As the title says, when i get up a bit of speed my gearbox start to make a very loud whining and when i let off the gas it make a very loud rattle/pining noise, anyone have a clue what it could be? it's a 4 speed a series gbox.

Yes, it means it's about to stop working. Get a good used 4-speed and change it out.

Whining ususually means the oil is low (or had been at one time) so that the gears were run dry.

Inspect your clutch visually when changing the gearbox, to make sure it is OK.

ok so i changed the gearbox and clutch and pressure plate, and the noise is still there.....

also when i pulled the gearbox out the bolts that hold the gearbox to the mount were missing, possible for the noise to be coming from the gearbox vibrating onto the gearbox mount or i noticed that the exhaust is very close to the gearbox aswell?

got any advice DD?

I would put money on it that it is your exhaust rattling on the body

i'll get some exhaust wrap see if that dampens it, if it works ill know and reweld it a bit further away

input shaft bearings?

Exhaust system won't cause a whining sound.

Exhaust wrap won't fix a whining sound. Or a pinging sound. Can you describe these sounds in more detail?

Quote:Did you get two replacement bolts and fit them?

I think the whining sound you describe is more likely to be the diff.

if it lightly shudders and make crap noises when u back off the power at low rpm.id check the input shaft for excessive play if u havent already.

didnt get a chance to do anything today but the noise sounds like a hollow vibration of metal, but very loud and very annoying, the whining i think is the diff because i welded it up and left the bearings in when doing so and could likely have #OOPS#ed them? i didnt change the bolts because when i put the 2nd gearbox in the mounts didnt line up so now i have to pull it all back out and throw the old one back in but i noticed that the bit on the gearbox where the half-circle bolt sits has snapped? is it possible that the gearbox just vibrated on the gearbox mount?

ill get some photo's up when i can and possibly a video of the sound

the input shaft is all good, throw out bearing was all good