I have a C6 tranny on a 460 that powers an E350 Motorhome.

The transmission does not downshift from 3rd to 2nd at virtually any speed. Ocassionally it will downshift if I am under 25mph. All other aspects of tranny performance appear to be normal. I don't think it is slipping because I can accelerate OK, the shifts are normal but might be a little soft, and I climb hills OK for having 14,000 lbs to haul. I can maintain 55mph on the steepest hills.

I know I can adjust the linkage / cable that controls this function but here is the real question.

Is there anything else that can effect this downshift function?

I recently had to replace my catalytic convertor and had to run for a day or so without a catalytic convertor. The very first thing I noticed without the Cat was that I had what I would call perfect transmission operation. Great acceleration, downshift, etc..

Unfortunately, I put a new catalytic convertor on and didn't pay much attention to the performance so I don't know if the downshift issue is associated with poor engine performance or the tranny. Since I burned up one Cat I may have fryed another one due to some engine problem.

Any comments or suggestions would be appreciated before I do a real live test and yank the Cat for a road test.