Transmission shift problems
 

Took car for test drive after new rubber installed, this is the first time the car has been on the road for some time. 63 Fairlane 260. Previous owner said transmission was no original and somewhat new. Got to take their word sometimes. I have not changed the fluid, it looks clean and full. Starts out fine and when shifting to next gear, it's automatic btw, it seems to wind up and then shift. It does not do a hard shift, just seems like the gears slip and then they catch. Any ideas? Does this sound like internal problem? Thanks for any feedback,

This goes back a bit, but I believe that trans used Ford TYPE F fluid which had a different friction coefficient from type A. If the wrong fluid was used it raised heck with the clutch friction material and bands. It also gave mushy shifts.

If you are not sure what is in the trans presently, might be a good idea to install the correct fluid . For some reason if type F was installed in other transmissions (Not Ford) all it did was provide abrupt shifts , but no damage. I believe some racing folks took advantage of more positive shifts and used Type F.

I definitely do not know what type of fluid is in there or how long it's been in. I may give your suggestion a try before taking it to a shop.

Thanks hanky.

Vacuum modulator possibly...

I don't have a lot of experience with transmissions so I just googled what the modulator does and it seems like that may also be a good part to check/replace. New fluid and modulator may happen this weekend. Thank you Hayapower.

Generally when a mod fails, when you remove the vacuum line there will be trans fluid present. Also make sure there’s a good vacuum supply to the mod.
If dry, you can always pull a vacuum on it prior to a replacement to check ops..

This Sat I took out the modulator and found I had the wrong part, I need the push in type and I had thread type. New one is on the way. Question, a pin about 1" long came out when I removed modulator, I searched online to find out what this was. When reinstalling, do I put pin into modulator hole and install together or do I put pin in first and then modulator? Seems like it would be easier to do together, as I don't know how far pin needs to go inside transmission. Thanks.

I found it worked best when I put the pin in the modulator.

Thanks hanky, I'll have a chance to install on Friday or Sat, let you know how it goes.

Almost there
 

Replaced trans fluid with type F and new modulator. Car ran a way way better. I still need to play with adjustment screw but I think the modulator was the issue. Thanks for the advice.