Drivetrain 5th gear in stock T5 hit or miss

[stangdrvr4life]

I have a stock T5 with 161K on the clock, and a while back noticed that on occasion, it doesn't like to go into 5th unless the moon and Jupiter are aligned and I sacrifice a baby goat. If I have to downshift out of 5th.....well, looks like I'm in 4th until I stop again. Sometimes, after I've been in reverse, the first time I have to shift into 5th, it goes in just fine. Most of the time I'm just left serenading myself to the sound of the engine at 3200RPM in 4th for the remainder of the trip, so it really keeps me from traveling too far. 1st through 4th are about flawless.

I'm leaning towards the synchro, but I figured I would conjure up the Oracles here and see if you all have seen anything similar, and what possible causes I could be looking at.

 

[Mustang5L5]

Reverse and 5th gear have their shifter linkages combined. So if shifting to reverse “resets” the ability to go into 5th, then I would guess something in your 5-R shift rail mechanism is off.

unfortunately only way to know is to open it up and inspect it.