Net: If you disassemble multiple 240 front-seat backs in a batch, mark them (pair each foam & frame) in case you have > 1 designs.

I'd saved several front seats (1983-93) to rebuild: patch & glue the foam, weld/brace frames, replace springs, sew/patch upholstery, .... I took ~10 seats apart, stacked the foam, sorted the bottom and back frames. I repaired the foam (mostly the backs); repaired frames, ....and went to put them together. There are multiple (4+) designs and the foams are not interchangeable without modification. The variation is in 3 areas: lumbar adjustment, shape of the arches, spring fastening points and layout:

1. Two lumbar-adjustment heights, ~1.5" different, measuring from the top, adjustment knob
a. 15.5"
b. 17"

You can cut out part of the hole and re-glue it above/below but the seat cover will have a visible hole unless you have spare material to patch in.


2. Seat back frames (see pic), considering the round bar that makes an arc behind your triceps as you sit - the bar that typically breaks through the foam (distance is from the front of the frame)
a. Low - 2", partial length of frame
b. Low - 2", full length of frame
c. High - 3", partial length of frame
d. High - 3", full length of frame
e. Some few have a round crossbar on the bottom but this doesn't affect the fit of the foam

The foam is shaped to conform to and fit tight against these arced bars so you can't interchange foam among different frame designs - although you might by cutting/padding if you were desperate. Bad idea to break the foam membrane though.


3. # of springs and positions: seat backs take either
a. 6 horizontal springs (3/side) pulling the foam out - the 2 lower are like the seat-bottom springs; the 4 upper ones are weaker.
b. 2 horizontal springs (1/side) pulling the foam out; + 2 small vertical springs pulling up around the headrest area

I drilled holes in some frames and used the 6 horizontal-spring config because this seemed stronger.


4. Aside: I noticed two lengths (~1" different) of seat-back angle adjustment tubes but all of the seats I reassembled took one-length rod (the shorter one I think).


I haven't matched seat design with years because a) I'm not sure which cars the seats came from; and b) there's no guarantee they weren't replaced with seats from a different year car eg. ~5 years ago I put a 1983 GL interior (seats + door panels) into a 1992. Two seats out of a 1985 had the deeper risers (arcs).


All seat bottom frames seemed the same.


(Art B: I took numerous pics - too many to post here IMO. You're welcome to look through and add in conjunction with Tony H's pics and write-up on your flametrap page.)
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240 drivers / parts cars - JH, Ohio