59 flat top front seatbelts

[390 man]

I am installing seat belts for my grandchildren. The rear belts are installed no problem. I am trying to install the front the easiest way possible. At some point this vehicle had an interior moisture problem the frames are badly rusted, and I feel would be difficult to dismantle. If I took my hand into the front seat and feel from the back with my other hand, it seems like a slit in the lower skirt of the rear of the seat, and I would be able to pass a seat belt through. Is this possible, or is there a frame or something in the way. Thanks Dave

[390 man]

In this area. I would put a few stitches at each end of the slit to keep it from ripping.

[59-in-pieces]

Dave,
I honestly don't know much about any other body style than the Eldos Biarritz.
However with speculation, I would look under the seat to find the rear of the seat frame, and fish the belt around the back of the seat cushion, and around the frame - below to the floor.
By using the seat frame it may keep the belt more square with your waist than if it went directly down to the floor in front of the seat frame - all speculation on my part.

OK, I have attached a copy of the November 1959 page from the The Cadillac Serviceman Bulletin which addresses the location of the dimples in the floor through which the anchor portion of the seat belt bolts should penetrate and be attached.

If you say the frame is iffy(can't tell if seat frame or body frame or floor panels), I would suggest backing the bolt nuts with 4"x4" steel plates.
My personal opinion for my own 59 cars is not to take a chance with 50+ year old sheet metal with the 3" diameter circular washers, that are often provided with the belt sets.  I have seen pictures where the circular washers have pulled through the floor - not good.

Have fun,
Steve B.

[390 man]

Actually the floor on this car is solid. It's a California car everything solid underneath but the inside is all crusty chrome aluminum trim etc. I am unable to reach out from underneath, there appears to be some kind of panel blocking my way to the front seat. Thanks Dave.

[390 man]

The more I got into this project I realize that the front seats need to be removed and dismantled, in order to get a good feed for the seat belt. After unbolting the seat from the car I pulled it out and removed both aluminum side panel trim pieces. I then had to remove the hog rings that are holding the lower skirt at the rear of the seat, along with several going up the side of the backrest to reveal two 5/16 flat head screws on each side, which allows removal of the backrest. I was able to make two incisions in the skirting material( not in the seat cushion itself) to pass the seatbelts through. There is a sharp edge on a frame brace, that I split a piece of hose and epoxy glued it to that brace to keep from chaffing the seatbelt. Hope this helps someone else doing this project. Thanks Dave.

[Scot Minesinger]

Those front seats and seat belt anchoring are everything in the event that they are needed.  You no doubt seen the crashes where a modern car seemingly less massive than a late 50's early 60's car crash head on at speed and the catastrophic damages suffered by the fake passengers in the older car as a result of seats ripped from their mountings and other issues.

If the seat belts hold and the seat does not - that is as bad as if the seat belts failed.

Here is a picture of how I fortified the seat anchoring for a 1970 Cadillac where the front seat is changed to a 40/60 dual comfort option.  This is 3/16" plate threaded, the bolt goes thru the seat mounting hardware above in passenger compartment, thru the floor pan, threading thru the 3/16" plate, and then a 3/8" hut threads onto the bottom of the bolt. 

Anchor the seat belts very well with plate steel that is against maybe at least some double layers of floor pan metal (size 4" x 4" minimum).  Then you also need to strengthen the seat mounting, especially in the rear of front seats.  Often the seats come with 8 mounting holes and the factory installs just four bolts - use all 8 and install a significant steel plate under floor pan to further improve the strength of the seat mounts.

[390 man]

Yes I did find that there was only 4 bolts holding the seat down. Only three were tightened. There are two groups of 4.  5/16-24 threaded inserts in my floor. There is only access to some of them from underneath. There are floor pan bracings there.

[59-in-pieces]

Dave,
I am impressed by your tenacity and ingenuity with respect to the anti-chaffing hose idea - brilliant as the "Brits" say.

Scot,
A man after my own heart as to how he approached anchoring the front seat - and I don't feel his approach is belt and suspenders or over engineering.
I too have seen the photos of a modern car - with its crumple zones - hit a 50's car (which you might think a tank of steel) - which came out the loser, to the windshield.

As I said earlier, I don't know sedans, but my Biarritz has welded threaded tube nuts/threaded holes in the frame - see pic - through the floor sheet metal for the seat bolts to go into for attachment.
Scot, I know you said your floors were solid, but any water which may have made its way to the threads of the threaded holes over the last 50+ years, could compromise-rust the threads and an accident could strip the bolts out from the floor.
Conclusion - well installed seat belts could make a huge difference.

I know, I sound like the boogieman is out there, but safety first, right along with making sure the brakes work.
Have fun,
Steve B.

[The Tassie Devil(le)]

It is good to see that you have realised that there is a need to modify the upholstery for the correct path of the inner belt webbing in these cars.

The pictures are on a '69 SDV that I rebuilt back in 2006 and although the seats had the springs modified for the webbing passage, I had the upholsterer sew a sleeve into the upholstery where the webbing went through for added protection.   I never did see the original seat upholstery, which was leather, but the replacement velour needed something.

Bruce.

[390 man]

On the floor where the seat brackets bolt down the intermost threaded inserts were covered with carpet. I used a 5/8 bolt and he did it with a torch to burn through to reveal the threaded inserts. I thought this was the original carpet but maybe not.

[390 man]

I'm posting these offer my phone using the voice scripting. I've got to start proof reading them before I post. Should read I used a torch to heat up a bolt and burn through the carpet.

[59-in-pieces]

Dave,
The rust stains around the anchor points are likely an indicator of the presents of water at some point in the past.
I would suggest to use a "Tap" on all threaded anchor points to clean up the threads.
Fortunately, you were tenacious, as I said before, and have found and can now correct that bolts were missing from the seat to floor brackets.
But even after cleaning up the threads, I would not count solely on their integrity to hold the front seat securely to the floor - seat belts may help too.
Have fun, but take care,
Steve B.

[390 man]

Yes here and rethreading dies through all the threads to clean them out they appear in good shape thanks to everyone for their responses.