Gearbox whine in 5th

[iandecjak]

Decided to go to Retro Rides hill climb this weekend, weather great and lots to see.....

On the motorway when in 5th there was a whine not loud but constant which reduced slightly when holding gear stick slightly forward, nothing in any other gear apart from it being occasionally stiff when selecting 5th and reverse.

Got home and haven't had chance to look at clutch slave etc or gbox oil level but just asking to see if there is a typical issue with the box; which has been fine for last 2500 miles or so.........

As always any suggestions greatly received.

 

[Rob Gaskin]

Has it suddenly appeared?

I have had a few of these gearboxes and they can whine in top. I assume it's quiet in 4th gear.

 

[iandecjak]

Yes in the last few miles in fact, the car is a round 85000 miles in total, and it is fine in all other gears.

I am planning to change gbox oil this weekend and also check out the mounts etc as well as clutch operation.

If there was a common problem then I would consider dropping it and giving it the once over!

 

[pmac]

Assumimg its a 280ZX box?? It could welll be the main shaft lock nut has backed off a little. The nut is only dot punched in place.This allows more end float of the gears on their shaft. Gears running at a slightly wrong place will whine. Wear in the main and layshaft bearings will also cause whining .
It will only get worse. Now is the time to investigate before it starts to wear/destroy gear teeth faces..
Good gearboxes are now rare and hard to find so repairing yours now makes sense.
All of course IMHO.
Plenty of others will disagree Im sure.

 

[MikeB]

What Pmac says sounds spot on. It's not too hard to get at once the box is out, from memory the tail of the box unbolts and comes off without any plungers, ball bearing and springs flying round the place, but read the workshop manual to be sure.

I had a whine in fifth on my box, which turned out to be a small bit of errant metal stuck on one of the teeth, once removed the noise disappeared, so have a good look at the gears when you have it apart as well as checking the tightness of the big nut