5th gear whining

[BARWICK]

Hi Guys,
just got a 1998 2.8L gu and noticed it has a gearbox whine in 5th gear.
Is this a common problem?
Any solutions? gearbox addatives, do they work?

Thank you

[patch697]

Yes it is a common problem in the patrols & yes gearbox additives can help but not all. If you go the road of an additive then buy a top shelf one & stay right away from the cheap crap.

A good quality gearbox oil would also help. I find find something in the Castrol range to be the best oil for the job.

[BARWICK]

Is there any particular gearbox addative that anyone can suggest?

[patch697]

Is there any particular gearbox addative that anyone can suggest?

I find Nulon to work quite well & Morey's oil stabilizer is also a top pick of mine as well.

What for some other members to reply to your thread cos im sure they will have some great input here as well

[nomadTech87]

The early GUs (pre 2004) had a problem with 5th gear. Later they lengthened the spline on the shaft and widened the gear
here is a new spline next to the old:
http://i204.photobucket.com/albums/bb318/nabstud/5thGearNewOld.jpg

I haven't been through this personally as mine's an auto but there are aftermarket solutions for strengthening 5th gear (ie: spline/gear replacement)
If the solutions that have been listed above don't sort the problem it might be worth looking after revising the gearbox, not very cheap I imagine

[happygu]

Nomad.....I thought the GU 2.8's ran a different box to the 4.5's and the 4.2's in that year.

Mic

[nomadTech87]

my bad. After some reading it appears that yes, the 2.8 had a lighter gearbox, related to the box used in Skylines.
In that case I guess it doesn't suffer from the other's manufacturing issue. The noise could just be lack of oil in the transmission?

[Robo]

I thought it was rb30 gq patrol and the 300zx box was one and the same the gear box.