37-38 front seat belts

[SteveR]

Has anyone installed front seatbelts on a 1937/38 4-door Plymouth, Dodge, Desoto, Chrysler? My concern is the mounting bolts location.

[greg g]

Do not attach to frame, attach to floor sheet metal.  JULIANOS STREET ROD PARTS sells under floor mounting hardware that spreads the load to provide better attaxcment bolt and washers.  Go to their website and look at lap belt mounting hardware. If your floor is in bad shape you need to address repairing it and attach to new meta lhe theory here is you want to stay with the body rather than having the body passing you by while you are tethered to the frame.

[SteveR]

I just had a look under the seat for mounting. There isn't much space there. What angle do seatbelts need to be at? Here is under my seat. Front is to the right.

[Plymouthy Adams]

depends on the seat belt retractors if so equipped....if just lap belts....contact points should angle to the belt line of the passenger when seated....

[Sniper]

4 hours ago, greg g said:

JULIANOS STREET ROD PARTS sells under floor mounting hardware

 

Just about anyone that sells seat belts also has this hardware.  Sometimes it is included.

 

Napa, for example, includes that hardware.

 

https://www.napaonline.com/en/p/BK_7303042

[DJ194950]

Julianos has some install videos on their website showing mounting of 2 point and 3 point mounting of belts in older cars.

 

Worth checking out .

 

DJ

[SteveR]

I understand about the anchorage of the seatbelts. The question is the pathway of the Belt. In looking at the seat frame it looks like I have to go straight up with the belt instead of it being at an angle as per what I have seen on normal belt placement

 

I noticed in Julianos the mounting is 'Behind' the seat. That seems impossible as my seat frame is in the way.

Edited April 14, 2025 by SteveR

[greg g]

If I remember the first car I had wih factory lap belts was a 1964 Fairlane.  The right hand of the driverswas anchored to the passenger side of the driveshaft tunnel and  the other was  bolted to the inner rocker panel.  The buckel reciever was on the pass side the male end was the adjustable end. In use it went around the seat frame of the seat where it hiinged for back seat acess.the drivers side receiver  crossed under the passenger belt in an X pattern. The male end just layed there when not in ue. The outer belts  were where the length adjuster was. So if you were the only driver, the length adjustment was set it and forget it.  Most folks left them loosely fitted.   If you were going to do some spirited driving you might cinch the a bit tighter.  Hope I splaind it sosyu can unnerstanit.

[Plymouthy Adams]

I believe the man is experiencing the all metal frame of the seat and how would one route the belt passing through a possible made man cut in the seat pan and STILL be very much able to adjust the seat with the belts passing through and not worry about chaffing or other damage to the belt and still be totally safe and comfortable install.  There are ways and suggest you walk through a wrecking yard for a good donor inside anchor that is not fabric for to retrofit...

[Dan Hiebert]

I think I am grasping your dilemma.  The front seat of our '37 Terraplane is similar to your car, there is that lower rear part of the frame that is pretty much in the way of mounting them to the floor behind the seat.  But - that is where they should go, just route the belts over the top of the frame and between the bottom and rear cushion.  I don't know about the Plymouth, but our Terraplane's seat frame is open there, although the upholstery covers it at the rear.  I would route them under the upholstery, over the frame and between cushions.  Ensure they are mounted where you can still adjust the seat for different drivers.  May need to put something over the frame to ease chaffing.  The angle may seem off, and it may not look aesthetically pleasing, but the purpose of the seat belts is to keep your heinie in the seat, not look pretty.      

[SteveR]

1 hour ago, Dan Hiebert said:

, just route the belts over the top of the frame and between the bottom and rear cushion.  I don't know about the Plymouth, but our Terraplane's seat frame is open there

There is the problem. Mine is NOT open. I understand going over the bottom seat. It is the frame that is in the way. I thought of cutting 4 slots large enough to get the anchor through and then try to line that slot with plastic or something to stop any fraying that might happen.

[Los_Control]

I'm guessing this is the seat frame you are talking about? .... Mine is for a truck and it is modified ... but kinda the same idea?

 

I know the cars had the same platform that was welded to the floor and the actual seats bolted to them. .... so same idea.

 

I thought about bolting seat belts to this frame ... on the back side and bring them up through the seat cushion and back rest.

Some might think that these frames are not strong enough for a seat belt and need to go to the floor pan. ... I'm guessing with the same reinforcement used here, as you would with the floor pan ... would be fine. ..... And easier to attach seat belts to.

Standard installation does use the floor .... but they do not have a frame welded to the floor ... or the standard installation might be to the frame.

 

Just throwing in my opinion .... I planned to attach seat belts to my frame .... I cut the welds off to remove it, really is nice when you need to lay on the floor and work under the dash.

Then I drilled it for 12 grade 5, 3/8" bolts with wide washers to bolt it back in instead of welding it ... keep it removable.

 

I also modified it to use modern Chevrolet bucket seats ... I do not like the condition of the older seats I have .... if I buy newer seats, shoulder belts are built into the seats.

