It is a firm or harsh shift from first to second only? The fact that it occurs warm could be sticking or binding in the valve body after metal expansion or warpage is more influenced. I will include the diagnostic info for 1-2 shift feel fault possibilities.
Harsh or Soft 1-2 Shift Feel
DEFINITION: One of the two following conditions occurs during a first to second gear steady throttle upshift, or a second to first gear coast, or a light to moderate throttle detent downshift:
" Harsh shift feel -- an unacceptable quick gear change occurs.
" Soft shift feel -- an unacceptable long gear change occurs.
Automatic Transmission Fluid Level - soft shift only
Low fluid level
Transmission Main Line pressure
Low or high transmission main line pressure
Oil Filter Assembly - soft shift only
" The oil filter assembly (100) is missing, plugged, or damaged.
" The oil filter seal assembly (101) is missing or damaged.
1-2 Accumulator Assembly
" Misassembled or upside down 1-2 accumulator assembly
" Damaged or missing 1-2 accumulator piston oil seal ring (137A)
" A damaged or missing 1-2 accumulator piston cushion spring (139) or outer spring (142)
" A stuck or binding 1-2 accumulator piston (136A)
" Debris in the passages of the accumulator cover spacer plate (134)
Control Valve Body Assembly
" Debris in the passages of the control valve body (301) or spacer plate assembly (370)
" Missing or mislocated #2 ball check valve (372)
" Misassembled 1-2 accumulator valve (340-345) line-up
" Stuck or binding 1-2 accumulator valve (341)
" Damaged or missing 1-2 accumulator valve spring (340)
" Missing, damaged, or misassembled 2-3 accumulator valve bushing (345), bore plug (343), or retainers (342, 385)
Driven Sprocket Support Assembly - soft shift only
" A damaged second clutch housing oil seal rings (613) or the four lobe oil seal ring seals (612)
" Worn or damaged second clutch housing bushings (616, 619)
Second Clutch Assembly
" Missing or not seated second clutch basking plate retaining ring (627)
" Missing or misassembled second clutch backing plate (626)
" Worn, damaged or misassembled clutch plates (623-625)
" Missing or not seated second clutch spring retaining ring (622)
" A damaged spring assembly (621) or piston (620)
" A missing or damaged second clutch housing ball check valve assembly (618)
" A damaged second clutch housing assembly (617)
Sunday, February 28th, 2010 AT 10:30 AM