R32 gtst diff whine after warmed up

[LINK17]

Hey All

I can't seem to find this problem anywhere. After highway driving for 20 mins or so and leaving it in 5th I hear a slight whine from diff at 80kph. I have changed the diff oil to nulon 75w90 correct spec and it made absolutely no difference. 

Any idea what the problem is? And no vibration at all.

Some say additives work some say they don't but I don't want to fork out for the redline stuff for it not yo fix anything. 

Ideas pls?

[Ben C34]

Wear. Either ignore or or get it fixed.

[GTSBoy]

Or come for a drive in my car and realise that you don't have any problems at all!

[Dil-Dog]

Time to weld it ?

[Blakeo]

On 10/4/2019 at 11:10 PM, Dil-Dog said:

Time to weld it ?

Welding won't fix it, it will be due to pinion bearing wear and the pinion/ring gear mesh is slightly off causing it whine. 

Needs rebuild to fix, and depending on how long its been driven like this the pinion/ring gear might need to be relapped. 

-Blake.

[BK]

My $0.02.

In other words, crown wheel and pinion is rooted. Maybe not totally rooted but if it's making noises the damage has been done and they're on the way out. Need new MATCHED set, installed and shimmed correctly for correct gear backlash. There is no magic fix for worn diffs and no additive is going to fix it, no not even that Redline crap everyone raves about.

I stuffed mine that bad in one of my GTRs in the front (where people usually run lighter oil) that the crown wheel and pinion gears were actually razor sharp to the touch, which is a lot of wear if your familiar with crown and pinion gears. It made all sorts crazy noises under load, and why your noise is appearing once the diff oil is hot and thinner in your differential. I will never run ANYTHING other than 75w - 140 in any GTR diff front or rear again after that. After 19 years of GTR ownership anyone who runs stuff like 75w - 90 in any GTR diff front or rear is asking for trouble. I know it's a gtst but same thing basically. Anyone tells you to run 75w - 90 is a dickhead and asking for a diff rebuild, unless changed very regularly and / or has very little power.

It's all about protecting the crown wheel and pinion and the heavy stuff does the job, especially when most people don't drop their diff oil that often.

Motul comp gear 75w - 140 or Castrol Syntrax 80w - 140 (used to be SAF-XA) or you may as well put water in your diff.

[LINK17]

I think this is the problem, I checked the diff oil and it's 75w90, thanks for the great advice. 

I love the motul stuff but can't find where to buy except stupid prices online?

[BK]

Both the Castrol and Motul is generally around the $30 - $45 a litre range. Most other reputable oil companies have diff oil in that range too, Castrol and Motul just seem to be the top pick and Castrol is readily available. Castrol used to be the most recommended by companies like Holinger and Albins until the Motul stuff came along.

[niZmO_Man]

On 04/10/2019 at 11:37 PM, GTSBoy said:

Or come for a drive in my car and realise that you don't have any problems at all!

You should've heard the old Borg Whiner diff in my R31

[KiwiRS4T]

On 10/7/2019 at 11:46 AM, LINK17 said:

I think this is the problem, I checked the diff oil and it's 75w90, thanks for the great advice. 

I love the motul stuff but can't find where to buy except stupid prices online?

I use the Motul or Nismo oil. Its expensive but you don't need much and have you priced a diff rebuild?