Technical Building wood seat base webbing vs sofa springs

I am building a seat for my 32 Ford Roadster. I have the stock metal seat base and planning on building a plywood base and back with holes cut out in the back and butts. I have seen it done with webbing, has anyone used the flat z springs used in sofas? What type of webbing is used?
Is 5/8 plywood thick enough?

 

What kind of plywood are you planning to use? If it's marine, 5/8" is overkill, 1/2" will do. Marine plywood sealed properly won't have you worrying about it rotting out or de-laminating when it gets wet. It's a little pricier than the rough crap with the voids in the plies like you would get at the big box store, but it's way better.

 

I was going to use Canadian exterior grade 5/8. It is very similar to marine, it can sit outside in the weather for years.

 

Just drill holes and put good, firm foam in them. Worked great in my 41 Plymouth.

 

I was at Windsor Plywood in Winnipeg where they had 3 sheets of 3/4" marine grade plywood. It takes 34 to renew the boat floor. The salesperson said if it is Canadian Exterior grade plywood that it is the same as marine plywood. The difference is the boat shaped patches that are used for the outside layers. So I took a sheet. I bought 100 sheets of US 1/2 exterior plywood in the US during covid to renew my garage. Beside the pile was a pile of 1/2" premium exterior grade plywood that was from Canada. The exterior plywood up here is definitely a higher quality. Lot of flaws and not careful QA/QC. A couple sheets were a 1/2" shy on width, a couple on lengths and outer layers missing in places. It would have sold as seconds here but I did not realize there was such a difference until I got it home. That may be the manufacturer and not the usual std. The boat plywood will get coated with West Systems epoxy.

 

Plywood sucks unless you have a serious layer of foam under yur butt, or a lot of built in padding. The burlap webbing is great compared to plywood, but it’s only as good as how it’s attached to the base.

Take a look at the various rubber bladders offered for the 50’s-60’s MG and other European cars (Moss Motors). Bend up a tube steel frame, suspend the rubber bladder, wrap with foam, apply horse blanket, and enjoy the ride!

 

This is the seat that Deuce Roadster ( Randy Nash) built for his Deuce 3 window. Randy just used high density foam, no webbing, no springs. HRP

 

I did the seat and interior in my deuce 3 window just like Randy's above and it's very comfortable. The upholstery shop I use has 40+ years of experience, knows haw to make a seat.

 

the trick is to use carpet rebound pad on the bottom layer....

 

boat and rv seats don't have the holes... but if you do put the holes you need to make sure to cover the foam...it'll rot...putting the holes gets the same results as the rebound pad... what you want to happen is to make sure the foam doesn't bottom out..and that the foam can re air when it gets compressed...I'd ratther see a few 2'' round holes cut in the wood than one big one.... with the small holes the foam will re air with each bump, where as the big hole the foam just gets pushed in the hole, then when you get out it takes a bit for the foam to re air back to shape...the quicker the foam re airs the better the seat.... if that makes sense

 

I am pretty opinioned on this subject. my buddy Meatball done some upholstery his view was if your setting on plywood it doesn't matter how much foam you put on top of it you are setting on plywood. I had a roadster the seat would get hard and uncomfortable after about an hour. took the seat out cut a hole wear butts sat put some foam for the thickness of the plywood then weaved some elastic straps from old office chairs across the holes stapled in place like an old lawn chair. after doing this you could set in the car all day & it was like adding suspension. got another roaster done it the same way same results

 

NICE!!!!!!!!!!!!!!!!!!!

 

Exact.... if the foam can't rebound it just flattens to nothing ... pretty soon you are just sitting on the plywood...

 

thats why big rigs have an air suspension base... the base gives way before the seat foam compresses to zero,

 

first rule... the density of the foam must match the mass of the ass

 

the nicest roaster I ever road in I was ready to get out of in about 50 miles .the seat was super hard after a short amount of time. my 32 on the west coast down from the Santa Monica Pier 2017 ,Lake Michigan and at the Mid-west roadster run 2023 last trip traded it the next day. I try to put in some seat time

 

you could drive to florida and back on this seat....perfect ride...

 

Would tie downs work well for webbing? Stopped in at an upholstery shop and they said the green upholstery webbing only lasts 5 years.
These are the springs I am wondering about. How do you pick foam? Cut up an OEM cushion?

 

A pic of the MG seat cushion bladders in my T

 

Those look good, did you build a metal seat frame? What foam is in top? Thanks

 

I used a modified back seat bottom from a 1970s VW beetle, in my 32. The outer structure of the entire seat is a narrowed 1930 Packard sedan seat frame which is wood. The backrest of mine has the stock Packard fine wire coils which are soft for rich people I guess.

Anyways, I took the removable VW seat frame bottom cushion and had to narrow the wire framing that the Z springs mount to. I knew you are not supposed to weld those hardened wire frames because they will break later from the normal seat flexing, so I made sheet metal sleeves to join two wires. Just cut the framing wires too long so they overlap, then wrap sheet metal around the joints, crimped with vice grips. The factory used these in other places, that's what I copied.

I'm no expert on anything but some cars I built, I used just foam with voids in the plywood and the seat bottoms were uncomfortable. The current 32 is my primary car so I would know by now if it feels ok, since being on the road since 2016

On the VW seat bottom Z springs , the VW factory used a flat layer of shredded coconut fibers held together like a 1-1/2" to 2" mat with a rubbery glue. You can get it from VW restoration suppliers. I don't recall what I used on top of my Z springs, maybe covered with cloth then thin foam or coconut mat, with Muslim over that.

I don't think I would buy Z springs to lay across the openings in a plywood bottom. I think they need to be part of a bottom structure like the VW had. The entire structure acts like a spring, not just the Z springs. Maybe find a VW bug video that shows someone putting new covers on a rear seat bottom, or an early VW bus rear bench seat bottom is the same concept.

 

I should be able to remove my seat cushion to take the same pic as Kevin did, but tomorrow though. If it would help understand what I wote. Let me know here.

 

I would use webbing to lace the bottom , to support the foam , not just rest on plywood . Helped a friend do a 34 seat . We used the webbing on bottom and top

 

A picture would be great, thank you

 

I am trying to make some wood bases with webbing for our '47. Red stripe webbing is the kind to use.

 

Is that Jute? Any specs on it?
Thanks

 

Specs unknown other than it is 3-1/2" red stripe jute webbing.

https://www.amazon.com/gp/product/B08V9FFK7T/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

Thank you

 

http://www.how-to-build-hotrods.com/upholstery.html

 

Thank you