Transmission noise

bman68, Oct 4, 8:35pm
I have a 96 laser with a 1.6 dohc motor and a manual fwd box the noise is like a rumble scraping noise. its only when driving it doesn't do it in 1st gear only in 2ed 3erd 4th and 5th and as soon as you take your foot of the gas the noise stops. its only when accelerating. and when you are driving but not accelerating you can slightly hear it any help at all will be much appreciated cheers josh.
intrade, Oct 4, 9:24pm
did you open the bung half way up the gearbox and check it hasgear oil in there
bman68, Oct 4, 9:45pm
Yes it has the correct amount of oil in the gearbox.
mantagsi, Oct 4, 10:54pm
I don't know much about gearboxes but I could only guess you have a failed bearing somewhere that's sounding bad under load. Said bearing may be on a shaft that's not loaded in first gear? Purely hypothetical useless guesswork on my part
gsimpson, Oct 5, 3:27am
Drain the oil. If it is full of metal filings you are in trouble. I recently did a gearbox on my car as when I dropped the oil a piece of a thrust washer fell out with oil. Ok, that's the problem.
If it all looks clear, replace the oil and look elsewhere.
franc123, Oct 5, 3:43am
I would certainly suspect one of the main bearings in the trans, could even be one of the final drive bearings, these can be a bit deceptive as they may not make noise at very low wheel/drive axle speeds, hence in first gear it may not be audible. It would be best to spin it up in 4th gear and simulate say 70kph on a two post hoist and probe various areas of the trans with a stethoscope or long screwdriver and see where the noise is loudest. Pay attention to the RH halfshaft centre support bearing too. The snag with oil inspection is some internal gearbox bearings are sealed and any debris from them may not show up in the oil.
ozz1, Oct 5, 3:45am
if its not too loud and you can live with it? just drive it. as you are going to need another gearbox. comes down to cost. end of the day.
bman68, Oct 6, 6:58am
cheers for the help pulled gear box apart on Sunday and the bearing on the input shaft is toast getting a replacement tomorrow and should be good to go.