The Stovebolt Site Forums The Shop Area Interiors 3 point seat belt upper mount (AD cab)

As many of you know I had a wee fender bender recently which has prompted me to finally install 3 point seat belts in the old gal.

I understand the techniques in performing such a modification.

Here's my question:
I was considering using a urethane bond to secure said threaded mount/load spreading plate to the inner skin,bearing in mind that in the case they are 'put to work' they would be stressed in a tensile loading.

It's been proven that a properly prepared and applied bond can in fact be just as strong as a similarly sized weld.

Can anyone here see any pitfalls/disadvantages in using urethane?

I once heard a body shop instructor who taught at the local
Jr. Collage talking about the two part body adhesive and he
said the same thing John. In a straight pull that may be true
but sudden acceleration can create very high G loads. Enough
that it may break the bond. For instance, jump off of a stool
36" off the ground and landing straight legged could result
in close to 100 G because of the sudden stop. During a head
on or impacting a solid object can also generate very high G
loads. Once read where that was the reason Princes Diana
didn't survive her accident, the sudden stop tore her aorta.
If it were mine, I would opt for a solid plate bolted in place.

Denny Graham
Sandwich, IL

I have seen that panel adhesive fail on body shop work. Best bet, put the plate behind the B pillar and forget about it! Seat belts are an excellent idea. Have them in my 47. Riding along without them is fine till you have that accident! That is why they call it an accident, you never know when and there is no time to put that belt on. I have seen what ejected from a vehicle does to a body. No thanks.
(Not that hard of a job)

Get someone to help you and do it right. You will be so glad you did.

http://devestechnet.com/Home/SeatBelts

I should have mentioned the 'spreader' plate will be behind the inner skin and not externally. This would leave just the drilled hole for the bolt to pass through into the nut which would in turn be welded to the load spreading plate forming a captive.

Point taken Denny,I have clarified my initial query in the post above regarding the actual securing of the mount.

Part of the problem as far as I know with Diana was she wasn't wearing a belt resulting in her impacting the seat/occupant in front.
If in fact had she been restrained the outcome may well have been survivable.

I also understand the biggest problem encountered these days in heavy impacts are deceleration injuries.
People are so well restrained and protected by all the air bags etc,whereas their internal organs aren't.
Their organs still travel forward at whatever the speed of impact is.....

Thanks for the link Deve,read and ingested!

Looks like you've concvinced yourself to put the glue tube
back in the tool box and bolt-er down solid.

Back in the 50's I remember reading in Popular Science and
seeing films on early TV of the tests they did with Rocket
sleds. Where they would accelerate the pilot to mach one in
a few seconds then stop them in about the same time with
water brakes. I don't remember the exact numbers, but I seem
to recall that the number they endured was something like
50 G's during the tests. And the test pilots walked away
unscathed.
Had they run the sled into a concrete wall, they would have
been scraping brains off the wall. Point is, it doesn't take
a whole lot of time to soften the deceleration, only a matter
of a few seconds. Body parts and mechanical systems hold
together much better when they are pulled rather than being
subject to an abrupt stop or jerk.
They give ya a day off to heal those ribs, did they????
DG

If there is any passage way, up thru or sideways, into the desired threaded plate location, just weld it to a small rod or tape to a stick. Locate it, with this device, to be centered in the drilled clearance hole. Place the upper shoulder bracket in place and start the bolt into the threaded plate. If the plate is a rectangle or triangle it will rotate and stop when it hits the side of pillar/frame and then you can completely tighten the bolt. Rip loose the taped on stick or abandon the welded rod. It also may be possible to hang the plate with string from above. Some installation instructions say cut a slot in pillar to slide plate into. Remember to consider that on old trucks, the seats are not designed for crash. So mounting to a seat bolt is possibly not advisable. But also consider, if belt mounted to floor, that the seat may come loose and the seat belt may stay bolted to floor and cause injury when you and the heavy seat move forward. It's good to read up on seat belt installation guides, recommendations and theories.

I don't think there is anyone who would rely on bonding in pull-out mode but to hold a plate in place until bolting is no problem. But letting it rotate to contact pillar is what you want. In a crash, if it breaks bond and rotates, that would NOT affect holding. The rivet or bond is to hold so as to tighten bolt during initial assy. It's mush easier and less holes to fish it in and grab with bolt and let it rotate to stop. Round off the corners a bit on plate so it does not dig into pillar. You want a "wedgie" effect.

Pictures of a flexible piece of metal shim/banding that worked for me. The banding off of a stack of plywood would be a good option to use.

Brad

Cletis has a good write up way back when on a 3 pt for a 56.. might be some tips
here

Thanks for the input gents,I think you've convinced me to get the plates welded in,better safe than sorry eh?


No deal on the time off Denny,i'm self employed.
Mercifully for my ribs it's been fairly quiet,not so good for the bank balance though!

I've seen the footage of the sleds,did Chuck Yeager not ride the rocket?
I seem to remember temporary blindness and or detached retinas were part of the deal too....
Not bad all things considered.

Modern day F1 drivers pull some impressive figures too,Kimi Raikkonen pulled 47G in a crash at the British GP a while back and thanks to the technology available now and no doubt lessons learned from those early pioneers is still alive.

I also seem to remember Richard Petty was temporarily blind after that crash at Daytona, that many rolls at those speeds can rattle things

And it doesn't take 47g's to do it. I once hit an outside
snap-roll in my Pitts at 150 IAS that had a max entry speed
of 110 IAS. What would have been a 4g max maneuver pulled my
hands and feet off the controls, about tore my head off and
pegged the g-meter. The high g load put my lights out
momentarily and all I saw when I came around were little
curlicue's floating in my field of vision for several seconds
and I was in a 65% power vertical dive. It was the first time
I'd tried that maneuver and luckily I had about 6000 feet of
air below me and the wings were still attached. High g loads
can really rattle your cage, especially when they go in the
opposite direction that your body is used to being pulled on
such as a crash or ....an outside snap-roll.
Denny Graham
Sandwich, IL

Denny,
That is a scary story, can't imagine it !