, I would not attach to the frame as if the vehicle body moved in an accident the seat belt might not and the force would be on the occupant.

This is just an opinion and does not constitute the correct installation of seat belts in a vehicle not designed for them. Please do your own research and determine if you did install seat belts the best place to install them.

Edited by Larry Schramm (see edit history)
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There have been a number of very deadly accidents in collectable cars in the last few years.

I would strongly suggest adding seatbelts to any collector car that did not come with them~

What's worth more~

Your car or a loved one's life ?

Larry: from your last legal disclaimer statement paragraph it almost seems that you were given legal advise before your last seatbelt posting ? Have we all come to this here too ? ; )

Edited by Silverghost (see edit history)
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I'm not sure of the first year that Olds started installing the seat belt anchors from the factory, by my 62 F-85 wagon had the anchor points and welded nuts installed already. All I had to do was cut a small hole in the carpet, pop out the rubber plug in the threads, and bolt the belt in place. In fact, the hardest part of the task was finding the correct Grade 8 7/16" fine thread fasteners.

Many street rod vendors (GASP!!!) sell DOT certified belts and the correct under-floor reinforcement plates if your car doesn't have them. Juliano's is but one source:

Juliano's Hot Rod Parts & Interior Products - Custom Car & Street Rod Accessories

yb.dll?parta~showpic~Z5Z5Z50000029b~Z5Z5Z5BAAMI~Z5Z5Z51~Z5Z5Z5~Z5Z5Z5

Edited by joe_padavano (see edit history)
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You won't take a judging deduction for seat belts, so they'd be a worthwhile installation. Pretty sure 1940 had a metal floor so using the kit Joe has shown us should work well for you. Floor reinforcement is critical when doing this though. You cannot just drill holes and run bolts thru the floor- in a crash or even hard braking, they could possibly pull thru.

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On the specific subject, I would question if simple lap belts will meet the requirements imposed for adequately securing the required child's seat and child.

As for adding seat belts to any vintage vehicle I have very distinct memories of seeing entire car seats being ripped from the floors of vehicles in both the 1950s and 1960s, even after seat belts were offered as an option or mandated. The significance of that statement being that a seat belt even if adequately secured in an older vehicle is going to be retaining not only the passenger but will be pining the passenger in such a position as to be suffering the foot pounds of pressure generated by the seat(s) being ripped out of the floor. If an accident occurs at fifty miles per hour or more the force from the seat being ripped out could easily amount to 3,000 foot pounds and more depending upon the seat. No human body is going to fare well with 3,000 foot pounds of force. No seat belt will keep a seat from being at minimum partially ripped out of the floor of an older vehicle, momentum will see to that. Point being if you add seat belts also provide better affixing of the seats, otherwise adding the seat belts is virtually pointless and maybe even represent a hazard equally as bad as no seat belt at all.

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Brad,

Just wanted to cover myself as best given how society is today. As the posts after me state there are many variables to something that is safety related. I know there is a lot of items that go into the design and placement of seat belts to make them crash worthy and the location is so dependent on the vehicle, condition (rust etc) that what looks like a good installation might not be the best.

Also, the first year I believe for standard front seat belts was 1963.

Edited by Larry Schramm (see edit history)
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Thanks for the suggestions.

I went to the big Muscle Car and Corvette show in Chicago this weekend and was talking to a few people with old Chrysler's there. It was suggested by a few of them that I weld an extra support panel to the bottom under the floor to disperse some of the tension then use the reinforcement plates suggested by Joe.

On the really good side, the my son just had his checkup and he is 38 lbs...only two lbs to go and I don't need the car seat...He should be able to gain that by the spring. Now I do not need to secure a full child seat or even a booster. (boosters are to ensure shoulder belts aren't going to choke the kid.) He is legal with just the lap belt.

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GM prolly installed belts as standard equipment the same year for each division (maybe Cadillac, excepted). They weren't required by the Fed (front outer) until Jan '66, and my '64 GP does not have them.... but IIRC, GM installed factory mounting provisions in the floor for front belts starting in '61 or '62.

>>"I have very distinct memories of seeing entire car seats being ripped from the floors of vehicles in both the 1950s and 1960s...

If an accident occurs at fifty miles per hour or more the force from the seat being ripped out could easily amount to 3,000 foot pounds and more depending upon the seat. No human body is going to fare well with 3,000 foot pounds of force. No seat belt will keep a seat from being at minimum partially ripped out of the floor of an older vehicle, momentum will see to that."<<

Just about every accident is different due to so many factors, and while I'm not doubting your recollection, IMO your post reads that the reason why is sheer momentum. I have not encountered mass seat ejection as being typical of the period.

