I finally got the tcc lockup working in my 700R4 trans in my 86 Caprice, after driving it well over a year without it working. The shifts seem to have improved quite a bit within a couple days of driving it with the lockup working again. All shifts are a lot more firm than before. Fluid was not dumped when it was fixed cause it was an external wiring problem. Just wondering if I should change the fluid, if theres any chance that the torque converter locking after not locking for so long could do anything to the fluid? It was changed not long ago cause of being overheated pretty good trying to get through heavy snow, but I might drain it again and add synthetic. Just wondering what the lockup working again, could have done to improve shift feel besides lower fluid temps. It seems to shift better whether its hot or cold?

 

If the fluid has been overheated you need to change it. The TCC not working shouldn't have had any affect on the fluid.

 

I think my post is confusing some people. The fluid was changed since the overheat.

The only thing that worries me is that from what I've read lots of times before, the lockup not working in a transmission that has lockup, creates a lot of extra heat at highway speeds. And the car has been driven 70mph 45 mins one way to work for the past couple months.