How to firm up an old original seat?

Is there a way other than total rebuild to firm up the springs in an old seat? Bench seat in my 37 Buick is so weak I feel like I am going to end up on the floor boards when sitting on it. Anyone try adding springs from another seat or something else?

 

I have added springs from an old seat in the past. Hard to find old springs now, most new seats don't have the same kind of springs as old cars. upholstery shop might be able to fix you up with new springs

 

The coil springs are probably broken,the ties that link them together,broken.
Take out the whole seat ot bottom cushion,flip it over and have a look.If it looks like **** remove the seat material.Should be held on by hog rings that can be removed pretty easily.I have used springs from other seats or even an old bedsprings.Weld the proken pieces, tie wire springs up etc.There's layers of various materials like horse hair,that can be replaced by modern materials found at fabric shops.Do the job on saw horses to save your back.
A vehicle that's fun to drive needs a comfortable seat.

 

My interior guy puts a layer of regular jute backed carpeting on top of the springs after he finishes making the repairs to the springs, then the fabric.

 

I rolled up pieces of foam rubber and put them in side of the coils. worked great i sat up 3 inches higher!!! i used carpet pad the first time...way to firm if you had some "blocks" of foam rubber about 3 by 3 and maybe 6 inches long would work real good

 

Okay this might sound cheap ,but find a old couch cushion and cut out 3x3 squares and screw them into the springs

 

Great, I will try adding something to the coils, would like to do it without pulling the cover off yet. If I pull the cover I will try the carpet deal. Springs looked good so I think they are just worn out. Cheap is fine so I may just grab a free couch off craigs list to get some foam rubber to put between the springs.

 

If you run 1/4" round stock 3 or 4 row all the way across on top of the springs it will firm up alot I did it to my 49 Chevy seat with stock springs. Im very happy!

 

I'll tell you how I do mine:
Strip the seat down to the springs... replace any busted springs. I've found '60s Chevy trucks to be good donors for long springs and coil springs.

Chances are the spring/wire around the perimeter of your seat is broken, where you slide into the car. I left the busted one in place on the last one I did, but doubled-up on it with a section from the donor seat, using small clamps made from short lengths of thin steel, bent like clips around both layers.

But the real key to comfort is to reproduce the burlap and listing wires that sit between the spring bed and the foam. You should see these wires in your original seat--they run side-to-side, and distribute your weight over the whole spring bed. Put a mic on one and find the diameter, then call your local piano tuner and buy a spool of piano wire from him.
Cut the wire to length, accordian-fold the burlap, and push the wires through the folds. Unfold, and your wires are woven into the burlap as per original. Get some clothesline from the hardware store and hem it into the perimeter of your burlap/wire mat, then crimp the edges of the wires over the hem.
Hog ring to the top of the spring bed, and cover with foam. I like to do 2- or 3-inch thick woven batting, followed with a 1-inch layer of open-cell foam on the seat bottom only.

It's like riding on the living room couch.

-Brad

 

I did this too, spreading the weight helps alot!

 

Just one word: FOAM!

Rip the seat apart, and do all necessary repairs to the frame...listings, springs, etc.
Hog-ring on a layer of burlap, then get some brand new foam from an upholstery shop. THAT is the thing that will make the biggest difference. Get the right thickness, and cut it to fit, with either an electric bread knife, a hacksaw or Sawzall blade, and finish contouring it with a regular disc sander.
Then a piece of cotton cloth, maybe some cotton batting, then seat cover.
The modern foams are nice and firm, and will give you great support. Your old foam rubber is deteriorated, and weak, if it's even there at all. Todays urethane foams are probably better that the new foam rubber was when it was new, but after 50 years...