I can tell you this- I had a heckuva time getting the back seat out of my '59 Buick- there the method of attachment was quite formidable.

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GM prolly installed belts as standard equipment the same year for each division (maybe Cadillac, excepted). They weren't required by the Fed (front outer) until Jan '66, and my '64 GP does not have them.... but IIRC, GM installed factory mounting provisions in the floor for front belts starting in '61 or '62.

>>"I have very distinct memories of seeing entire car seats being ripped from the floors of vehicles in both the 1950s and 1960s...

If an accident occurs at fifty miles per hour or more the force from the seat being ripped out could easily amount to 3,000 foot pounds and more depending upon the seat. No human body is going to fare well with 3,000 foot pounds of force. No seat belt will keep a seat from being at minimum partially ripped out of the floor of an older vehicle, momentum will see to that."<<

Just about every accident is different due to so many factors, and while I'm not doubting your recollection, IMO your post reads that the reason why is sheer momentum. I have not encountered mass seat ejection as being typical of the period.

I can tell you this- I had a heckuva time getting the back seat out of my '59 Buick- there the method of attachment was quite formidable.

"Ejection?" No seats were not ejected. However I can tell you for a fact from riding in ambulances during the late 1950's, and picking up the results of head on collisions no car made in that era or before had seats sufficiently secured to prevent them from being ripped right out of the floor from momentum, or in the case of rear seats, the lower seat assembly would just fly out of the retainer clips that held the front of the seat in place, making it a missile. Rear seat backs rarely broke loose. I've seen people forced up under the dash from forward momentum of seats pushing them there. Only on one occasion do I recall the person surviving. That particular accident was from a car running into a stationary object at less than 50 miles per hour. Out of five occupants in the car that was the only survivor. In those days if you rode in ambulance all required was a strong stomach. We had no medical training and no medical equipment in the ambulances, just a siren and a heavy foot hoping to get whomever we picked up to a hospital before they died. No telling how many people we might have actually killed just getting them into the ambulances because all we could do was pick them up with no back boards and put them on a gurney (no back boards existed then). If you had a serious auto accident 50+ years ago the chances of your surviving were not at all good.

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This is a very difficult subject. It's been discussed many times.

There was an automotive engineer that was quoted as saying that installing a seat belt in any car not designed for it was more dangerous than not having.

Most pre-war cars had no anchoring whatsoever for bottom seat cushions, and very little for the backrest, so one concern would be that you're held in a seat as the cushion is trying to leave.

Also, there are tremendous point forces (from an engineering standpoint) that result at the seatbelt anchoring points. Just putting a washer on each side of a thin metal floorboard will not, in all probability, withstand those forces. If you are going to install seatbelts, it needs to be to a very stout part of the car.

Now, the first thought on that is, anchor to the frame. But, again, in a bad wreck, the body in a pre-war car (held on by a few bolts to the frame) may very well distort or partially leave the frame, and now you're pinned in place by forces you don't want to think about.

All that said, I put a belt in the back seat of my Pierce, for my young son. That might give a sense of some security, but the only real security is to drive with great caution, and always assume that the other driver is going to do something wrong.............

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This is a very difficult subject. It's been discussed many times.

There was an automotive engineer that was quoted as saying that installing a seat belt in any car not designed for it was more dangerous than not having.

Most pre-war cars had no anchoring whatsoever for bottom seat cushions, and very little for the backrest, so one concern would be that you're held in a seat as the cushion is trying to leave.

Also, there are tremendous point forces (from an engineering standpoint) that result at the seatbelt anchoring points. Just putting a washer on each side of a thin metal floorboard will not, in all probability, withstand those forces. If you are going to install seatbelts, it needs to be to a very stout part of the car.

Now, the first thought on that is, anchor to the frame. But, again, in a bad wreck, the body in a pre-war car (held on by a few bolts to the frame) may very well distort or partially leave the frame, and now you're pinned in place by forces you don't want to think about.

All that said, I put a belt in the back seat of my Pierce, for my young son. That might give a sense of some security, but the only real security is to drive with great caution, and always assume that the other driver is going to do something wrong.............

