Not Holding 5Th Gear

[R34GTFOUR]

Hi everyone,

I was hoping this is a common problem and someone can shead some light on it for me.

Quick Background: The car is actually a 180SX with an SR20DET with the stock 5 speed manual, however they share the same gearbox internals as a N/A Skyline so I thought it was worth a shot here. The car has never had an issue before and is actually my missus's car that I've kinda broken haha.

I thought it would be a good idea to take it down the drags to see what time it would do and on the return trip back home it wouldn't hold 5th gear on the freeway - just great. It didn't have the issue prior to the drags so I'd say I've damaged something down the strip and now I'm in the dog house..

The gearbox still selects ALL gears perfectly fine, no crunching etc, and its only 5th gear the pops out. If I select 5th and place a small amount of pressure to hold it in, it will hold the gear fine. If I don't hold it, then after about 5-10 seconds it just slides out and free-revs.

The car has 270rwhp so I only got into 4th gear down the strip - never hit 5th so I don't know why 5th got damaged.

I'm leaning towards a selector fork issue (possibly bent?) but I've never had this issue before.

I was going to put a 2nd hand gearbox in it and be done with it, but I thought if I could get away with something cheaper, i.e. like a new fork, then it maybe worthwhile. But if I have to go to the extent of replacing syncros etc then I won't bother with it.

Any ideas on what caused the damage and what the fix is?

Cheers for your help!

Steve

Edited November 13, 2012 by R34GTFOUR

[Hadouken]

Maybe change the fluid and see if the problem goes away

[R33 Sleeper]

4th gear kept popping out in my car, turned out didn't have enough oil!

[R34GTFOUR]

Thats interesting.. never thought that low oil would cause that problem?

It still selects all gears fine and isnt making any odd noises so I think the oil level is fine but I will check this weekend.

Cheers