VCCA Home Forums TECHNICAL - GENERAL Upholstery - Interiors & Glass Beefing up a seat

People were not my size in 1938. The seat in my 38 business coupe isn't broken but I sit very low. Even though I'm 6'4" tall I'm also north of 300 lbs.. I'm looking for ideas on how to bolster the seat. The upholstery is in great condition. How do I make the seat springs able to support 300+? I contacted one upholsterer in Wichita and he apparently has no clue as to the seat construction in a stock 38 seat. All he would talk about is putting more foam in the seat. Adding more cushioning would do nothing to stiffen the springs. Ideas?

Hi Tiny!

I agree with your thinking that ultimately the load is carried by the coil springs. The real question then becomes how many or how stiff are they.

When I rebuilt the seat in my "37 we replaced most of the cotton batting with a layer of 1" very high density (stiff) foam. It made a real difference in how far i sank into the seat. The stiffer foam spread the load out over a larger number of springs.

I wonder if one of these approaches might improve your situation. Use a much stiffer covering over the top of the springs. Instated of the burlap use a really stiff canvas or vinyl covering, maybe even multiple layers. I would even consider a layer of corrugated box board. Or maybe a piece of really thin vinyl sheet flooring.

Is there a way that you could add springs in the driver and passenger seating area? I have seen pictures of seat rebuilds where they added ties between the existing springs as well as tied additional springs from a donor seat base. In the pictures I saw they twisted safety wire loops to ties things together. Heavy duty wire ties might work but they might not be strong enough.

I think I would shy away from wood, although a piece of thin plywood, or luan came to mind. After reading the previous post a couple times again I thought about a piece of UHMW. Maybe all it would take is an 1/8" thick piece between springs and padding. It would support, but also flex a bit so you didn't feel like you were sitting on a board.
My 2 cents.

I would think adding inner springs to the ones already there would work or rebuilding with heavier ones.

I spent a lot of time messing with different springs to use on my 1940 Chevy PU.
I found you need to use spring steel in all the parts. If not, it will just kink when bent. That includes the rim wires and spring ties.
Finding the springs in the correct size and shape is also a problem. Even modifying and repurposing ........ Until I found an old box spring. It has all of the parts you need.... The tie springs, rim wires and the springs themselves. If they are too big, they can be cut down. A small bolt cutter works well for that. And if they seem too week, you can double them up although I find that if it can hold up under sleeping conditions, it works under sitting.
I use burlap over to cover the springs, then foam then another layer of burlap on top, pulled down to the past the lowest rim wire and hogwired past the wire and underneath there. That gives it a smother look for the cover. The cover holds it all together. I find stiffer foam works better than a board in confort as well as moving around.

Some box springs are taller than others but that doesn't seem to matter when sitting, but might as to how high the seat sits for you tall guys....

Mike

i agree that you need "spring" steel in this application You need the higher yield and tensile strength so the spring can deflect further without permanent deformation.

Most people forget that all steel deflects the same amount for a given load - up to the elastic limit!

Haven't heard "Elastic Limit" for a long time...... Going from elastic to plastic then breaking... I wonder if they still teach that now ...??? 🤣

Mike

Cut up some pool noodles and slip them inside the springs.

If you take thick strips of heavy foam rubber and put a strip through each row of coils. Try one strip first. This will allow the coil to only compress so far. A second strip through the next coil above the first will make the coil’s even firmer. Wire ties or hog rigs can be used to keep the strips from moving out of the coils.