Whining noise only in 4th & 5th.

[izanagi]

Hi all,
My 86 trueno is whining only in 4th & 5th gear but i can't hear if it comes from, my first opinion, the gearbox or the rear end because this has new bearings and if it would be the rear end it makes no differences between gears.
Someone could help me please ?
Thanks

[jondee86]

(09-22-2014 04:33 PM)izanagi Wrote:  My 86 trueno is whining only in 4th & 5th gear but i can't hear if it comes
from, my first opinion, the gearbox or the rear end because this has new
bearings and if it would be the rear end it makes no differences between
gears.

If the noise remains the same when you change from 4th into 5th, then it
is very likely the the noise comes from the rear end. If it came from the
gearbox you would expect the pitch (frequency) to drop when you
changed from 4th to 5th.

I doubt if there is anything that can be done if the noise is the only
problem. My differential (which I consider to be in good condition) gets a
small amount of whining (ringing) under light load at higher speed, but only
at one particular speed. Above or below that speed it is quiet.

You may get some improvement by experimenting with different oils.
Otherwise, if the noise is just annoying, and does not make your ears
bleed, you may just have to get used to it

Cheers... jondee86

[izanagi]

(09-24-2014 06:18 AM)jondee86 Wrote:  

(09-22-2014 04:33 PM)izanagi Wrote:  My 86 trueno is whining only in 4th & 5th gear but i can't hear if it comes
from, my first opinion, the gearbox or the rear end because this has new
bearings and if it would be the rear end it makes no differences between
gears.

If the noise remains the same when you change from 4th into 5th, then it
is very likely the the noise comes from the rear end. If it came from the
gearbox you would expect the pitch (frequency) to drop when you
changed from 4th to 5th.

I doubt if there is anything that can be done if the noise is the only
problem. My differential (which I consider to be in good condition) gets a
small amount of whining (ringing) under light load at higher speed, but only
at one particular speed. Above or below that speed it is quiet.

You may get some improvement by experimenting with different oils.
Otherwise, if the noise is just annoying, and does not make your ears
bleed, you may just have to get used to it

Cheers... jondee86

I have castrol 75w140 oil. Special differential.
My diff is setted up correctly and i would like to know why this noise.
The noise is at every speed and only in 4th & 5th.
I jacked up the car and tested it.

[jondee86]

So you are saying that if you are moving 50kph in 3rd there is no
whining, but you change to 4th and the noise starts immediately ?

That is strange, because the 4th and 5th gears use different sets
in the gearbox, but you get no noise in 3rd or other gears ???

Does the noise remain the same with your foot on the gas and off
the gas ? If going uphill in 4th the noise remains the same ?

Cheers... jondee86

[izanagi]

(09-25-2014 05:10 AM)jondee86 Wrote:  So you are saying that if you are moving 50kph in 3rd there is no
whining, but you change to 4th and the noise starts immediately ?

That is strange, because the 4th and 5th gears use different sets
in the gearbox, but you get no noise in 3rd or other gears ???

Does the noise remain the same with your foot on the gas and off
the gas ? If going uphill in 4th the noise remains the same ?

Cheers... jondee86

Yes it starts in 4 th.
If i go in example at 50 kph in 3rd i hear no noise but if i do the same in 4th i hear the noise.
The noise decrease with my foot off and increase with my foot on.
I've just called the guy who installed my diff and he said that he didn't checked the contact pattern.
This is what i have:
It is located on the top heel drive side and i think it's a bad contact pattern.
Do i need to decrease backlash or add the thicker shim to the pinion ?
I did these researches on the net and now i understand.

[Jan Pedersen]

I think you have an axle out of balance in your gearbox. 4th and 5th is on the same axle as I recall...

[izanagi]

(09-25-2014 11:31 AM)Jan Pedersen Wrote:  I think you have an axle out of balance in your gearbox. 4th and 5th is on the same axle as I recall...

Ok but i really think that the whining noise comes from the rear of my car.

[Uzelac]

(09-25-2014 11:31 AM)Jan Pedersen Wrote:  I think you have an axle out of balance in your gearbox. 4th and 5th is on the same axle as I recall...

4th is direct, 1:1 ratio, layshaft isn't used.
5th is on layshaft, as other three gears.