So just bolt the seats in and belts come with it and again, depending on the frame below to be strong enough for the seat belts.

 

I figure if we get hit by a driver going high speed .... might be better off with no seat belt and getting thrown clear of the accident.

Edited April 14, 2025 by Los_Control

[SteveR]

1 hour ago, Los_Control said:

I'm guessing this is the seat frame you are talking about?

Mine is bolted to the floor as seen in the photo above. Interesting bolting the belts to this frame. I'll have to look into it. My concern would be the strength of the frame withstanding a crash. Will it rip out or buckle? The other thought is your face is not that far from the windshield and seatbelts might lessen the impact, but if they rip out your still going to go splat.

[Los_Control]

2 minutes ago, SteveR said:

if they rip out your still going to go splat.

If they hold you perfectly still in place, the steering column will turn you into a shish kabob ... whats the lesser of two evils?

 

These cars had no thought for safety when they were built ... why I suggested earlier, maybe no seat belt .... doors fly open and you get thrown clear .... who knows.

 

My thought is, if you look at a more modern vehicle like a 1980 Toyota that has seat belts bolted to the floor ... our metal on the frame is heavier gauge then their floor metal.

Then they always reinforce the area with more metal. ... the kits they sell include large 3" washers for this purpose .... when bolted tight, the bolt would have to rip through both metal surfaces ...  that would require so much force, that you would have already splatted anyways.

 

I figure if I was driving 45 mph and had a blow out and ended up out of control and ran into a light pole .... The seat frame will hold just fine and the belt will really help me keep control of the vehicle and save from more serious injury.

 

If it is a more serious accident, a drunk driver T-bones you at 75 mph .... or they cross the line and hit you head on .... I'm not sure the seat belt would hold up or if it would even help in our old cars ....

 

I only have a opinion and not offering advice .... just my opinion .... I have been hit at high speed from a drunk driver before.

At normal speeds, mounting the belts to the seat frame will hold up and be a huge help.

 

If it is a serious accident ... our cars from the 30's-50's are just not built or designed to withstand this kind of damage.

Does not matter how well you mount your lap belt.

 

 

In this situation, a passenger would have died ... I was alone.

The impact and force of being hit this hard, the lap belt broke the pelvic bone and the shoulder belt broke the collar bone and several ribs while causing internal bleeding.

The bonus is you get knocked out instantly and do not remember a thing.

 

A lap belt is a tool that is designed to do just so much .... it will work fine as long as the seat frame holds up. Or are what our vehicles are capable of handling.

When the situation arises that you need a bigger tool ... air bags, collapsible steering column, designed crunch zones .... our cars have none of that.

[Eneto-55]

I don't know if you are expecting to have rear seat passengers, but the normal angle of the lap belts (if fastened to the floor) will end up somewhere in the middle of the the rear passenger's foot well. I have a 4-door P15, and my plan is to reinforce the stock seat frame and replace the slider mechanism with one out of a late model vehicle, like a minivan.  My opinion is that the more modern seat frames are stouter than what is stock for our old cars, because that adjuster mechanism was not designed to hold the weight of the occupants in place - only to keep the seat itself in place. The metal where the notches are cut in is not nearly as thick as that used in a MoPar minivan, even the seat rails that are only intended for use on a bucket seat - ONE occupant. 

 

As has been mentioned, there is an additional danger in old vehicles - the steering shaft. But I think this that danger would be greatly reduced if the seat belt mechanism stops forward movement of the occupants' torso as close to instantly as possible upon impact.  Modern technology also involves a slight release after the initial body movement is 'arrested'. Sometimes this is through the use of a short section with the belt being stitched back in a sort of loop, with thread that is intended to tear loose on that initial point when the forward movement of the upper torso is stopped. This lessens the strain on the body. Another system has some sort of mechanical release that lets out a bit more belt from the retractor.

 

In researching this, I encountered safety research dealing with being hit from behind, which produces an entirely different set of dangers. But at least the 4-doors vehicle seats that do not tilt avoid the case where the seat back breaks loose, and shoots the front occupant through the rear glass, or crashing into the face of the occupant seated behind them. Children are often killed in rear collisions when the front seat occupant's head crashes right into their face.

 

In the end, we can only do so much to protect ourselves and our passengers, but I would not be discouraged and just dismiss the entire seat belt adaptation project.

[SteveR]

Thanks Los Eneto. My thought was not how do I survive a 50+mph collision. I won't. I have that steering wheel and windshield only feet from my chest & face. I have only had one instance in the last 7 years we have owned Miss Daisy where some idiot cut in front of me and then turned right across traffic. I had to apply the brakes hard. It made my wife come out of her seat a bit. At least a seatbelt would have secured her a bit better. That is my goal. I drive my car like I did my motorcycle cautiously with plenty of space in front. It is no guarantee but, it helps. Now how am I going to mount this thing?

