3rd gear problem

[Thomask]

hello all i have a 2009 mk7 transit 350 lwb rwd when I bout the van it was a 5 speed and the gearbox selectors where worn so I put a 6 speed in along with the clutch and flywheel I first drove the van with no problems but reverse and 3rd gear would crunch but I went steady with it to get home I then replaced the gear cables and the reverse Is no longer grinding or crunching but 3rd gear not a crunch as such more like it's trying the engage with another gear and the two cogs teeth are spinning at very high rpm the gearbox selects 3rd gear easy but always with this smashing of teeth I can upshift from 2nd to 3rd silently but only at low rpm like 1500rpm downshifting from 4th to 3rd at any speed or any rpm is impossible without smashing gears sought of speak even with the engine turned off at 25mph cannot get 3rd gear without smashing gears all other gears are fine can anyone suggest what it may be. When I went on a trip with it and the neutral cable come off slightly and since then it has made the noise before it didn't thanks in advance.

[fortyeight]

maybe 3rd gear cog worn

[metalworker0]

Sounds like the synchros are worn, these are brass rings that sit between the gears that match speeds of gears by letting gears slip, speed up or slow down before they engage with each other, whilst the clutch is depressed.
Fixing requires a full strip down of the box.

could still be a clutch not fully disengaging problem though.