Thread: Question about model A seat

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Originally posted by brianrupnow
Don----in regards to your "potty holes"----I have built seats using this technique, and it really helps with the comfort factor in a car with home-made seats. My first 2 rods that I built were either chopped, channeled, or both. In a coupe, to avoid the "bent neck syndrome" and in a roadster to avoid the "head sticking above windshield" syndrome, I has to make the seat bases extremely low, using high density foam and 3/4" plywood, which sat right flat on the floor. If you just use foam and plywood, after the first 10 miles of riding the high density foam "solids out", that is to say there is no farther compressibility in it. Every road shock is then transmitted directly through the plywood to the end of your spine, and it gets uncomfortable darn fast.Brian Rupnow

I think a lot of it has to do with the foam you use.
The upholstery shop guy who did the upholstery and foam in my 32 used a very firm foam on the bottom and a medium density foam for the rest.
The foam sandwich rests directly on the plywood and there is no Potty Hole (PH) in my 32.
42,000 miles of driving and the seat is still very comfortable.
Hard bottom out type bumps when driving aren't a problem either.

Regardless, I do think the PH method has a lot of merit.
In my case a finished PH could be added by sawing a hole in the plywood - use a shortened sabre saw blade so you don't tear up the foam.
Make a 3/4" thick plywood ring that fits around the PH.
Make a 3/4" plywood closed base to go under the ring.

That would give you 1 1/2" for additional foam.
If you needed more foam you could stack another 3/4" plywood ring in there.

A little sanding to round off the sharp edges.

Cut a piece of foam to fit the hole within the ring.

Use sheet metal screws and glue to retain the plywood PH.

Granted, you could add the webbing etc. after cutting the requisite PH, but in my case the wiring et al is under the seat and I want to be sure the upholstery/foam doesn't sink down and contact the wiring.
The plywood PH makes for a positive stop.