[Eneto-55]

3 hours ago, SteveR said:

Thanks Lots Eneto. My thought was not how do I survive a 50+mph collision. I won't. I have that steering wheel and windshield only feet from my chest & face. I have only had one instance in the last 7 years we have owned Miss Daisy where some idiot cut in front of me and then turned right across traffic. I had to apply the brakes hard. It made my wife come out of her seat a bit. At least a seatbelt would have secured her a bit better. That is my goal. I drive my car like I did my motorcycle cautiously with plenty of space in front. It is no guarantee but, it helps. Now how am I going to mount this thing?

Our local police often sit in a small parking area across from the building space I rent (for my business), and so one day I walked over and asked him from his observation, how often a rear collision results in a seat back failure (where it breaks off and the front seat occupants end up in the rear seat, or through the rear glass.  As I recall, he said pretty much always, in any wreck where a vehicle hits the other one at a speed of 45 or greater.  (And I think the speeds listed in the research articles I've read were lower than what he said.) Obviously it makes a huge difference if the vehicle that is struck from behind is moving at all, even at the slightest low speed, or completely stopped. But from what I read, and also from what he told me, in lower speed accidents, rear collisions tend to more often result in serious injury than frontal impact, which has received much more attention in safety testing.

 

I wrote up something here some months ago about the research articles I had read, but I have difficulty doing a productive search on forums in general. (I should keep links to stuff like that, but haven't been good about that.)

 

I was involved in an accident in a VW Kombi years ago, where I was not wearing the seat belt, and was thrown clear up out of the seat, and hit my head on the frame above the windshield.  This was in town, in Brazil, where the highest speed limit in the entire city is 60 KPH (around 36 MPH), and that was on a small street, where the speed limit was 40 KPH. I was crossing an intersection, and had slowed down because I didn't see any stop sign anywhere. (Some miscreant had chopped it down - the posts are wooden there.) So I was likely not even going 15 MPH, and the car I hit was a Fiat.

[Plymouthy Adams]

FIAT  fully integrated artillery transport...surely this was the driver's thinking maybe.

Edited April 15, 2025 by Plymouthy Adams

[Adam H P15 D30]

8 hours ago, SteveR said:

Thanks Los Eneto. My thought was not how do I survive a 50+mph collision. I won't. I have that steering wheel and windshield only feet from my chest & face. I have only had one instance in the last 7 years we have owned Miss Daisy where some idiot cut in front of me and then turned right across traffic. I had to apply the brakes hard. It made my wife come out of her seat a bit. At least a seatbelt would have secured her a bit better. That is my goal. I drive my car like I did my motorcycle cautiously with plenty of space in front. It is no guarantee but, it helps. Now how am I going to mount this thing?

I attached mine to the floor in the back and the seat frame in the front.  The advantage is I can move my seat without interference from the seat belts.  As Steve said above, the seat belts are there to hold you in place during a sudden stop or maneuver.  If you wreck hard enough where the frame gives way, you're dead anyway.  That's also why I don't have shoulder harnesses

[Plymouthy Adams]

lot of negative talk here but for sure, the older cars unlike the new designs do not have crumple zones built it to sacrifice the frame and outer structure of the car to save the occupant.  However that being said, if you are installing belts common sense applies....if at all possible, do incorporate 3 point belts and make good use of the shoulder strap.  These are not that hard to install in the older car if you buy the right model belts....I have no aftermarket brand that I would recommend here.   I also do not care for the most commonly referred to brand cheap washers.  I also suggest you take a good in depth assessment of your older cars metal before any install.  I use donor set ups for my  cars and have never had to crash test them, but I feel more than comfortable they will do the task if called upon.  At least at one time the design was tested.  You have never seen the NHTSB issue a statement saying at x year change a belt.  Some calls are made after an accident however and a rebuild of the car.  IF you do go to the donor belts, just be careful the vehicle you glean them from were never exposed to the elements while in-op with broken glass or missing doors allowing the elements in, again, common sense.   

Edited April 15, 2025 by Plymouthy Adams

[Adam H P15 D30]

Nothing negative, just realistic...  The steel dash is close and does not collapse, the steering shaft is a harpoon, you're going to hit them with either a 2 or 3 point seat belt.  A choice we all make when we drive these things.

But, life is too short to drive boring cars.

[Plymouthy Adams]

well....my 48 Plymouth has an active air bag......three point belts and front crumple zones.....but that is just what I wanted with the build....

[Dan Hiebert]

I wouldn't want to cut into the seat frame.  In that case I would just attach the belts to the seat frame.  As I and others mentioned, keeping your and your passenger's rear end in the seat is the primary goal.  The secondary impact(s) if you come out of the seat is just as bad, if not worse, than the initial impact.  When I was a kid, I was riding center seat in our Dad's car, bench seat, there was no center belt, my brother was on the passenger side with his belt on.  (This was "way back when" - no such thing as child safety seats or seat belt laws.)  We were stopped at a red light and got rear ended, in town so it was low speed, but I still bounced off the dashboard of the car like a pinball.  Got a really nice shiner (first one!) out of it.  My belted in brother barely spilled his milkshake.  

Edited April 18, 2025 by Dan Hiebert