Being the questioning person I am, I seriously question that the floors of most pre 1970 vehicles are sufficient to keep seat bolts from ripping out. Even cars after seat belts were mandated I would question the belts being adequately secured. No car that I'm aware of has a floor that consists of metal thicker than 14 gauge, and most probably 16 or 18 gauge steel. Not a lot of strength there, even with strengthing demples and ridges! Considering the average driver probably weighs 150-160 lbs., in a collision where a vehicle is moving at 60 mph the seat belt anchors have to be able to handle the 9,000 foot pounds of force involved without considering the fact the seat may also be a part of the equation. About the only thing seat belts may be good for is reducing the number of ejections from the vehicle, though at the risk of serious enternal injuries.

If anyone examines the way seats in even current production vehicles are attached to the floor you'll wonder what could possibly keep them from being ripped right out in a collision. Factually, many are. Just visit the nearest yard where vehicles that have been in a collision can be found. One or more of the seat to floor fasteners will likely have failed.

As mentioned the best safety device is being aware and considering all other vehicles on the road are being driven by idiots.

Jim

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I've held off posting in this thread up until now, but as an aerospace engineer specializing in structures, I feel the need to address a few issues.

First, the whole concept of the seat fasteners pulling through the floor lacks some engineering judgement. Every US-built car I've ever seen from the 1950s onward has had the seat attachment points welded to a structural reinforcing crossmember under the floorpan. The fatigue loads on these attach points from normal driving requires this and that loading (low amplitude cyclical loading over a long period of time) actually requires a stronger and stiffer mounting point than do crash loads.

Second, even if the seat mounting points DID pull through the floor (which is unlikely, see point one), the very action of ripping and distorting the metal dissipates crash energy, reducing the residual momentum of the seat.

Third, if one argues that the seat mountings will pull through the floor in a crash when there is a belted passenger restraining the seat, what will it do when there is no belt providing that restraint? The bottom line is that the loads on the seat attaching points are ALWAYS higher if no belts are used.

Fourth, when I lived in SoCal in the 1980s, I spend a lot of time in the Pick-Your-Part wrecking yard in Wilmington. I saw lots of 1950s and early 1960s cars in that yard that had been in front-end collisions. Not one had the seats ripped from the floor, however EVERY one had circular smash marks in the windshield in front of the driver and passenger. :eek:

Finally, engineering aside, as a betting man I'll take the CHANCE of the seat coming loose over the CERTAINTY of flying through the windshield any day.

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I don't often call anyone out for being absolutely wrong, but in this case Joe you are absolutely wrong! I'm not going to get into a verbal exchange about the subject because all you have to do is a google search on "automobile seat mounting failures", "automotive seat back failures", and "automotive seat belt failures." The auto industry around the world can best be described as dismally failing in mountings of seats and seat belts, right up to and including 2010 models from various manufacturers.

Jim

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Well, I can speak from personal experience here. I am not an engineer, but I have stayed at a Holiday Inn Express a time or two!

Anyway, back to the real world. Back in the 1960's I had the experience of plowing the front end of my 1960 Olds Super 88 into the driver side door of a 1958 Ford 4 door. The impact was such that the bench seat of the Ford separated from the floor, rose up, hit the passenger door handle, opened the door and expelled both the driver and the bench seat!

So, I know seats can, and do, separate from the floor.

Yes, both parties to this accident survived.

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The point on the mounting pulling through the floor pan was relating to cars ENGINEERED to have seat belts.

What was being discussed is adding seat belts to an antique (let's say pre-WW2) car, by just bolting though the floor pan. That just plain won't work.

It's very difficult to go back and re-engineer a car to be safe, when the standards at the time the car were built were not safety oriented. The simple fact is, brutal as it sounds, that you'll survive a 60mph crash in a new Mercedes9 9% of the time, but your same chances in an antique car are very small.......

Again, best defense is to drive very, very defensively. For example, assume any cross street will have someone running a stop sign. Assume the guy riding your bumper is a fool, and pull over and let him by. Assume the guy in front of you is going to slam on his brakes at any moment, and stay that much further behind him. Assume anyone coming toward you on a two way road will drift over the line, and be watching.

And so forth.....

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WOW! When I started this thread I wasn't looking to start such a heated debate, just looking for some advice on seat belts. I fully agree on the defensive driving, especially with my son in the vehicle.

Personally I feel that even seatbelts on modern vehicles are not a fail safe, I've known people that have been seriously injured because of them and would have been better off without them.

And whether seat belts work or not I still have to put something in to comply with state laws. I don't plan to have him in it often, he will probably be in my husbands Firebird on the way to and from car shows, but I do know that there will be times he will be in my olds.

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