I just wanted to update the topic involving 69 GM Buckets seats with #8738440 that appear to be one off or used in design car. Heres some data based on facts. The seats with #8738440 were molded from HR(high Resillency) and were first used in GM in the middle of 1969 in Fbodys only . So far we know the only pair we have seen have been in 69 firebird although data I found said used in Camaro/Firebirds.
--In the late 1960, early 1970s a new type of urethane foam was introduced and promoted by several of the major chemical companies.
-- Since this foam had a much higher resiliency--- it was termed High Resiliency foam.-----
However, since it was possible to mold at much lower or even ambient mold temperatures, it was also called “cold cure” molded foam.
-- In this thread I will refer to it as high resiliency (HR) molded foam---
In late 1969 mid-year, General Motors took the molded urethane cushioning concept still further. There are a plethora of components that are either molded into or attached foam seat parts, which provide comfort, address safety, and provide ease of assembly.
Advanced polyurethane foam chemistry allows very complicated parts to be successfully molded.
Today Optimization of chemistry and processing also allows for the production of complex shapes, e.g. hooded seat backs, etc.
Thanks to GM pursuing this chemistry in mid 1969 aggressively
--Previously two separate parts were molded and glued together to form the finished part.
They introduced substantially thicker PU seat pads which they claimed were more comfortable,more luxurious and from their viewpoint, easier to handle and less seat parts were now involved.
--- Gone was the burlap-cotton batting/padding and many of the small support wires and springs. These springs were now incorporated in the HR Foam seat backs in at least 1 Fbody we are aware of that has GM# 8738440 which appeared in GM July 1969 Parts Catalog.
Pads up to 127mm (5 inches) were molded using new high temperature ovens and demold times of 18-20 minutes or less.(10)
These thicker pads were introduced into Chevrolet Camaro and Pontiac Firebird models late 1969 and the foam had to meet the recently issued (1969 Sept 10) foam spec FBMS 7-1.
The aim of this HR foam work was to produce deep molded foam cushioning with improved comfort, fatigue, flame resistance,and low smoke generation.
This success with HR Molding was encouraging and it was projected that one-piece bucket seats (presumably cushion and back) would be feasible.
All sorts of components could be molded in place and frames were targeted for incorporation (PICS BELOW 8738440 springs molded into seat back ).
-- Trim Attachments, Cloth Reinforcement, Border Wire, and Wire Frame--
Although GM marched successfully down the HR foam route, others were not as aggressive/advanced.
American Motors Corp. (AMC) did produce some HR backrests in-house
but Ford (25-30% of N.A. production) still had a springs and topper pad approach to seating
-GM Fisher Body personnel have indicated the swing to HR foam
was partially fortuitous.
-They had decided to switch to full depth seating late in 1969 but were going to scale-up production using hot foam technology.
The advent of the new HR foam chemistry based on polymer polyols and its improved processing and desirable physical properties convinced them to go with HR foam.
Advances in chemistry and process allow parts to be molded with a thermoplastic or cloth cover in place, hence the name foam-in-place seating. This trim / molding process provides a finished seat cushion.
In the late 1960s, a typical seat construction using a thin urethane part would have consisted of:
1. Frame + S-shaped springs
2. Wire, cotton batting and burlap support pad
3. 38-50mm (1½-2 inches) molded urethane cushion
4. Fibre foam pleating insert
5. Fabric or fabric-backed vinyl cover
--This type of seat construction was still in use for some seats until 1972.--
GM operated in-house Molding lines and these switched over to full time HR foam production in 1973.
--1968 The first commercially polymer polyols were introduced by Union Carbide Corporation (now Bayer Material Science) in a technical bulletin entitled “Cold Cure Flexible Foam Molding”. [Polymer polyols are also termed graft polyols (BASF) or copolymer polyols (DOW)
**Today HR molded foam is the predominant material used in automotive seating.**
-----------------------------------------------------------------------
**W. Patten (Union Carbide Corp – retired) – private communication**
**A.F. Reilly, Chem. Eng. Progress, Vol. 63 no. 5, p. 104, 1967 “Urethane Slab Foam for Automotive Markets**
* *H. W. Wolfe, “Designing HR Molded Foams”, J. Cellular Plastics, **
**L.M. Zwolinski and J.W. Frink, “High Resiliency CoLD-Molded Urethane Foam**
**K.D. Cavender (Arco Chemical – retired) – private communication**
--In the late 1960, early 1970s a new type of urethane foam was introduced and promoted by several of the major chemical companies.
