The rattling clacking and knocking gearboxes - a strange experience

Hi there,
we recently replaced the two gearboxes, the R380 and the LT270T because of horrible grinding and whining of the old boxes. However, since then these boxes still trouble us lot, when changing the gears of the R380 or changing the load just at the moment between acceleration and deceleration there is a loud rather single clacking noise from the gearboxes that could come from either of them. In higher revs there is also some low pitch whine, but that is perhaps not a big deal for the time being.

More importantly, and that is the frightening part, when standing and putting the LT230 in neutral and running the engine from low throttle up with the gears 2-5 there is a loud rattling/knocking/clacking coming from the gearboxes most likely from the LT230 that increases with engine speed. It sounds like a screw banging around in the box.

As we could not hear that when driving, and were actually uncertain, and therefor, we were lifting the vehicle up to free the wheels, and running the LT230 in high and the R380 in the 2nd gear. However, the rattling/knocking/clacking is still there, but not as loud and intensive since the engine speed is kept at low throttle. But it is there.

We were wondering whether there is a lack of load on the gears, so that they cause this noise or even a lack of preload on the bearings of the LT230 input gear or the bearings of the intermediate shaft gears. Or something else we do not even think of yet.
I have attached a small recording of the sound recorded directly 10 cm over the boxes between gear sticks and the frame of the bench

http://earth-traveller.info/local/R380_5th_gear-LT230_Neutral.mp3

The question is also whether you hear something like that when you put your LT230 in neutral and the R380 in the 5th ? We are lost right now.

cheers,
the big green

Could be a knacked bearing in the transfer box, at a guess.

take the sump off the lt230 and look and feel the gears ,also have you spilt t/box from g/box and refitted them back together

thanks for your comments.
taking t/box off again is a possibility, opening the sump may invalidate any warranty, no go without consent, not agreed yet

with t/box off perhaps we could check whether there is a movement of the input gear with a dial gauge

biggreen_bcn said:

thanks for your comments.
taking t/box off again is a possibility, opening the sump may invalidate any warranty, no go without consent, not agreed yet

with t/box off perhaps we could check whether there is a movement of the input gear with a dial gauge

Click to expand...

Warranty? Those boxes havent been made for years? If you mean a warranty on a recon, tell them to give you another one!

I would just do what James said, it is the most likely source of the noise you describe.