2013 Fiesta SE Hatch 1.6 DOHC USA. How to remove and replace input shaft seal. iB/5 transmission. Can this be done without taking transmission apart? Installing used transmission. Already replaced the  2 halfshaft seals.

You must remove the drive axles from your Fiesta. You should have a quart of synthetic transmission fluid in the proper specification to top up the gearbox fluid level when you have completed the installation of the new output shaft seals.

 This is not an expensive job but it is very important to do it correctly so you don’t damage your transmission because of low fluid level. Those seals are what allows the transmission to hold the proper level of gear oil. You will need to invest in a decent seal install tool kit and a seal puller tool as well. Not at all expensive and are universal for that service purpose.

I added a picture of the Motorcraft synthetic transmission fluid required and the seal pulling tool. You can get a good seal driving kit at either Northern tool and equipment or Harbor Freight stores for about $40 usd.

the output shaft seals are the only external seals that am aware of except for the rubber O ring on the filler plug. The case sealing gaskets are RTV. 

Why are you discussing the output drive shafts to the wheels?

I was asking about the input shaft seal. It is exposed after you remove the transmission. It is a ridiculous idea that you have to tear down the transmission and install it from the inside of the transmission. I would think the Germans could design a better transmission.

After driving manual transmissions for over 60 years I have never had a synchromesh that could no be shifted into 1st unless you are under 3MPH. That's VW Beetle, TR3B, TR4's, Volvos, BMW's, Opel Cadets, a list to long to enumerate. The excuse that is because something catastrophic would happen is BS. If you can shift out of 1st at 15 MPH with no catastrophe that means you ought to be able to downshift at the same speed.

The IB/5 was originally a 4 speed that they hacked another gear onto - too much mass for the synchro to deal with. Also GETRAG Kluged the Reverse gear onto the 1st/2nd synchro assy. That's way too much rotational force for the synchros to deal with.