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Will all my 79 f-body control arms, spindles, steering linkage,
etc bolt on to the 73 f-body?).
And Phil (B.), did you ever put that later model subframe on your
Firebird?
=================================================================== The following answer is thanks to Ken Carothers and Phil Boylan.
At 05:48 PM 10/27/1998 -0600, Ken Carothers wrote:
Okay folks, I measured a few things. The HPP (High Performance Pontiac) article appears to be right, they (early and late 2nd gen f-body subframes) are different. All measurements were taken at the location where the tranny crossmember bolts up. The subframe & crossmember are still under the Bird, so my measurements are approximate, but I think I'm within an 1/8".
'73 Subframe:
Outside to outside dim: 37"
Inside to inside dim: 29"
Tranny X-member bolt holes: 30-3/4" Centerline
Distance between holes: 2-1/2"
'79 X-member:
Tranny X-member bolt holes: 32" Centerline
Distance between holes: 2-3/4"
Then from Phil we have:
Thanks Ken, I believe that clears up the mystery. My numbers off the '78 subframe pretty much agree with your numbers from the '79 cross member:
'78 Subframe:
Outside to outside dim: 36.5"
Inside to inside dim: 28.5"
Tranny X-member bolt holes: 31.5" Centerline
Distance between holes: 2-3/4"
The bolt hole centerlines were taken measuring from the top of the subframe(easier because the holes are much smaller on top). I had interpreted theHPP article to say there was a significant difference in the distance between the frame rails, but as you can see we found only a 1/2" difference. But the X-member bolt centerlines are more problematic. Probably the easiest thing to do when mounting a TH-400 in a later subframe is to convert a later TH-350 X-member by flipping the trans mount from rear-facing to front-facing (while being careful to maintain the drivetrain centered between the rails).
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