Stupid Question, putting seatbelts in a '56 T-bird

Hey guys, as the tittle states I got a dumb question for ya. I'm a tech at a Ford dealer and just had a customer drop off a '56 T-bird for us to install clip-in seatbelts in(you install two eye bolts in the floor and clip the belt to them). He also dropped off the belts and hardware but no instructions.

The install looks pretty straight forward, but I've never installed belts that haven't had factory anchor points to tie into, and these parts being such a major safty device I figured I'd beter ask. So I guess I'm looking for pointers, ideas and suggestions from you guys that have done this before.

Thanks, Justin...

 

I can't believe that a Ford Dealer would actually take this in! WOW

Make Sure you use some large (3-4") washers under the floor

 

X2 I'd actually go overkill on a plate underneath- you DONT want the liability of them pulling through and having to explain why there was a meat missle flying down I-70 after the crash.

-rick

 

Cool, just to make sure were on the same page you can anchor them to the floor pan? Without reinforcement? Just want to make sure they don't have to be tied into the frame.

Edit: 69Fury, what kinda plate? I got some 4''x3/16 strip I can use, probably weld it in?

And yes we do take this kinda stuff in, got some oldtimers here who worked on this stuff when it was almost new, and if they don't take the boss knows he can stick me with it

 

bump

 

my 2 cents
dont do it liability is too great for your dealership

 

I'll try and remember to look at my 56 T Bird tonight and see how they are mounted.

Still can't get over a Dealership working on old cars - never happen here!

 

you don't want to tie them to the frame the reason behind it is in case severe accident the body could separate from the frame I relay doubt that this could ever happen but the guy who does the interiors on our cars has instructed us to make the seat belts part of the body substructure. I know race cars the belt system is tied to the frame work for the most part but usually the seat is too. most seal belt kits come with a reinforcement plate that is at least 3x4". if you are doing a complete build its nice to make hat channel or something else to help distribute the load.

Just my two cents not worth much. Don't you just love it when people drop off half the parts and partial instructions and ask you to fix it. usually there is a reason they didn't complete the project they started.

 

I used info from this link-

http://www.wescoperformance.com/3-po...r-mt-door.html

Lots of info on the sight, but hard to find.

http://www.wescoperformance.com/seat-belt-install-3-point-retract.html

 

Thanks for the input guys, gonna wait tell tomarrow morning to get started on this job so keep the info coming...

Ha! Ain't that the truth!

 

If I am not mistaken, 56 was the first year for factory anchor points in Fords. Ford was selling safety that year,

 

My 56 does not have factory anchor points. It does have seat belts that have been there for many years and they are backed up by 3" round washers. They use an Eye bolt and then clip to it. According to a couple of T Bird restorer's I checked with this was a factory option and this is the way they were mounted.

 

yeah, i've seen the washers thing but i'm not a fan- maybe it's fine but a fender washer sized piece of metal doesn't get it for me. If there's room i'd use a 4x4" plate of the same thickness of the floorpan (or next gauge thicker). Perimeter weld, dont burn the carpet.

If i'm especially nervous about plate attachments, i'll drill for plug welds. halfway between the plate corners and center of load (eyebolt in this instance)

May not be needed, but i like the idea of the load pulling on the bolt, and the plug welds preloading the perimeter weld, like pulling your buddy's truck out of the mud with a snatch strap instead of a cable or chain...

And yes you dont want to attach to the frame for that exact reason-if the body tears free in a bad accident, you want to roll with/in the body, not be strained through it as it leaves....

-rick

 

Thanks guys, so here's the plan (maybe a little overkill). Gonna mark my belt mounting locations, pull back the carpet, strip paint and undercoat from a 6x6 square around each mounting point, weld in some 4x4x.125(already have metal) mild steel plates(perimeter weld for now). Drill mounting holes, and use some rustolium for the topside and have our undercoat guy touch up the bottom. Install belts, carpet and seat and send em down the road.

Next question, any do's or don't as far as belt anchor location? Thanks..

 

Could you elaborate on this just a bit... Not sure I understand the 'plug welds' and how it preloads the setup.

Thanks

 

I think seat belts were standard (or at least an option) in the '57 bird. You might check one out.

Charlie Stephens

 

My '55 has them. They are just drilled into the pan with big ol' hefty washers.
Thankfully I haven't had to test their stength.