-- Since this foam had a much higher resiliency--- it was termed High Resiliency foam.-----
However, since it was possible to mold at much lower or even ambient mold temperatures, it was also called “cold cure” molded foam.
-- In this thread I will refer to it as high resiliency (HR) molded foam---
In late 1969 mid-year, General Motors took the molded urethane cushioning concept still further. There are a plethora of components that are either molded into or attached foam seat parts, which provide comfort, address safety, and provide ease of assembly.
Advanced polyurethane foam chemistry allows very complicated parts to be successfully molded.
Today Optimization of chemistry and processing also allows for the production of complex shapes, e.g. hooded seat backs, etc.
Thanks to GM pursuing this chemistry in mid 1969 aggressively
--Previously two separate parts were molded and glued together to form the finished part.
They introduced substantially thicker PU seat pads which they claimed were more comfortable,more luxurious and from their viewpoint, easier to handle and less seat parts were now involved.
--- Gone was the burlap-cotton batting/padding and many of the small support wires and springs. These springs were now incorporated in the HR Foam seat backs in at least 1 Fbody we are aware of that has GM# 8738440 which appeared in GM July 1969 Parts Catalog.
Pads up to 127mm (5 inches) were molded using new high temperature ovens and demold times of 18-20 minutes or less.(10)
These thicker pads were introduced into Chevrolet Camaro and Pontiac Firebird models late 1969 and the foam had to meet the recently issued (1969 Sept 10) foam spec FBMS 7-1.
The aim of this HR foam work was to produce deep molded foam cushioning with improved comfort, fatigue, flame resistance,and low smoke generation.
This success with HR Molding was encouraging and it was projected that one-piece bucket seats (presumably cushion and back) would be feasible.
All sorts of components could be molded in place and frames were targeted for incorporation (PICS BELOW 8738440 springs molded into seat back ).
-- Trim Attachments, Cloth Reinforcement, Border Wire, and Wire Frame--
Although GM marched successfully down the HR foam route, others were not as aggressive/advanced.
American Motors Corp. (AMC) did produce some HR backrests in-house
but Ford (25-30% of N.A. production) still had a springs and topper pad approach to seating
-GM Fisher Body personnel have indicated the swing to HR foam
was partially fortuitous.
-They had decided to switch to full depth seating late in 1969 but were going to scale-up production using hot foam technology.
The advent of the new HR foam chemistry based on polymer polyols and its improved processing and desirable physical properties convinced them to go with HR foam.
Advances in chemistry and process allow parts to be molded with a thermoplastic or cloth cover in place, hence the name foam-in-place seating. This trim / molding process provides a finished seat cushion.
In the late 1960s, a typical seat construction using a thin urethane part would have consisted of:
1. Frame + S-shaped springs
2. Wire, cotton batting and burlap support pad
3. 38-50mm (1½-2 inches) molded urethane cushion
4. Fibre foam pleating insert
5. Fabric or fabric-backed vinyl cover
--This type of seat construction was still in use for some seats until 1972.--
GM operated in-house Molding lines and these switched over to full time HR foam production in 1973.
--1968 The first commercially polymer polyols were introduced by Union Carbide Corporation (now Bayer Material Science) in a technical bulletin entitled “Cold Cure Flexible Foam Molding”. [Polymer polyols are also termed graft polyols (BASF) or copolymer polyols (DOW)
**Today HR molded foam is the predominant material used in automotive seating.**
-----------------------------------------------------------------------
**W. Patten (Union Carbide Corp – retired) – private communication**
**A.F. Reilly, Chem. Eng. Progress, Vol. 63 no. 5, p. 104, 1967 “Urethane Slab Foam for Automotive Markets**
* *H. W. Wolfe, “Designing HR Molded Foams”, J. Cellular Plastics, **
**L.M. Zwolinski and J.W. Frink, “High Resiliency CoLD-Molded Urethane Foam**
**K.D. Cavender (Arco Chemical – retired) – private communication**
