I have a 2001 Toyota Tacoma, 5spd atandard with 126000 miles. I recently tried to put it into 4th and noticied that it did not pull back as far as normal. It popped out of gear immdeiately. This happened all evening, so I skipped over 4th. It felt as though the stick was simply not moving back far enoungh, regardless of the pressure I applied. I changed the transmission fluid about 2 years ago at 80-90K miles. I changed the fluid once again the following morning and things have gotten better.
Is there possibly a problem in the transmission or could it have simply been the fluid?
I’ve heard of theoretical physics; but, theoretical mechanics?!..
Inspect the transmission linkage and bushings. Replace, and adjust, as needed.
Your tranny is a top loader. There MAY be an access cover under the floor mat where you can get at the shifter or you might have to pull the tranny out to get at it.
One other thing to check is all the bolts to the tranny/bell-housing are tight.
It could be a wear problem in the 3/4 shift fork and 3/4 synchronizer hub assembly.
If you do a lot of stop and go driving (and in 4th a lot) and have a tendency to rest your hand on the shifter the pressure exerted by your hand is multiplied by the shifter onto the fork and sleeve.
This means the shift fork rubs against the walls of the synchronizer sleeve and prematurely wears both of them down. Eventually the excess play gets bad enough the shifter moves before the synchronizer sleeve does.
If you want an analogy about the shift fork/synchro sleeve contact area, think of an old pulley and V-belt cross-section view. Think of a good V-belt fitting snugly into the pulley. Now remove the snug-fitting belt and replace it with one that is much narrower. Notice how the belt moves back and forth in the pulley? Essentially the same principle.
Hope that helps anyway.