 

The plug weld is pretty simple for a square plate you'd have a perimeter weld, a center hole for the eyebolt then four extra holes drilled in the reinforcing plate BEFORE welding it to the car. drill all five holes before mounting then weld the perimeter and four outer holes to the floor pan.

the plate will have 5 holes drilled in an X pattern-center for eyebolt- the other 4 halfway between the eyebolt and the plate corners. but you will only drill the eyebolt hole in the car itself

If the plate's on top of the floor and the eye bolt pulls real hard (wreck) then the top plate can be stretched up and away from the floorpan, maybe tearing free, but the plug welds help hold the two layers together and allow everything to "take up the slack" of the force with some stretch instead of SHOCK. (re:earlier reference to snatch strap and mudhole).

If you mount the plate on the BOTTOM of the floor pan then the 4 plug welds probably aren't needed cuz you probably wont pull the plate through the floor.

i'm no expert, that's just how i do it.


-rick

 

There sure is a lot of overkill in this thread. Ford offered seatbelts in '56 as an option. They were installed using a large diameter washeron the bottom side of the floorpan and another on the top forming a sandwich. They are only designed to hold you in place during a crash so the only concern is the shear strength and the washer setup is more than adequate.

 

I was a Tech Inspector for the SCCA for a number of years. It was totally legal to install belts using the large, thick washer under the floor board mounting procedure.
As an engineer explained it to meat the time round is much better then square as a square plate as the floor deforms under the sudden shock can more easily induce a tear through the metal than a round one will. He also stated that welding to the bottom of the floor doesn't really add any strength as the force vector is trying to pull through the floor so it is the additional metal that adds the strength, nothing else. Ideally a reinforcement plate that has the edges rolled away from the surface will be even better at not trying to pull through the floor.
Most brands of aftermarket racing belts supply the large round washers in the kit.

 

I did several Tbirds in the old days when they were new.
I went straight through to the frame with the eyebolts.
The frame on older cars was the basic structure and consequently the strongest part.
The idea of seat belts it to keep the person in the car at all costs.
Mounting to anything but the frame is a compromise.
I am surprised a dealership would touch that kind of job in these "sue happy" times and
then have to get on the internet to find out how to do the job...

 

Simple Stuff from apprenticeship. Duplicate the factory weld size and locations. Use support plates at least 3" X 3" under the floor. Four plug welds in to corners should do. And don't forget the Weld through primer. For added protection and corrosion protection you could also add some structural adhesive between the panels.

The Old Tinbasher

 

Ditto on that. We used to put large, heavy washers (they looked like fender washers on steroids) underneath the floorboards or chassis, depending on whether the car was unibody or not.

It is interesting for us old guys to hear that this question has been posted via the HAMB, but I hope that the responses help. (Pete, I liked your comment about today's 'sue happy' times - that aspect never figured when I was asked to put seatbelts into cars back in California some 40+ years ago... )

 

Just got done welding in the reinforcement plates. there 3x4x3/16. 4 1/2 plug welds each. welds are ground flat to allow 3" washers from kit to sit flush. maybe overkill but whatever. still gotta install the eye bolts, carpet, seat and touch up the undercoating. got a late start and of course the customer needs it back tomorrow, so i better get back to work, hopefully i can get out of here before morning rolls around... and sorry for the shitty pics, having to use a cell phone and flashlight cause most of the lights are shut off now

 

Bump for the morning crew

 

Yea like a 2x2 or 4x4" 1/8 plate. That's what I do in my old cars anyway. It gets tacked in under the floor.

 

Pete,

Totally agree about the mounting going to the frame. In my B/SM drag car which was put together with the 1979 NHRA rule book/and now certified for NHRA racing currently; the mounts are to the subframe/cage/frame for the lap and submarine belts with thick round washers in the office area.

HotRodDon,

Being an SCCA Tech Inspector up until last year, the 2009 GCR states that the grade of bolts must be at least grade 5, and that the shoulder harness, lap belt and submarine belts should be mounted to the roll structure or frame of the car..................where that is not possible, large diameter washers or equivalent should be used to spread the load, both top and bottom.

While inspecting cars for the Laguna Seca Historic races......................you could not believe what I have seen......................and the stewards let them race anyway.......
I would not sign off on the log book and made the steward do that...............

 

I would suggest you use large diameter "fender" washers. Typically, they are 2+ inches in diameter with the appropriate hole for seat belt attachments. If you want to be super safe, put a fender bolt on the inside against the floor pan, as well as a fender bolt on the exterior of the floor pan. The trick here is to really cinch the two fender washers together, making a "sandwich" of the floor pan between the two fender washers. In an impact the "g" loading can be substantial, as much as 4 or 5 "g's". So, if you have a 200 pound passenger, at the time of impact those fender washers will have a momentary load of over 1,000 pounds.

Hope this helps

 

Would suggest you also replace the seat hold down bolts with grade 8 and put good washers under the floor. On old cars it is possible to tear the seat loose in an accident and squish the passengers against the seat belt or dash board.