Wont go into gear under Med to High Revs

[R31Heaven]

Went to Heathcote drags on the Weekend and my car won't change up into third if the revs are above 4 grand it just grinds any idea of the problem, except my box has a problem, wich is abvious:( would changing to a good oil fix this or is it a more serious problem as a synchro gone.

[kjb_r33]

could also be either your clutch is dragging or your spigot bearing seized, not allowing the input shaft to spin freely of the engine. Is it only going into third or other gears as well?

[R31Heaven]

Only third. Just had a Daiken extra heavy duty clutch put in about a month ago also. I also find it hard to go into reverse when sitting stationary & motor cold some times.

[BOOSTD]

fill it up with auto trans fluid ! works quite well also Nulon G70 makes a noticable difference.

[Duncan]

or our old mate Redline oil - fixed (hid?) my synchro problems

[R31Heaven]

I think I will try the Redline oil first and see how I go first. I have a low k's box lined up if this doesnt work so thanks for the info guys

[R34GTT-R]

its 3rd gear synchro my r31 did exactly same thing except it was second.if replacing box put r33 in it