1991 240sx automatic transmission issues.
 

I have a 1991 240SX LE KA24DE and an automatic transmission and 159k miles

When I first start the car up the trans is at its worst. It feels as if it had a clutch and it is riding it. In the morning it also doesn't want to shift out of 1st for a while. After driving around for a little bit (give or take 5-10 miles) the issue clears up some but not all the way. I thought that it might be the TC or maybe it needs to be shimmed. Anybody have any ideas. I plan to do a swap to 5spd but I don't have all the parts yet.

No idea what your issue could be but it shouldn't be too hard to source out all the 5 speed parts you need from your local junk yards/drift clubs. The hardest parts to find are clutch fork seal, tranny seal, tranny seal clamp ring and the adapter for the fitting from clutch line(use brake line its cheap) into the trans. The trans seal, clamp and fork seal can be sourced online or through stealership, Nissan will bend you over for about $300...

I would say hold out until the 5 speed but if your willing to try something..

Whens the last time you flushed the old fluid out and put new transmission fluid in the system?

I just got the car on the 15aug so I haven't done a flush but was going to on my next paycheck.

Yeah check the fluid out, Might be Old and Used pretty bad. Can cause some weird shifting problems. Its really all you can do unless you want to tear it down and investigate.

I just resolved a transmission issue, car would not switch gears randomly, slip or would have some terrible shifting. It had royal purple in it. Flushed it, Switched to FSM recommended transmission fluid, made sure it was at proper level, and the car shifts like butter & has no slipping.

Thanks for all of your help. Ill post on how it goes afterwards.

Not a problem, Good luck!