Drivetrain noise, any ideas?
Posted: Mon Jun 27, 2011 10:21 pm
Ok so as previous post ive been driving my brothers E30 while my own car is off the road, and i'm sorting out the niggles it has to we can put it up for sale once my cars sorted.
The car has a whine coming from the drivetrain, which my brother thaught was the rear diff. Its had this whine for a long time, and hes never tried very hard to actually get rid of it. A few years back he'd baught a "sport LSD" on ebay as an upgrade to the diff on his car that he'd thaught was noisey, thinking cure the fault and get an upgrade at the same time. When it turned up it was a standard 4.10 small case, so got launched in the cupboard and he continued to ignore the whine.
When i got the car from him, i got the diff as well, and swapped it in yestarday aiming to cure said whine, thinking that even though it wasnt an upgrade, it would at least shut the noise up. However the noise is completely unchanged.
So i went out and paid some really close attention to the sounds, and discovered that theres two different components to the whine. First component starts as soon as you move away, is most noticeable in first and second gears and ties in with the engine RPM. Its directly related to load and changes as you apply and remove power. As such i'm pretty sure its coming from the gearbox itself.
The second component of the noise i cant put my finger on, and i'm wondering if anyone has any ideas as to what it could be. Its related ONLY to road speed, does not change pitch with load, and doesnt seem to change pitch if i steer from side to side.
It starts making a noticable noise when the car reaches maybe 20mph (i think it is still there below this but the gearbox whine drowns it out at lower speeds), and then steadily increases in pitch as road speed climbs from there.
Obviously the first thaught would be wheel bearings, but i'd expect them to change in pitch if i loaded them up, ie steered hard into a corner, and this noise doesnt do that, which has left me a bit stumped. I jacked up the rear of the car and spun the wheels to see if there were noisey and they seemed fine.
The only other component that runs at road speed is the diff, and it seems unlikely that two completely different diffs would make exactly the same noise, leaving me a bit puzzled.
I guess its possible that its yet another bearing in the gearbox, perhaps the one on the output shaft, but i'd like some other peoples thaughts?!
Cheers
The car has a whine coming from the drivetrain, which my brother thaught was the rear diff. Its had this whine for a long time, and hes never tried very hard to actually get rid of it. A few years back he'd baught a "sport LSD" on ebay as an upgrade to the diff on his car that he'd thaught was noisey, thinking cure the fault and get an upgrade at the same time. When it turned up it was a standard 4.10 small case, so got launched in the cupboard and he continued to ignore the whine.
When i got the car from him, i got the diff as well, and swapped it in yestarday aiming to cure said whine, thinking that even though it wasnt an upgrade, it would at least shut the noise up. However the noise is completely unchanged.
So i went out and paid some really close attention to the sounds, and discovered that theres two different components to the whine. First component starts as soon as you move away, is most noticeable in first and second gears and ties in with the engine RPM. Its directly related to load and changes as you apply and remove power. As such i'm pretty sure its coming from the gearbox itself.
The second component of the noise i cant put my finger on, and i'm wondering if anyone has any ideas as to what it could be. Its related ONLY to road speed, does not change pitch with load, and doesnt seem to change pitch if i steer from side to side.
It starts making a noticable noise when the car reaches maybe 20mph (i think it is still there below this but the gearbox whine drowns it out at lower speeds), and then steadily increases in pitch as road speed climbs from there.
Obviously the first thaught would be wheel bearings, but i'd expect them to change in pitch if i loaded them up, ie steered hard into a corner, and this noise doesnt do that, which has left me a bit stumped. I jacked up the rear of the car and spun the wheels to see if there were noisey and they seemed fine.
The only other component that runs at road speed is the diff, and it seems unlikely that two completely different diffs would make exactly the same noise, leaving me a bit puzzled.
I guess its possible that its yet another bearing in the gearbox, perhaps the one on the output shaft, but i'd like some other peoples thaughts?!
Cheers
