Rb25 Transmission Whine?

[RedDrifter]

Hi I recently installed an rb25 box into my r32 and I have noticed the gearbox to have a slight whine/whirr in 1st gear, only under acceleration.

Gears shift smoothly and the box feels ok as a whole.

Noise is like a supercharger increasing with revs (best way I can describe it, not real loud but definitely very noticeable).

I'm taking a guess that one of the bearings in the box is worn but not sure why only 1st gear would only have the noise?

Or is this just how these boxes are being a lot larger than the rb20 box etc as I did noticed how much more room it took up in the transmission tunnel when we put it in.

I'm using nismo mounts(engine and box ) and it came with a short shifter, plus I got a custom 2 piece fishtail made up by Hardy Spicier (fitted like a glove).

Box Oil is Castrol Syntrans 75w90 (4 litres in box)

I did do a bit of a search on SAU and on the net but found conflicting information.

cheers!

[The Bogan]

I killed a few boxes in my old boat, it was making some good torque 675nMish which was stripping the hardening off the 1-3 gears, they sounded like what your describing.

It did do some hard work on drag radials.

[jiffo]

These sorts of problems are always hard to diagnose, but as it's only on 1st it's more likely a gear noise than a bearing noise.

Of course worn bearings makes for poor gear mesh which leads to gear noise, but usually in all the cluster gears.

Is there a similar noise in 3rd too?

Unless a 25 gearbox is a gift, there's merit in purchasing a brand new box. ($3k approx)

If you fork out $1200-$1500 for an unknown 2nd hand box and then have to overhaul it, the $3k is looking pretty good.